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|                                                                              |
|                                                                              |
|                                                                              |
|                  An Introduction to LOG with AnaLOG                          |
|                           5.58                                        |
|    LOG and DigLOG, Copyright (C) 1985, 1990 by David Gillespie               |
|    AnaLOG, Copyright (C) 1985, 1990 by John Lazzaro                          |
|    Correspondence to lazzaro@cs.berkeley.edu or daveg@synaptics.com          |
|                                                                              |
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_______________________________________________________________________________

                              Table of Contents

   General information
   Digital simulator
   Analog simulator
   Other simulation features
   Plotting circuits and data
   LOG-to-NTK conversion
   LOG-to-SPICE conversion
   Creating your own gates
   Reference material
_______________________________________________________________________________

                             General Information

   Getting started
   Using the program
   Circuit editing
   Configuring gates
   More about editing
   LOG survival tips



GETTING STARTED

   1.  LOG is a large circuit editing and simulation system.  It has
       facilities for digital simulation (the original LOG), analog
       simulation (AnaLOG), network generation (LOGNTK), and plotting
       (LPLOT).  You probably won't need to use all of these, so large
       parts of this document may not be relevant to you.  This
       document was originally written to describe AnaLOG, so it is
       biased toward that application. Another learning aid for anaLOG
       are the lessons files located in the /usr/chipmunk/log/lib directory.

   2.  To run LOG, give the command:

            % diglog   or
	    % analog

       This runs LOG and sets it up for digital or analog simulation.
       Both simulators are present in both of these files; the only
       difference is which gates you get in your default menu.

   3.  To exit at any time, use the Exit command from the menus.

   4.  To report bugs, send e-mail to:

	    lazzaro@cs.berkeley.edu
	or  daveg@synaptics.com



USING THE PROGRAM

   1.  You control LOG mainly with the mouse, and also from the
       keyboard.  It takes some time to get comfortable with the
       mouse in LOG, but it will soon become second nature.  There are
       three basic mouse motions you need to learn:

   2.  TAP.  Press and release the left button on a spot.  This should
       feel like tapping a key on a keyboard.  The spot you are tapping
       is indicated by the cursor on the screen, usually a small
       arrow.

   3.  PRESS/DRAG.  Press down and hold the left button, move the cursor
       somewhere else, and release.

   4.  REST.  Press the right button and release.  This is used to cancel
       operations like drawing wires.

   5.  Some LOG functions appear right on the screen, so you can
       activate them just by tapping the word.  Others are in "menus,"
       which you get by pressing on one of the words Frills,
       Editing, Cursor, or Misc, then dragging to and releasing
       on the word you want.  If you decide you didn't want the menu
       after all, just release on some other part of the screen.

   6.  There are also keyboard commands, though everything you really
       need as a novice can be found in on-screen menus.  When you
       press a key for LOG, be sure the cursor is in one of the LOG
       windows (it doesn't matter which one).  There are several
       features of the keyboard to notice:

   7.  SINGLE KEYS.  Many commands appear on keys as well as menus,
       just for convenience.  For example, you can press the letter
       "s" to do the same thing as SCOPE in the Misc menu.

   8.  ":" COMMANDS.  You can give full-word commands by pressing the
       ":" key, then typing the command.  This is sometimes more
       convenient; for example, if you know the name of the file you
       want to load, typing ":LOAD FOOBAR" is faster than selecting
       LOAD from Misc, then pointing to the file name.  [NOTE: The
       Unix version of LOG does not support this feature yet.]

   9.  <CNTRL>-C. Press the Control key and the "C" key together
       to exit from any mode you may find yourself in.

     SURVIVAL TIP #1:  If you get lost and confused, press <CNTRL>-C
                       until you know where you are.

  10.  SPACE BAR.  The space bar at most times means to refresh the
       screen.  If the screen has gotten trashed by too much editing,
       press this key to clean it up.  LOG will also silently clean
       up the screen if you stop editing for a few seconds.


CIRCUIT EDITING

   1.  At the bottom of the screen are several circuit symbols.  In
       LOG lingo, these are called gates.  The area above the blue
       lines is the drawing area, where you draw your circuit
       diagrams.  When you start AnaLOG, two very special gates, the
       the clock icon and the AnaLOG "scoreboard," show up automatically.
       You are welcome to move these around or delete them if you like,
       but you will find them extremely handy to have nearby.  (If you
       are using LOG as a digital simulator these gates will not appear.)

   2.  To begin drawing a circuit, choose the circuit symbol you want,
       press down on it and drag it (still holding down)
       to the desired place.  To move a gate, just press and drag.
       To delete a single gate, just "throw it away" by moving it to
       the bottom corners of the screen.

   3.  If you don't see the gate you want in the menus, tap the word
       CAT to see the "gate catalog."  You can then press and drag any
       of these gates to add it to your circuit.  If you will be using
       a lot of a particular kind of gate, you can drop it into one of
       the several menu slots to replace another less interesting gate.
       If you get into the catalog by accident, press an empty part of
       the screen, or, as usual, hit <CNTRL>-C to get out.

   4.  If you look closely at a gate that has been put into the drawing
       area, you will see some red dots.  These are called the gate's
       red dots, or pins, and they are the places to connect other
       circuit elements.  The easiest way to connect two gates together
       is to put them down with the appropriate red dots on top of each
       other.

     SURVIVAL TIP #2:  The single most common mistake in LOG is to
                       stick two gates, e.g. a capacitor and a ground,
                       so close together that they look connected but
                       their red dots pass through each other.  The gates
                       are NOT connected, and the circuit will NOT simulate
                       correctly.  The solution is to nudge the gates
                       apart a bit, then refresh the screen (space bar)
                       to make sure the red dots are aligned.

   5.  If the gate comes in an awkward orientation, you can tap it to
       rotate it by 90 degrees.  This works for gates in the circuit
       as well as for menu-area gates.  Notice that LOG distinguishes
       between tapping a gate, to rotate it, and pressing a gate, to
       move it.  Practice a few times until you can tap and press at
       will, without getting confused.  (Some gates, like switches,
       do special things when you tap them in the circuit.  These can
       only be rotated in the menu area.)

   6.  A much neater way to connect things is with wires.  To draw a
       wire, just tap the place you want to start, move horizontally
       or vertically, then tap the endpoint.  This automatically starts
       a new wire at the endpoint, so you can make a chain of connected
       wires.  To finish the chain, just tap the right mouse button.  The
       whole sequence of tap-tap-rest takes a few minutes to learn but
       soon feels very natural.

   7.  You can move wires by pressing and dragging, just like gates.
       If you press in the middle of the wire, you move it from side
       to side but keep the same length.  If you press one of the ends,
       you also get to stretch that end.  As usual, to delete a wire
       just grab it and drag to the edge of the screen.

   8.  Wires are connective along their whole lengths, so you can be
       sloppy about connecting to gates as long as you at least overlap
       the red dot.  Wires and gates are drawn in slightly different
       colors so you can tell them apart if you need to.

   9.  If you connect wires in a "T", LOG "solders" them automatically.
       If you cross them in a +, LOG assumes they are unconnected, so
       you must go back and tap the intersection to solder them.
       Because of this, "T"-connections are preferable.

  10.  If you should run out of room on the screen for your circuit,
       you have several options:  press ">" or "<" to "zoom" in or out
       on the circuit (these are also available in the Frills menu),
       or use the arrow keys to "scroll" up, down, left, or right.  The
       drawing area is essentially infinitely large; so large, in fact,
       that you can get lost due to excessive scrolling.  If this
       happens, HOME in the Cursor menu will take you back to the
       center of the drawing universe.

  11.  LOG can keep up to 9 circuit diagram "pages" in memory at a time.
       Each page is associated with a different file.  To switch to a
       new page, press one of the digit keys 1 through 9.



CONFIGURING GATES

   1.  Once you have drawn, say, a capacitor, you may wonder what its
       capacitance is, and how to set the capacitance you want.  The
       way to do this is called configuration.

   2.  In the lower-right corner of the screen is the word ROT with a
       curving arrow.  This tells LOG that when you tap a gate, it should
       rotate it by 90 degrees.  If you press the word ROT, it changes to
       MIR.  Now if you tap a gate it mirrors itself left-to-right.
       Pressing MIR leads to MIR with a bar (up-down mirroring), then to
       CNFG in yellow, then back to ROT.  If you tap a gate while in CNFG
       mode, instead of reorienting it you open it up for configuration.

   3.  Each kind of gate has a set of "attributes," usually numbers,
       that tell more specifically what kind of circuit element it is.
       For example, AnaLOG capacitors have a "capacitance" attribute,
       and transistors have a hatfull of attributes about width/length,
       kT/q, parasitic capacitances, etc.

   4.  In the digital world, most gates do not have attributes.  An
       exception is the clock generator, CLOCK, which you can configure to
       control the clock frequency and waveform.  Also, many digital gates
       have text on their attribute screens that describes how to use the
       gate.

   5.  One of the attributes is highlighted.  To highlight a different
       attribute, press the up- and down-arrow keys.

   6.  To enter a new value for an attribute, highlight it, then just
       type in the value you desire.

   7.  Some attributes can have scale factors, e.g., "m" for milli-
       and "u" for micro-.  These will show up as, say, "1.2mV",
       meaning 1.2 millivolts.  When you type a new value, you can
       always leave off the V since that part is obvious, but don't
       forget to include the "m" if that's what you want!  A common
       mistake is to change 20pA to 30A, thus seriously perturbing
       the operation of the simulated circuit.  When in doubt, you
       can always type scientific notation in "1.2E-4" format.

   8.  Some attributes are choices instead of numbers.  For example,
       voltage sources let you choose a waveform of either "DC,"
       "Pulse," or "Sine."  You can type whole words to change these
       attributes, or use the arrow keys to cycle through the choices.

   9.  To return an attribute to its default value, just press ENTER
       all by itself on that line.  Some attributes can be blank, in
       which case whatever feature they correspond to is disabled.
       Others must have values, and LOG will use some default if you
       try to enter "blank."

  10.  When a gate is first created, all its attributes have their
       default values.  However, if you change a gate's attributes,
       then drop that gate into one of the menu area slots, then
       new gates drawn from that slot will get those new values
       for their attributes.  You can also reconfigure gates in
       their menu slots using Probe mode (in the Frills menu.)

  11.  To finish configuring a gate, press the right mouse button again, or
       hit <CNTRL>-C.



MORE ABOUT EDITING

   1.  In the Editing menu there are commands for doing large-scale
       circuit editing that would be unreasonable with just the basic
       mouse motions.

   2.  DELETE:  Press Editing, drag to Delete, release left mouse button.
       Now when you move up into the drawing area, the cursor is shaped
       like a pair of scissors.  You can now delete individual things by
       touching them (with the point where the blades of the scissors
       cross), or you can delete everything in a rectangular region by
       pressing at one corner of the region and dragging to the opposite
       corner.  Press the right button to exit Delete mode.  You can also
       press the "d" key to get the Delete mode scissors. Due to an
       intermittent bug, you may need to click the right button a second
       time for the scissors to appear.

   3.  PASTE:  After you have deleted a group of objects, you can
       select Paste to "paste" down copies of what was in that region.
       The Paste command highlights the region that was actually
       deleted; you can paste back in there for a simple "undelete,"
       or you can paste other places for moving or replicating a chunk
       of the circuit.  This is also on the "*" key.

   4.  COPY:  This is similar to Delete, except that it doesn't actually
       delete the contents of the rectangle.  It is for making copies
       of something without disturbing the original.  After you have
       copied your object or area of objects, you are automatically
       switched into Paste mode.  This is also on the "/" key.

   5.  MOVE:  Move an area.  This command is like a DELETE followed by
       a PASTE; it moves an object, or all the objects in a given area,
       to a new location.  It is also on the "m" key.  Note that
       the pressing "m" and tapping on a wire moves the wire in a
       different (often useful) way than simply grabbing the wire.

   6.  Implicit MOVE/COPY:  Pressing in empty space and dragging out a
       box automatically does a combination MOVE and COPY command.  The
       first place you select moves the contents of the box to that place;
       if you press at additional places, extra copies are drawn there.

   7.  Open/Close commands:  These are for expert users only, because
       using them improperly may damage LOG's internal data structures.
       What they do is shift things around on the screen to make extra
       room for additions, or to close up excess space.  If you want to
       do this, use Delete/Paste instead, or ask someone.

   8.  The Labels command in the Frills menu lets you add text labels to
       your diagram.  Select Labels, type the label you want, then grab it
       and drag it, as usual, into place.  You can edit a label by tapping
       it, then using the keyboard.  Labels generally have no effect on the
       simulation, but they make plots look much nicer.  Also, certain
       tools such as LOGNTK and the Digital LOG hierarchical simulation
       gates can read the labels for additional information about the
       circuit.

   9.  The Boxes command in the Frills menu adds yellow dashed boxes
       to the diagram, again for cosmetic purposes only.  Once you're
       in Boxes mode, you can drag out boxes in the usual fashion.
       To edit boxes, grab a corner for reshaping or an edge for
       moving.  Both labels and boxes can be deleted by throwing them
       off the bottom corners of the screen.

  10.  To save your circuit, select Save in the Misc menu, then type
       the file name to use.  It's a good idea to hit Shift-S, or type
       ":SAVE", periodically to save the circuit under the previous name
       if any changes have been made.  ":SAVE" with no file name argument
       saves all pages which have been editing back into their original
       files.  Circuits are saved in files ending with ".lgf" (for LOG
       Format).  The previous version of the file is backed up under the
       same name but with ".lfo".

  11.  To load a circuit you have saved before, select Load from the Misc
       menu.  You will get a list of saved circuits in your directory.  You
       can tap one of these to load it, or just type the name. 
       [NOTE: The UNIX version doesn't support directory listing yet,
       you'll need to type the name of the file]. AnaLOG saves the complete
       simulation state along with the circuit, but you may want to do a
       RESET after loading anyway.

  12.  The Grid command in the Cursor menu switches between the
       usual arrow cursor and a cross-hair cursor which is useful for
       aligning things.

  13.  The Yardstick command in the Frills menu lets you draw an
       arrow on the screen which you can use to check the geometric
       arrangement of objects on the screen.  The yardsticks are not
       "real"---they go away when you refresh the screen.  You can also
       press the "y" key to get a yardstick.

  14.  If you select Status from the Misc menu, you get a set of screens
       describing various aspects of the LOG system.  Move from screen to
       screen with the arrow keys.  The first screen includes the date and
       time, amount of memory free (approx.), plus various other stuff.
       Later screens display the status of the LOG editing buffers and
       keyboard mappings, then there is a screen for the LPLOT program
       (that handles the PLOT command described below), and for the analog
       simulator.



SURVIVAL TIPS

     SURVIVAL TIP #0:  Select Exit from Misc to exit LOG.

     SURVIVAL TIP #1:  If you get lost and confused, press <CNTRL>-C
                       until you know where you are.

     SURVIVAL TIP #3:  The single most common mistake in LOG is to
                       stick two gates, e.g. a capacitor and a ground,
                       so close together that they look connected but
                       their red dots pass through each other.  The gates
                       are NOT connected, and the circuit will NOT simulate
                       correctly.  The solution is to nudge the gates
                       apart a bit, then refresh the screen (space bar)
                       to make sure the red dots are aligned.

                              DIGITAL SIMULATION

   Basics of digital simulation
   A tour of the digital gates
   Hierarchical digital simulation
   Digital VLSI simulation



BASICS OF DIGITAL SIMULATION

   1.  Digital LOG is simulating your circuit constantly, even as
       you edit.  Every wire has a "state," corresponding to the
       voltage on the wire:

            Zero        a wire connected to ground,
            One         a wire connected to Vdd,
            Weak one    a wire connected to Vdd through a pullup resistor,
            None        a wire that is floating (not connected)

   2.  You send signals into the circuit using switches, and read
       the state of the circuit using displays such as LED's.

   3.  If you ever drive a node (wire) with both One and Zero at the
       same time, the node starts flashing to indicate a "conflict."
       Since this is not an analog circuit simulator, digital LOG can
       not represent the correct value of the wire, so it flashes the
       wire and picks either One or Zero arbitrarily.

   4.  Digital LOG uses a "unit delay" simulation model.  All gates
       are considered to have the same delay, whether they are NAND
       gates or complex counters.  (The STABILIZE command may change
       this behavior for short periods of time.)



A TOUR OF THE DIGITAL GATES

   1.  The standard gates in the Digital LOG library provide all
       of the logic functions you will need to build a digital
       circuit.  If you need a function that is not provided, you
       can design it yourself with the LOGED program, or using
       digital hierarchy.

   2.  All the standard library gates use consistent conventions for
       their pins.  For example, when a row of pins carries a binary
       number, the most significant bit is on the left or bottom end
       of the row.  Signals are active-high unless a "bubble" shows
       otherwise.

   3.  Input/output devices and controls:

       SWITCH     Looks like a small pointed box.  It is a voltage
                  source that drives either One or Zero onto its
                  output.  The center lights up black or red to
                  indicate the state of the switch.  Touch the switch
                  to change its state.

       SWITCH2    A smaller switch suitable for packing into tight
                  rows.

       PULSE      Pulse switch.  Looks like a double-pointed box.
                  It acts much like SWITCH, except that when you
                  touch it it goes to One only briefly, then back
                  to Zero.

       LED        Digital display; small square box.  It lights up
                  according to the value being driven on it:  red for
                  One (or weak One), black for Zero, and background
                  gray for undriven wires (None).  It has connection
                  points all around so you can connect to it from any
                  direction.  (Note:  This means that placing two
                  LED's right next to each other will short their
                  pins together.)

       LED2       Structurally the same as LED, but the input pins
                  are treated a little differently.  In LED, all
                  eight pins are connected together.  Thus touching
                  LED's will short each other out.  In LED2, the
                  eight pins are independent.  If any of then is
                  driven high, the LED2 glows red.  If any is driven
                  low, it glows black.  If some drive high and some
                  low at the same time, the LED2 does not glow.
                  Since the pins are not internally connected, you
                  can let LED2's touch and they won't mind.

       LED3       This is a miniature LED useful for tightly packed
                  situations.  Connect to it by running the wire
                  right through the center.

       EDGE       Edge detector.  This is the differently-pointed box.
                  It lights up red whenever it sees any change on its
                  input, and only resets to black when you touch it.

       KEYPAD     Numeric keypad.  This is a 16-key keypad that generates
                  a binary number from 0000 to 1111 when you press one
                  of the 16 keys on the keypad.  The lowest output is
                  most significant.  There is also a "strobe" output
                  on the bottom, that generates a pulse each time a
                  key is pressed.

       7SEG       Numeric display.  This is a 7-segment LED display,
                  which displays the symbols 0 through F for inputs
                  0000 through 1111.  It has two equivalent sets of
                  inputs, for your convenience.  The most significant
                  bit is on the left, and at the bottom.  (The two
                  sets of pins are equivalent; you may use either.)

       ASCKBD     ASCII keyboard.  Analogous to KEYPAD, but with an
                  alphanumeric keyboard instead which generates
                  8-bit ASCII codes.  Tap a key to generate its
                  ASCII code (plus a strobe signal).  Tap SH, then
                  a key, to shift that key.  CT is the Control key.
                  Configure the gate and select Key-Codes mode to
                  generate positional codes for all the keys instead
                  of ASCII.  This lets you handle Shift and Control
                  yourself, if you like.

       ASCDISP    ASCII terminal display.  Shows 16x64 characters.
                  To print a character, put its ASCII code on the
                  data pins and pulse the Strobe pin.  Above Strobe
                  is the Clear pin, which resets the terminal.  This
                  terminal understands most standard Chipmunk control
                  codes such as Carriage Return and Line Feed.  Form
                  Feed clears the screen.  Certain variations on the
                  control codes can be had by Configuring the gate.

