DOS ain't dead - MSDOS close to Unix

MSDOS close to Unix (Developers)

posted by tkchia , 26.12.2021, 09:05

Hello kerravon,

> I recently noticed that the MSDOS 2.0 API is very
> close to Unix with INT 21H APIs like open, read,
> write, seek, close.

This is almost certainly by design. The recently published DOS 2.x source code referred to the new system calls as XENIX CALLS.

Also, while syscall 0x4b is named $EXEC, it actually starts a child process, so it is really more akin to POSIX's posix_spawn. There is actually no MS-DOS execve-like syscall that lets a running process replace itself with another program. The MS-DOS syscall ABI is also kind of deficient in other ways.

Thank you!

---
https://gitlab.com/tkchia · https://codeberg.org/tkchia · 😴 "MOV AX,0D500H+CMOS_REG_D+NMI"

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Complete thread:

MSDOS close to Unix - kerravon, 26.12.2021, 08:17 (Developers)
- MSDOS close to Unix - kerravon, 26.12.2021, 08:18
- MSDOS close to Unix - tkchia, 26.12.2021, 09:05
  - MSDOS close to Unix - kerravon, 27.12.2021, 04:31
    - MSDOS close to Unix - jhall, 27.12.2021, 20:02
- MSDOS close to Unix - DosWorld, 10.01.2022, 20:35
  - MSDOS close to Unix - kerravon, 11.01.2022, 02:19