COM Format
Intel byte order

Information from File Format List 2.0 by Max Maischein.

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If you notice any mistakes or omissions, please let me know!  It is only
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This file has been authored in the style of the INTERxxy.* file list
by Ralf Brown, and uses almost the same format.

Please read the file FILEFMTS.1ST before asking me any questions. You may find
that they have already been addressed.

         Max Maischein

Max Maischein, 2:244/1106.17
Max_Maischein@spam.fido.de
corion@informatik.uni-frankfurt.de
Corion on #coders@IRC
--------!-DISCLAIMER------------------------
DISCLAIMER:  THIS MATERIAL IS PROVIDED "AS IS".  I verify the information
contained in this list to the best of my ability, but I cannot be held
responsible for any problems caused by use or misuse of the information,
especially for those file formats foreign to the PC, like AMIGA or SUN file
formats. If an information it is marked "guesswork" or undocumented, you
should check it carefully to make sure your program will not break with
an unexpected value (and please let me know whether or not it works
the same way).

Information marked with "???" is known to be incomplete or guesswork.

Some file formats were not released by their creators, others are regarded
as proprietary, which means that if your programs deal with them, you
might be looking for trouble. I don't care about this.
--------------------------------------------

The COM files are raw binary executables and are a leftover from the old
CP/M machines with 64K RAM.  A COM program can only have a size of less
than one segment (64K), including code and static data since no fixups for
segment relocation or anything else is included. One method to check for a
COM file is to check if the first byte in the file could be a valid jump
or call opcode, but this is a very weak test since a COM file is not
required to start with a jump or a call. In principle, a COM file is just
loaded at offset 100h in the segment and then executed.

OFFSET              Count TYPE   Description
0000h                   1 byte   ID=0E9h
                                 ID=0EBh
                                 Those are not safe ways to determine wether a
                                 file is a COM file or not, but most COM files
                                 start with a jump.
Further information not available.
EXTENSION:COM
OCCURENCES:PC
SEE ALSO:EXE,MZ EXE,NE EXE