       CLOCK      This is a two- or four-phase clock generator or
                  oscillator.  By default, it is a two-phase square
                  wave generator in which the outputs are CLK and
                  not-CLK; the output changes on every time step
                  (i.e., once per standard gate delay).  You can
                  reconfigure it to take several time steps per clock
                  phase, or to clock according to real, physical time,
                  or to be a "synchronous" clock which changes as
                  soon as the rest of the circuit has settled down
                  from the last change.  Also, you can change the
                  waveform to four-phase mode, where the outputs are
                  completely non-overlapping CLK1 and CLK2, each with
                  25% duty cycle.

       BREAK      Breakpoint.  This is a box with an X in it.  This
                  gate is the circuit equivalent of a software
                  "breakpoint."  When its inputs see a positive- or
                  negative-going edge (respectively), it turns the
                  simulation off so you can examine what was the state
                  of the system at the instant the transition
                  occurred.

       TIE        Pullup resistor.  This generates a weak One, which
                  can be overridden without conflict by an open-
                  collector output pulling down.

       TIEGND     Pulldown resistor.  Generates a weak Zero.


   4.  Connection gates:

       VDD        Power supply.  Provides a constant One signal.

       GND        Ground.  Provides a constant Zero signal.

       TO/FROM    Terminals.  These are the two arrow-shaped gates
                  in the Catalog.  They are equivalent except for
                  appearance.  They are used for putting names on
                  signals:  To name a signal FOO, connect a terminal
                  to it, then tap the space next to the arrow and type
                  FOO.  If there are several terminals in the
                  circuit with the same names, they are all
                  electrically connected as if by wires.  TO/FROM
                  names can be used to pass signals between circuit
                  pages.  Signal names are also used with the Scope
                  mode, to be described below.  Dropping a TO/FROM
                  into the menu area preserves its programmed name;
                  if the name ends in a number, each fresh gate pulled
                  from the slot gets a new number.  Predefined signal
                  names include "Gnd" and "Vdd", equivalent to the
                  GND and VDD gates, and "Reset", which is normally
                  grounded but receives a pulse every time you do a
                  Reset command (in the Misc menu).


   5.  Standard digital gates:

       AND, OR, NAND, NOR, XOR, XNOR
                  Standard two-input logic gates.  Also, AND3, NOR4,
                  etc. are multiple-input gates, and INV is an
                  inverter.

       ANDX, ORX  etc.  These are versions of AND, OR, etc. whose
                  pictures have been transformed according to
                  DeMorgan's theorem of logic, which says that an AND
                  gate is just like an OR gate with its output and all
                  its inputs inverted.

       COMPL      This is a complementary-output buffer.  Its two
                  outputs provide the input and its complement, with
                  identical propagation delays.

       DNEG, DPOS, JKNEG, JKPOS, TNEG, TPOS
                  Flip-flops.  Each kind comes in negative- and
                  positive-edge-triggered flavors.  There is a choice
                  of D flip-flops (which latch a Data bit on each
                  clock), or J-K flip-flops (which set, reset, toggle,
                  or stay the same on each clock), or Toggle flip-
                  flops (which toggle or stay the same on each
                  clock).

       LATCH      A level-sensitive latch.  When G is One, the output
                  follows the D input.  When G is Zero, the output
                  freezes at the last D input value that was followed.

       SHIFT      A four-bit shift register.  On a falling clock
                  transition, it either loads from the parallel inputs
                  (if M is One), or shifts in the direction of the
                  arrow (if M is Zero).

       SRAM8K     Static RAM or ROM, storing 8K bytes of 8 bits.
                  Address inputs are on the left (MSB lowest).  Data
                  input/output pins are at the bottom (MSB on the
                  the left).  Control pins are Chip Enable (CE), Read,
                  and Output Enable (OE).  If Read is high and CE and
                  OE are low, the addressed byte is driven on the Data
                  pins.  If Read and CE are low (regardless of OE),
                  the value on the Data pins is stored in the RAM.
                  Otherwise, the Data pins are undriven and ignored.
                  (To make a ROM, simply leave Read unconnected.)

                  Configuring the SRAM8K allows you to examine or
                  change any byte in the memory, control whether the
                  memory contents should be recorded in saved circuit
                  files, and save or load the memory to ".hex" data
                  files.  SRAM8K has the same unit propagation delay
                  as all Digital LOG gates---bear in mind that real
                  memory chips are much slower!


   6.  There is also a large number of 7400's series TTL gates to choose
       from in the gate library.  These are all intended to be close
       models of their true counterparts, but there are no guarantees.
       In particular, remember all propagation delays are the same.

   7.  A set of gates for simulating digital VLSI transistors exists.
       All of these gates begin with "V_" and are described below.

   8.  The gates whose names begin with "A_" are for use with the ACTEL
       design system.  This is a special box which takes network files
       produced by LOGNTK from circuits consisting of "A_" gates, and
       programs gate array chips while-U-wait to produce fast, custom
       digital chips for prototyping.  Use of the ACTEL system is beyond
       the scope of this document.

   9.  The gates DIGH, FORCEDRV, and INST1 through INST5 are intended
       for use with hierarchical definitions, described in the next
       section.

  10.  To view the "program" that the simulator uses for a gate, press
       the shift-D key, then touch the gate in the circuit diagram.
       A small window pops up containing the program.  Press somewhere
       not on a gate to exit this mode.  To erase the definitions, just
       hit the space bar to refresh the screen.  Notations like "#4"
       refer to pin numbers; letters like "E" refer to internal state
       variables of the gate.  For further documentation, see the
       LOGED manual.



HIERARCHICAL DIGITAL SIMULATION

   1.  The Digital LOG simulator is capable of simulating hierarchical
       designs.  That is, you can draw a complicated circuit on one
       page, then include any number of "instances" of that circuit
       on other pages in the form of single LOG gates.  While this
       feature is specific to the digital simulator (AnaLOG has no
       hierarchy, for example), the LOGNTK network file generator also
       understands hierarchy using the same notation and conventions.

   2.  The simplest way to build hierarchically is by using the
       standard digital "instance" gates, INST1 through INST5.  These
       gates look like blocks of various sizes, with connection pins
       all along their rims.  They also have little arrows so you can
       tell if they have been rotated or mirrored.  (NOTE: There are
       also "general-purpose" instance gates GINST1 through GINST5
       in the library.  They are not digital gates and the digital
       simulator will not understand them!  These gates are for use
       only with the LOGNTK program.)

   3.  To create a new gate from a circuit diagram, simply put your
       diagram into one of LOG's nine editing pages.  Now, take an
       INSTn gate of an appropriate size and add it to your diagram.
       Connect wires to the gate from the diagram in the same way
       you plan to connect the gate "in real life".  For example,
       you might have three input wires on the left edge, one output
       on the right edge, and a clock input on the bottom edge.

   4.  Exact positions don't matter for the instance gates.  They
       simply divide your connections into four classes, "top",
       "bottom", "left" and "right", and count the wires along
       each edge.  When you use the gate in another circuit, you
       must make the same number of connections on each edge.  The
       order of the wires you connect matters, but not their exact
       positions along the edge.

   5.  Create a label (by pressing the "l" key) which is the
       name you want to give this circuit, in double-quotes: "Joe".
       This label can be located anywhere on the page that contains
       the definition of "Joe".  (An alternate, older notation is
       to make a label of the form:  <name: Joe> .)

   6.  Switch to the CNFG (configuring) gate-tapping mode, then
       tap the instance gate and enter the same name in the
       "Instance of" field: Joe.  Quotes are optional, and
       upper/lower case don't matter.  Since this gate has the
       same name as the page it is on, it becomes a "template" or
       "example" gate.  You now have a complete definition for
       your new gate.

   7.  To use this gate, create another instance gate on a different
       page and configure its "Instance of" attribute to have the
       name of the definition you want to use.  You do not need to
       use the same size or shape of instance gate as you did before.
       As long as you make the right number of connections, it will
       work.  Instance gates will be dim until they are "happy", that
       is, correctly connected and configured in order to match their
       (also correct and complete) definition.

   8.  If the generic instance gates are too boring, you can create your
       own instance gate, with any picture you like, using the LOGED
       program.  The easiest way is to copy a gate like INST1 from the
       "log.gate" file (ask your local maintainer) into your own private
       gate file, then throw away its picture and draw your own.  You can
       use this gate in just the same way as the standard instance gates,
       except that typically you will only include as many pins on the gate
       as you actually plan to use.

   9.  If you don't like template gates, you can instead use labels
       containing "port lists."  This works well only for instance
       gates you have drawn yourself.  Pins on a gate are numbered
       from 1 to N, the total number of pins.  Include in your
       definition, instead of the template or example gate,
       a label of the form:  <Port: A B C D>  where "A B C D" is
       a list of TO/FROM signal names.  In this example, A will be
       associated with pin 1 of the instance gate, B with pin 2,
       etc.  The port list must have exactly the right number of
       names.  In general, port lists are more awkward to use than
       templates.  They exist mostly for historical reasons only.

  10.  If you run out of pages you might want to put more than one
       definition on a single page.  Simply enclose each definition
       in a dashed box (press the "b" key to draw one of those).
       When Digital LOG looks for the "Joe" label to find the
       definition called Joe, and that label is inside a dashed box,
       then it considers only the things on that page which lie inside
       the box to be part of that definition.  Since each page can be
       scrolled essentially infinitely far, there is plenty of room
       for all the definitions you need.

  11.  Instances may be nested.  The definition for "A" can include
       instance gates for definition "B"---as long as "B" does not
       include instances of "A"!  Aside from circular references,
       any combination is allowed.  (The template gate is a special
       kind of "circular reference" which is excused.)

  12.  If you include switches or keypads in your definition, they
       will be propagated to all instances.  For example, if you make
       a definition with a switch set to "0", then the equivalent
       node inside every instance will also be "0".  If you flip the
       switch, every instance of that definition will simultaneously
       switch along with it.  LED's and other "display" gates have
       no effect inside hierarchical definitions.

  13.  If the definition includes a label of the form:  <Inert A B C>
       then gate types A, B, and C are ignored if they appear in the
       definition.  Every definition effectively includes the
       command <Inert LED 7SEG>.  The word "Inert" and the names of
       the gates are case-insensitive.

  14.  Digital hierarchy works by compiling the behavioral descriptions
       of all the gates in the definition into one big program which
       simulates the instance gates.  Most gates' programs are written
       purely in this language, which is described in the documentation
       for the LOGED program.  However, some gates, such as the 8K static
       RAM, are defined by Pascal procedures instead.  The digital
       hierarchy compiler can not compile these gates, and will display
       an error message if you try to use one in a definition.  Nearly
       every SSI- and MSI-level gate in the standard library is written
       purely in LOGED-language, though, so this is not often an issue.

  15.  Every time you make any change to the definition, Digital LOG must
       "recompile" the definition.  If the definition is large, this can
       take time.  While you are editing a definition, you may wish to
       turn simulation off (press the "o" key).  No digital gate
       definitions will be recompiled until you turn the simulator back
       on.

  16.  To gain more control over the digital hierarchy compiler, include
       a DIGH gate in your definition.  The DIGH gate displays the status
       of the compilation of the definition it is in, and also has
       controls that affect the kind of compilation that is performed.
       You can see the results of the compilation by pressing Shift-D
       (the DEFINE command) and tapping on any relevant instance gate
       (including the template).

  17.  Normally, Digital LOG applies many optimization steps when compiling
       a definition which make the resulting instance program simpler.
       Depending on what is in the definition, optimization can make the
       gate substantially faster to simulate, both by making the overall
       simulator faster, and by reducing the propagation delay of the gate.
       Optimization may not be safe for definitions that include race
       conditions or other effects dependent on exact gate delays; also, it
       may be slow for large definitions.  You can configure the DIGH gate
       (by tapping it while in CNFG mode, on the blue border of the gate)
       to specify optimization only on request, in which case you must
       touch the "Optimize" button on the DIGH gate in order to optimize
       the definition.

  18.  The DIGH gate's configuration screen also has a switch to disable
       delay-folding optimizations; with these disabled, gate delay
       characteristics of the defining circuit are exactly modeled,
       with only simple local optimizations performed.

  19.  Another useful optimization for instance programs involves the
       FORCEDRV gate, which looks like a little diamond.  Placing this
       diamond on any wire in a definition tells the digital instance
       compiler to assume this node will always be driven with a "1" or
       "0" during operation, that is, it will never be left floating.
       You can still leave one of these nodes unconnected if you wish,
       but the simulator will no longer guarantee that the results will
       be the same as for original definition circuit.  In some cases
       the presence of FORCEDRV's allows LOG to create a much more
       compact and efficient instance program.  FORCEDRV's are ignored
       if the optimizer is turned off.

  20.  Configuring DIGH lets you control other aspects of the hierarchy
       compiler.  In particular, you can set the "Dump mode" to "Write",
       then specify the name of a file.  Then, if you touch "Write" on the
       DIGH gate at some later time, the definition will be recompiled and
       written into a file which LOGED can read.  This allows you to
       convert your definition into a permanent gate in the library.
       To configure the DIGH gate, touch around the blue-colored edges of
       the gate, away from the buttons in the center of the gate. WARNING:
       converting definitions into permanent gates is buggy, and is not
       recommended. Expect this bug to be fixed in an upcoming release.


DIGITAL VLSI SIMULATION

   1.  The group of gates whose names begin with "V_" are intended to
       emulate digital CMOS transistors and structures in the Digital LOG
       simulator.  Naturally they are not as accurate a simulation as
       AnaLOG's transistors, but they have the advantages that the digital
       simulator is much faster, and that they can be used in combination
       with all the other digital gates in the library.

   2.  The basic VLSI gates are V_NFET and V_PFET, the CMOS transistors.
       These gates can model most digital CMOS circuits which do not
       involve charge sharing or other "analog" effects.  The transistors'
       gate pins have "capacitance" which holds the last charge stored on
       them, allowing you to build dynamic as well as static registers.
       The transistors are symmetric:  You don't have to worry about which
       end is the source and which is the drain.

   3.  V_NFET conducts zeros between its source and drain pins whenever its
       gate pin is one.  It does not conduct logic ones at all.  Similarly,
       V_PFET conducts logic ones when its gate is zero.  In other words,
       V_NFET and V_PFET act just like CMOS transistors, as far as most
       digital applications are concerned, and that's all you need to know.
       If you are interested in a detailed understanding of how the CMOS
       simulation works in LOG, read the following few paragraphs.

   4.  Because Digital LOG is a gate-level simulator, it needs to know at
       any given time which pins are "inputs" and which are "outputs".
       Since transistors are symmetrical devices which can conduct in
       either direction, the V_NFET and V_PFET gates are implemented as
       bidirectional buffers which can change their direction of transfer
       according to their environment.  Specifically, any time a V_NFET
       sees a zero on its output, and an undriven node on its input, it
       changes direction so that it can conduct the zero onto the undriven
       node.  This change of direction occurs only if the gate is switched
       on.  Likewise, the V_PFET switches direction in order to conduct a
       one onto an undriven node.  In most circuits, this all happens
       automatically and you can ignore it.  But if a particular V_NFET or
       V_PFET looks like it is getting confused, you might swap it for a
       V_NFETD or V_PFETD (described below).

   5.  The "gate capacitance" is implemented by driving a "weak" one or
       zero onto the gate, according to the last "strong" value seen there.
       A weak one or zero is the kind of signal produced by a TIE (resistor
       to Vdd) or TIEGND (resistor to Gnd) gate.  If another circuit drives
       an actual value onto the gate, this strong value overrides the weak
       "capacitative" value.  To avoid undesirable charge-sharing problems,
       the sources and drains of transistors treat weakly driven ones or
       zeros as if they were undriven.  This means, for example, that a
       value stored dynamically on the gate of a transistor will not leak
       back through any "pass" transistors connected to that gate.

   6.  There are also "directional" transistors, V_NFETD and V_PFETD.
       These gates are similar to V_NFET and V_PFET, respectively, except
       that they conduct in a fixed direction.  Information is always
       propagated *from* the pin with the arrow, *to* the other pin.  In
       terms of current, the directions of the arrows show the direction of
       current flow.

   7.  Finally, there are V_NFETX and V_PFETX.  They are directional
       transistors that do not "weakly" drive their gates to show the
       dynamically stored value there.  Instead, they record the value in
       a hidden internal state variable in the transistor.  V_NFETX and
       V_PFETX are provided as a minimal-frills transistor, in case the
       fancier transistors are too "smart" to work properly in your
       circuit.  Also, since the programs for V_NFETX and V_PFETX are
       simple they will simulate faster, especially in hierarchical
       designs.

   8.  V_NFETX and V_PFETX can pass weakly driven signals as well as
       strongly driven ones.  As a result, you can use them to simulate
       NMOS circuits.  Use V_NFETX for enhancement devices, and the
       standard TIE gate as a depletion (pull-up) device.  The fancier
       transistors will not work in this way because the the weak one from
       the TIE gate will not be able to overpower the weak one or zero
       being driven by the transistor's capacitance.

   9.  The following additional gates are provided in the VLSI library:

       V_BUF      VLSI buffer.  This gate acts like a non-inverting
                  buffer made out of V_NFETX and V_PFETX transistors.  That
                  is, it does not affect its input pin in any way, but the
                  output pin gets a copy of the most recently driven input
                  value.  You can use V_BUF to get a visible indication of
                  what value is stored on the hidden gate capacitances of
                  V_NFETX's and V_PFETX's on the same wire.

       V_INV      VLSI inverter.  This gate acts like a usual digital
                  inverter.  The difference between V_INV and the standard
                  INV gate is that V_INV's input is dynamic in the same way
                  as the V_NFET and V_PFET transistors' gates.  V_INV
                  weakly drives its input according to the capacitively
                  stored value.  It is provided simply as a shorthand to
                  drawing the two transistors.

       V_AND, V_OR, V_NAND, V_NOR
                  VLSI AND, OR, NAND, and NOR gates.  These gates have
                  capacitive inputs, just as in V_INV.

       V_TRANS, V_TRANSN
                  CMOS transmission gates (with active-high or active-low
                  control).  These gates act much like V_NFET's and
                  V_PFET's connected together to form the traditional CMOS
                  "pass" gate.  They require only a single control input,
                  generating the inverted control signal internally.  For
                  V_TRANS, the gate conducts ones or zeros in either
                  direction whenever the control is one, and is an open
                  circuit when the control is zero.  For V_TRANSN, the gate
                  conducts only when the control is zero.  If the gates get
                  confused and you need a directional transmission gate,
                  you can use the 74125 and 74126 "tri-state buffer" gates
                  from the library.

       V_CSRL     Complementary Set-Reset Logic element.  This is a one-bit
                  latch designed to emulate a CSRL gate.  If the "latch"
                  input is high, then a zero on the upper data input clears
                  the latch and a zero on the lower data input sets the
                  latch.  If the latch input is low, or if both data inputs
                  are high or undriven, the latch remembers its previous
                  value.  The result is undefined if the latch is high and
                  both data inputs are low.  The latched value and its
                  complement are driven on the outputs.

       V_CSRL0    To get a complete two-phase master-slave flip-flop,
                  connect two V_CSRL's in series.  The V_CSRL0 gate is
                  electrically equivalent to V_CSRL, but with the control
                  pin in a different place so that parallel "phase 1" and
                  "phase 2" clock busses can be used.

       V_CSRL2    Two-bit parallel CSRL latch.

       V_CSRL4    Four-bit parallel CSRL latch.

