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mkdisk(1) mkdisk(1)
[1mName[0m
mkdisk - Make a blank emulated floppy or hard disk for xtrs, or
add/remove an emulated write protect tab
[1mSyntax[0m
[1mmkdisk -1 filename[0m
[1mmkdisk [-3] filename[0m
[1mmkdisk -k [-s sides] [-d density] [-8] [-i] filename[0m
[1mmkdisk -h [-c cyl] [-s sec] [-g gran] filename[0m
[1mmkdisk {-p|-u} {-1|-3|-k|-h} filename[0m
[1mDescription[0m
The mkdisk program is part of the [1mxtrs[22m(1) package. It has two distinct
functions: (1) It can make a blank (unformatted) emulated floppy or
hard drive in a file. (2) With the -p or -u flag, it can turn the
write protect flag on or off for an existing emulated floppy or hard
drive file. See the xtrs man page for background information.
The conventional file extensions are .dsk for emulated floppies and
.hdv for emulated hard drives, but [1mmkdisk [22mdoes not enforce this conven-
tion; you can use any filename. Other extensions sometimes used for
emulated floppies are .jv1, .jv3, .8in, and .dmk.
[1mMaking Emulated Floppies[0m
With the -1 flag, [1mmkdisk [22mmakes an unformatted emulated floppy of type
JV1. No additional flags are accepted.
With the -3 flag (which is the default and should normally be used),
[1mmkdisk [22mmakes an unformatted emulated floppy of type JV3. No additional
flags are accepted.
With the -k flag, [1mmkdisk [22mmakes an unformatted emulated floppy of type
DMK. With -k, the optional flags -s, -d, -8, and -i can be used to
give the emulated floppy special properties. Specifying -s1 limits the
floppy to one side; with -s2 (the default), the floppy can be formatted
as either one- or two-sided. Specifying -d1 limits the floppy to sin-
gle density; with -d2 (the default), the floppy can be formatted in
either single or double density. Specifying -8 allows the floppy to be
formatted in an emulated 8" drive; by default it will work properly
only in an emulated 5" drive. Setting -s1 or -d1 saves space after the
floppy is formatted; setting -8 consumes additional space. Specifying
-i activates a peculiar feature in some TRS-80 emulators that causes
each formatted sector to appear to be both single and double density.
[1mMaking Emulated Hard Drives[0m
With the -h flag, [1mmkdisk [22mmakes an unformatted emulated hard drive with
[4mcyl[24m cylinders, [4msec[24m sectors, and [4mgran[24m granules (LDOS allocation units)
per cylinder. The hard drive will have cylinder [4mdir[24m marked for use as
its directory.
You will usually want to use the default values for all these parame-
ters. The default is 202 cylinders, 256 sectors per cylinder (that is,
8 heads and 32 sectors per track), and 8 granules per cylinder. This
is the largest hard drive that can be used by all LDOS/LS-DOS operating
systems without partitioning the drive or patching the FORMAT command.
The details on what nondefault values are possible vary, depending on
which of xtrs's two hard drive emulations you are using and which other
emulators you want to be compatible with, and it is probably best not
to delve into these complexities, but read on if you really want to.
For [4mcyl[24m, the number of cylinders on the drive, the default value is
202, the minimum is 3, and the maximum that can be represented in the
HDV file's header is 256. You can use 203 cylinders with LDOS and LS-
DOS if you format the drive with Model 4 LS-DOS; a minor bug in Model
I/III FORMAT/CMD prevents more than 202 cylinders from being formatted,
but the system can use 203 thereafter. 203 cylinders is the absolute
maximum for LDOS/LS-DOS drivers that do not support partitioning,
including the emulator-specific drivers supplied with xtrs (XTR-
SHARD/DCT), with Matthew Reed's emulator (HARD/CMD), and with David
Keil's emulator (EHARD/DCT).
In xtrs 4.1 and later, and in David Keil's emulator version 6.0 and
later, a true emulation of Radio Shack's WD1010-based hard disk con-
troller is also available, which works with the native drivers for the
original hardware, such as RSHARDx/DCT and the hard disk drivers for
NEWDOS and CP/M. In xtrs, the WD1010 emulation ignores the maximum
number of cylinders specified in the HDV file's header and allows the
driver to format up to 65536 cylinders. This may be useful if your
drivers support partitioning (but why would anyone want to partition an
emulated hard drive instead of just making two smaller ones?), or if
your operating system supports more than 203 cylinders per partition.
