Re: [Freedos-devel] Learning DOS assembly programming

[Steve N. <uso...@bu...>]

On Tue, 26 Dec 2023, Jim Hall via Freedos-devel wrote:

> I actually never learned DOS assembly programming, but decided I'd
> like to start.
>
> What assembler do you recommend, and where is a good place to start
> learning about DOS assembly programming? Start with a "Hello world"
> program and eventually move up to writing an assembly version of TYPE
> and CHOICE, things like that.
>
> I was thinking about NASM, since it's open source and we include it in
> the distribution. Looking around, I found a bunch of tutorials on
> https://asmtutor.com/ that look easy enough to follow, although it's
> for Linux. Any similar tutorials to learn DOS assembly programming?

I've used NASM because it's easier than the traditional x86 assemblers.  A 
simple .COM might look like this:

           cpu       8086
           org       0x0100
entry:    mov       dx, msg
           mov       ah, 0x09            ; PUTSTR
           int       0x21
           mov       ax, 0x4C00
           int       0x21                ; EXIT CODE 0
msg:      db        "Hello, cruel world.", 13, 10, "$"

My own implementation of CHOICE is actually written in NASM - it's one of 
the programs I wrote to learn x86 ASM (and it reads a lot like I was 
thinking in 6502).

-uso.