       V_CSRLN    CSRL latch with active-low control.
_______________________________________________________________________________

                              ANALOG SIMULATION

   Basics of analog simulation
   A tour of the analog gates
   Analog input waveforms



BASICS OF ANALOG SIMULATION

   1.  LOG and AnaLOG are simulating your circuit constantly, even
       as you edit.  But unlike the digital simulator, AnaLOG requires
       your circuit to be "complete" before it can simulate.  That is,
       every pin must be connected to another pin, not left dangling.
       If the circuit is incomplete, i.e., there are still unconnected pins
       on some of the gates, AnaLOG will display a message to that effect
       on its scoreboard.  As soon as the circuit is complete, the
       scoreboard will switch to "Simulation in Progress".

   2.  The gate that looks like a box with an arrow on it is the METER.
       To monitor your simulation, sprinkle meters liberally around on
       all of the interesting voltages.  There is no limit to the
       number of meters you can have.  Remember that the meter's red
       dot is at the tip of the arrow, so the tip must be exactly
       touching the wire or pin of interest.  If the meter is
       unconnected or unhappy, it will display a "~" sign.

   3.  The "clock icon" is the round thing in the upper-right corner
       that looks vaguely like a clock.  Its importance is in the two
       numbers directly below it.  These are the current time and
       current timestep, respectively.  At the beginning, these are
       both zero.  As soon as the simulation begins, the current
       time will start advancing.  How fast it is advancing is shown
       as the current time-step, and may vary depending on how fast
       things are happening in the circuit.

   4.  A common error is to watch, say, a capacitor charging, then
       go in and double the capacitance, and complain that it still
       seems to be charging "at the same rate."  If you look at the
       clock icon, though, you will find that the timestep is twice
       what it used to be:  AnaLOG can simulate the ramp function
       just as quickly in "real time," but the circuit is (correctly)
       half as fast in "simulated time."  Make a habit of paying
       attention to the clock so that your observations have the
       correct frame of reference in time.

   5.  Although simulation happens continuously, it is sometimes
       necessary to "reset" the circuit back to its starting conditions.
       For example, suppose you remove a wire from a running circuit and
       the voltages that were in the circuit at the time are "impossible"
       for the new circuit.  The simulator will work as hard as it can
       to figure out what to do, but may eventually give up and print a
       message.  Another example is that you may want to reset various
       nodes to the initial voltages that you have programmed for them,
       as described in the next paragraph.  In any case, all you have to
       do is select RESET in the Misc menu, or press the "R" key.  This
       sets the simulation clock back to 0 seconds, and returns the
       voltages to their initial values.

   6.  If you open any AnaLOG gate for configuration, one thing you will
       find is a set of three attributes for every pin on the gate.
       These attributes are present voltage, reset voltage, and parasitic
       capacitance, respectively.  Every pin has a slight parasitic
       capacitance to ground, initially 10fF.  This capacitance must
       exist for the simulation to run, but you can set it lower if
       you find that it's in your way.  The "present voltage" is an
       actual indicator of the voltage currently on that pin, and it
       changes while you watch during simulation.  You can enter new
       values here if you wish, but the simulator may not like you if you
       go around making instantaneous changes in the circuit's voltages.
       The "reset voltage" is used by the RESET command.  If you leave
       it blank, AnaLOG will solve for an appropriate initial voltage
       at RESET time.  Notice that Present and Reset voltages are for
       nodes, not gates: if you change a pin's reset voltage, then
       open up another gate connected to that same node, the reset
       voltage shows up there, too.

   7.  When you reset, you will notice that the timestep jumps down,
       usually to about 1E-18 seconds, then starts increasing.  This
       is partly because AnaLOG is cautiously trying to discover how
       fast it can safely proceed in the simulation, and partly
       because it has to solve for unspecified initial voltages by
       simulating the brief charge-up that would occur when you
       powered up a real circuit from scratch.  If you push RESET
       and the voltages seem to be frozen, don't despair -- wait for
       the timestep to get out of the femtosecond range!

   8.  The AnaLOG scoreboard has some words on its left and right
       sides.  On the left is Memory, with indicators Set and Erase.
       If you tap the word "Erase," all of your "reset voltages" will
       be erased.  You might do this if editing has caused your reset
       voltages to be no longer appropriate, and you want AnaLOG to
       solve the circuit from scratch.  If you tap the word "Set,"
       all of the present voltages in the circuit are copied into the
       reset voltages.  For example, you might turn your input
       waveforms off, let the circuit settle to a stable state, then
       push Set so that next time you RESET, the circuit will start
       out at that stable state and you won't have to wait again.

   9.  AnaLOG is normally very cautious about voltage changes.  If it
       is going along at a particular timestep and some node suddenly
       starts changing more than about .1V per timestep, AnaLOG will
       reduce the timestep and simulate in smaller chunks.  This is
       because trying to simulate fast voltage changes all at once
       results in ugly and inaccurate waveforms.

  10.  Sometimes all you are looking for is a DC point anyway, and
       you don't care how ugly your transient waveforms are.  In this
       case, you can touch the word "Relaxed" on the scoreboard.  This
       tells AnaLOG to take timesteps as large as it can regardless of
       how fast the voltages are changing.  Touch "Exact" to return to
       an accurate simulation.  Often what people do is touch Relaxed
       right after a RESET so that the initial charge-up proceeds
       quickly, then touch Exact when the timestep gets up to the
       picosecond-nanosecond range.



A TOUR OF THE ANALOG GATES

   1.  Clock Icon (TIME).  This displays the current time and timestep.
       It also has a square in the center that changes color to indicate
       how the simulation is going:

            Black       Simulation is turned off
            Red         Computing the next timestep
            Yellow      A timestep has been computed

       If you configure the clock icon you will find that it can
       display a few other time-related values, of interest mostly
       to AnaLOG implementors only.  Note that TIME is not actually
       part of the analog simulator---you can use it for the digital
       simulator, too, but it's not very useful there since the
       digital simulator has such a crude concept of time.


   2.  VDD and GND.  Global power supply.  VDD defaults to +5V.
       You can change the value of Vdd in the NUMBERS gate, but
       Gnd is always zero, and Vdd is always positive.


   3.  Terminals (TO, FROM).  These are the two arrow-shaped gates
       in the Catalog.  They are equivalent except for appearance.
       They are used for putting names on signals: to name a signal
       FOO, connect a terminal to it, then tap the space next to
       the arrow and type FOO.  If there are several terminals in
       the circuit with the same names, they are all electrically
       connected as if by wires.  Signal names are also used with
       the Scope mode, to be described below.


   4.  Scoreboard (NUMBERS).  This gate serves many purposes.  On
       the screen it displays whether simulation is proceeding and
       why; it gives controls for set/erase/exact/relaxed modes;
       and, when you tap the center bar, it lets you configure
       AnaLOG's "global" parameters, such as the value of VDD and
       the maximum allowable timestep.  More on these parameters
       below.


   5.  Transistors. Both three-terminal (NFET7T, PFET7T) and 
       four-terminal (NFET7F, PFET7F) transistor models are 
       provided. Only geometric information and parameter 
       variations are specified on the screens of these gates.
       Other gates control the physical constants (PHYSICAL)
       device technology parameters (DEVTECHP, DEVTECHN), and
       fab-run specific parameter variations (RUNSPEC) of all
       transistors in the FET7 series. In addition, the temperature
       of all FET7 gates can be varied using the THERMAL gate. For
       backward compatability, earlier MOS models are also available
       (NFET4, PFET4, NFET5, PFET5, PFET6) as well as FET models
       (NSPC1, PSPC1, contributed by Bhusan Gupta) designed to be
       used with the SPICE netlist tool (see LOGSPC section). Bipolar
       transistor gates and a diode gate (NPN1, PNP1, DIODE) are
       experimental Ebers-Moll models. The log/lib/mos.cnf
       and log/lib/models.cnf hold default configuration
       parameters for transistor models. 


   6.  Capacitor (CAPFLOAT).  Typical capacitor, defaults to 1pF.
       Notice that, like all circuit elements, it has a slight
       parasitic capacitance to ground as well as the capacitance
       between the two leads.


   7.  Resistor (RESFLOAT).  A plain linear resistor.  For a more
       VLSI-like resistor, see HRES below.


   8.  Transconductance amplifiers (OPAMP, WRAMP).  These are
       simulations of the narrow- and wide-range amplifiers in Carver's
       book.  Their behavior is modeled after the circuits at the
       transistor level (as modeled by AnaLOG), at least if you use
       them in the normal range of voltages (between 0 and 5V).  A
       little red light turns on if the voltages go outside the range
       in which the model is a safe approximation for the "real" circuit.
       Note that the "Iset" pin at the bottom wants a voltage, not
       a current.  If you want to set the current manually, connect
       a voltage source to the pin and also to a standalone transistor,
       then measure the current through the transistor.


   9.  Rectifiers (HWR, FWR).  These are half-wave and full-wave
       rectifiers.  An HWR models an OPAMP driving a two-transistor
       current mirror; an FWR models is like a pair of HWR's.


  10.  Horizontal resistor (HRES).  This big ugly thing is the
       "horizontal resistor" circuit, which predates the circuit in
        Carver's book. Obsolete for new designs. 


  11.  Ganglion (GANGLION).  This is the basic ganglion circuit,
       as described in Carver's Book.


  12.  Voltage/current meter (MMETER).  This meter displays the voltage
       on whatever wire or pin it is connected to.  If you configure it
       you can change it to a current meter, in which case it measures
       current into the gate from whatever pin it is connected to.
       (If you connect a current meter to the middle of a wire, it
       doesn't work because the direction of the current is not well-
       defined.)


  13.  Special magic current meter (ISCOPE).  This is a widget for
       use in plotting currents in Scope mode, and will be discussed
       in the later section on Scope mode.


  14.  Voltage source (VDIFF).  This gate creates a differential
       voltage between its two pins (the bottom pin is typically
       connected to ground).  It has a finite output resistance
       (initially 50 ohms), so it is not an "ideal" source in the
       sense of SPICE.  You can use it as a simple DC source with
       a certain voltage (set by configuring the gate), or you can
       set to output a pulsed or sinusoidal waveform.  This is all
       described below, under Input Waveforms.  Voltage sources
       display the current-limiting condition by lighting up a
       little red light, just like the ones on the lab bench!
       They also have a switch, in the lower-right, that you can
       switch to freeze the waveform in time.


  15.  Current source (IDIFF).  Basically a current-sourcing version
       of the voltage source.  It can generate the same kinds of
       waveforms.  It voltage-limits if the voltage across the pins
       goes below the "crowbar voltage," 0.1V by default.


  16.  Step generator (STAIRS).  A voltage source generating a
       stairstep function, which moves from one voltage to another
       in a certain number of steps, then repeats.


  17.  Voltage switch (VSWITCH).  A voltage source that can be
       manually switched between "on" and "off" voltage levels.
       This one also has a tiny switch on its face, this time to
       select which voltage is generated.  It can also be set in
       "monostable" mode, in which a tap on the switch will turn
       it on for a certain period of time, then back off again
       automatically.  Note that voltages here are implicitly
       relative to ground.


  18.  Current switches (ISWITCH1, ISWITCH2).  Current-sourcing and
       current-sinking versions of the VSWITCH.  The current source
       (arrow pointing out) is like an IDIFF connected to VDD, and
       the current sink (arrow pointing in) is like IDIFF connected
       to GND.

  19.  Piece-wise linear two-terminal element (PWL, contributed by
       Harold Levy). Implements an arbitrary two-terminal element,
       with an i-v transfer curve. Cd to the log/lib directory, 
       start analog, and load the file pwl-test.lgf to learn more.

  20.  Resonant tunneling diode (RTD, contributed by Harold Levy).
       Models a class of quantum well devices. If you do research
       in this area and want more details, contact har@caltech.edu.


ANALOG INPUT WAVEFORMS

   1.  DC.  This is just a constant amount of voltage or current.

   2.  Pulse.  Depending on how you set it up, this can be a square wave,
       triangle, or sawtooth.  Referring to the attributes for Pulse mode,
       the output waveform starts at "initial voltage," then, after
       "delay time" (plus "reset time" for the first cycle), it begins
       ramping to "pulsed voltage," at a rate determined by "rise time."
       It stays at that voltage for "pulse width," then ramps back to the
       "initial voltage" in "fall time."  The cycle repeats the the period
       specified.  NOTES:  If rise and fall time are both relatively
       small, you get a square wave.  If one is large and the other small,
       you get a sawtooth.  If both are large, and the pulse width is zero,
       you get a triangle.

   3.  Sine.  This generates a sine wave, with the frequency, offset, and
       amplitude desired.  The "phase" is specified in degrees.  If the
       "delay" is nonzero, the wave waits that amount of time after RESET
       before it begins to change.

   4.  Stairs.  Starts at "initial voltage," waits there for "time per
       step" time, then ramps to next voltage in time "rise/fall time."
       This occurs "number of steps" times, for a total of "steps"+1
       voltages between "initial voltage" and "ending voltage,"
       inclusive.  After the cycle, it ramps all the way back to
       "initial voltage," again in "rise/fall time," and starts over.
       If "initial delay" is nonzero, the waveform remains constant
       for that long before beginning.

   5.  Bistable switch.  If the switch is "off," output is "initial
       voltage."  If it is "on," output is "pulsed voltage."  When the
       switch is changed, output switches from initial to pulsed
       voltage in time "rise time," or from pulsed to initial voltage
       in time "fall time" (regardless of whether the voltage was
       actually increasing or decreasing).  On RESET, the switch is
       set to on or off according to "reset state."

   6.  Monostable switch.  Output is normally "initial voltage."  When
       switch is tapped, output ramps to "pulsed voltage" in time
       "rise time," holds for "pulse width," them ramps back in time
       "fall time."


THE FET7 MOS MODELS IN ANALOG


This release features a new family of MOS models, the FET7 series
(three-terminal gates PFET7T and NFET7T, and four-terminal gates
PFET7F and NFET7F) as well as several supporting gates. These
models are different from previous MOS models in analog, in structure as
well as form.

This Web page is a quick introduction to these models; for
complete details, see the paper log/lib/fet7model.ps or fet7model.pdf.

The model on which these gates are based is parameterized in a new
way. The parameters are properties of the physical construction of
devices. In addition, they are independent properties. Therefore, it makes
sense to vary one parameter while the others are left fixed. This is useful
in terms of finding values which give a good fit to a given process, and
also as a way of exploring the effect of process values on device and
circuit behavior.

The simulator has been modified so that the simulation environment itself
holds information about MOS physics and fabrication; in previous models,
each gate held this information redundantly. This information has been
broken up into several categories: 

Temperature: The THERMAL gate lets the user view and
change the ambient chip temperature. Temperature-dependent
quantities in the MOS modeling system are automatically updated
to reflect temperature changes. Unfortunately, the ambient
temperature set by the THERMAL gate is not presently used by
gates outside the FET7 family, such as the DIODE1 gate. 

Physical Constants: The PHYSICAL gate holds fundamental
physical quantities, such as the Boltzmann constant, and derived
quantities from these constants, such as kT/q. Derived quantities
are denoted by the annotation (Computed) in the parameter
description. These derived quantities cannot be directly changed
by the user, but will automatically be updated if the user changes
their underlying parameters. 

Fabrication Parameters: The channel-specific fabrication
parameters for N- and P-channel devices, along with derived
quantities of interest, are displayed in the DEVTECHN and
DEVTECHP gates. Several channel-independent fabrication
parameters are in the PHYSICAL gate. 

Run-Specific Parameters: The parameters in the DEVTECHN
and DEVTECHP gates are relatively constant from run to run of a
given process. In contrast, a small number of channel-specific
parameters do vary significantly from run to run, and from
transistor to transistor. The gate RUNSPEC provides a way to
change these parameters for all transistors in the simulation; in
addition, these parameters can be varied on a per-transistor
basis, to simulate various forms of device mismatch. 

Transistor-Specific Parameters: The user can change the
geometry of each FET7 gate (drawn width and length in lambda,
source and drain area in square microns), and the offset
parameters mentioned above. Derived parameters (which may be
voltage and temperature dependent) are displayed for each
transistor (Vt, kappa, Early voltage and linear-lumped
capacitances). These parameters cannot be directly changed, but
reflect changes in their underlying parameters and voltages in real
time. 

At start-up, the simulator reads in the default parameters for the FET7
series from the file log/lib/mos.cnf. The default mos.cnf file contains
parameter values suitable for the MOSIS SCN 1.2u process (SCN12, fab
run N52V); this file also appears as mosscn12.cnf. Parameter files for the
HP CMOS26G 0.8um process (mos26g.cnf) and the HP CMOS14TB
0.5um process (mos14tb.cnf) are also supplied. 

The annotated file mos_example.cnf explains the process of converting
MOSIS-supplied documentation for a process to a cnf file. We hope
users will create cnf files for other processes, and send them along to us
for inclusion in later releases. 

The LOGSPC utility for creating Spice files from Log schematics has
been updated to be FET7-aware. See the file log/lib/spctest.lgf for an
example of using FET7 transistors for SPICE-deck creation. 

_______________________________________________________________________________




                          OTHER SIMULATION FEATURES

   Simulation goodies
   "Scope" mode



SIMULATION GOODIES

   1.  If there are any circuit elements with unconnected pins, AnaLOG
       will refuse to simulate.  If you meant to leave the pin
       unconnected, you must connect it to something like a "dummy"
       capacitor to ground.  If there are unconnected gates, the
       NUMBERS icon will display a message of the form "OPAMP is
       unconnected".  Digital LOG doesn't mind unconnected pins on
       gates.

   2.  If you give a ":DIM" command, AnaLOG gates will be drawn in dim
       colors until they are fully connected.  Another ":DIM" turns this
       mode off.  This command only works with the analog simulator.

   3.  Select Probe in the Cursor menu (or press the "." key) to enable
       Probe mode.  The cursor changes to a different style arrow; when
       you move this arrow over a gate or wire, a message below the
       AnaLOG NUMBERS icon shows the internal state of the gate and/or
       node.  In Digital LOG, the lines at the bottom of the screen light
       up according to the state of the node being probed.  Probe mode
       also displays the name of a gate being touched.  Select again
       to turn the mode off.  You can also press "e" or "x"
       ("Examine") for a temporary Probe mode which turns off
       automatically when you click the right button.

   4.  Select Glow in the Cursor menu (or press the "g" key) to enable
       Glow mode.  Wires "glow" in colors according to the voltages
       they carry.  In AnaLOG:

            Black       means at (or below) ground.
            Dark red    means within one transistor threshold of ground.
            Red         means an intermediate voltage.
            Pink        means within one transistor threshold of VDD.
            White       means at (or above) VDD.
            Green       means the wire is not driven by an analog gate.

       In digital LOG:

            Black       means the wire carries a Zero.
            Red         means the wire carries a One.
            Green       means the wire is not driven.

       Glow mode may be left on at all times, though it may make the
       simulation a little slower.

   5.  Select Simulation in the Misc menu (or press the "o" key)
       to turn the simulator off or back on again.  When simulation is
       off, the gates and nodes of the circuit appear to freeze at their
       last simulated values.  Turning the simulator back on resumes the
       simulation.

   6.  Press the "t" key to simulate for one time-step, then stop.
       You can press t as many time as you wish to see the simulation
       evolve, then press o to turn full-speed simulation back on.

   7.  LOG tries to balance simulation speed against response time for
       the mouse and keyboard.  If you let go of the mouse and don't press
       any keys, LOG slowly shifts the balance to prefer simulation.
       When you again use the mouse or keyboard the balance reverts to
       favoring editing.  You can press the "f" key to switch
       immediately to "fast" mode (preferring simulation over editing).



