This is a summary of the differences between VIM and vi. It is not complete.
see also reference.doc and look for comments in {}.


The most interesting additions:

Vi compatibility.
When the 'compatible' option is set, all options are given a vi-compatible
value. Vim will behave like the "real" vi as much as possible.


Multi level undo.
'u' goes backward in time, 'ctrl-R' goes forward again. Set option 
'undolines' to the number of changes to be remembered (default 100). Set 
'undolines' to 0 for vi-compatible one level undo.

When all changes in a buffer have been undone, the buffer is not considered
changed anymore. You can exit it with :q, without <!>.


Multiple windows and buffers.
Vim can split the screen into several windows, each editing a different
buffer or the same buffer at a different location. Buffers can still be
loaded (and changed) but not displayed in a window. This is called a hidden
buffer. Many commands and options have been added for this facility, see
windows.doc.


Repeat a series of commands.
'q'<c> starts recording typed characters into named register <c> (append to
the register if register name is upper case). A subsequent 'q' stops
recording. The register can then be executed with the '@'<c> command. This is
very useful to repeat a complex action.


Flexible insert mode.
The arrow keys can be used in insert mode to move around in the file. This 
breaks the insert in two parts as far as undo and redo is concerned.

CTRL-O can be used to execute a single command-mode command. This is almost 
the same as hitting ESC, typing the command and hitting 'a'. For undo/redo 
only those inserts are remembered where something was actually inserted.


Visual mode.
Visual can be used to first choose a piece of text and then give a command 
to do something with it. This is an (easy to use) alternative to first giving 
the operator and then moving to the end of the text to be operated upon. 'v' 
and 'V' are used to start Visual mode. 'v' works on characters and 'V' on
lines. Move the cursor to extend the Visual part. It is shown highlighted on
the screen. By typing 'o' the other end of the Visual text can be moved. The
Visual text can be affected by an operator:
	d	delete
	c	change
	y	yank
	> or <	insert or delete indent
	!	filter through external program
	=	filter through indent
	:	start ":" command for the Visual lines.
	Q	format text to 'textwidth' columns
	J	join lines
	~	swap case
	u	make lowercase
	U	make uppercase


Block operators.
With Visual a rectangular block of text can be selected. Start Visual with 
CTRL-V. The block can be deleted ('d'), yanked ('y') or its case can be 
changed ('~', 'u' and 'U'). A deleted or yanked block can be put into the
text with the 'p' and 'P' commands.


Online help.
':help' command and help key (F1 for MSDOS) display several pages of concise 
help. The name of the help file can be set with the "helpfile" option.


Command line editing.
You can insert or delete at any place in the command line using the cursor 
keys. The right/left cursor keys can be used to move forward/backward one 
character. The shifted right/left cursor keys can be used to move 
forward/backward one word. CTRL-B/CTRL-E can be used to go to the begin/end
of the command line.

The command lines are remembered. The up/down cursor keys can be used to 
recall previous command lines. The 'history' option can be set to the number 
of lines that will be remembered.


Command line completion.
While entering a command line (on the bottom line of the screen) <TAB> can be 
typed to complete
   what		example		where
- a command	:e<TAB>		at start of command line
- a tag		:ta no<TAB>	after :ta
- an option	:set sc<TAB>	after :set
- a filename	:e v<TAB>	after any command that accepts a filename

If there are multiple matches, CTRL-N (next) and CTRL-P (previous) will walk
through the matches. <TAB> works line CTRL-N, but wraps around to the first
match.

The 'wildchar' option can be set to the character for command line
completion, <TAB> is the default. CTRL-D can be typed after an (incomplete)
wildcard; all matches will be listed. CTRL-A will insert all matches.
CTRL-L will insert the longest common part of the matches.


Horizontal scrolling.
If the 'wrap' option is off, long lines will not wrap and only part of them
will be shown. When the cursor is moved to a part that is not shown, the
screen will scroll horizontally. The minimal number of columns to scroll can
be set with the 'sidescroll' option.


Text formatting.
The 'textwidth' (tw) option can be used to automatically limit the line 
length. This supplements the 'wrapmargin' option of Vi, which was not very 
useful. The 'Q' operator can be used to format a piece of text ("Q}" formats 
a paragraph). Commands for text alignment: ":center", ":left" and ":right".


