DOS ain't dead

not setting carry (Developers)

posted by kerravon , Ligao, Free World North, 16.10.2025, 10:29

I believe unimplemented INT 21H functions with high AH don't set the carry flag, unlike ones with low AH. Instead, I think you are supposed to check AL? Now that we have the MSDOS 4.0 source code, do we know whether that is deliberate policy, and perhaps a reason for that policy, or whether it was an accident?

Complete thread:

• not setting carry - kerravon, 16.10.2025, 10:29
  • not setting carry - ecm, 16.10.2025, 16:17
    • not setting carry - bretjohn, 16.10.2025, 23:59
      • not setting carry - ecm, 17.10.2025, 09:30
    • not setting carry - kerravon, 17.10.2025, 07:58
      • not setting carry - ecm, 17.10.2025, 10:29
        • not setting carry - kerravon, 17.10.2025, 10:55
          • not setting carry - ecm, 17.10.2025, 11:31
            • not setting carry - kerravon, 17.10.2025, 16:51
              • not setting carry - ecm, 17.10.2025, 18:43
                • not setting carry - kerravon, 17.10.2025, 19:05