"SCOPE" MODE

   1.  Numbers are great, but real people like to see plots of their
       output waveforms.  In LOG, the mechanism for this is called
       Scope mode.  To use it, first connect terminals (TO or FROM)
       to each signal to be monitored and give the signals unique
       names, then select SCOPE in the Misc menu, or press the "s"
       key.  The scope can display both digital and analog signals.

   2.  The Scope screen consists of a large field of dots representing
       the "divisions" on a normal scope face, an area to the left of
       the dots where signal names can go, and some menu words at the
       bottom.  Use the mouse as usual to select menu words for the
       functions that you want.  In particular, touch QUIT (there's
       one on each side, for your convenience!) or hit <CNTRL>-C to
       return to the circuit diagram.

   3.  To display a certain signal on the scope, just type the name
       of the signal and press ENTER.  The name will appear somewhere
       at the left edge.  You can use the mouse to press and drag the
       name to any vertical location.  To remove a signal name, drag
       it off the top or bottom edge.

   4.  Initially, the scope is not "triggered," so nothing is
       displayed.  To begin taking data, touch Trigger.  The scope
       also automatically triggers when you reset the simulation; there
       is a handy Reset on the menu too.  A few moments after you
       trigger the scope, lines to the right of the signal names
       will begin to appear.

   5.  In all probability, the lines will be absurdly wide or
       ridiculously thin.  In other words, the time scale is wrong.
       To fix this, press the "<" or ">" keys to shrink or expand
       (respectively) the plot until it fits nicely on the screen.
       You can also use the arrow keys to scroll around the plots in time;
       by scrolling and expanding you can focus in on any part of the
       simulation history.

   6.  Touch Config to change the various Scope mode parameters.
       You will find here the seconds-per-division and seconds-at-
       left-edge parameters that the zoom and scroll commands
       manipulate graphically; you can set them numerically if you
       prefer.  The current time and timestep are displayed for
       your reference in setting these values.

   7.  Scope mode has a limit on the number of data points it will
       take before stopping, initially 2000.  You can set this in
       the Config screen, but beware that if you set it too high
       AnaLOG will run out of memory and lose ALL of your data!.
       This screen also displays the number of data points taken
       so far.  What happens when this reaches the maximum depends
       on the "trigger mode" attribute:

            Manual:        Scope starts taking data when you touch
                           "Trigger," and stops when you touch "Trigger"
                           again, or when all the data points are used.
                           Beware that when memory fills, there is no way
                           to resume taking data except by retriggering
                           and losing all of your old data!  LOG prints
                           warning messages when you are about to run
                           out of data points.

            On Reset:      Like Manual, but also triggers automatically
                           on RESET.  This is the default mode.

            Triggered:     Like Manual, but also triggers automatically
                           when a triggering pulse is detected on the
                           signal that you specify.  Not relevant for
                           AnaLOG, because triggering on analog signals
                           has not yet been implemented.

            Continuous:    Triggers manually or on RESET.  When data
                           memory is full, old data points are removed
                           from the left and new ones added to the
                           right.  Never stops triggering unless you
                           turn it off by hand.

       On Reset mode is typically used when you are interested in the
       first data points of a long simulation; Continuous mode is for
       when you are interested in the most recent data points.

       Note that the word "Trigger" is lit whenever the Scope is taking
       data, and unlit otherwise.

   8.  Normally, Scope mode records exactly one data point per timestep
       returned by the simulator.  The "minimum timestep" and "maximum
       timestep" attributes can modify this.  If you would like to
       conserve memory and take data points only at, say, 100us intervals,
       you could set "minimum timestep" to 100us.  Scope mode will then
       record a data point only if it's been at least 100us since the last
       point was taken.  The other attribute, "maximum timestep," does
       not work with the analog simulator.

   9.  When you touch (instead of dragging) a signal name on the left edge,
       you Configure the parameters for that signal's particular trace.  In
       AnaLOG, you can set volts-per-division, plus an "origin" voltage for
       plotting small signals (for example, if you have a signal that
       varies slightly around 2V, set the origin to 2V and the scale to,
       say, 50mV per division).  You can also change the color of the
       trace, very helpful for plotting several traces on top of one
       another.  You can also set logarithmic mode, in which case you
       specify "Vzero" which is the voltage to plot at the origin, with one
       decimal order of magnitude per division above and below.

  10.  To plot an AnaLOG current, you must take an ISCOPE gate, which is
       the funny-looking meter with a hook coming out the back, connect it
       to the pin to be measured, and connect a terminal (TO or FROM) to
       the "hook." Now, when you monitor that name in Scope mode, you will
       measure Amps instead of Volts.  Note that the "hook" pin of the
       ISCOPE is a special "current-mode" data type, and any attempt to
       connect it to a normal analog signal will fail.  If an ISCOPE ever
       appears to undergo spontaneous combustion, it is because you put it
       down with the hook touching an analog wire.

  11.  If you try pressing down the mouse anywhere in the grid of dots,
       you will get a horizontal and/or vertical line whose meaning
       depends on two indicators at the bottom of the screen:

            Absolute:      Display the value of time, or of the
                           currently-selected signal, that corresponds
                           to the mouse position.

            Delta:         Display the difference in time or signal
                           value that corresponds to the distance between
                           the current mouse position, and the position at
                           which it was first pressed down.

            Value:         Display the value of the current signal as
                           of the time that corresponds to the mouse
                           position.  For example, you move the mouse to
                           the "2.3ns" point, and the Scope displays the
                           value that the current signal had at that time.

            Slope:         Display the slope of the line between the
                           starting and current mouse positions, where
                           rise is measured in the units of the current
                           signal, and run is measured in seconds.

               Time        Display absolute or delta time, in seconds.

               Freq        Display delta time, in Hz (= 1/seconds).

               Signal      Display the value of the signal whose name is
                           highlighted, in Volts or Amps.  As you touch
                           this word, each signal is highlighted one by
                           one.  You can also select a current signal
                           by tapping its trace on the screen.

  12.  The word ON is a "power switch" for the simulation.  If you touch
       it, it changes to OFF and the simulation halts.  When you touch it
       again, simulation continues.  (In the circuit-diagram screen, this
       function is called Simulation in the Misc menu.)

  13.  When you touch Dump, the Scope writes out all of the data into a
       file in a standard format.  You may want to do this in order to
       use a more hefty data analysis tool with data generated by AnaLOG.
       The CNS 182 "View" program is one such tool, with a special "aload"
       command for loading AnaLOG dump files.
_______________________________________________________________________________

                                   PLOTTING

   Plotting a circuit
   Plotting your data
   Customizing your plots



PLOTTING A CIRCUIT

   1.  To make a hardcopy plot of your circuit, press "p" or select
       Plotting in the Misc menu.  You get a screen with an (admittedly
       ugly) view of what your circuit will look like on paper.

   2.  To zoom in on an area, just use the mouse to sweep out a rectangle
       around that area.  Press Zoom out to return to viewing the
       full circuit.  The Zoom feature uses "markers," which are little
       red brackets that show up in the circuit diagram.  You can move
       the markers around in circuit-editing mode, too, and turn them
       on or off with the Markers command in Frills.

   3.  Touch Config to configure the plotter.  You can change the
       font that is used for labels (there is a wide selection of fonts
       available, though most of them are silly).  You can select how
       the plot will be oriented on paper (default is to let LOG choose
       the orientation to make it come out as large as possible).  You
       can set the size of the paper if your plotter is too primitive
       to know that for itself.  (For the laser printer, the printer
       always determines the paper size itself.)

   4.  Touch Options to configure the circuit-diagram plot.  The only
       interesting attribute here is the size of the solder dots
       (oh, boy!).

   5.  When you are all ready press File and away it goes, to the system
       Postscript printer. The PLOT button used to control pen plotters
       directly, but now a better way of using pen plotters involves
       plotting into a file (see 6 below) using HPGL.  [NOTE: The Unix
       version is not able to drive pen-plotters directly.]

   6.  You can also plot into a PostScript file, for inclusion, say, in
       a TeX document.  Set the file name in Config, then touch File.



PLOTTING YOUR DATA

   1.  Take data on all interesting signals using the Scope screen.

   2.  To get a high-quality plot, touch the word PLOT on the SCOPE screen.
       This switches to an alternate menu of commands.

   3.  The word "Y-axis" is lit up, meaning that if you touch any signal
       name or signal trace, or the word "Time," or type any signal name
       or arithmetic expression involving signals, then that signal will
       go on the Y axis of the graph.

   4.  When "X-axis" is lit, you are selecting what should go on the
       X axis of the graph.  After both axes have been specified, you can
       change your mind by touching one of the two words, then touching a
       new signal.

   5.  Touch Plot to run the plotting program.

   6.  In the plotting program, touch Config for general plotting options,
       or Options for options specific to data plotting.

   7.  In the Options screen, you get function name, plus label, units,
       log/linear, and minimum and maximum values for each axis.  If you
       don't specify a min and max, they are calculated from the data.
       You can enter any arithmetic expression as the function; variables
       in the expression may be any signal name from the Scope screen, or
       Time, or one of A through F.  These last are user-defined parameters
       you can change in the Variables screen.

   8.  You can also specify line style, and a symbol to plot on data points.

   9.  Normally the axis labels are drawn at a larger size so that you can
       read the numbers and exponents.  When plotting on paper, the axis
       labels are regular-size.

  10.  Zoom out just clears the min and max for both axes to blank.

  11.  Touch Plot to send the current graph to a local plotter.

  12.  Touch File to send the current graph to a file or device, as
       described in the Config screen.  Default is the Apple LaserWriter.

  13.  The simulation is still running while you are in the plotting tool.
       If the scope is still triggered, the set of data plotted will be
       those taken as of the time the screen was last refreshed, or the
       Plot button was pushed.  Thus if you just sit and press the space
       bar, the plot will be slightly different each time.  If this is
       confusing, we suggest turning the simulator off first by changing
       ON to OFF in the Scope menu.

  14.  Touch QUIT to return to the Scope.

  15.  For more advanced data munching, touch instead "Dump" from the SCOPE
       menu, then give some file name, by pressing the "!" key) and run the
       "View" program also written at Caltech.  This program has a "load"
       command which can read the Dump file, using signal names as curves.
       (Note that the Dump command appends to the dump file if it already
       exists.  "Load" will take the most recent curve if the file contains
       several by the same name.)


CUSTOMIZING YOUR PLOT

   1.  When LOG starts up, it reads lplot.cnf in the /lib directory (ask
       your local anaLOG maintainer), which contains certain commands for
       setting up the plotting system.  This file in turn reads pens.cnf,
       which has mappings of colors onto pen numbers.  Each of these
       commands begins with "lplot:", which signifies that the command is
       intended for the LOG plotting tool.

   2.  You can give these commands yourself, either while LOG is running
       by pressing ":" and then typing, e.g., "lplot: size B", or by
       including such a line in your own "log.cnf" file.

   3.  The most interesting configurable thing for the plotting tool
       is color.  LPLOT uses a two-step method for determining color.
       Each kind of object has a particular "color-name".  These
       color names (like GATE or WIRE) are looked up in the color-name
       table to produce a pen-name (like RED or BLACK), which in turn
       is looked up in the pen-name table to get the actual pen
       number to use for pen plotters.

   4.  The following commands may be used after the word "lplot:".


       LPLOT: COLOR  color-name  pen-name
                  This maps a given color-name onto a given pen-name.
                  Standard pen names are "black", "red", "green",
                  "purple", "blue", "yellow", and "none" (which
                  suppresses drawing of that color).  You can also
                  specify a second color-name in place of a pen-name,
                  in which case the first color-name uses the same
                  pen as the one which was recorded for the second.


       LPLOT: COLORS
                  Display a list of all color names that have been
                  recorded in "LPLOT: COLOR" commands.


       LPLOT: CONFIG
                  Open up the plotter configuration attribute screen.
                  This is the same as touching "Config" while in the
                  plot mode.


       LPLOT: DOTS  gate-name  gate-name  ...
                  Undo the effect of previous "NODOTS" commands for
                  the specified gates.

       LPLOT: FILE psfilename
                  Specify the filename for saving or printing a PostScript
		   plot.  The ".ps" is automatically postpended.

       LPLOT: FONT  font-file
                  Use the specified font file for text.  The default
                  file is "lplot.font" in the /lib directory for log.


       LPLOT: INVISIBLE  gate-name  gate-name  ...
                  Add the specified gates to the list of gates which
                  do not show up in plots.  By default, TIME, NUMBERS,
                  and DIGH are on this list.


       LPLOT: LABELFONT  font-number
                  Specify the font number to use for text labels in
                  plots.  For the standard font file, this should be
                  a number from 1 to 13.  Common numbers are 1 for a
                  very simple font, 2 for a standard Roman font, and
                  3 for Roman italics.  Default is 2.


       LPLOT: NODOTS  gate-name  gate-name  ...
                  Add the specified gates to the list of gates for
                  which extra solder blobs will not be generated.
                  By default, only the digital LED gate is on this
                  list.


       LPLOT: PENCOLOR  pen-name  pen-number
                  This specifies the mapping of pen names (such as RED or
                  BLACK) onto pen numbers for the plotter.  The standard
                  configuration file "pens.cnf", which is included by all
                  the standard "log.cnf" files, contains good default
                  PENCOLOR commands.


       LPLOT: PENS
                  Display a list of all pen names that have been
                  recorded in "LPLOT: PENCOLOR" commands.


       LPLOT: PLOTTER  hpib-address
                  When using a pen plotter on the HPIB bus, this
                  command specifies the HPIB address of the plotter.
                  Default is 5.

       LPLOT: PSFILE psfilename
                  Specify the filename or command for saving or
                  printing a PostScript plot.  This can either be
                  a regular filename, such as "plot.ps", or a
                  filename piped to a command, such as "/tmp/*.ps | lpr *"
                  (the default).  

       LPLOT: SIGFONT  font-number
                  Specify the font number to use for signal names
                  in plots.  (See LABELFONT command.)  Default is 2.

       LPLOT: SIZE  paper-size
                  Set the size for paper in pen plotters.  Other output
                  devices, such as the laser printer, compute the size
                  on their own.  Size A is standard 8.5" by 11" sheets;
                  size B is about 11" by 17".  Size AUTO means to
                  compute the size automatically.


       LPLOT: VISIBLE  gate-name  gate-name  ...
                  Remove the specified names from the list of
                  INVISIBLE gates.



   5.  Here is a list of gate-color names used by LPLOT.  Where an
       alternate name is given, LPLOT looks up that color-name if
       the main color-name is not found.  The ultimate default is
       pen-name BLACK.  Except for SCOPE and BORDER, all of these
       apply only to circuit-diagram plots.


       BORDER     Color of the dotted border on the screen that indicates
                  the limits of the page.  Default in "lplot.cnf"
                  is RED.

       DASHBOX    (Alternate: LABELTEXT.)  Color of "yellow boxes" (as
                  gotten from the Frills menu).

       GATE       Color of regular gates.

       LABELTEXT  (Alternate: DASHBOX.)  Color of labels (as gotten
                  from the Frills menu).

       NODE       (Alternate: GATE.)  Color of node names, drawn when
                  requested by the Options screen for gate plotting.
                  Node names are invented by LPLOT and do not
                  correspond to node names used by any other program.

       OFFLED     (Alternate: GATE.)  Color of digital LED's and other
                  readouts which are "off".  Default is YELLOW.

       ONLED      (Alternate: GATE.)  Color of digital LED's and other
                  readouts which are "on".  Default is RED.

       SCOPE      Color of data plots.

       SIGNAL     (Alternate: GATE.)  Color of signal names in TO and FROM.

       SOLDER     (Alternate: WIRE.)  Color of solder blobs.

       WIRE       Color of wires.
_______________________________________________________________________________

                            LOG-TO-NTK CONVERSION

   Overview
   LOGNTK commands
   Identifying things
   LOGNTK messages
   Notes



OVERVIEW OF LOGNTK

   1.  LOGNTK is a program to convert diagrams in AnaLOG (.LGF files)
       into network descriptions of circuits (.NTK files).  When you give
       the ":LOGNTK" command in AnaLOG, it reads the diagram on the
       screen, treating the AnaLOG or Digital LOG transistors as NTK
       transistors, other Analog gates as NTK cells, and certain labels as
       LOGNTK commands.  Only labels surrounded by < and > or in quotation
       marks are significant to LOGNTK.

   2.  LOGNTK manages hierarchical definitions.  The notation used for
       hierarchy is the same as that used by the Digital LOG simulator.
       LOGNTK sees the world as cells; each cell turns into one NTK
       file.  To define a cell, draw a circuit diagram, add a label which
       consists of the cell name enclosed in quotes (as in "Fred"), then
       define the cell's connectivity either with a template gate or with
       a port list label.  To put several definitions on a page, enclose
       each definition in a dashed box (from the Frills menu).  All of this
       is described in the documentation for the digital simulator.

   3.  One difference is that while in Digital LOG you normally use INST
       gates (like INST3), in LOGNTK you normally use "generic instance"
       GINST gates (like GINST3) instead.  LOGNTK recognizes both families
       of instance gates, but the INST gates can connect only to digital
       components, whereas the GINST gates can connect to anything.

   4.  A complete project in LOGNTK may include any number of cells.  The
       top-level cell describes the whole circuit and includes instances
       of the other cells, which may themselves contain instances, etc.
       Anything goes, as long as no circular references exist among the
       instances.  At the bottom of the hierarchy are transistors and/or
       primitive gates.  Examples of transistors are the AnaLOG gates
       NFET5 and PFET5, and the Digital LOG gates V_NFET and V_PFET.
       Examples of primitive gates are all the A_ gates from the ACTEL
       gate library.

   5.  Each NTK file produced by LOGNTK is completely self-contained.
       When you LOGNTK a cell that has instances of another cell, the
       program copies the definition of that cell into the output file.
       An NTK file consists of any number of cell definitions, followed
       by a "main program" which calls the outermost cells.  If your
       top-level LOGNTK page does not include a cell name, that page
       defines the "main program" for the project.  If you do name your
       top-level page, LOGNTK puts that page in a cell as usual, and
       then creates a dummy main program which "calls" that cell once.
       Most simple programs like NETCMP, the NTK file comparator, do
       not care about this distinction.

   6.  When you give the ":LOGNTK" command, LOG converts the definition
       on the current page into an NTK file.  The file name is usually
       derived from the cell name, with ".ntk" appended.  (The name of
       the LGF file that contains the circuit diagram is irrelevant.)
       If there are several cell definitions on the page, LOGNTK does
       each of them in turn.  You can also pick a specific definition
       by typing ":LOGNTK cell-name", where "cell-name" is one of the
       definitions on the current page.  (You can give a list of cell
       names, and the names may include "*" and "?" wildcards.)



LOGNTK COMMANDS

   1.  LOGNTK diagrams often contain additional commands in the form of
       labels.  These labels are always surrounded by "<" and ">" brackets.
       Any labels of this form, but with commands that LOGNTK cannot
       recognize, are simply ignored.  LOGNTK assumes these commands belong
       to some other program, such as Digital LOG's hierarchy compiler.

   2.  You can also include these commands in your "log.cnf" file,
       preceded by "logntk:".  For example, the label <global clock*>
       defines global signals just for one cell; the CNF command
       "logntk: global clock*" defines global signals permanently.
       Finally, you could also press the ":" and type the
       "logntk: global clock*" command during your LOG session.

