Hi all,

I've been looking for a utility that will let me step through a dos program and look at the instructions while also being able to see what is displayed on the screen. I've not had much luck in finding anything that'll do the job and open to suggestions if anyone knows of something that'll do the job.

Thanks,
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Re: Debugging 16 bit dos programs
By: Nelgin to All on Fri Jul 21 2023 05:17:38

NE> I've been looking for a utility that will let me step through a dos
NE> program and look at the instructions while also being able to see what
NE> is displayed on the screen. I've not had much luck in finding anything
NE> that'll do the job and open to suggestions if anyone knows of something
NE> that'll do the job.

Just brainstorming:

1) Use a serial port connected to a terminal emulator

DOS console:
ctty com1

Terminal emulator:
debug.com prog.exe

2) Dosbox debugger

https://www.vogons.org/viewtopic.php?t=3944

3) Bochs debugger

https://wiki.osdev.org/Bochs#Bochs_debugging_facilities

I have also seen utilities that support multi-headed PC configurations,
commonly a combination of CGA and Hercules adapters. Unfortunately, i
do not remember which debugger supports that.
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Re: Debugging 16 bit dos programs
By: Nelgin to All on Fri Jul 21 2023 05:17 am

> Hi all,
>
> I've been looking for a utility that will let me step through a dos program
> and look at the instructions while also being able to see what is displayed
> on the screen. I've not had much luck in finding anything that'll do the job
> and open to suggestions if anyone knows of something that'll do the job.

debug.exe is included with MS-DOS, isn't it?
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Re: Debugging 16 bit dos programs
By: Nelgin to All on Fri Jul 21 2023 05:17 am

Ne> I've been looking for a utility that will let me step through a dos
Ne> program and look at the instructions while also being able to see what is
Ne> displayed on the screen. I've not had much luck in finding anything
Ne> that'll do the job and open to suggestions if anyone knows of something
Ne> that'll do the job.

If you do that, you'll be seeing assembly code, and it will be without any meaningful variable names, etc.. IMO it tends to be more challenging to debug that than with higher-level code.

Nightfox

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-=> Nightfox wrote to Nelgin <=-

Ni> If you do that, you'll be seeing assembly code, and it will be without
Ni> any meaningful variable names, etc.. IMO it tends to be more
Ni> challenging to debug that than with higher-level code.

Unless the program you are debugging was compiled in debug mode, there won't be
any meaningful variables names anyway.

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Re: Debugging 16 bit dos prog
By: Dr. What to Nightfox on Sat Jul 22 2023 08:21 am

Ni>> If you do that, you'll be seeing assembly code, and it will be
Ni>> without any meaningful variable names, etc.. IMO it tends to be
Ni>> more challenging to debug that than with higher-level code.

DW> Unless the program you are debugging was compiled in debug mode, there
DW> won't be any meaningful variables names anyway.

Yeah, but who releases a program built in debug mode? Normally, a debug build would only be used by developers while developing the program. When releasing it, a release build makes the most sense. A release build runs faster; also, many software companies wouldn't want people to easily reverse-engineer their binaries.

Nightfox

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-=> Nightfox wrote to Dr. What <=-

DW> Unless the program you are debugging was compiled in debug mode, there
DW> won't be any meaningful variables names anyway.

Ni> Yeah, but who releases a program built in debug mode?

Nobody, which was my point.

If you want to step through someone else's software in a debugger, it will be
in assembly language.

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Re: Debugging 16 bit dos programs
By: Digital Man to Nelgin on Fri Jul 21 2023 12:27:46

> > I've been looking for a utility that will let me step through a dos
> > program and look at the instructions while also being able to see what is
> > displayed on the screen. I've not had much luck in finding anything
> > that'll do the job and open to suggestions if anyone knows of something
> > that'll do the job.
>
> debug.exe is included with MS-DOS, isn't it?

I don't think that also shows you the program running in real time along with the debug lines.
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Re: Debugging 16 bit dos programs
By: Nelgin to Digital Man on Wed Aug 09 2023 11:33 pm

> Re: Debugging 16 bit dos programs
> By: Digital Man to Nelgin on Fri Jul 21 2023 12:27:46
>
> > > I've been looking for a utility that will let me step through a dos
> > > program and look at the instructions while also being able to see what
> > > is displayed on the screen. I've not had much luck in finding anything
> > > that'll do the job and open to suggestions if anyone knows of
> > > something that'll do the job.
>
> > debug.exe is included with MS-DOS, isn't it?
>
> I don't think that also shows you the program running in real time along
> with the debug lines.

It lets you set break points, examine registers, memory, stack. Those are the pretty standard features of a debugger. "Debug lines" aren't really a standard thing, certainly MS-DOS had no such concept.
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