Mail Archives: djgpp/1999/09/15/22:26:47
JAB wrote:
>
> In article <7rmnjl$9fd$1 AT solomon DOT cs DOT rose-hulman DOT edu>,
> "Damian Yerrick" <reply DOT at DOT your DOT own DOT risk AT pineight DOT 8m DOT com> wrote:
> >
> > JAB <jab_joe AT my-deja DOT com> wrote in message
> > news:7rmff2$5rt$1 AT nnrp1 DOT deja DOT com...
> >
> > > Now I'm converting it over to the PC, compiling it with
> > > djgpp. I've got code to change to the screen mode I want
> > > (640 by 480 in 32 bit) but I can't get the screen address to
> > > write to. On the Acorn you just get the screen address and
> > > start writing to it. I can't beleive that you need the pages
> > > and pages of code I'm told I need. Ploting to screen is
> > > simple; how can it be so hard on the PC?
> >
> > The PC is a patched together system. Memory is all over
> > the place. VGA video memory used to be at absolute
> > address 0x000A0000 (formerly known as A000:0000);
> > SVGA card makers independently placed it at various
> > positions and folded it in weird ways to fit into the address
> > space of the PC; now VESA provides a way to get at the
> > memory.
>
> Erk. I hope this memory mess problem gets sorted out. I knew it was
> bad, but the more I find out the worse it is. I think a new type of
> computer is needed. That would get rid of the memory poblem and finally
> mean freedom from the x86 chips.
Incidentally, it's not specifically because of x86. A reasonable
implementation (linear framebuffer) is quite possible on a 386 or above,
and used under many OS'es. It's really a relic of the 8086 (20 bit
address space) and the original IBM PC architecture.
There are certainly reasons why x86 is not an ideal CPU architecture,
but IMHO this isn't one of them.
--
Nate Eldredge
neldredge AT hmc DOT edu
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