Edit-compile-edit speedup.
The ":make" command can be used to run the compilation and jump to the first
error. Alternatively Vim can be started with the "-e" option from the
compiler. A file with compiler error messages is interpreted. Each line in
the error file is scanned for the name of a file, line number and error
message. Vim starts editing at the first error. Optionally the name of the
error file can be given with "-e errorfile". The ":cn" command can be used to
jump to the next error. ":cl" lists all the error messages. Other commands
are available (almost the same as with Manx's Z editor). The 'errorfile'
option has the name of the file with error messages. The 'errorformat' option
can be set to a scanf-like string to handle output from many compilers. The
'makeprg' option contains the name of the program to be executed with the
":make" command. The 'shellpipe' option contains the string to be used to put
the output of the compiler into the errorfile.


Command line options:

When Vim is started with "-v" (View) then readonly mode is used (includes 
"-n").

When Vim is started with "-b" (Binary) then some options are set to be able
to edit binary or executable files.

When Vim is started with "-s scriptfile", the characters read from 
"scriptfile" are treated as if you typed them. If end of file is reached 
before the editor exits, further characters are read from the console.

The "-w" option can be used to record all typed characters in a script file. 
This file can then be used to redo the editing, possibly on another file or 
after changing some commands in the script file.

The "-n" option disables the writing of a ".swp" file (see below).

The "-c command" option does the same as the the "+command" option.

The "-T terminal" option sets the terminal type.

The "-e" option starts Vim in quickfix mode.

The "-o" option opens a window for each argument. "-o4" opens four windows.


In command mode:

Missing command: 'Q' (go to Ex mode).
Missing Ex commands: append, change, insert, open, recover and z.

The command characters are shown in the last line of the screen. They are 
removed when the command is finished. If you do not want this (on a slow 
terminal) reset the 'showcmd' option.

If the 'ruler' option is set, the current cursor position is shown in the 
last line of the screen.

'u' and CTRL-R accept a count for the number of undos/redos.

'U' still works after having moved off of the last changed line and after 
'u'.

Nulls in the file are replaced by <LF> internally. This allows editing of 
binary files (more or less).

Characters with the 8th bit set are displayed. The characters between '~' and 
0xa0 are displayed as "~?", "~@", "~A", etc., unless the "graphic' option is 
set.

'=' is an operator to filter lines through an external command (vi: lisp 
stuff). The name of the command can be set with the 'equalprg' option. The 
default is "indent".

'][' goes to the next ending of a C function ('}' in column 1).
'[]' goes to the previous ending of a C function ('}' in column 1).

']f', '[f' and 'gf' start editing the file whose name is under the cursor.
CTRL-W f splits the window and starts editint the file whose name is under
the cursor.

'*' searches forward for the identifier under the cursor, '#' backward.
'K' runs the program defined by the "keywordprg" option, with the identifier 
under the cursor as argument.

'%' can be preceded with a count. The cursor jumps to the line that 
percentage down in the file. The normal '%' function to jump to the matching
brace skips braces inside quotes.

With the CTRL-] command, the cursor may be in the middle of the identifier.

The used tags are remembered. Commands that can be used with the tag stack 
are CTRL-T, ':pop' and ':tag'. ':tags' lists the tag stack.

The 'tags' option can be set to a list of tag file names. Thus multiple 
tag files can be used.

Previously used file names are remembered in the alternate file name list.
CTRL-^ accepts a count, which is an index in this list.

Search patterns have more features. The <NL> character is seen as part of the
search pattern and the substitute string of ":s". Vi sees it as the end of
the command.

Searches can put the cursor on the end of a match and may include a character
offset.

Count added to '~', ':next', ':Next', 'n' and 'N'.

The command ":next!" with 'autowrite' set does not write the file. In vi the
file was written, but this is considered to be a bug, because one does not
expect it and the file is not written with ':rewind!'.

"5r<CR>" replaces five characters by five line breaks. Vi replaces five
characters with a single line break.

Added :wnext command. Same as ":write" followed by ":next".

The ":w!" command always writes, also when the file is write protected.

If option "tildeop" has been set, '~' is an operator (must be followed by a 
movement command).

With the 'J' (join) command you can reset the 'joinspaces' (js) option to 
have only one space after a period (Vi inserts two spaces).

'cw' can be used to change white space formed by several characters (Vi is 
confusing: 'cw' only changes one space, while 'dw' deletes all white space).

'o' and 'O' accept a count for repeating the insert (Vi clears a part of 
display).

':dis' command shows the contents of the yank register.

Previously used file names are remembered in the alternate file name list.
":files" command shows the list of alternate filenames.
'#'<N> is replaced by the <N>th alternate filename in the list.
"#<" is replaced by the current filename without extension.

Flags after command not supported (no plans to include it).

On non-UNIX systems ":cd" command shows current directory instead of going to
the home directory. ":pwd" prints the current directory on all systems.