   3.  Certain arguments may include wildcard characters.  LOGNTK uses the
       same kinds of wildcards as Unix: "?" matches any character, "*"
       matches any zero or more characters, and "[ABC]" matches either
       A, B, or C.  Also, most names in LOGNTK are case-insensitive, but
       LOGNTK still strives to duplicate the upper/lower-casing that you
       use into the output file, and always capitalizes all the uses of a
       name consistently.

   4.  Every LOGNTK definition needs at least some commands.  To create a
       named cell, you need a NAME command (or a quoted label; see below),
       and either a PORT command or a template gate.  For an unnamed
       top-level cell, you need at least a FILE command.

   5.  Here is the list of LOGNTK commands.  The ":" following the command
       names are optional.


       GLOBAL: signal-names
                  This command lists names which should be "global" to
                  the entire project.  For example, VDD and GND are made
                  global by the standard "logntk.cnf" file.
                  This means that if you create a cell which includes
                  VDD and GND gates, those nodes will automatically be
                  made into "hidden" ports on the cell.  Instances of
                  that cell will gate VDD and GND wired to them
                  automatically.  All you have to do is used VDD and GND
                  naturally, and let the system keep track of it for you.
                  You can declare your own TO/FROM signal names to be
                  global in the same way.  The "signal-names" are case-
                  insensitive, and may include wildcard characters.


       PORT: signal-names
                  This command gives the list of ports in the cell.  It
                  may be used in place of a "template" or "example" gate.
                  Port lists are supported for historical compatibility,
                  but future designs should probably use template gates
                  instead.

                  Each name in the list should correspond to a signal name
                  in the circuit diagram.  VDD and GND refer to the VDD and
                  GND circuit symbols.  The position of a name in the port
                  list, not counting global names, corresponds to the pin
                  number of the associated instance gate.  For example, if
                  the .GATE picture for an inverter has the input as pin 1
                  and the output as pin 2, then the appropriate command for
                  the inverter's circuit diagram would be:

                        <port: in out vdd gnd>     or
                        <port: gnd vdd in out>     or whatever.

                  The positioning and ordering of global names in the list
                  is irrelevant, but any global signal that is used by the
                  cell or by its sub-cells must be present.  (When you use
                  a template gate instead of a port list, LOGNTK manages
                  all this for you.)  If you give a ":LOGNTK" command and
                  their is neither a port label nor a template gate in the
                  definition, LOGNTK will sort the signal names into
                  alphabetic order and create a PORT label.  You will
                  probably need to edit this command to put the ports in
                  the proper order.

                  If several PORT labels appear in the cell definition,
                  they are appended together in an undefined order.  If
                  you don't mind this uncertainty, LOGNTK can handle an
                  unlimited number of ports.


       ORPHAN: gate-names
                  This command gives the gate(s) which are used to
                  represent "orphan" nodes, i.e., nodes that are not
                  connected to any transistors or subcells.  By default,
                  the built-in gate CIRC1 is considered an orphan gate, so
                  that a circuit with five CIRC1's will have five orphan
                  nodes in its NTK file.  The gate-names may use wildcards.


       IGNORE: gate-names
                  This command gives a list of gates to be ignored.  This
                  is rarely necessary, because if LOGNTK sees a gate which
                  has not been defined as a transistor or cell, and for
                  which no "gatename.NTK" file exists, then it will
                  automatically ignore that gate with a warning message.
                  This command suppresses the warning.  The gate-names
                  may include wildcards.


       NAME: cell-name
                  This specifies the name of the cell in the NTK file.
                  This is an alternate form for the quoted "cell-name"
                  label.  There must be exactly one such label for each
                  cell.


       FILE: file-name
                  This specifies the name of the output file.  The suffix
                  ".NTK" will be added if necessary.  If you omit the FILE
                  command, the file name will be taken from the cell name.
                  (Every LOGNTK page must specify either a cell name or
                  a file name, or both.)


       CELL: gate-name  cell-name  file-name
                  This command links gates in the circuit diagram
                  to the NTK files they represent.  A good idea is
                  to use the same name for the gate, cell, and file;
                  if you give only one name in the command, that
                  name will be used for all three.  One time you
                  might need to give the long form is if the NTK
                  file is not in the standard directories, so you
                  need to give a full path for it:

                        <cell: opamp tc_amp /lib/wollib/stdlib/opamp>

                  In this example, OPAMP gates, or generic instance
                  gates programmed as OPAMP's, will convert to calls
                  to the cell TC_AMP, which may be found in the .NTK
                  file specified.  CELL commands describing cells that
                  are never instantiated in a file are ignored.


       LIB: directories
                  This command names directories in which .NTK files
                  for sub-cells may be found.  LOGNTK looks first in
                  the current directory, then in each of these
                  directories in turn.


       SIZE: number
                  This specifies the sizes of nodes.  Currently,
                  there is no way to override this for particular
                  nodes.  The default size of 1 should be sufficient
                  for CMOS users.  Most NTK-reading programs ignore
                  node sizes, anyway.


       STRENGTH: number
                  This specifies the strengths for transistors.
                  This can be overridden as described for TRANS.
                  The default strength is 2.  Most NTK-reading
                  programs ignore transistor strengths.


       TRANS: gate-name  type  strength
                  This command declares transistor symbols.  If you
                  need to make your own transistor gates, you will
                  need to use this command.  The "type" is one of
                  N, P, or D.  The strength is optional; if it is
                  a positive number N, then the strength of the
                  transistor is N; if it is missing, the strength
                  is the default value; if it is -N, the strength
                  is found in attribute number N of the transistor
                  gate, which must be an integer-valued attribute.
                  The file logntk.cnf contains TRANS commands
                  for all the standard LOG transistors.


       PRIMITIVE: gate-name  cell-name
                  This command declares primitive gates, gates which
                  should be converted into instances of cells which
                  have no definition.  If the gate has N pins, then
                  the output file will call the cell with N ports,
                  in order of pin numbers on the gate.  For example,

                        <primitive: a_and2 and2>

                  Causes the ACTEL gate A_AND2 to convert to a call
                  to cell AND2.  Both names may contain wildcards;
                  the actual commands in logntk.cnf are:

                        logntk:  primitive  a_*  *
                        logntk:  primitive  a_tribuf  tribuff

                  which maps A_AND2 to AND2, A_DFC to DFC, etc.,
                  and A_TRIBUF to TRIBUFF (a special case).  Note
                  that more specific names come after more general
                  names.  The command PRIMITIVE may be abbreviated
                  as PRIM.


       TOP        Force this to be a top-level NTK file, that is,
                  after the main cell has been defined, one "call"
                  to the cell is also written into the file.  The
                  NETCMP program can only read top-level NTK files.
                  This mode is the default; you only need the TOP
                  command to override an earlier LEAF command.


       LEAF       Force this to be a leaf-level NTK file, that is,
                  only the cell's definition is included (plus
                  definitions for any subcells used).  There is
                  usually no reason to use LEAF, since most programs
                  can read top-level NTK files and ignore the top part.


       NOTOP      Set a compatibility mode in which a LOGNTK command
                  on a page with no NAME command (or quoted name label)
                  will produce an error instead of creating a top-
                  level NTK file.  If you are a stick-in-the-mud like
                  John Lazzaro, you can put this in your log.cnf file.



IDENTIFYING THINGS

   1.  Cells and nodes in the NTK file are assigned names automatically by
       LOGNTK.  The one exception is that if a node has a signal name
       associated with it, that name is used.  The :IDENTIFY command in
       AnaLOG lets you find out what names correspond to what circuit
       objects.  Type:

            :IDENTIFY

       and move the cursor over any node or gate.  The associated name
       appears at the bottom of the screen.  The IDENTIFY command is
       finished when you press the mouse left button down, or hit the
       <CNTRL>-C or SELECT key.

   2.  NOTE:  If you change anything in the circuit between :LOGNTK and
       :IDENTIFY, the names chosen may not be the same for the two
       commands.  This is true even if you changed it and then put it
       back the way it was.

   3.  You can also type:

            :IDENTIFY name name name ...

       to "light up" the gates or nodes corresponding to those names.
       You can press the space bar to refresh the screen afterwards.



LOGNTK MESSAGES

   1.  LOGNTK displays the following messages at the top of the screen
       during operation.  If there is a "fatal" message, the output NTK
       file will not be complete.


       Can't understand command: FOO
                  This command appeared in a LOGNTK: line in the LOG.CNF
                  file, and it is not one of the command words listed
                  above.  Unrecognized commands in < > labels are
                  ignored, since it is assumed that they belong to some
                  other LOGNTK-like program.


       Syntax error in TRANS command
                  The transistor-type argument is missing or wrong.


       Cell file FOO.NTK not found     (fatal, unless next message
                                        is shown too)
                  The file named in a CELL command does not exist.


       Using file FOO.NTK instead of file BAR.NTK
                  The CELL command listed a file which does not exist,
                  but the "gatename.NTK" algorithm found the file.  You
                  should edit the label accordingly.  (The above example
                  corresponds to a command of <cell:  foo xxx bar>.)


       <cell: FOO>
                  This is a label added if the "gatename.NTK" algorithm
                  worked and there was no CELL command for this gate.
                  This just serves as a reminder that LOGNTK made this
                  assumption for you.


       No cell or file name!                             (fatal)
       <file: (place file name here)>
                  There were no <name: xxx>, <file: xxx> or "xxx" labels
                  on the page.  LOGNTK assumes you are making a top-level
                  file, and creates a <file> label which you can edit.
                  If you are making a cell instead, throw away the <file>
                  label and make a cell-name label.


       No cell name!                                     (fatal)
       <name: (place cell name here)>
                  No name was specified for this cell.  You are given a
                  label which you can edit to specify the cell name.
                  This error occurs only in NOTOP mode.


       More than one <name: xxx> or "xxx" label on the page!     (fatal)
                  Multiple cell-name labels appeared, not enclosed in
                  dashed boxes.


       Cell FOO is recursively defined!                  (fatal)
                  LOGNTK detects some, but not all, such errors.


       Warning: Port FOO does not appear in the circuit
                  A name in the PORT command does not correspond to any
                  signal name in the circuit.  This may be because your
                  subcells use GND and VDD but you don't explicitly use
                  them here (not an error), or it may be because you
                  forgot to label part of your circuit.


       Signal FOO is missing from the port list          (fatal)
       Global node FOO is not a port
                  You used a cell that requires a certain global signal,
                  such as VDD or GND, which you omitted from your own
                  PORT list.  All global signals used by a cell must be
                  passed down through all higher-level cells in the
                  hierarchy.


       Warning: FOO appears more than once on port list
                  You included the same name more than once in a PORT
                  command.  The NTK file format has no way to express
                  that two ports of a cell are shorted together, so
                  LOGNTK can not write an NTK file for such a cell.
                  The later occurrence of the name on the port list
                  is ignored.


       Template has pins shorted together                (fatal)
                  Analogous problem as "FOO appears more than once
                  on port list", but for template-defined gates.


       Warning: Template gate has no connections
                  This is not strictly an error, but in NTK a cell
                  with no ports is usually a sign of trouble.


       Using port list: A B C D
                  If the cell was defined with a template gate, this
                  message shows the order in which the signals were
                  assigned as ports, just for your information.


       Port list ignored for top-level NTK file
                  This is a top-level file (not a cell), but there
                  was a PORT command present.  The PORT command is
                  ignored.


       More ports than pins in cell FOO                  (fatal)
       Too few connections in cell FOO                   (fatal)
                  The NTK file for subcell FOO listed more non-global
                  ports than there are pins (on an instance gate
                  created in LOGED) or connections (on a generic
                  instance gate).  This could be because the .GATE
                  and .LGF files for that subcell are out of sync, or
                  because you forgot to list some of the ports as
                  GLOBAL.


       More pins than ports in cell FOO                  (fatal)
       Too many connections in cell FOO
                  The NTK file for subcell FOO listed too few non-global
                  ports.


       Warning: Gate FOO was ignored
                  A gate of type FOO was ignored because no definition
                  for it could be found, but that gate was not listed
                  in an IGNORE command.


       No nodes or gates called FOO
                  An :IDENTIFY command gave a name which does not exist.


   2.  There are also a few "informational" messages which can be turned
       off by giving a ":VERBOSE OFF" command in LOG.



NOTES

   1.  LOG nodes which are not connected to any transistors or cells
       are ignored.  Thus, you can not get orphan nodes just by drawing
       stray wires.  You must explicitly use "orphan" gates as described
       above under ORPHAN.


   2.  Cells which pass "global" nodes to their subcells, but which do
       not actually use those nodes themselves, must include those
       global names in their own port lists.  For example, if a
       higher-level cell does not use GND and VDD but its subcells do,
       you must include GND and VDD in this cell's PORT list.  (Note
       that if you are using the recommended "template gate" method
       rather than writing a PORT list, this is all handled for you
       automatically.)


   3.  LOGNTK is case-insensitive, but case-preserving.  That is, if you
       call something FOO in some places, and Foo in others, the names
       will be considered the same, and one of the names will be chosen
       for use everywhere in the output file.  Which name is chosen is
       arbitrary, except that preference is given to usage in the PORT
       command.  Note that LOG itself is case-sensitive in some ways,
       for example, TO/FROM signal names "Vdd" and "VDD" are considered
       to be different by LOG but this difference is not acknowledged by
       LOGNTK.  This sort of disagreement can cause LOGNTK to produce
       strange or erroneous output files.


   4.  The "VDD" and "GND" symbols are exactly equivalent to TO's or
       FROM's with the names Vdd and Gnd, respectively.


   5.  In LOGED, you can use the CONNECT command to cause two pins to be
       connected internally.  (For example, the crossing-wires gate
       CROSS2 and the toggle switch SW2 work this way.) If you use such
       a gate as an instance in LOGNTK, only the lowest-numbered of the
       connected pins corresponds to a port in the PORT list; the other
       pins in the connection group are skipped when being matched to
       ports, in the same way as global ports are skipped when being
       matched to pins.  Once again, using a template gate to describe
       your ports handles this automatically.

_______________________________________________________________________________

                            LOG-TO-SPICE CONVERSION

   Description
   Logspc Additions


  DESCRIPTION

        Harold Levy of Caltech modified the LOGNTK program to create a
  new program, LOGSPC, that creates SPICE decks instead of .ntk files.
  The tool is used identically to LOGNTK, so the manual section above
  describes LOGSPC also. The command to invoke the tool is :logspc, and
  configuration information is in the file lib/logspc.cnf. The FET
  models NSPC1 and PSPC1, contributed by Bhusan Gupta at Caltech, are
  perfect for use with LOGSPC.  These gates also simulate in analog;
  however, these models are considered "experimental" as opposed to
  "standard" models in analog, and are not supported by the chipmunk
  maintainers.

  LOGSPC ADDITIONS
 
        A few additional commands have been built into LOGSPC to better
  support SPICE capabilities.  Note that the SIZE and STRENGTH commands
  of LOGNTK are ignored in LOGSPC, and that the following commands are
  used instead:
 
 
          NBULK: signal-name
          PBULK: signal-name
                    These commands assign explicit names to the implicit
                    bulk terminals for 3-terminal FET (e.g. p/n-FETs 4 and 5)
                    and bipolar (e.g. NPN1, PNP1) models.  The signal-name
                    is output in capitals unless quoted.
 
	  LAMBDA: number
                    This command assigns an explicit lambda value (in
                    microns) to the FET7 model series.

          CHLEN: number
                    This command assigns an explicit channel length (in
                    microns) to FET models using w/l ratios (e.g. p/n-FETs
                    4, 5, and 6).
 
 	  PRE: filename
          POST: filename

                    Specifies a file for inclusion into .spc files before
                    and after netlist.


  Also note that as of LOGSPC version 0.5b the ability to extract VDIFF
  gates is provided.  This feature may be shut off with the command
 
           LOGSPC: IGNORE VDIFF


  Finally, the TRANS command has been extended, to supporting adding new
  gate types to logspc, as shown in the example below.

  EXAMPLE 

  Copy the files chipmunk/log/lib/{spctest.lgf,pre.spc,post.spc} to your
  directory, and examine and run logspc on spctest.lgf, to see the features
  described above in action.

  FILE CONVERSIONS

        The supplementary toolkit includes companion programs to LOGSCP,
  that simplify using LOGSPC output with other tools. These tools are located
  in the spc-tools subdirectory of the toolkit. Three scripts are included:

         sf:  Flattens hierarchical LOGSPC (version 1.0) output.

         ss:  Converts output from "sf" into UCB SIM format for use with
              UW's "gemini" layout-versus-schematic (LVS) comparison program.

     ucbsim:  Appends "format: UCB" to the first line of SIM files generated
               by ext2sim.

_______________________________________________________________________________

                              THE LOGED PROGRAM

   Introduction
   List of commands
   DRAW command
   LABEL command
   DEF command
   Digital gate definition language
   Text file format
   .GATE file format



INTRODUCTION

   1.  The LOGED program is responsible for maintaining the libraries of
       gates stored in .GATE files.  When LOG starts, the GATES commands
       in its configuration file specify which gate libraries to use.

   2.  The "loged" command may be given by itself or with a the name of
       a file to load initially.  Additional arguments are interpreted
       as they would be for a LOAD command, as a list of gates to load
       from the file.  Note that in LOGED terms, a "gate" is a kind of
       gate, such as NAND or 74138, not an instance of the gate-kind.

   3.  To exit LOGED, type QUIT.  You will be given a chance to save the
       gates in memory if they have been modified.  If the gates came from
       one file originally, LOGED uses that name.  Otherwise, if no file
       was loaded or several files were mixed together, LOGED prompts for
       the file name to use.

   4.  At any time in LOGED there is a "current gate."  Many commands
       operate on the current gate.  The GATE, NEXT or PREV commands can
       be used to select the current gate.  LOGED stores the following
       information for each gate:

          a. The name of the gate, up to eight characters (uppercase).
          b. The group number (library-screen page number), from 0 to 8.
          c. The gate's picture, including pins and grab box.
          d. The "simtype" number, telling which simulator "owns" the gate.
          e. The gate's definition or program, simulator-dependent.
          f. Connectivity information in case pins are hard-wired together.
          g. Miscellaneous flags affecting LOG's treatment of the gate.
          h. The gate's labels screen, shown when configuring the gate.

       Various commands described below manipulate all these parameters
       for the current gate.

   5.  Many commands accept gate-name arguments which may include
       wildcard characters.  The '.' and '*' characters stand for exactly
       one, or zero or more, characters respectively.  Use '%' or '?'
       (respectively) instead for wildcards which prompt yes-or-no for
       each potential match.  A terminating ';' followed by digits
       matches only gates in the groups specified.  For example, the
       pattern 'a*bc;23' matches only gates whose names begin with 'a'
       and end with 'bc', and which are in groups 2 or 3.  If a list of
       several names is given separated by spaces, gates which match
       any of those names are accepted.



LIST OF COMMANDS

   1.  A complete list of LOGED top-level commands follows.  Some
       commands are discussed in detail in later sections.

   2.  Command and gate names are case-insensitive.  Commands can
       usually be abbreviated to one or two letters.

   3.  In addition to these commands, you can execute any Shell
       command by preceding it with a '!' character, or enter an
       interactive sub-shell by typing '!' alone.  Type QUIT to
       the sub-shell to return to LOGED.


       CONNECT  num num num ...
                  Connect the specified pins together in the current
                  gate.  When an instance of the gate is made in LOG,
                  these pins will be forced to the same electrical node.
                  For example, the CROSS gates in the standard library
                  emulate crossing wires by having pairs of connected
                  pins.  The pins of a gate are divided into connectivity
                  classes; initially every pin is in its own class.  The
                  CONNECT command with two or more numbers joins the
                  classes of the specified pins.  CONNECT with one pin
                  number unconnects the pin, splitting it back into its
                  own class.  CONNECT with no arguments displays the
                  current connectivity of the gate.


