DOS ain't dead

hot dos (Developers)

posted by rmcconne, 11.05.2025, 15:15

> When I run DOS 4.0 or Freedos under Virtualbox or qemu, it maxes out a CPU
> core (as far as I can tell).
>
> Even though it is just sitting at the command prompt waiting for a
> keystroke.
>
> Any idea what is causing that?
>

Ah yes, the dreaded busy-wait syndrome. This has been a recognized issue since the days of CP/M, with many suggested solutions. For the 8-bit processors, it wasn't much of an problem. They were too slow for it to make a real difference. It wasn't until the second generation of 16-bit CPUs that it actually gained notice, due to the extra heat it generated. A simple Google search on "handling busy-wait" will return lots of ideas and suggestions. I also remember more than one magazine article on the topic back in the late 1900's, but they may be difficult to find now.

Good luck,

Bob

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