DOS ain't dead - DS and ES matching

DS and ES matching - PDB meaning (Developers)

posted by ecm , Düsseldorf, Germany, 18.10.2025, 18:32

> > > Since we have the normal non-MT source code, I was just
> > > wondering how definite it is that DS and ES match. ie will
> > > they always be set the same, or are there some special
> > > conditions? Is there a deliberate attempt to make them
> > > the same (seems a bit odd actually, but that's ok).
> >
> > https://hg.pushbx.org/ecm/msdos4/file/51ad27d225a8/src/DOS/EXEC.ASM#l796
>
> Thanks for the reference!
>
> This comment threw me for a moment:
>
> ; DX has PDB pointer
>
> Not sure what that is, but I know it as PSP.

https://hg.pushbx.org/ecm/msdos4/file/51ad27d225a8/src/DOS/MISC.ASM#l357

Process Data Block. It means the same as the Process Segment Prefix, yes.

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Complete thread:

DS and ES matching - kerravon, 18.10.2025, 11:29 (Developers)
- DS and ES matching - ecm, 18.10.2025, 12:48
  - DS and ES matching - kerravon, 18.10.2025, 14:43
    - DS and ES matching - PDB meaning - ecm, 18.10.2025, 18:32
      - DS and ES matching - PDB meaning - kerravon, 18.10.2025, 19:04
        DS and ES matching - PDB meaning - ecm, 18.10.2025, 19:41
        DS and ES matching - PDB meaning - kerravon, 18.10.2025, 19:59
        DS and ES matching - PDB meaning - kerravon, 18.10.2025, 20:01
- DS and ES matching - kerravon, 19.10.2025, 10:32