DOS ain't dead

Is there a DOS with source code available written in ML? (Announce)

posted by Rugxulo , Usono, 21.04.2026, 02:10

> > https://mikeos.sourceforge.net/
>
> I ran into this one years ago. It has one problem: it is written in 80286
> assembly. I used its boot program as base for my own 8088 compatible one
> (with permission). The rest was to much "polluted" with 286 code to be
> interesting to convert. But I still learned a lot.

You say 286, but beyond 186, I think the 286 only added protected mode stuff. The 186 proper did make changes but nothing too onerous to "downgrade" to 8086, AFAICT. In fact, A86 has +P64 that will assemble 186 code as 8086, IIRC.

Just to quote A86MANU.TXT :

> The switch setting +P64 specifies assembly of the base-level 8086/8088
> instruction set, but with special handling of a few of the later instruction
> forms, to generate compatible code. Specifically: all shift and rotate
> instructions with an immediate shift value greater than 1 will generate that
> many repetitions of the 1-value instruction form; e.g., ROL BL,3 will
> generate 3 copies of ROL BL,1. The mnemonics PUSHA and POPA will be honored,
> generating appropriate sequences of multiple PUSHes and POPs.
> The default setting for this switch is for A86 to assemble for the processor
> on which it is currently running; +P64 if that processor is an 8086 or 8088.

Complete thread:

• Is there a DOS with source code available written in ML? - Ruud, 13.04.2026, 08:31 (Announce)
  • Is there a DOS with source code available written in ML? - kerravon, 13.04.2026, 09:10
    • Is there a DOS with source code available written in ML? - Oso2k, 13.04.2026, 19:12
      • Is there a DOS with source code available written in ML? - Ruud, 14.04.2026, 09:17
        • Is there a DOS with source code available written in assembly - ecm, 14.04.2026, 12:29
        • Is there a DOS with source code available written in ML? - Oso2k, 15.04.2026, 21:27
  • Is there a DOS with source code available written in ML? - rr, 15.04.2026, 21:41
    • Is there a DOS with source code available written in ML? - Ruud, 20.04.2026, 09:56
      • Is there a DOS with source code available written in ML? - Rugxulo, 21.04.2026, 02:10