Re: Next round of console patches
Vladimir Dergachev (vladimid@red.seas.upenn.edu)
Wed, 2 Sep 1998 15:16:35 -0400 (EDT)
> > > cards - they map their MMIO over the last kilobyte of video RAM in the
> > > aperture.
> > ^^^^^^^^
> > Could you explain this? My dictionary has'nt conputer-speak translation
> > for this...
>
> Sort of 'address space which maps to that card' ... I think, though I'm
> no native english speaker as well, that this really is similar to the optical
> meaning of aperture.
>
As far as I know aperture is when the video memory of your card is mapped
to the address space of your cpu so you don't know the difference between
putting something in usual memory or the video card memory (at least in
first approximation). This is opposed to "banked" memory where not all the
memory is accessible at once so you have to switch banks in order to get
to the different parts of memory.
I also think that the newer RageII+ cards have a separate segment for MMIO
registers.
The reason for all this hassle is that numbers weren't so
expensive just two years ago. The computers with 64megs of ram were
exotic. So you could afford to reserve a 4meg chunk of address space when
in reality your video card needed 2megs + a little for registers. This is
in fact similar to the 640K phenomenon - nobody thought the same computer
will have more than 1meg RAM..
A little offtopic - I would really appreciate if people tell me if I am
correct about RageII+.
Vladimir Dergachev
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