       COPY  new-name
                  Make a copy of the current gate under the specified
                  name.  All aspects of that gate are identical to the
                  current gate, except the name.  The new copy becomes
                  the new current gate.


       DEF        Edit the simulator's definition for this gate.  Exact
                  effect depends upon the current simtype of the gate.
                  This command only works of the relevant simulator is
                  available.  The type 0, 1, and 7 DEF commands always
                  work; type 16 and 32 commands work only if DIGLOG or
                  ANALOG have been permed, respectively.  (Note that
                  ANALOG actually supports both simulators.)


       DELETE     Delete the current gate.  Given a name, deletes all
                  gates which match the name.


       DO  name  command-line
                  For each gate that matches the specified name, make
                  it the current gate and execute the LOGED command
                  shown.  This command must not delete or rename the
                  gate; to delete multiple gates, use DELETE directly.


       DRAW       Edit the current gate's picture.  Defined below.


       DUMP       Print a "data sheet" for the current gate on the laser
                  printer.  If a file name is given, the PostScript for
                  the data sheet is written to the file.


       EDIT       Edit the current gate's information using the text
                  editor, CAGED.  Given a name, edits all gates which
                  match the name.  The information is written into a
                  temporary text file as if by the WRITE command;
                  CAGED is run on the file; when the editor returns,
                  the file is reloaded as if by a READ command.


       FLAG  flag-name
                  Turn the specified flag on or off for the current gate.
                  Flag names are case-insensitive and may be abbreviated.

                        NOFLIP   This disables flipping or rotation of
                                 the gate.  Tapping on the gate always
                                 acts as if CNFG mode were selected.

                        TOGGLE   The gate is a toggle switch.  When an
                                 instance is tapped, it always mirrors
                                 about its (original) y-axis.  The gate
                                 can still be rotated in the menu area.

                        VISIBLE  The gate is visible even in Invisible
                                 gates mode.

                        NAMED    The gate has an editable signal name,
                                 like TO or FROM.  Should be used only
                                 for simtype 1 gates.

                        NRIGHT   The gate's name is on the right, as in
                                 the TO gate.  Used with NAMED, above.

                        NOSOLDER When plotted, the gate should not have
                                 solder blobs added for T-connections
                                 involving the pins.

                        USER1    A user-definable flag.  A simulator, tool,
                                 or individual gate program can interpret
                                 this flag in any way desired.  Currently,
                                 this flag is unused.

                        USER2    Another user-definable flag.

                  With no argument, this command just displays the current
                  flag settings.


       GATE       Switch to a new current gate.  If the specified gate does
                  not exist, a new "blank" gate is created.  (Often it is
                  easier to create a new gate by copying an existing,
                  similar one.)  The NEXT command can be used to switch to
                  a new gate with no danger of accidentally creating one.


       GROUP n    Set the current gate's group number to "n", an integer
                  from 0 to 8.  With no argument, displays the current
                  group number.  The group number determines which
                  library page the gate appears in.  Group numbers for
                  the standard libraries are:

                        0        General-purpose gates
                        1        Generic digital gates
                        2        7400's series digital gates
                        3        (unassigned)
                        4        Analog gates
                        5        Digital VLSI gates
                        6        Digital ACTEL gates
                        7        (unassigned)
                        8        (obsolete gates)


       HELP       Run the Chipmunk Help System on this help file.


       LABEL      Edit the current gate's labels and attributes.  See
                  below.


       LIB        Display a list of all gates, or the gates which match
                  the specified names.


       LOAD  file-name  gate-name gate-name ...
                  Load the gates in a file into memory.  If gate-names are
                  specified, only those gates which match the names are
                  loaded.  By default a ".gate" extension is added to the
                  name; to load from a textual file, specify ".text"
                  explicitly.


       MEMORY     Display the amount of memory free.


       NEXT       Switch to the next gate in alphabetical order, or to the
                  next gate which matches the specified name.


       PREV       Switch to the previous gate in alphabetical order, or to
                  the previous gate that matches the specified name.


       QUIT       (or EXIT.)  Leave the LOGED program.  If any gates have
                  been changed, you are given the option to save them first.


       READ       Much the same as LOAD, except the default file name
                  extension is ".def", typically a file written by the
                  "Write" option of the digital hierarchy compiler.


       RENAME  new-name
                  Change the name of the current gate to the new name.
                  If a gate by that name already exists in memory, you
                  are given the option to replace it.


       SAVE  file-name  gate-name gate-name ...
                  Save all gates in memory, or only the specified gates,
                  into a file.  With no arguments, saves all gates back
                  into the original file.  A ".gate" extension is appended
                  by default.  If the extension is not ".gate", the file
                  is written in a textual format readable by humans.


       SIMTYPE n  Set the simulator number of the gate to "n".  This is
                  an integer from 0 to 255 which identifies the simulator
                  responsible for the gate.  Currently assigned simtypes
                  include:

                        0        General-purpose, "inert" gates.  Used
                                 labeling (e.g., ARROW) and connection
                                 (e.g., CRUNCH) gates.

                        1        Signal-name gates.  Pin 1 of the gate
                                 is connected to a certain signal name,
                                 which is either hard-wired (as in VDD
                                 and GND) or configurable (as in TO
                                 and FROM).

                        7        Self-sufficient Pascal gates.  The
                                 code which defines this gate is given
                                 complete access to LOG's simulator
                                 interface.  For example, the TIME gate
                                 is a general-purpose simulation timing
                                 and performance monitor.

                        16       Digital gates.  Simulation definition
                                 is written in a simple language specific
                                 to the digital simulator.  This language
                                 includes a CALL statement for calling
                                 more general Pascal procedures to
                                 simulate the gate.

                        32       Analog gates.  Definition consists of
                                 the name of a Pascal procedure for
                                 simulating the gate.

                        33       Analog current-mode simtype.  This type
                                 is used internally by the analog simulator
                                 to support current meters.

                  The gate's simtype defines which procedure is called
                  when you give a DEF command.  This command is defined
                  in greater detail below.


       WRITE      Similar to SAVE, except the default file extension is
                  ".text", and if no arguments are given, the current
                  gate is saved in a file named after the gate.



THE "DRAW" COMMAND

   1.  The "DRAW" command puts you in a graphical editor mode for drawing
       the visible picture of the gate.  It also allows you to place the
       gate's pins and "grab box".

   2.  To exit the DRAW command, press "q" or the <CNTRL>-C key.  (On
       the Bobcat keyboard, this key is marked "Select".)

   3.  Gate pictures are made up of many kinds of objects.  Initially,
       you are set to draw the usual cyan vectors (line segments).
       Tap the mouse at two locations to draw a new vector between those
       points (analogous to drawing a wire in LOG).  Grab the body of
       the vector to move it; grab an endpoint to change its direction
       and size.  Move the vector off the grid to delete it.

   4.  Tap the mouse on the color or shape name to change.  Circles and
       ellipses are defined by a vector; an ellipse's diameters equal
       the sides of the bounding box of the vector, and a circle's
       diameter equals the larger of the two sides.  Filled ellipses
       are also available.  Filled polygons are defined by four points;
       to make a triangle, put two points in the same place; to make a
       larger polygon, combine several triangles or quadrilaterals.
       Rounded boxes are rectangles with circular arcs for corners.
       "Curves" are Bezier curves defined by four points; the two
       inner points govern the curve's slope at its endpoints.  Text
       objects contain a string of characters of a particular size;
       LOG will draw the characters at that size if possible, but
       will not draw them at all if there is no font small enough.
       Point-markers and box-markers are invisible placeholders which
       a gate's program may use to specify the location of some
       dynamic display such as an LED.

   5.  Some aspects of a picture can not be edited graphically.  These
       include the radius of the corners of a rounded box, and the size,
       orientation and contents of a text object.  To edit the picture
       textually, you can press the "e" key.  This is analogous to
       the EDIT command of LOGED; it runs the text editor CAGED on a
       temporary file containing the gate's definition.  See below for
       a description of this format.

   6.  The gate's "grab box" is a dotted yellow box that starts out at
       the edges of the drawing grid.  This box defines what portion of
       the picture is considered the gate's "body", for purposes of
       tapping and dragging the gate in LOG.  It should generally be as
       large as possible, but must not enclose any pins.  (If a pin were
       inside the box, it would not be possible to draw a wire to touch
       the pin.)  To move the grab box, press on any edge or corner of
       the box.

   7.  The pins of a gate are numbered consecutively from 1.  To create
       a new pin, grab one of the numbers on the left edge of the screen
       and drag it into place.  Only one pin of a given number may exist
       at a time, and when the gate is saved, the pin numbers must be
       contiguous (if there are "n" pins, they must be numbered 1 through
       "n").  Pins are forced to multiple-of-five pixel grid lines, as are
       the user's editing actions while in LOG; this makes it easier for
       the user to connect exactly to the pins.

   8.  To move all objects in a given rectangular area, just press the
       mouse at one corner of the area (with no objects under it) and
       drag out a rectangle, then move the objects into place and press
       the mouse again.  This is analogous to LOG's MOVE command.  To
       cancel the move, click the right button.

   9.  To copy another gate's picture, press "c", then give the name
       of the gate to be copied.  The current gate's picture is replaced
       by the picture, pins, and grab box of that gate.  Other aspects of
       the current gate (such as the name, labels, and definition) are
       not affected.

  10.  If you are drawing a gate which must look similar to another gate,
       you can press "s" to "shadow" that gate.  Its picture will
       appear dimly in the background of the editing grid.  To remove the
       shadow, press "s" and enter a blank name.

  11.  By default the editing grid is the exact size of a cell in the
       Catalog screen or menu area.  To draw a larger gate, press "<" and
       ">" to zoom up or down.  If the gate is larger than the default
       grid, it will be shrunk to fit in a Catalog or menu area space, but
       will be shown full-size in an actual drawing.

  12.  If you need more pins than there are numbers for on the screen,
       press "[" and "]" to change the range of pin numbers shown.
       Pin numbers may currently range up to 128.

  13.  To switch to the next or previous gate in alphabetical order, press
       the "n" or "p" key.  On a Bobcat, you can press the Next and Prev
       keys.  This is exactly like leaving DRAW mode, typing NEXT or PREV,
       and giving another DRAW command.

  14.  Other keys you can press are space bar to refresh, "!" to start a
       sub-shell, and "?" for help.



THE "LABEL" COMMAND

   1.  To edit the text shown when the user taps on a gate in CNFG mode,
       use the LABEL command.  This command runs a simple text editor.
       To exit the editor, press <CNTRL>-C (or Select on Bobcats).

   2.  The labels editor lets you move the cursor with the arrow keys,
       delete or insert a line using the <CNTRL-F> and RETURN keys, insert
       characters, or erase characters with <CNTRL-G>.  (Currently, there
       is no way to recover a deleted line, or to move or copy lines except
       by retyping them.)

   3.  Any line without a colon (":") is displayed as-is on the screen
       when the gate is configured.  To include a colon in a label, use
       a double colon ("::").

   4.  If a line does contain a colon, it describes an attribute.
       Everything to the left of the colon is a coded string showing
       the name, type, and default value of the attribute.  Everything
       after the colon is shown as-is as the label for the attribute.
       Blanks are ignored between parts of the attribute information.

            <name> <variant> <precision> <type> <default> ':' <label>

   5.  The name is optional, and must be enclosed in square brackets.
       Actually, several bracketed names may be used if for some
       reason the attribute must have several names.  The code for a
       gate may refer to an attribute by its name, or by an integer
       index ranging from 1 to the number of attributes.

   6.  The type is a single capital letter.  The following types are
       defined:

            I     Integer.  If a precision is given, the number is
                  blank-padded to at least that width when displayed.
                  If a default is given, it becomes the initial value
                  of the attribute for newly created gates.  If there
                  is no default, the attribute is initially blank.

            H     Hexadecimal integer.  The number is zero-padded to at
                  least the specified width; if no precision is given
                  but there is a default, the precision is equal to the
                  number of digits in the default.

            R     Real number.  The precision gives the number of decimal
                  places shown on the number; if no precision is given
                  the number will be shown in floating format.  Large
                  and small numbers are shown in scientific notation.

            U     Real number with units.  The default is of the form,

                        <units-string> ',' <default>

                  where the comma and default may be omitted if the
                  attribute should be blank by default.  The number is
                  shown followed by the units-string; large and small
                  numbers are shown using standard engineering notation
                  abbreviations.  The attribute:

                        [clock-freq] 2FHz,10000:Clock frequency::

                  will display its default as "10KHz".

            F     Real number with units, scientific notation.  This is
                  just like "U" format except large and small numbers
                  are shown in scientific notation with the units-string
                  appended.

            C     String attribute.  The precision specifies the number
                  of characters of length the string may have; with no
                  precision the string length is unlimited.  The default
                  may be any string of characters, unmodified except that
                  leading and trailing blanks are removed.

            A     String attribute.  To the user, this is just like a
                  "C" type attribute with no precision specified.
                  Internally, this is stored as a variable-length
                  string, whereas a "C" type attribute is stored as a
                  fixed length string.  Precision is ignored.

            B     Boolean value.  The default may be "Y" or "N" (or "T"
                  or "F") to specify true or false.  If the default is
                  blank (or "X"), the attribute is initially blank.
                  If the default is "T" or "F" or "X", the attribute is
                  displayed as "True" or "False".  If the default is
                  "Y" or "N" or blank, the attribute is displayed as
                  "Yes" or "No".

            V     Variant.  This attribute represents a choice among
                  several named options.  The default string is actually
                  a sequence of comma-separated phrases.  These phrases
                  are numbered from 0.  The precision actually specifies
                  the default variant shown; with no precision, variant 0
                  is the default.  If the attribute should be able to be
                  blank, simply leave one of the phrases empty.

                        1 V , Yes, No, Maybe : What do you think?

                  This attribute takes on one of the four values blank,
                  Yes, No, or Maybe; it is initially Yes.

   7.  A variant name may be included in any attribute, followed by a
       semicolon.  The name must be one of the options for a variant
       attribute that precedes this attribute in the list.  The attribute
       will be invisible unless the proper variant was selected.

            V Square,Circle: Kind of shape::
            Square; R:Width::
            Square; R:Height::
            Circle; R:Radius::

   8.  If the type letter is preceded by the letter 'O', the attribute is
       optional and can be made blank by typing a blank line.  An attribute
       with no default is always optional.  If the attribute has a default
       and is not optional, then it must always have a nonblank value.  (This
       is true even of string attributes.)  Entering a blank line for a
       nonoptional attribute restores the default value.



THE "DEF" COMMAND

   1.  The DEF command edits the simulator's definition for the gate.
       What happens when you type DEF depends entirely on what simtype
       you have given to the gate.  Also, for simtypes 16 and above, the
       relevant simulator must have been loaded into the computer already
       via a "perm" or "use" command.

   2.  For simtype 0, the gate has no simulation behavior and its DEF
       command does nothing.

   3.  For simtype 1, the DEF command displays the signal name current
       programmed into the gate, then gives you the option to change this
       name if you wish.  If you leave the name blank, the gate will not
       connect to any signal by default; presumably, you have set the
       NAMED flag so that a signal name can be entered at run time.

   4.  For simtype 7, the DEF command displays and allows you to change
       the name of the Pascal procedure responsible for the gate.  This
       must be of the form, "modulename_procedurename".  The writing of
       Pascal coded gates is beyond the scope of this manual; refer to
       Dave Gillespie's Master thesis, or examine the LOG sources for
       examples.

   5.  For simtype 16, you enter a simple text editor.  Use the up arrow
       and down arrow keys to move, press <cntrl-K> and <cntrl-I>
       to delete or insert lines. Editing functions currently not implemented
       implemented are RECALL, to restore a deleted line, and left arrow
       and right arrow to edit a line.  Indentation and formatting
       is handled automatically.  If LOGED detects a syntax error in your
       line, it converts it into a comment.  However, note that some
       syntax errors are not caught but will produce code that may cause
       the simulator to crash or behave strangely.  For a description of
       the LOG digital gate language, see below.  Press <CNTRL>-C
       or <CNTRL-D> to exit.

   6.  For simtype 32, you are prompted for the name of a Pascal procedure
       which takes responsibility for the gate, in much the same way as
       for simtype 7.



DIGITAL GATE DEFINITION LANGUAGE

   1.  Simple digital gates in LOG can be described entirely in the
       modest interpreted language described here.  For more complicated
       functionality, for displays and user interaction, or for access
       to the gate's attributes, you must write Pascal code using a
       CALL statement.  The interpreted language is usually referred to
       as "LOGED language," though it is really part of the digital
       simulator, not of LOGED proper.  The language is also called
       Gate Description Language, or GDL.

   2.  A GDL program consists of a sequence of statements, displayed one
       per line.  These statements are typically either assignments to
       pins or variables, or IF/ELSE/END constructions.  GDL contains no
       loops, arrays, or arithmetic.  The program is executed once per
       LOG time-step, from top to bottom, performing boolean operations
       on values in the gate.

   3.  Resources available to a GDL program are pins, notated as in "#3";
       internal nodes, notated as in "##6"; and state variables, such
       as "A", "P", or "V26".  A state variable is much like a Pascal
       variable; an assignment to it replaces the previously assigned
       value, and lasts until the next assignment.  It is a 1-bit quantity
       whose value is interpreted as a boolean logic 1 or 0.  A pin or
       internal node is a true LOG node; it uses a five-valued logic
       (One, Zero, undriven or "None", and weak One and Zero) and must be
       assigned to once per time-step.  The assigned value does not show up
       on the node until the next time-step.  If the gate uses only nodes
       (no state variables), the order of execution of statements within
       the gate is essentially arbitrary.

   4.  Pin numbers range from 1 to the number of pins on the gate.
       The 16 state variables A through P are always available.  For
       internal nodes and additional state variables, you can use the
       INST statement described below.  All state variables are initially
       Zero when the gate is created.

   4.  Each GDL statement must be one of the following:


       <variable> = <expression>
                  Assign the value of the expression to the variable.
                  The previous value of the variable is replaced.  This
                  is exactly like a variable assignment in a conventional
                  language.  If the value of the expression's value is
                  None, the variable is set to One.


       <node> = <expression>
                  Output the value of the expression to the pin or
                  internal node.  If two statements (in the same or
                  different gates) output conflicting values to the
                  node in the same time-step, a conflict is registered
                  on the node.  Outputting None to a node has no effect.


       <node> = PULLUP   or   PULLDN
                  Output a weak One or Zero (respectively) to the
                  node.  This essentially registers a default value
                  for the node; if no other GDL statement assigns a
                  strong value to the node in this time-step, the
                  weak default will be used.  A strong value overrides
                  a weak value without conflict.  A conflict will be
                  registered if the node is weakly pulled to One and
                  Zero simultaneously.

       <node> '<' <expression>
                  Output an open-collector value to the node.  If
                  the expression's value is Zero, it is driven to the
                  node.  If the expression's value is One or None,
                  the node is left alone.


       IF <condition> <expression>
          <statements>
       ELSE
          <statements>
       END
                  If the condition is satisfied, the first set of
                  statements are executed.  Otherwise, the second set
                  (if any) are executed.  The conditions available
                  cover all possibilities of One, Zero, and None
                  values for the expression:

                        IF x        True if x=One or None.
                        IFONE x     True if x=One.
                        IFZN x      True if x=Zero or None.
                        IFZERO x    True if x=Zero.
                        IFCONN x    True if x=One or Zero.
                        IFNONE x    True if x=None.


