On 20/05/2011 14:00, clipka wrote:
> Am 20.05.2011 10:12, schrieb Invisible:
>
>>> A COM file is raw machine code without any headers, at least on CP/M. A
>>> COM file was executed by reading it into 0x100 and branching to 0x100.
>>
>> That appears to be the case for MS-DOS as well. (I know gasm has a "COM
>> output" option which appears to match this description.)
>
> I'm not exactly sure, but AFAIR the MS-DOS COM files had a small header
> before the actual code. (That one was simply copied into memory as well
> though.)

http://en.wikipedia.org/wiki/COM_file

Claims there's no header for CP/M or MS-DOS.

> MS-DOS also didn't place COM files at address 0x100, but rather at a
> fixed offset in an arbitrary segment.

You might be right about that. I was reading about it because I wanted 
to write a boot loader - which really *is* loaded at a fixed physical 
address...

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