Questions tagged [dos-com]

COM files are headerless 16-bit executable files which were used in CP/M, PC-DOS, and MS-DOS. The files also run under 32-bit versions of Windows via NTVDM or in emulation software such as DosBox or DOSEMU.. For Component Object Model, use the tag "com" instead.

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How to create executable COM file from hexdump code of msdos 8086

I've got an hexdump of COM MSDOS 8086 file, and I'm trying to transform it to COM executable. After looking around, I found a site1 that gives reasonable disassembly of the hexdump. Although, when I ...
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2answers
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Why does IDA add “db” statements between disassembled code

I'm trying to analyze a MS-DOS COM file that I wrote a few years ago with IDA Free 5.0, I've since renamed the segment to code_and_data and named constants and set data types correctly. However, when ...
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1answer
152 views

COM file starting point

I'm having issue reversing a small old COM file from the early 90s. My understanding was that code begins at 0x100, however the one I have seems to begin at 0x90 (0s before). However some of the ...
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5answers
7k views

Decompilation techniques for DOS .COM files

I've found a binary copy of a DOS freeware game I was fond of back in the day (Firefighter, downloadable as FIRE.COM) but the source code is not available. I'd like to re-implement it in C or Python ...
4
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1answer
392 views

Cannot trace an MS-DOS COM file

When debugging the following com file in MS-DOS, I can successfully run the program with -g and it terminates normally, but when I trace it -t 1000, the program throws an illegal operation exception ...
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3answers
673 views

Working with DOS .COM files

What can I do to reverse engineer a DOS .COM file? As far as debugging goes, I've looked DEBUG and DEBUGX from the creators of FreeDOS, as well as the default DEBUG command that comes with Windows. ...