':source!' command reads Vi commands from a file.

':mkexrc' command writes current modified options and mappings to a ".exrc" 
file. ':mkvimrc' writes to a ".vimrc" file.

No check for "tail recursion" with mappings. This allows things like
":map! foo ^]foo".

The :put! command inserts the contents of a register above the current line.

The 'p' and 'P' commands of vi cannot be repeated with '.' when the putted
text is less than a line. In Vim they can always be repeated.

The named register '.' can be used with commands p, P and :put. The contents 
of the register is the last inserted text.

":noremap" command can be used to enter a mapping that will not be remapped.
This is useful to exchange the meaning of two keys. ":cmap", ":cunmap" and
":cnoremap" can be used for mapping in command line editing only. ":imap",
":iunmap" and ":inoremap" can be used for mapping in insert mode only.
Similar commands exist for abbreviations: ":noreabbrev", ":iabbrev"
":cabbrev", ":iunabbrev", ":cunabbrev", ":inoreabbrev", ":cnoreabbrev".

In vi the command ":map foo bar" would remove a previous mapping
":map bug foo". This is considered a bug, so it is not included in Vim.
":unmap! foo" does remove ":map! bug foo", because unmapping would be very
difficult otherwise (this is vi compatible).

":@r" command executes register r (is in some versions of vi).

The ':' register contains the last command line.
The '%' register contians the current file name.

CTRL-O/CTRL-I can be used to jump to older/newer positions. These are the 
same positions as used with the '' command, but may be in another file. The 
':jumps' command lists the older positions.

If the 'shiftround' option is set, an indent is rounded to a multiple of 
'shiftwidth' with '>' and '<' commands.

The 'scrolljump' option can be set to the minimal number of lines to scroll 
when the cursor gets off the screen. Use this when scrolling is slow.

Uppercase marks can be used to jump between files. The ':marks' command lists 
all currently set marks. The commands "']" and "`]" jump to the end of the 
previous operator or end of the text inserted with the put command. "'[" and 
"`[" do jump to the start.

The 'shelltype' option can be set to reflect the type of shell used.

The 'highlight' option can be set for the higlight mode to be used for
several commands.

The CTRL-A (add) and CTRL-X (subtract) commands are new. The count to the 
command (default 1) is added to/subtracted from the number at or after the 
cursor. That number may be decimal, octal (starts with a '0') or hexadecimal 
(starts with '0x'). Very useful in macros.

With the :set command the prefix "inv" can be used to invert toggle options.

In both Vi and Vim you can create a line break with the ":substitute" command
by using a CTRL-M. For Vi this means you cannot insert a real CTRL-M in the
text. With Vim you can put a real CTRL-M in the text by preceding it with a
CTRL-V.


In insert mode:

If the 'revins' option is set, insert happens backwards. This is for typing
Hebrew. When inserting normal characters the cursor will not be shifted and
the text moves rightwards. In replace mode the cursor will move leftwards.
Backspace, CTRL-W and CTRL-U will also work in the opposite direction. CTRL-B
toggles the 'revins' option.

The backspace key can be used just like CTRL-D to remove auto-indents.

You can backspace, ctrl-U and CTRL-W over line breaks if the 'backspace' (bs) 
option is set to non-zero. You can backspace over the start of insert if the 
'backspace' option is set to 2.

When the 'paste' option is set, a few option are reset and mapping in insert
mode and abbreviation are disabled. This allows for pasting text in windowing
systems without unexpected results. When the 'paste' option is reset, the old
option values are restored.

CTRL-T/CTRL-D always insert/delete an indent in the current line, no matter 
what column the cursor is in.

CTRL-@ (insert previously inserted text) works always (Vi: only when typed as 
first character).

CTRL-A works like CTRL-@ but does not leave insert mode.

CTRL-R <0-9a-z> can be used to insert the contents of a register.

When the 'smartindent' (si) option is set, C programs will be better 
auto-indented.

CTRL-Y and CTRL-E can be used to copy a character from above/below the 
current cursor position.

After CTRL-V you can enter a three digit decimal number. This byte value is 
inserted in the text as a single character. Useful for international 
characters that are not on your keyboard.

When the 'expandtab' (et) option is set, a <TAB> is expanded to the 
appropriate number of spaces.

The window always reflects the contents of the buffer (Vi does not do this 
when changing text and in some other cases).

If Vim is compiled with DIGRAPHS defined, digraphs are supported. A set of 
normal Amiga digraphs is included. They are shown with the :digraph" command. 
More can be added with ":digraph {char1}{char2} {number}". A digraph is 
entered with "CTRL-K {char1} {char2}" or "{char1} BS {char2}" (only when 
'digraph' option is set).