Note that although RSHARDx/DCT allows up to 406 cylinders per parti-
tion, if you use more than 203, the maximum number of sectors per
cylinder is limited to 128, so you gain nothing; the maximum size of a
partition is still the same.
For [4msec[24m, the number of sectors per cylinder, the default value is 256,
the maximum is 256, and the minimum is 4. There are some restrictions
on the values that will work. For the greatest portability, choose a
value that is divisible by 32. With xtrs's XTRSHARD/DCT and David
Keil's EHARD/DCT, any value is allowed that can be evenly divided into
granules; see the next paragraph. With Matthew Reed's HARD/CMD, if [4msec[0m
is greater than 32, it must be divisible by 32. With the emulation of
a real WD1010 in newer versions of xtrs (and probably David Keil's emu-
lator too), [4msec[24m must always be divisible by 32, because we always emu-
late a drive with 32 sectors per track and from 1 to 8 heads (tracks
per cylinder). The RSHARDx/DCT driver assumes that there are always 32
sectors per track.
For [4mgran[24m, the default value is 8, the maximum is 8, and the minimum is
1. In addition, it is necessary that [4msec[24m be evenly divisible by [4mgran[24m,
and that [4msec/gran[24m be less than or equal to 32. This value is used only
with the emulator-specific drivers listed above; it is ignored when
xtrs is using native hardware drivers such as RSHARDx/DCT.
The maximum size of a hard drive image is controlled by [4mcyl[24m and [4msec[24m: it
can be at most [4mcyl*sec[24m 256-byte sectors. The image file starts out
small and grows as you write to more cylinders. The allocation effi-
ciency is controlled by the granule size: LDOS allocates file space in
granules. Therefore (1) [4mgran[24m should always be set as large as possible
and (2) reducing [4msec[24m, thereby making the granules smaller, reduces
wasted space due to fragmentation but limits the maximum size of the
drive.
Seeing that the maximum unpartitioned drive size is less than 13 MB and
that the maximum granule size is only 8 KB, wasted space should not be
much of a concern for most [1mxtrs [22musers. Therefore the default parame-
ters have been chosen to give you the largest drive possible without
partitioning.
[1mWrite Protection[0m
With the -p flag, [1mmkdisk [22mturns on write protection for an existing emu-
lated floppy or hard drive. It turns off all Unix write permission
bits on the file, and (except for JV1 floppies) also sets a write-pro-
tected flag inside the file.
With the -u flag, [1mmkdisk [22mturns off write protection for an existing
emulated floppy or hard drive. It turns on Unix write permissions to
the file, masked by your current umask and the file's current read per-
missions. It also clears a write-protected flag inside the file
(except on JV1 floppies, which don't have such a flag).
[1mmkdisk [22mcurrently does not have code to auto-recognize file formats, so
the -p or -u flag must be accompanied by either -1 (JV1), -3 (JV3), -k
(DMK), or -h (hard disk) to identify the file format. There is also no
checking for the correct file format, so if you give the wrong flag,
the wrong byte inside your file will be changed.
[1mTechnical data[0m
The JV1 format is just an array of 256-byte sectors, in the order
(track 0 sector 0, track 0 sector 1, ... track 0 sector 9, track 1 sec-
tor 0, ...). It can represent only single-sided, single-density flop-
pies. The directory is assumed to be track 17.
The original JV3 format is documented in the printed manual for Jeff
Vavasour's commercial Model III/4 emulator. The xtrs implementation
includes some extensions.
Full documentation for both JV1 and JV3 can be found at http://www.tim-
mann.org/trs80/dskspec.html. A copy of this html file is also included
in the [1mxtrs [22mdistribution.
The DMK format is documented in a file on David Keil's web site,
http://discover-net.net/~dmkeil/trsdoc.htm#Technical-disks; this file
is also included with his emulator. Some updates to the 4.00 version
of the document: (1) If neither the single density nor ignore density
option is set and single density data is recorded, each single density
byte is written twice (i.e., the four bytes 12345678 would be written
as 1212343456567878). This ensures that when single and double density
sectors are mixed, each type occupies the correct relative amount of
space in the track. This update will be effective in version 4.3 of
David's emulator; it is incompatible with previous versions. (2) Bit 15
of an IDAM offset is 1 if the sector is double-density, 0 if single
density. Bit 14 is reserved; it currently must be 0. The actual off-
set is in bits 13-0. These offsets are relative to the start of the
track header, they must be in ascending order (I hope!!), and an offset
of 0 or 0xffff terminates the list.