       CALL <procedure-name>
                  Call the Pascal procedure specified.  The name has the
                  usual "modulename_procedurename" form.  If there is are
                  CALL statements in a gate's procedure, those procedures
                  are called in order when the gate is simulated, drawn,
                  tapped, created, destroyed, copied, configured, etc.


       INST <num-nodes> , <num-vars>
                  This statement, if used, must be the first statement of
                  the program (before even comments and blank lines).
                  The statement "INST 17,6" reserves 17 internal nodes,
                  ##0 through ##16, and 6 additional state variables,
                  V0 through V5, for the gate.  If the number of variables
                  is zero, it and the comma can be omitted.


   5.  GDL statements may also be blank lines or comments.  A comment
       line begins with a "#" not followed by a digit.  Blank lines and
       comments do have a small impact on the simulator's performance.


   6.  A GDL expression is a series of "factors" joined by binary
       operators.  All operators have the same precedence and are
       evaluated left-to-right.  In the following list of operators,
       X is any expression and Y is any factor.


       x AND y    Boolean AND, OR, or exclusive OR of X and Y.  If
       x OR y     either X or Y is None, the result is the other input.
       x XOR y    If both are None, the result is None.


       x NAND y   Equivalent to "NOT (x AND y)".


       x NOR y    Equivalent to "NOT (x OR y)".


       x SAME y   Both X and Y must be pins.  Equal to One if both
                  pins are connected to the same electrical node, or
                  Zero if the pins are not on the same node.


   7.  A GDL factor is either an expression in parentheses, or one of
       the following (X is any factor; P is any pin or internal node):


       <var>      A state variable.  The result is One or Zero depending
                  on the current value of the variable.


       <node>     A pin number or internal node.  The result is either
                  One, Zero, or None, depending on the value driven on
                  the node in the previous time-step.


       ONE        The constant value, One.  This can also be written
                  "TRUE" or "1".


       ZERO       The constant value, Zero.  Also "FALSE" or "0".


       NOT x      The result is One if X is Zero, Zero if X is One, or
                  None if X is None.


       RISE p     The result is One if the specified node is receiving
                  a rising transition, that is, the previous time-step
                  drove the pin to a One, but the time-step before that
                  drove it to a Zero.  Otherwise, the result is Zero.


       FALL p     The result is One if the specified node is receiving
                  a falling (One to Zero) transition.


       FIX x      The value of X, with None converted to Zero.


       STRONG p   The result is One or Zero if the specified node was
                  driven by a strong (i.e., normal) value on the previous
                  time-step, or None if the node was undriven or was only
                  weakly driven.


   8.  For examples of GDL programs, consult the many gates in the files
       "log.cnf" and "actel.cnf".



TEXT FILE FORMAT


   (This section is not yet completed.)



".GATE" FILE FORMAT


   (This section is not yet completed.)
_______________________________________________________________________________

                              REFERENCE MATERIAL

   List of commands
   Configuration files
   Digital simulator commands
   Analog simulator commands
   Single-key commands
   Color names
   Command-line options
   X Display Preferences

LIST OF COMMANDS

   1.  This is a partial list of commands that may be entered in their
       full-length form (i.e., press ":", then type the command).
       Many of these commands may also appear in the file "log.cnf"
       which is read when LOG starts up.

   2.  In this list, "ON/OFF" means either the word "ON", to turn an
       option on, or "OFF", to turn an option off, or no word at all,
       to "toggle" the option between on and off.

   3.  Many commands have single-key equivalents.  The bindings shown
       here are the defaults, which may be changed by the MACRO command.

   4.  The following commands, when used in the form of single-key
       commands, may be used even in the middle of drawing a wire,
       selecting a rectangle, etc.:

           ALTPOSN       GLOW          OFF           SIM/ONOFF/POWER
           ARROW         GLOWSOLDER    ON            SNAP
           AVOID         GRID          PAGE n        TRACE
           CLOSEFILES    HELP          PROBE         TRACEFILE
           CONFLICT      HOME          QUIET         VERBOSE
           DOTS          INVISIBLE     RESET         ZOOMDN
           DUMP          INVLABEL      RESPONSE      ZOOMUP
           DUMPFILE

       Other commands will cause any other operation in progress to
       abort before the new command begins.

   5.  Here is the complete list of LOG commands:


       ABORT      (<CNTRL>-C) Abort the current command, mode, or screen.


       ALTPOSN    ("," key.)  Scroll to an alternate location on the
                  page.  LOG essentially maintains two current locations
                  on the page, like the "mark" in the Emacs text editor;
                  this command exchanges them.


       ARROW      Revert to the standard arrow-shaped cursor.  This undoes
                  any previous PROBE or GRID command.

       AUTOWINDOW Toggle a new window management mode. In this mode
                  whenever text input into the newcrt window is necessary
                  the newcrt window automatically rises in front of any
		  windows that occlude it.  Once the window is  no longer
		  needed, it returns to its previous condition.  

       BOX        ("b" key.)  Draw a dashed box.


       CAT        (Shift-"C" key.)  Switch to the Catalog screen.


       CENTER     Shift the entire circuit so that it is centered in the
                  LOG circuit universe, i.e., so that a Home command will
                  home to the center of the circuit.  Note that this
                  actually moves the circuit elements, whereas scrolling
                  with the knob just changes your view on the elements.


       CLEAR      Delete the entire circuit page.  Use with caution!


       CLOSEFILES
                  Close the "dump" and "trace" files, if they are open.
                  These files will automatically be re-opened (for
                  appending) if they are again used.  The dump file is
                  used by the "Dump" command in the Scope.  The trace
                  file is used by various LOG debugging commands.


       CLOSEH     Enter "close-horizontal-space" mode, similar to OPENH
                  except that it deletes the contents of the box you draw
                  and shifts other things to the left.  DANGEROUS!


       CLOSEV     Enter "close-vertical-space" mode, similar to OPENV.
                  DANGEROUS!


       CNFG       ("c" key.)  Switch gate-tapping mode to open a gate's
                  configuration screen when it is tapped.


       COLOR  screen-color  red-value  green-value  blue-value
       COLOR  color-name  screen-color
                  Customize the LOG color scheme.  LOG's colors are
                  determined in two steps.  A "palette" of up to 16
                  available colors is specified by the first form of
                  the command.  "Screen-color" is either a number from
                  0 to 15, or one of the names listed below.  Each of
                  the red, green, and blue values run from 0 (black)
                  to 255 (full intensity).  The second form of the
                  COLOR command determines which of these 16 colors
                  is used for various kinds of objects.  The color
                  names defined by LOG are listed in a later section.

                  Screen-colors:
                     0  GRAY     4  MRED     8  BLACK    12 DCYAN
                     1  RED      5  ORANGE   9  PINK     13 DRED
                     2  GREEN    6  CYAN     10 DYELLOW  14 LGRAY
                     3  YELLOW   7  WHITE    11 XGREEN   15 CRED

                  On eight-color screens, all sixteen names or numbers
                  may still be used; LOG combines similar colors
                  internally.  The effect will be that changing the
                  red/green/blue content of one of the above colors
                  may affect other colors as well on an 8-color screen.


       CONFLICT n
       CONFLICT ON/OFF
                  Turn conflict reporting on or off.  In Digital LOG,
                  node conflicts are reported if one gate tries to drive
                  a node to "1" while another is driving it to "0".
                  AnaLOG does not report conflicts.  Conflicts are
                  shown by a bright pulsating red.  If conflicts are
                  turned off, they are not visible on the screen.  If
                  an integer "n" is given, conflicts are turned on and
                  the number of time steps to wait before reporting a
                  given conflict is set to "n".  For example, if n=0,
                  conflicts are reported immediately.  For n=1, each
                  conflict must remain for at least two simulation
                  timesteps before it is considered interesting.
                  The default is conflict reporting on, with n=1.


       COPY       ("/" key.)  Enter copy-area mode.


       CSTOP ON/OFF
                  Turn conflict-stopping mode on or off.  When this mode
                  is on, the simulation stops (as if you had given an
                  OFF command) the instant any conflict is reported.
                  The CONFLICT command can be used to select how long a
                  conflict must persist before it is reported.  This
                  mode is off by default.


       DEFINE     (Shift-"D" key.)  Display the simulator's definition for
                  a gate-kind, specified either on the command line or by
                  touching a representative gate.  Pressing shift-"D" in
                  the Catalog screen also displays the definition for the
                  gate the cursor is over.


       DEL        ("d" key.)  Enter delete mode.


       DOTS ON/OFF
                  Control dots-visible mode.  When this is on (default),
                  red connection dots on gates are always visible.  When
                  this is off, red dots are usually visible only on pins
                  that are not connected to wires.


       DUMP       Write out a "debugging dump" to the printer.  For LOG
                  maintainers only.


       DUMPFILE filename
                  Close any current dump file, then select "filename.text"
                  as the new dump file.  If this file already exists, new
                  text will be appended to it.


       EXAMINE    ("e" or "x" key.)  Enter Probe mode temporarily.
                  The cursor returns to normal as soon as you click the
                  right button.  This is in contrast to the PROBE command,
                  which turns the Probe cursor on until you explicitly
                  turn it off again.


       EXIT       Exit from LOG.  Also in the Misc menu, or on the Shift-Q,
                  Shift-Z, and Control-D keys.


       EXTRACT    Delete and re-paste the entire contents of the page.  If
                  LOG's electrical connectivity information becomes corrupt,
                  this will usually fix it.


       FAST       ("f" key.)  Turn on fast mode.  This happens
                  automatically after a certain amount of time passes with
                  no mouse or keyboard inputs.


       GET gatename gatename gatename ...
                  Load the specified gates into the Catalog screen from
                  the gate library.  The gate names may include wildcard
                  characters '*' and '?'.


       GLOW ON/OFF
                  ("g" key.)  Turn glow mode on or off.


       GLOWSOLDER ON/OFF
                  Turn glowing-solder mode on or off.  This controls
                  whether solder dots are visible while in GLOW mode.
                  It is on by default; turning glowing-solder off may
                  improve simulation performance in GLOW mode.


       GRID       (Shift-"G" key.)  Change the cursor to a cross-hair
                  shape.  If the cursor is already a cross-hair, change
                  it back to the regular arrow cursor.


       GROUP n "Name"
                  Set the name that appears on the top of page number "n"
                  of the Library screen.  The number "n" must be from 0
                  to 8.  If the "Name" argument is omitted, this command
                  instead selects which page number the Library screen
                  will display next time it is entered.


       HELP       ("?" key.)  Display this file using the Chipmunk
                  Help System.


       HOME       ("h" key.)  Reset the scroll and zoom amounts to the
                  default position on the page.


       IDENTIFY   Used by the LOG-to-NTK conversion tool.


       INVISIBLE ON/OFF
                  ("i" key.)  Turn "Invisible" mode on or off.  In this
                  mode, wires and most gates are invisible.  However, labels,
                  boxes, and switch/indicator gates are visible.  Also,
                  operations that edit the circuit are disallowed.  Thus,
                  a user can switch into Invisible mode and then operate a
                  simulated "front panel" without confusion or fear of
                  changing the circuit.


       INVLABEL ON/OFF
                  (Shift-"I" key.)  Turn "Invisible Labels" mode on or
                  off.  In this mode, labels and boxes are invisible.


       LABEL message
                  ("l" key.)  Create a new label on the page.  If a
                  "message" argument is supplied, a label with the
                  specified text is created on the lower-left corner of
                  the screen.  If no argument is supplied, LOG interactively
                  enters the text for the label.


       LIBRARY    ("l" key or LIBR item in the Catalog screen.)  Switch
                  directly to the Gate Library screen.


       LOAD filename
                  (Shift-"L" key.)  Load the specified circuit file onto
                  the current page, replacing anything that was on that
                  page before.  If no file name is specified, LOG displays
                  a list of files in the current directory and asks the
                  user to select one, or type the name.  If the file name
                  is '*', LOG simply asks the user to type the name.  The
                  shift-L key is bound to "LOAD *".


       LOGNTK     Start the LOG-to-NTK conversion tool.


       LOGNTK: parameter value
                  Set up a configuration parameter for the LOGNTK tool.
                  Commands of this form usually appear in the file
                  "/lib/log/logntk.cnf".


       LPLOT: parameter value
                  Set up a configuration parameter for the PLOT tool.
                  Commands of this form usually appear in the file
                  "/lib/log/lplot.cnf".


       MACRO  key-name  command
                  Associate the specified command with a key.  The key-name
                  may be a single letter or other character (lower-case
                  letters represent unshifted keys; upper-case letters
                  represent shifted keys); or one of the words "bs", "tab",
                  "sp" (space bar), or "cr" (Return or Enter); or a control
                  key of the form "^A" or "^["; or a three-digit decimal
                  ASCII code.  The "command" may be any of the commands
                  listed here, and may include arguments.  If you give only
                  a key-name, the computer displays the command that is
                  currently bound to the key.  MACRO with no arguments
                  displays a list of all current key bindings.


       MAKE gate-name
                  Bring a gate in from the catalog by name, and put it in
                  the drawing area.  A shorthand for using the mouse in the
                  the CAT and LIBR screens.  If the gate-name contains
                  wildcard characters, multiple gates may be loaded into
                  the Catalog but only one of them will be created on the
                  circuit page.


       MARKER ON/OFF
                  ("m" key.)  Turn printing markers on or off.  The
                  printing markers are used mainly by the "PLOT" command;
                  they indicate the area of the circuit page which is to
                  be fitted into the printed page.  The printing markers
                  appear on the corners of the visible screen, and you
                  can move them by regular editing operations to bracket
                  any rectangular area of the page.


       MESSAGE message
                  Display the specified message in the "message area" of
                  the screen.  The message area runs down the left edge
                  of the screen; messages are drawn in yellow overlaying
                  the drawing area.


       MIRX       Select "mirror-in-X" gate-tapping mode.  When a gate is
                  tapped in this mode, it is flipped across its vertical
                  axis.  This works both in the menu area and in the
                  drawing area, although some gates (such as switches)
                  have special behaviors when tapped in the drawing area.


       MIRY       Select "mirror-in-Y" gate-tapping mode.


       MOVE       ("m" key.)  Move an area of the diagram.  This is
                  similar to deleting the area with DEL, then pasting
                  it back in a new location with PASTE.


       NAME file-name
                  See and/or change the "current file name" for the
                  circuit page.  This is the file name that will be
                  used by default in later "SAVE" commands.


       OFF        Turn simulation OFF.


       ON         Turn simulation ON.


       OPENH      Enter open-horizontal-area mode.  Sweep out a rectangle;
                  everything to the right of the lefthand edge of the
                  rectangle is moved to the right by the amount of the
                  width of the rectangle.  Wires straddling the left edge
                  are stretched appropriately.  BEWARE:  This command
                  may corrupt the LOG data structures if used in such a
                  way as to break or make electrical connections in the
                  circuit.  Unless you really know what you are doing,
                  use the cut-and-paste method of moving things.


       OPENV      Enter open-vertical-area mode, similar to OPENH.
                  DANGEROUS!


       PAGE n     Switch the display to circuit page "n", from 1 to 9.
                  "n" may also be "+" or "-", to switch to the next or
                  previous numbered page.


       PASTE      Enter Paste mode.


       PLOT       Run the circuit plotting tool.


       POPUP  menu  position  kind  command  message
                  Change one of the locations in the pop-up menus.  "Menu"
                  is a number that selects which menu (1=Frills, 2=Editing,
                  3=Cursor, 4=Misc); "position" is an integer from 1 to 8
                  that identifies which spot in the menu:   [ 1  3  5  7 ]
                                                            [ 2  4  6  8 ]
                  "Kind" is normally zero; "command" is the command (from
                  this list) that is to be executed if the menu is selected,
                  enclosed in "quotes" if it contains spaces; and "message"
                  is the wording for that menu element.  If "message" begins
                  with '*' or '#', it will be colored red or light blue,
                  otherwise it will be green.


       PROBE      ("." key.)  Change to the Probe cursor.  If already
                  using the Probe cursor, change back to an arrow.  In
                  Probe mode, holding the cursor near a wire or gate pin
                  displays the value on that electrical node, in a
                  simulator-dependent way.  Holding the cursor near a
                  gate in the drawing or menu areas displays the name
                  of the gate on the screen.  Tapping a gate or node
                  opens it for configuring, if it has anything to
                  configure.  (Neither AnaLOG nor Digital LOG nodes
                  are configurable, but many gates are.)  Tapping and
                  configuring a gate in the menu area sets the defaults
                  for newly created gates pulled out of that menu slot.
                  Finally, tapping out in the drawing area draws a
                  yardstick.  See also the EXAMINE command (on the
                  "e" and "x" keys) which selects a temporary
                  Probe mode.


       QUIET      ("q" key.)  Turn sound prompting on or off.


       READ  filename
                  Read in a circuit from a file.  This is similar to the
                  LOAD command, but it rebuilds the circuit's connectivity
                  information as it loads, rather than simply reading it
                  from the file.  As a result, READ is much slower than
                  LOAD, but it is far more robust in case the file is
                  corrupt or out of date.  For example, if you run LOGED
                  and add more pins to a gate, then try to LOAD a circuit
                  diagram containing that gate, LOG may crash since the
                  connectivity recorded in the file is out of date.  But
                  the READ command will read the file with no problems.
                  In general, use the fast LOAD command unless you have
                  a good reason not to.


       REFRESH    (Space bar.)  Refresh the screen.


       RESET      (Shift-"R" key.)  Send a Reset signal to the simulator(s).
                  This resets simulation time back to zero, and has other
                  simulator-dependent effects.  For AnaLOG, it resets all
                  voltages to their initial values.  For Digital LOG,
                  nothing happens except that the TO/FROM signal "Reset",
                  if used, gets a brief "1" pulse.


       RESPONSE  min  max  rate
                  Set response-time parameters.  With no arguments,
                  displays current parameters.  Initial values are
                  2, 50, and 35, respectively.  During editing, LOG
                  tries to check the mouse and keyboard at least every
                  "min" centi-seconds.  If the user stops editing,
                  this rate slowly increases until the maximum of
                  "max" centi-seconds.  The rate of increase is
                  one unit per "rate" centi-seconds of idle time.


       ROT        Select "Rotate by 90 degrees" gate-tapping mode.  When
                  a gate is tapped in this mode, it rotates 90 degrees
                  counter-clockwise.  This works both in the menu area and
                  in the drawing area, although some gates (such as
                  switches) have special behaviors when tapped in the
                  drawing area.


       SAVE filename
                  Save circuit page(s).  If a name is given, saves the
                  current page in "name.LGF".  If the name is "*", prompts
                  the user to enter the name to save.  If no name is
                  given, re-saves all circuit pages which have been
                  since last saved or loaded.  Shift-"S" is bound
                  to "SAVE *".


       SCOPE      ("s" key.)  Switches to the Scope screen.


       SHELL shell-command    ( or:  !shell-command )
                  (Also, "!" as a single-key command.)  Start a sub-Shell.
                  If a shell-command is provided the shell executes this
                  one command and returns.  If no shell-command is provided,
                  you get an interactive sub-shell.  Type quit or press
                  control-D to return from the sub-shell.


       SIM (or ONOFF or POWER)
                  Turn simulation ON or OFF (toggling).


       SNAP       ("$" key.)  Turn "snap-to-grid" mode on or off.  Default
                  is off.  In this mode, the cursor arrow always jumps
                  to the nearest spot on the LOG editing grid rather
                  than moving smoothly.


