DOS ain't dead

hot dos (Developers)

posted by kerravon , Sydney, Free World South, 09.05.2025, 02:01

> > This would only be if you are actually in protected
> > mode though, right?
>
> Yes.
>
> > I am interested in adding hlt to DOS 4.0 which would
> > be real mode. It should always be a valid instruction,
> > right?
>
> In Real 86 Mode yes. But the DOS can run with an EMM using V86 Mode, and
> then HLT may or may not work in the 86 Mode code.

I'm not familiar with V86 mode.

So DOS 4.0 can run in V86 mode, and then some instructions
are potentially no longer available? Is it just HLT or
could I potentially be denied access to do OUT etc?

And if so, I should ideally avoid such instructions and
do what instead? BIOS calls? ie with the benefit of
hindsight, DOS 4.0 shouldn't issue HLT etc, it should
instead just do BIOS calls?

Complete thread:

• hot dos - kerravon, 08.05.2025, 00:24
  • 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