[Coco] CoCo 1 64K upgrade failed :(.

Mike Pepe lamune at doki-doki.net
Fri Sep 26 16:38:05 EDT 2008


Ryan Pritchard wrote:
> I got to thinking this afternoon that there should be nothing preventing me
> from taking 41256 chips and merely grounding out pin 1 (A8) to keep the
> signal LOW (or is it HIGH? I don't remember my electronics logic that well)
> to allow me to use the chips to provide access to the 64K using the A0
> through A7 lines with the state of A8 always locked.  A0 - A7 on the DRAM is
> MA0 - MA7 according to CoCo Technical Manual.
> 
> I wonder if I have an old 8 chip 256K VGA video card kicking around.
> 

That'll work if you have a LS785 SAM and not the older LS783. The second 
version of the SAM supports 256 column refresh, the 783 does 128.

And it wouldn't matter what you tied A8 to as long as it doesn't change.



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