Re: I am working on a GS accelerator, can you help?

[CUTjefbla@bconnex.net (Jeff Blakeney)]

On Sun, 13 Dec 1998 23:46:48 -0500, sheldon@atlcom.net (Sheldon Simms)
wrote:

>Well I've thought about this a little bit, and personally I would put
>RAM on it, since RAM is pretty darn cheap these days I'd say screw the
>cache, and all the complexity it adds, just put all the RAM right there
>on the board. Putting VGA on the board is something that would be really
>slick, (and would help speed up the system) but it's really overkill.

Yes, RAM is cheap nowadays but "cache RAM", which is what would be
required to use with a fast 65816 at full speed, is still quite
expensive.

Standard RAM you buy for your machines nowadays is DRAM (Dynamic RAM),
which is cheap but requires constant refreshing, still has relatively
slow access time (which is why caching was invented and is still in
use today).

Cache RAM is SRAM (Static RAM), which is more expensive because it
doesn't require constant refreshing, is quite expensive because it is
more complex to manufacture and is in less demand because there is a
cheaper alternative that works for regular RAM (see DRAM above).

Also, beyond it being quite expensive to put 4 MB or more of SRAM on
an accelerator card, you will end up losing the ability to do DMA from
Apple's High Speed SCSI card and the RamFAST.  You would also end up
losing the softswitches and all the $Cxxx range of address for dealing
with the expansion slots.

Basically, there would need to be a lot of work done to circumvent
every problem that could arise with this design and if you were going
to go to the bother to get it to work correctly, you might as well
just make a new IIgs compatible motherboard.  Which is what I'd like
to do someday but I don't have the time or money to do so yet.

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