DOS ain't dead

DOS for 64 bits? (Users)

posted by kerravon , Ligao, Free World North, 23.10.2025, 04:16

> The most relevant section for this seems to be 'University Challenge x64'
> So, what I miss is a tutorial where it could be shown step by step what to
> do to have pdos booting in a x86_64 hardware (and in other ones as well).
> I'm unaware of what could be done using EFI. It seems that you've
> programmed pdos to run as a UEFI module, is that correct?

Yes - I'm not sure "module" is the correct term, but I don't
know what the correct term is.

Modern x64 computers all use UEFI. It's very difficult to find
a BIOS now.

Do you want to run on real hardware or under Virtualbox etc?

I provide a VHD. You can use that directly in Virtualbox or
you can burn it to USB stick using Win32 Disk Imager. If
doing the latter I think you need to rename it to .img.

> Can pdos run 64 bit programs and use GBs of RAM and big files?

Theoretically it can be rebuilt to do that.

Currently it is mimicking Microsoft Windows and Microsoft
Visual C, which uses 32-bit long still - and that is what C90
gives.

So for now, no big files.

For big memory - a different issue - previously I was using
cc64 and that needed to be restricted to the lower 2 GiB.
I am now using mcc, but haven't fully migrated, so the
restriction remains.

> Can pdos run all ancient MSDOS programs, like Turbo Pascal, Norton
> Commander, etc?

It can't run any of them. You need to recompile for the x64
platform.

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

Genuine question - I'm interested in your opinion on the
very definition of "DOS". It's philosophy to me.

It will run some existing genuine Win64 x64 programs though
(mainly ones that I built).

But that is also a philosophical question - is the Win64 command
prompt "64-bit DOS" too?

> Some howtos and some videos would be of great help for me and for others
> like me that don't have your level of expertise in the subject.
> I know, I know, it's a lot of work that I'm asking.

I can guide you through it (in this forum, in text) if you start by
telling me where you want to run it. You can make a video at
the end of that process if you wish. Or a HOWTO. You offered
to do something non-programming for the "64-bit DOS", right?

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