DOS ain't dead - masm without tiny

kerravon

Ligao, Free World North,
29.01.2026, 21:54

masm without tiny (Announce)

I have a boot sector (not MBR) written in assembler.

It works with various assemblers, and you can see it here:

https://sourceforge.net/p/pdos/gitcode/ci/master/tree/src/pbootsec.asm

I want to use the freely-available MASM 5.1. But I found it doesn't have the "tiny" memory model.

What are the implications for a bootloader if I am forced to use "small"? It didn't work at runtime when I used "small", although it did build. I was testing by booting from a floppy image using qemu.

What changes would be advised for this code so that it can work with MASM 5.1 as well as the other assemblers that it already works with?

Thanks. Paul.

usotsuki

29.01.2026, 22:06

@ kerravon

masm without tiny

Post reply

> I have a boot sector (not MBR) written in assembler.
>
> It works with various assemblers, and you can see it here:
>
> https://sourceforge.net/p/pdos/gitcode/ci/master/tree/src/pbootsec.asm
>
> I want to use the freely-available MASM 5.1. But I found it doesn't have
> the "tiny" memory model.
>
> What are the implications for a bootloader if I am forced to use "small"?
> It didn't work at runtime when I used "small", although it did build. I was
> testing by booting from a floppy image using qemu.
>
> What changes would be advised for this code so that it can work with MASM
> 5.1 as well as the other assemblers that it already works with?
>
> Thanks. Paul.

Isn't it just small with the need to run "exe2bin", as far as masm is concerned?

kerravon Ligao, Free World North, 29.01.2026, 23:33 @ usotsuki	masm without tiny Post reply
	> Isn't it just small with the need to run "exe2bin", as far as masm is > concerned? I don't know, but normally tiny and small are different in that ds points to DGROUP instead of TEXT. But I don't know what the implications of that are and how to get around that.

andrewbird Cornwall, UK, 29.01.2026, 23:52 @ kerravon	masm without tiny Post reply
	> > Isn't it just small with the need to run "exe2bin", as far as masm is > > concerned? > > I don't know, but normally tiny and small are different in that > ds points to DGROUP instead of TEXT. But I don't know what > the implications of that are and how to get around that. The second answer here stackoverflow suggests it's possible.

kerravon Ligao, Free World North, 30.01.2026, 00:40 @ andrewbird	masm without tiny Post reply
	> The second answer here > stackoverflow > suggests it's possible. Thanks - those manual segment registers fixed the problem and I have committed a fix to my source.