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64bit access in DOS mode...

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  64bit access in DOS mode... liaoo <jimmyliaoo@gmail.com> - 2013-03-08 01:19 -0800
    Re: 64bit access in DOS mode... Robert AH Prins <spamtrap@prino.org> - 2013-03-08 12:12 +0000
    Re: 64bit access in DOS mode... rugxulo@gmail.com - 2013-03-14 07:22 -0700

#848 — 64bit access in DOS mode...

Hi all,
I have one question about the 64-bit access in DOS mode...

Before I wrote one application using (watcom c+dos/32a) and it can access all the memory space under 4GB successfully...
* DOS/32a provides flat mode !

Ex. I used below function to write 4-Byte:
============================================
void PciMemWtDW( DWORD memaddr, DWORD data )
{
 DWORD *ptr = (DWORD *)memaddr;
 *ptr = data;
}	
============================================

My question is: is it possible to access the memory above 4GB if I installed 8GB DRAM ?

If not... then is there any other way to solve this issue ?

Thanks,
liaoo

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#849

On 2013-03-08 09:19, liaoo wrote:
> I have one question about the 64-bit access in DOS mode...
>
> Before I wrote one application using (watcom c+dos/32a) and it can access all
> the memory space under 4GB successfully... * DOS/32a provides flat mode !
>
> Ex. I used below function to write 4-Byte:
> ============================================
 > void PciMemWtDW( DWORD memaddr,
>  DWORD data ) { DWORD *ptr = (DWORD *)memaddr; *ptr = data; }
> ============================================
>
> My question is: is it possible to access the memory above 4GB if I installed
>  8GB DRAM ?
>
> If not... then is there any other way to solve this issue ?

http://board.flatassembler.net/topic.php?t=8768
http://www.japheth.de/JWasm/Dos64.html

Robert
-- 
Robert AH Prins
robert(a)prino(d)org

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#864

Hi,

On Friday, March 8, 2013 3:19:09 AM UTC-6, liaoo wrote:
> 
> I have one question about the 64-bit access in DOS mode...
>
> Before I wrote one application using (watcom c+dos/32a) and it can
> access all the memory space under 4GB successfully...

Even with so-called memory holes? Congrats!

> * DOS/32a provides flat mode !
> 
> My question is: is it possible to access the memory above 4GB if I
> installed 8GB DRAM ?

By default, I don't think so. I assume you're aware of the
experimental PAE hack for DOS/32A, found on the homepage (though 
you'll have to assemble it yourself or ask around here for someone
with a copy). Not sure how stable it is, but it's at least a proof
of concept.

I think PAE (up to 64 GB) is your best hope for this (though I
personally think 4 GB is plenty, am I wrong?).

CWS (of CWSDPMI fame) has been busy with work lately, but he still
intends CWSDPMI to work stably with at least 4 GB, and maybe
eventually with PAE too. You could try emailing him for just some
casual tips, but like I said, don't expect much, he's always busy.
(He did some work over the winter holidays but never finalized it.)
If anybody can help you, it's him!

http://homer.rice.edu/~sandmann/

> If not... then is there any other way to solve this issue ?

Sure, just use (xyz OS flavor of the month).   :-)

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