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INT 15.87 in protected mode (Developers)

posted by RayeR Homepage, CZ, 07.09.2011, 10:28

> Hi!
> I learned how to use int 15h/ax=87h in real mode. Now I am able to draw via
> LFB even in real mode or I can work with ACPI in real mode.
>
> But I tried to use this interrupt in 32.bit DPMI via call INT 31h/AX=300h
> I prepared all needed realmode buffers but when I call the service it fails
> and in AH is returned 86h what means "Function not supported".

What you are going to do with this func in pmode? I can't see an advantage of calling it for LFB acces as it is limited to 64kB so you will have to call it more times like when bank-switching so I guess it will impact the speed. Well for accessing MMIO with small areas of memory it would be OK.
How does this function works under NTVDM? I doubt that Bill allows access to full RAM this way.

BTW when I was mailing with C.Sandmann about memory mapping he told me they (together with ID software) was negotiating suport for phys memory mapping under NTVDM to allow run Quake game under WinNT but M$ did not accepted it mostly for a reason that NT is not a gaming platform and didn't implemented it :(

---
DOS gives me freedom to unlimited HW access.

 

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