Re: Western design chip

[jpenne@ee.ualberta.ca (Jerry Penner)]

cb408@cleveland.Freenet.Edu (Jason Reames) writes:

>I read in the Feb. issue of A+/InCider that Western Design has a chip for the
>GS, the W65C81PL-E, that will double the speed of the GS.  Is this on the
>level?  Anyone have one that can confirm it really works?  How about the
>cost?  Thanks!!

Interesting concept, but I doubt it exists.  As Matt "Unknown"
Ackeret mentions in another post to this thread, there are some
details resolving accelerators that need to be resolved.

Furthermore, the main reason I don't think it would work is for such a
chip to speed up a stock GS, it would need to reduce the number of
clock cycles each instruction takes to execute.  This would wreak
havoc with all sorts of I/O routines built into your ROMs and
basically the machine would break.  This was actually a reason some
6502 instructions didn't have their timings "fixed" when the 65816 was
fabricated--Disk II timing compatibility would be forgone.  Such is
the cost of compatibility.  After all, if it can't run Applevision
from a 5.25" Dos 3.3 disk, it's not an Apple II.

It would have been neat if the 65816 "native" mode could have run
instructions with new, better timings, while maintaining 6502 clock
timings for emulation mode.  That way, MVP and MVN could have been
done so each byte moved only took 2 clock cycles rather than 7.
Anyway, it's a moot point now, and dreaming about what should have
been is a waste of time, except you know how not to do it in the
future.  But I digress... :)
-- 
Jerry Penner   jpenne@ee.ualberta.ca   or   jjp@myrias.ab.ca