When repeating an insert, e.g. "10atest <ESC>" vi would only handle wrapmargin
for the first insert. Vim does it for all.


In command line mode:

ESC terminates the command line without executing it. In vi the command line
would be executed, which is not what most people expect (hitting ESC should
always get you back to command mode). To avoid problems with some
obscure macros, an ESC in a macro will execute the command. If you want a
typed ESC to execute the command like vi does you can fix this with
	":cmap ^V<ESC> ^V<CR>"

general:

Missing options: autoprint (ap), beautify (bf), edcompatible, hardtabs (ht), 
lisp, mesg, open, optimize (op), prompt, redraw, slowopen (slow), terse,
window, w300, w1200 and w9600. These options can be set but are otherwise
ignored.

When the 'compatible' option is set, all options are set for maximum 
vi-compatibility

The 'ttimeout' option is like 'timeout', but only works for cursor and 
function keys, not for ordinary mapped characters. The 'timoutlen' option
gives the number of milliseconds that is waited for. If the 'esckeys' option
is not set, cursor and function keys that start with <ESC> are not recognized
in insert mode.

There is an option for each terminal string. Can be used when termcap is not 
supported or to change individual strings.

When the 'textmode' option is set (default for MSDOS) <CR><LF> is used as
line separator. When reset (default for Unix and Amiga) <LF> is used. When
the 'textauto' option is set, Vim tries to detect the type of line separator
used by reading up to the first <LF>. The 'textmode' option is set
accordingly.

On systems that have no job control (most systems but BSD-UNIX) the CTRL-Z, 
":stop" or ":suspend" command starts a new shell.

If Vim is started on the Amiga without an interactive window for output, a 
window is opened (and :sh still works). You can give a device to use for 
editing with the '-d' argument, e.g. "-d con:20/20/600/150".

On startup the VIMINIT or EXINIT environment variables, the file s:.vimrc or 
s:.exrc and .vimrc or .exrc are read for initialization commands. When 
reading .vimrc and .exrc some commands are not allowed because of security 
reasons (shell commands and writing to a file, :map commands are echoed). 
This can be overrided with the 'secure' option.

Line lenght can be at least upto the maximum value of an int (for the Amiga
32767 characters, for most 32-bit systems much larger). Editing such lines is
not always possible. File length upto 2147483646 lines. If a line is larger
than the screen, the last line is filled with <@>s and only the part of the
line before that is shown (unless 'wrap' option is reset).

The 'columns' option is used to set or get the width of the display.

The name of the current file name is shown in the title bar of the window.

Wildcards in file names are expanded.

Option settings are read from the first and last few lines of the file. 
Option 'modelines' determines how many lines are tried (default is 5). Note 
that this is different from the Vi versions that can execute any Ex command 
in a modeline (a major security problem).

If the 'insertmode' option is set (e.g. in .exrc), Vim starts in insert mode.

All text is kept in memory. Available memory limits the file size (and other 
things such as undo). This may be a problem with MSDOS, is hardly a problem 
ont the Amiga and almost never with Unix.

If the 'backup' or 'writebackup' option is set: Before a file is overwritten, 
a backup file (.bak) is made. If the "backup" option is set it is left 
behind.

If the 'binary' option is set and the file does not have an end-of-line for
the last line, the end-of-line is not appended when writing.

Vim creates a file ending in ".swp" to store parts of the file that have been
changed or that do not fit in memory. This file can be used to recover from
an aborted editing session with "vim -r file". Using the swap file can be
switched off by setting the 'updatecount' option to 0 or starting Vim with
the "-n" option. Use the 'directory' option for placing the .swp file
somewhere else.

The 'shortname' (sn) option, when set, tells Vim that ".bak" and ".swp" 
filenames are to be MSDOS-like: 8 characters plus 3 for extention. This 
should be used on messydos or crossdos filesystems on the Amiga. If this 
option is off, Vim tries to guess if MSDOS filename restrictions are 
effective.

Recovery after a crash has a smaller chance for success, because there is no 
temporary file.

Error messages are shown at least one second (Vi overwrites error messages).

If Vim asks to "Hit RETURN to continue", you can hit any key. Characters 
other than <CR>, <LF> and <SPACE> are interpreted as the (start of) a 
command. (Vi only accepts a command starting with ':').

The contents of the numbered and unnamed registers is remembered when
changing files.

The AUX: device of the Amiga is supported.

vi:tw=77: