I'm wondering what steps to take to get a debugger to load a .fas file. I did see this thread on the subject but I tried OllyDBG to load a .fas file and it said it wasn't a valid 32-bit program.

look here http://board.flatassembler.net/topic.php?p=114370, youshould use a plugin to load .fas file AS debug info for ollydbg. you cannot just load a .fas file in olydbg as an executable binary, because it inot an executable binary at all.

Also note that Ollydbg is a 32-bit debugger. It doesn't support 16-bit mode.

So now I'm confused, there is no way even with hacking to get it to work with 16 bit or there are workarounds.



Tried that. I decided to just to TASM for my 16 bit stuff and translate them to FASM code once its debugged.

It would require a very considerable amount of hacking (code talk for: a complete rewrite) to get OllyDbg to work with 16-bit code.

http://japheth.de/
Look for 'debugger'

http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/devel/c/openwatcom/1.9/

http://ladsoft.tripod.com/grdb.htm

http://www.japheth.de/debxxf.html

None of these work with .FAS, though, but hey, they do support 16-bit.

GRDB | FreeDOS DEBUG | Insight (the right one) RTFW no "FAS" though

In good old times I've been most successful with Periscope debugger even without hardware add-on. Non-Windows version did worked under plain DOS in 16bit mode. Another debugger that a lot of people used was Borland Turbo Debugger. Another good but not widely used debugger is D86 from A86 package: http://eji.com/a86/

I like it becouse of two column disassembly display.

Unfortunately none of those packages support fas files. Also keep in mind that D86 does not work under DosBox if I remember correctly.