DOS ain't dead

DOS for 64 bits? (Users)

posted by libz, 27.10.2025, 12:07

Hi kerravon,

My answers are interlined in yours, below.


> > 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 have several low powered thin computers that are able to run both BIOS and UEFI.
UEFI is the future so I'm fine with using it from the time being, and can use one of them to run PDOS.
So, I'm interested in running in real hardware, although can test in a virtual host before, for convenience.

> > 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 lowerpdos 2 GiB.
> I am now using mcc, but haven't fully migrated, so the
> restriction remains.
Ok, for the time being.


> > 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.
Ok.
I'll have some work to do, then!


> 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.
Ah, ah, my definition will be short in scope to your expectations, I guess.
DOS for me is what I recall my experience has been in the past where I used MS-DOS, DR-DOS and I think 4DOS. So, something close to that.
I've read that 4DOS is public domain.
Have you compiled it to PDOS?

>
> 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?
In my point of view, I don't consider it a DOS as it's some indirect interaction with the hardware.


> > 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?
Yes, I'll do it, at a very slow pace, but I'm interested.
So, to begin with, copy the ucx64.zip (unzipped) or the pdos.zip to the UEFI partition and boot from there, right?
Are the two ucx64 and pdos systems at the same level of development, or which one is more advanced for me to try?
Given what you said above regarding the limitations of the 64 bit version, can it be considered to be equally constrained at the 32 bit word and 2GB of RAM?

Best regards.

Complete thread:

• DOS for 64 bits? - libz, 17.10.2025, 23:37
  • 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