DOS ain't dead

DOS for 64 bits? (Users)

posted by kerravon , Ligao, Free World North, 23.10.2025, 05:59

> What did you expect when you asked for DOS to be 64-bit?

Just a bit more on the philosophy.

The traditional MSDOS interface was defined in assembler,
with calls to INT 21H, that included some calls with parameters
given in segment registers.

It's not possible to reproduce that exactly in x64. You can't
manipulate segment registers like that, and it defeats the
purpose to use the exact same 16-bit registers - you need
to upgrade to 64-bit registers.

So. Existing assembler source needs to change.

And most people - even on MSDOS - were writing in C, not
assembler, anyway.

And if existing assembler source needs to change - then what
is "acceptable" to get the "DOS" label?

Also - is there a particular reason to want that exact label?
What's the underlying objective?

And if the original source is written in C - particularly if it
conforms to the C90 standard - then yes, that "DOS program"
will work on 64-bit "DOS" too.

It will also work on any machine that is called "definitely not DOS".

So at some point, I get lost.

Being lost in terminology doesn't prevent me from getting
software to run though.

Complete thread:

• DOS for 64 bits? - libz, 17.10.2025, 23:37 (Users)
  • DOS for 64 bits? - kerravon, 18.10.2025, 10:34
    • DOS for 64 bits? - kerravon, 18.10.2025, 10:38
      • DOS for 64 bits? - kerravon, 18.10.2025, 11:03
        • DOS for 64 bits? - libz, 22.10.2025, 22:00
          • DOS for 64 bits? - kerravon, 23.10.2025, 04:16
            • DOS for 64 bits? - kerravon, 23.10.2025, 04:29
            • DOS for 64 bits? - kerravon, 23.10.2025, 05:59
            • DOS for 64 bits? - libz, 27.10.2025, 12:07
              • DOS for 64 bits? - kerravon, 27.10.2025, 13:17