DOS ain't dead

DS and ES matching - PDB meaning (Developers)

posted by ecm  , Düsseldorf, Germany, 18.10.2025, 19:41

> > 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.
>
> Thanks. I didn't check what "hell" is, in Microsoft's professional opinion.
>
>
> invoke DOSINIT ; go to hell

It's a branch that's intended to crash. It used to do this by running the DOSINIT code, which is code that is no longer resident at this point: https://hg.pushbx.org/ecm/msdos4/file/51ad27d225a8/src/DOS/MSINIT.ASM#l180 IIRC it's overwritten by parts of the SDA later.

I changed it so it branches to a dedicated function: https://hg.pushbx.org/ecm/msdos4/file/28de3823a0fd/src/DOS/misc.nas#l552

This function is defined here (technically in the "msbio" part but both "msdos" and "msbio" are linked to one binary now): https://hg.pushbx.org/ecm/msdos4/file/28de3823a0fd/src/BIOS/code.asm#l333

The old DOSINIT is now called NEARDOSINIT and lives in the SYSINIT segment (hence it is called "near") rather than in the (what used to be) combined DOSDATA + DOSCODE: https://hg.pushbx.org/ecm/msdos4/file/28de3823a0fd/src/DOS/dosinit.nas#l570

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l

Complete thread:

• DS and ES matching - kerravon, 18.10.2025, 11:29
  • 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