DOS ain't dead

hot dos (Developers)

posted by RayeR , CZ, 12.05.2025, 19:51

> And during those (some instructions) the keyboard
> may have been hit, the interrupt processed, the
> key is now in the buffer, ready for next time I
> call the "is keyboard hit?" bios interrupt.

Interesting problem, from what I read here: https://wiki.osdev.org/Interrupts#From_the_keyboard's_perspective

It seems that PIC is blocked to send more IRQs during handling it until you explicitly finish the handling by:

When the CPU finishes handling the interrupt, it tells the PIC that it's OK to resume sending interrupts:
mov al,20h
out 20h,al

So if some key is hit in meantime, KBC should hold it in the internal queue and it will generate new interrupt just after you exit your ISR and do HLT it should fire IRQ again to wake you up. Am I right?

---
DOS gives me freedom to unlimited HW access.

Complete thread:

• hot dos - kerravon, 08.05.2025, 00:24 (Developers)
  • hot dos - ecm, 08.05.2025, 00:36
    • hot dos - kerravon, 08.05.2025, 01:25
      • hot dos - ecm, 08.05.2025, 10:42
        • hot dos - kerravon, 08.05.2025, 12:55
          • hot dos - ecm, 08.05.2025, 20:07
            • hot dos - kerravon, 08.05.2025, 23:21
              • hot dos - ecm, 09.05.2025, 01:16
                • hot dos - kerravon, 09.05.2025, 02:01
                  • hot dos - Ringding, 09.05.2025, 14:33
                    • hot dos - kerravon, 09.05.2025, 15:22
                      • hot dos - Ringding, 09.05.2025, 16:13
                        • hot dos - kerravon, 10.05.2025, 01:32
            • hot dos - kerravon, 13.05.2025, 09:04
          • hot dos - Ringding, 10.05.2025, 09:21
            • hot dos - kerravon, 10.05.2025, 14:40
              • hot dos - RayeR, 12.05.2025, 19:51
                • hot dos - kerravon, 12.05.2025, 23:02
  • hot dos - Rugxulo, 08.05.2025, 03:22
    • hot dos - kerravon, 08.05.2025, 07:24
  • hot dos - rmcconne, 11.05.2025, 15:15