       STATUS     Enter the "Status" display.  Use the knob or arrow
                  keys to switch among various pages.  A page-name may
                  also be given with the STATUS command:

                        LOG      General system status
                        MEMORY   Memory usage status
                        MACRO    Keyboard mappings
                        16       Digital simulator
                        32       Analog simulator
                        LPLOT    Plotting tool
                        LOGNTK   LOG-to-NTK tool


       STEP n     Turn simulation OFF, if necessary, then step the
                  simulation by one time-step.  If an integer "n" is
                  provided, executes "n" time-steps before stopping.


       TAPMODE    (menu selection, or shift-"M" key.)  Select the next
                  gate-tapping mode, in order:  ROT, MIRX, MIRY, CNFG.


       TOOL name  Send a "select" command to the specified tool.  Various
                  tools respond to this in various ways; the default is
                  to ignore the signal.  (The Digital LOG simulator, tool
                  name "16", responds by putting up a configuration
                  screen of digital-LOG parameters.)  If a TOOL command
                  is given with no "name" argument, it puts up a screen of
                  available tool names and "selects" whatever tool the
                  user chooses with the mouse.  The shift-"T" key calls
                  up an interactive TOOL command.


       TRACE      Turn the debugging "wallpaper" mode on or off.  Please
                  don't do this unless a LOG maintainer is there.  Trace
                  output goes to the "Trace" file, which by default is an
                  appropriate printer.


       TRACEFILE filename
                  Close any current trace file, then select "filename.text"
                  as the new trace file.  If this file already exists, new
                  text will be appended to it.


       VERBOSE    ("v" key.)  Turn informational messages on or off.  These
                  messages are mostly of the "Glow mode is now OFF"
                  variety.


       VMESSAGE   Similar to MESSAGE, but works only if in
                  Verbose mode.


       YARDSTICK  Draw a "yardstick", useful for measuring the spacing of
                  objects in your diagram.


       ZOOMDN     Zoom down, to view more of the circuit page.


       ZOOMUP     Zoom up, to view part of the circuit in greater
                  detail.



CONFIGURATION FILES

   1.  LOG reads the file "log.cnf" every time it starts up.  If you do
       not have one in the current directory, it uses "/lib/log/log.cnf".
       You can give the "-c" command-line switch to specify your own
       configuration file.  The "use log" script actually loads the
       program "diglog" into the computer and aliases the "log" command
       to "diglog -cdlog", causing "dlog.cnf" (in the current directory
       or in /lib/log) to be used.  Similarly, "use analog" loads the
       program "analog" and aliases "log" to "analog -calog".

   2.  To create your own configuration file, the best approach is to
       make a file named "log.cnf", "alog.cnf", or "dlog.cnf", whichever
       is appropriate, in your current directory.  In that file, put a
       line something like "include /lib/log/alog.cnf", followed by any
       additional commands to override the system defaults.  Do not
       copy the system CNF files if you can avoid it; these files are
       subject to change at any time.

   3.  For example, your CNF file might look like this:

               { A comment saying what this is used for }
               include /lib/log/dlog.cnf     { Inherit from Digital LOG }
               gates + ~me/log/mygates       { Add on my own gates file }
               menu a b c d e vdd gnd        { Choose my own menu gates }
               glow on                       { Turn on "glow" mode }

       In this example, the "+" in the GATES command means to add the
       name(s) to the existing list of gates files.  Since the MENU
       command does not have a "+", it replaces the list from the
       other file.  This notation works with the GATES, GET, GETGROUP,
       and MENU commands in configuration files.

   4.  The following ":" commands may also be used in a "log.cnf"
       configuration file:

           AVOID         GLOWSOLDER    OFF           QUIET
           COLOR         GROUP         ON            RESPONSE
           CONFLICT      INVISIBLE     SIM           SNAP
           DOTS          INVLABEL      POPUP         VERBOSE
           GLOW          MACRO         PROBE

   5.  The following additional commands are allowed in configuration
       files:


       BOBCAT  command-line
       CHIPMUNK  command-line
                  Process the command only if LOG is being run on the
                  specified kind of computer.  The "command-line" here
                  is any of the commands listed in this section; in other
                  words, the words BOBCAT and CHIPMUNK are prefixes that
                  can be added to any command in a CNF file.


       COMMAND  toolname  command command command ...
                  Register that the listed commands are handled by the
                  indicated tool.  If a command is given and its owning
                  tool has not been initialized, that tool will be
                  initialized.

       DO command-line
                  Add the command-line to a list of ":" commands to be
                  done as soon as LOG is started.  These commands are
                  executed as if typed from the keyboard, i.e., they
                  may be commands which are ordinarily forbidden in
                  CNF files.  The "DO" commands are executed in the
                  order they originally appeared in the CNF files.


       GATES filename filename filename ...
                  Register the specified ".gate" files into the LOG
                  gate library.  Files are searched for a given gate
                  starting at the first filename of the first GATES
                  command in the CNF file.  Ordinarily, the presence
                  of the first GATES command in a given CNF file
                  overrides all GATES commands in previously read
                  CNF files (i.e., INCLUDE files).  If the first
                  word after GATES is "+", the listed filenames will
                  instead be added to the existing list of gates
                  files.  If no explicit directory is given, LOG
                  looks first in the current directory, then in
                  the "home" directory, then in /lib/log.  If the
                  gates file is not found, it is ignored.


       GET gate gate gate ...
                  Load the specified gates into the gate catalog.  The
                  gate names may include wildcard characters "*" and "?",
                  and may also specify one or more group numbers from
                  0 to 8:  "GET A*;34" gets all gates whose names begin
                  with A, which are found on pages 3 or 4 of the Library.
                  If this is the first GET command in its CNF file, it
                  overrides any previous GET commands from other files
                  unless GET is followed by the word "+".  (The obsolete
                  word LOAD is accepted as a synonym for GET.)


       GETGROUP gate gate gate ...
                  Load the specified group of gates into the gate catalog.
                  This like a normal GET command, except the gates are
                  guaranteed to be placed together (provided there's
                  room), and a box is drawn around them on the catalog
                  screen.


       HELP filename
                  Name of a ".help" file to be used when the user
                  asks for help.


       HOME directory-name
                  Specify a directory to be used as the "home"
                  directory.  If a CNF file, gates file, help file,
                  or news file is not found in the current directory,
                  LOG looks next in this "home" directory, then
                  finally in "/lib/log".  The default "home" directory
                  is "~/log", that is, the "log" subdirectory of the
                  user's home directory.


       INCLUDE cnf-file
                  Read commands from the specified ".cnf" file, then
                  resume reading from this file.  Include files may
                  be nested.


       MENU gate gate gate ...
                  Load the specified gates into the menu area.  If
                  there are more gate names than menu slots, only the
                  first few names are used.  The first word may be
                  "+" to add the specified gates to a list from a
                  previous CNF file.


       NEWS file-name
                  Name of a ".text" file whose contents are displayed
                  when LOG begins.


       SIGNALS number
                  (or NODES.)  Specifies the maximum number of TO/FROM
                  signal names that can exist at one time during the
                  LOG session.  Default is 200.


       TABLET number
                  Set the HP-IB address of the graphics tablet to be
                  used.  Default is 0, which means look for the tablet
                  on the HP-HIL or at the standard address.


       TOOL tool-name "full-name"
                  Register a tool name so that the run-time TOOL command
                  will display its name.  (Ordinarily, tools are
                  automatically registered as soon as they are needed.)


       UNDO       Delete all "DO" commands registered up to this point.


       tool-name: tool-command
                  This directs a command to a particular LOG "tool".
                  The standard tool names are:

                        16       Digital simulator
                        32       Analog simulator
                        LPLOT    Plotting tool
                        LOGNTK   LOG-to-NTK tool



DIGITAL SIMULATOR COMMANDS

   1.  The following additional ":" commands are available with the
       Digital LOG simulator.  Except for STABILIZE they may be used
       in "log.cnf" files by preceding them with the word "16:", as
       in "16: stabdelay 2.5".


       DIGON      Turn digital simulation ON.  This is the normal case.


       DIGOFF     Turn digital simulation OFF.  This command is similar
                  the regular OFF command, except only the digital
                  simulator is affected.  If several simulators are
                  being run at once (say, digital and analog), the
                  other simulators will proceed unaffected.


       DIGONOFF ON/OFF
                  Turn digital simulation ON or OFF.


       STABDELAY time
                  Set amount of time to wait for circuit stabilization
                  (see STABILIZE) to "time" seconds.  Default is 5.0.
                  With no argument, the command shows the current value.


       STABILIZE  Attempt to stabilize an oscillating circuit.  Because
                  all digital gates have identical, exact propagation
                  delays, oscillations can develop in feedback circuits
                  that would never arise in a real circuit, where the
                  propagation delays are not so exactly balanced.  The
                  STABILIZE command randomizes the propagation delays of
                  gates in order to kill such oscillations.  Of course,
                  a circuit that really is oscillating will continue
                  to do so.  The "stabilization" effect wears off after
                  about five seconds, usually plenty of time.


       DIGSTEP time-step
                  Set the amount of simulated time per digital timestep.
                  Since every digital time step is the same, this value
                  normally does matter unless you are using the digital
                  simulator along with another simulator which has a more
                  concrete idea of time (such as AnaLOG).  The default
                  value is "10ns", i.e., 1E-8 seconds.  The value may
                  be specified in engineering or real-number notation.
                  With no argument, the command shows the current value.



ANALOG SIMULATOR COMMANDS

   1.  The following additional ":" commands are available with the
       AnaLOG simulator.


       DIM ON/OFF
                  Turn dim-unconnected-gates mode on or off.


       ERASE      Same as touching Erase on the "Scoreboard" gate.
                  If you are selecting Set and Erase often, you might
                  want to use the MACRO command to put SET and ERASE on
                  a pair of keys, for convenience.


       EXACT      Same as touching Exact on the "Scoreboard" gate.


       NEWMODEL   Set non-saving device-model mode, in which modeling
                  parameters for transistors, and simulation constants
                  such as "Vdd", are reset to their default values
                  rather than being loaded from each circuit file.


       OLDMODEL   Set the default device-model mode, in which modeling
                  parameters for transistors, and simulation constants
                  such as "Vdd", are saved in circuit files along with
                  the transistor and "Scoreboard" (NUMBERS) gates.


       PROBEPREC digits
                  Set the number of decimal digits for voltages displayed
                  by the "probe" cursor.  Default is 3.


       RELAXED    Same as touching Relaxed on the "Scoreboard" gate.


       SET        Same as touching Erase on the "Scoreboard" gate.



   2.  Also, a great many AnaLOG parameters may be set in ".CNF" files.
       These commands all begin with the prefix "32:".  Defaults appear
       in the file "models.cnf" in the analog /lib directory -- ask
       your local maintainer for details


SINGLE-KEY COMMANDS

   Many commands also appear in single-key forms.  In this list, lower-case
   letters represent unshifted keys, and capital letters are shifted keys.

     :         Enter a full-line command.
     space     Refresh the screen:  REFRESH.
     knob      (or arrow keys.)  Scroll across the page.
     <CNTRL>-C Abort the current command or mode.
     1-9       (Digits.)  Switch to a new page.  Same as PAGE 1 to PAGE 9.
     !         Shell escape:  SHELL.
     *         Draw the contents of the Paste buffer:  PASTE.
     ,         (Comma.)  Switch to alternate viewing position:  ALTPOSN.
     .         (Period.)  Enter or leave PROBE mode.
     /         Copy an object or area into the Paste buffer:  COPY.
     <         Zoom down, to see more of the diagram at once:  ZOOMDN.
     >         Zoom up, to focus on a smaller area of the diagram:  ZOOMUP.
     ?         Display this help file.
     +         (also NEXT on Bobcats.)  Switch to next higher page number.
     -         (also PREV on Bobcats.)  Switch to next lower page number.
     b         Draw a dashed box:  BOX.
     c         Switch to "CNFG" gate-tapping mode:  CNFG.
     C         Enter the Catalog screen:  CAT.
     d         Delete objects:  DEL.
     D         Show simulator's definition for a gate:  DEFINE.
     e         Enter temporary PROBE mode:  EXAMINE.
     f         Turn on FAST mode.
     g         Turn GLOW mode on or off.
     G         Turn GRID (cross-hair cursor) mode on or off.
     h         Return to home (unscrolled) position:  HOME.
     i         Turn INVISIBLE mode on or off.
     I         Turn INVLABEL (invisible labels) mode on or off.
     l         Draw a label:  LABEL.
     L         Load a new circuit page:  LOAD.
     m         Move an object or area:  MOVE.
     M         Select the next gate-tapping mode:  TAPMODE.
     $         Turn SNAP-to-grid mode on or off.
     o         Turn simulation on or off:  ONOFF.
     p         Enter the circuit-plotting tool:  PLOT.
     r         Switch to "ROT" gate-tapping mode:  ROT.
     R or 0    Reset the simulators:  RESET.
     q         Turn QUIET mode on or off.
     Q or Z    (or Control-D.)  Exit from the LOG system:  EXIT.
     s         Enter the Scope screen:  SCOPE.
     S         Save the current page to a file:  SAVE.
     t         Run simulation for one time-step, then stop:  STEP.
     T         Enter the Tool screen:  TOOL.
     v         Turn VERBOSE mode on or off.
     x         Enter temporary PROBE mode:  EXAMINE.
     y         Draw a YARDSTICK.



COLOR NAMES

   1.  The following list is the complete set of color-names defined so
       far in the LOG system.  See the COLOR command for details
       on how to reconfigure these color names.

   2.  After each color-name is its default color, then a description of
       what screen objects that color-name governs.

       BACKGR     Gray              Screen background color.
       BASELINE   Cyan              Color of line above menu area.
       BLUEWORD   Cyan              Light blue text in pop-up menus.
       CATALOGBOX Dim yellow        Gate grouping box in Catalog screen.
       CATGATE    Cyan              Color of gates in Catalog screen.
       CHART      Yellow            Default color of traces in Scope.
       CONFLICT   C-Red             Color of "signal-conflict" in a wire.
       CURSOR     White             Regular cursor color.
       DASHBOX    Dim yellow        Color of dashed boxes in circuits.
       DEFINEBACK Black             DEFINE command's box background.
       DEFINEBOX  Cyan              DEFINE command's box outline.
       DEFINETEXT Green             DEFINE command's text color.
       DIMGATE    Dim cyan          Color of "dimmed" gates in circuits.
       DIVISION   White             Color of grid dots in Scope.
       GATE       Cyan              Normal color of gates in circuits.
       GATEBLACK  Black             Black parts of gate pictures.
       GATEGREEN  Green             Green parts of gate pictures.
       GATEORANGE Orange            Orange parts of gate pictures.
       GATEPIN    Red               Color of gate connection dots.
       GATERED    Red               Red parts of gate pictures.
       GATEWHITE  White             White parts of gate pictures.
       GATEYELLOW Yellow            Yellow parts of gate pictures.
       GLOW1      Black             AnaLOG glow color for <= 0 volts.
       GLOW2      Dim red           AnaLOG glow color for 0-15
       GLOW3      Medium red        AnaLOG glow color for 15-50
       GLOW4      Red               AnaLOG glow color for 50-85
       GLOW5      Pink              AnaLOG glow color for 85-100
       GLOW6      White             AnaLOG glow color for >= Vdd.
       IDENTIFY   Red               Color of identified things in LOGNTK.
       IMETER     Orange            AnaLOG current meter readout.
       INSTANCE   Dim yellow        Name shown in Digital instance gates.
       KINDGATE   Green             Color of gates in menu area.
       LABELTEXT  Dim yellow        Color of circuit labels.
       LIMITON    Red               AnaLOG current-limit indicator.
       MARKER     Pink              Color of printing markers.
       MENUWORD   Green             Color of text in menu area.
       MESSAGE    Yellow            Informative messages in drawing area.
       OFFLED     Black             Digital LOG logic "0" signal.
       ONLED      Red               Digital LOG logic "1" signal.
       PAGE1      Green             Color of the word "PAGE".
       PAGE2      Yellow            Color of current page number.
       PAGE3      Green             Color of the word "OF".
       PAGE4      Yellow            Color of maximum page number.
       PEN1       White             Color for plotter pens #1-6.
       PEN2       Red               . These colors are used by the PLOT
       PEN3       Green             . command for circuit and data
       PEN4       Orange            . plotting.
       PEN5       Cyan              .
       PEN6       Yellow            .
       POPUPBOX   White             Outline of pop-up menus.
       POPUPWORD  Green             Text in pop-up menus.
       POPUPSEL   Pink              Highlighted text in pop-up menus.
       PROBE      Dim yellow        AnaLOG probe-mode display color.
       REDWORD    Red               Red text in pop-up menus.
       SCROLL     White             Color of scroll-indication lines.
       SELECT     White             Color of area-selection rectangle.
       SELWORD    Yellow            Highlighted words in menu area.
       SIGNAL     Pink              Color of TO/FROM signal names.
       SOLDER     Green             Color of solder dots on wires.
       SWITCHOFF  Light gray        AnaLOG switch "off" color.
       SWITCHON   Light gray        AnaLOG switch "on" color.
       TEMPLATE   Pink              Name shown in Digital template gates.
       TIME       Dim yellow        Color of TIME gate display
       VMETER     Dim yellow        AnaLOG voltage meter readout.
       WIRE       Green             Color of non-glowing wires.
       XWIRE      X-Green           Color of wires being drawn.

COMMAND-LINE OPTIONS

	These are all the command-line options log currently understands:

	-x displayname     : This option specifies the screen where the
			     newcrt and mylib windows will appear. For
			     example, the command analog -x foo.school.edu:0.0
                             results in the newcrt and mylib windows 
			     appearing on the console of the machine
			     foo.school.edu. An alternative to setting the
			     DISPLAY environment variable in the launch shell.

	-c filename        : Specifies a .cnf configuration file.


X DISPLAY PREFERENCES
	
	Log looks in your .Xresources file for geometry information.  If set
	properly, this allows windows of a certain size to be automatically
	placed at a particular place at every invocation of log; manual
	placement of windows is no longer necessary. This feature was added by
	Jim Clark at Harvard. Adding these lines to your .Xresources file:

	mylib.geometry: =1150x550+0+0
	newcrt.geometry: +510+586

	will result in good placement and sizing for the color monitors
	shipped with SPARC IPC's; for other screens, charge the numbers after
	"+" signs for new positions, and change the numbers between the "x"
	for modify the size of the mylib window. The newcrt window cannot be
	modified; log expects it to be a fixed size.

	Psys now senses if a display screen is black and white, and tries to
	use stipple instead of colors. However, there are times where you want
	to force the tools to display in black and white, even if the display
	screen is color. These times include using an OS/2 based color PC as an
	X terminal for the analog tools, because of present incompatibilities
	between PC graphics cards and analog. To force a black and white
	display, add this line to your .Xresources file:

	mylib.color:  black_and_white

	and then restart your X server. Black and white support was provided
	by Tor Sverre Lande (Oslo), and the .Xresources flag was added by Mike
	Godfrey (Stanford).

	Color functions can also be set via an environment variable, 
        LOG_COLOR. 

        Chipmunk tools currently support monochrome, 8-bit, 16-bit, and 24-bit
        displays.  The 16-bit and 24-bit display modes are only known to work
        on the PC architecture (X11 under Linux and OS/2).

        By default, the Chipmunk tools select a color mode using these rules: 

         If Pseudo-Color mode is supported with a depth of at least 8 bits, the
         tool uses 8-bit mode. 
     
         If Pseudo-Color mode is not supported but TrueColor mode is supported,
         the tool uses 24-bit depth if available, or 16-bit depth if 24-bit
         depth is not available.

         If all else fails, monochrome mode is selected. 

       The user can force the color mode of a Chipmunk tool by setting the
       environment variable LOG_COLOR to be the string bw or 8bit or 16bit or
       24bit.


(End of LOG documentation.)