An HDV (hard disk) image has the following format. This information is
based on email from Matthew Reed. There is an initial 256-byte header
block, followed by an array of sectors. The geometry of the drive is
defined in the header block, which looks like this (from mkdisk.c):
typedef unsigned char Uchar;
typedef struct {
Uchar id1; /* 0: Identifier #1: 56H */
Uchar id2; /* 1: Identifier #2: CBH */
Uchar ver; /* 2: Version of format: 10H = version 1.0 */
Uchar cksum; /* 3: Simple checksum:
To calculate, add together bytes 0 to 31 of header
(excepting byte 3), then XOR result with 4CH */
Uchar blks; /* 4: Number of 256 byte blocks in header: should be 1 */
Uchar mb4; /* 5: Not used, currently set to 4 */
Uchar media; /* 6: Media type: 0 for hard disk */
Uchar flag1; /* 7: Flags #1:
bit 7: Write protected: 0 for no, 1 for yes
[warning: xtrs currently ignores this flag]
bit 6: Must be 0
bit 5 - 0: reserved */
Uchar flag2; /* 8: Flags #2: reserved */
Uchar flag3; /* 9: Flags #3: reserved */
Uchar crtr; /* 10: Created by:
14H = HDFORMAT
42H = xtrs mkdisk
80H = Cervasio xtrshard port to Vavasour M4 emulator */
Uchar dfmt; /* 11: Disk format: 0 = LDOS/LS-DOS */
Uchar mm; /* 12: Creation month: mm */
Uchar dd; /* 13: Creation day: dd */
Uchar yy; /* 14: Creation year: yy (offset from 1900) */
Uchar res1[12]; /* 15 - 26: reserved */
Uchar dparm; /* 27: Disk parameters: (unused with hard drives)
bit 7: Density: 0 = double, 1 = single
bit 6: Sides: 0 = one side, 1 = 2 sides
bit 5: First sector: 0 if sector 0, 1 if sector 1
bit 4: DAM convention: 0 if normal (LDOS),
1 if reversed (TRSDOS 1.3)
bit 3 - 0: reserved */
Uchar cyl; /* 28: Number of cylinders per disk */
Uchar sec; /* 29: Number of sectors per track (floppy); cyl (hard) */
Uchar gran; /* 30: Number of granules per track (floppy); cyl (hard)*/
Uchar dcyl; /* 31: Directory cylinder [mkdisk sets to 1; xtrs
ignores, but value must be correct if image is
to be used with Reed emulators.] */
char label[32]; /* 32: Volume label: 31 bytes terminated by 0 */
char filename[8];/* 64 - 71: 8 characters of filename (without extension)
[Cervasio addition. xtrs actually doesn't limit this
to 8 chars or strip the extension] */
Uchar res2[184]; /* 72 - 255: reserved */
} ReedHardHeader;
[1mSee also[0m
[1mxtrs[22m(1)
http://www.tim-mann.org/trs80/dskspec.html
[1mAuthors[0m
[1mmkdisk [22mwas written by Timothy Mann (see http://tim-mann.org/).
The floppy file formats here called JV1 and JV3 were developed by Jeff
Vavasour for his MSDOS-based Model I and Model III/4 emulators (respec-
tively). They have become a de facto standard in the TRS-80 emulation
community, and much TRS-80 software is available on the Internet in
.dsk format. Thanks to Jeff for designing and documenting the formats.
The format here called DMK was developed by David Keil for his MSDOS-
based Model 4 emulator. This format has the advantage that it can rep-
resent essentially everything the original TRS-80 floppy disk con-
trollers can write, including all forms of copy protected disk. Thanks
to David for designing and documenting this format.
The hard drive format was developed by Matthew Reed for his MSDOS-based
Model I/III and Model 4 emulators. I have duplicated his format to
allow users to exchange .hdv hard drive images between [1mxtrs [22mand
Matthew's emulators. Thanks to Matthew for designing the format and
providing documentation.
mkdisk(1)
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