From: "Tony Ingenoso" 

Actually, the 640K limit has little to do with the way DOS was designed,
and everything to do with the location of the EGA/VGA graphics memory that
was unfortunately parked at A000:0000.  An unhacked stock DOS with a BIOS
that supports memory scanning beyond 640K (a Taiwan BIOS by an outfit named
RIMOS had one in a clone I had) will happily count memory up to whatever
you have in the box.

I had a mono card in the RIMOS clone and some video card with 64K at A000.
I wasn't using the graphics card, but the RIMOS bios saw the vid memory
there, scanned it, and DOS saw the 704K it reported just fine.

FWIW, a slightly differently wired up 8088 (in 'maximum' mode, like the XT
had) could directly address 4M of memory by decoding the segment status
signals as part of the address.  Doing this would give references off CS:
DS: ES: SS: 1M of addressability in four *physically* seperate 1M address
spaces.

"Gregg N"  wrote in message
news:Xns9661E0BB01F3Fgregginvalidinvalid{at}216.144.1.254...
> "Glenn Meadows"  wrote in
> news:429523c7$1{at}w3.nls.net:
>
> > Ok, something new to ask.
> >
> > MANY moons ago, if I recall correctly, it was Bill Gates  who said
> > "Who will ever need more than 64k  or memory?
> >
>
> A similar statement about 640k has been attributed to him, but he denies
> ever having said it, and apparently there are no citations for it.
>
> http://www.wired.com/news/print/0,1294,1484,00.html
>
> The original 640k limit was due to the design of the original PC and the
> 8088 microprocessor within. The persistence of that limit in software
> (kludgy workarounds notwithstanding) after the removal of the hardware
> limit is due to the way DOS was designed.
>
> Gregg

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