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

Chuck Youse cyouse at serialtechnologies.com
Fri Sep 26 16:55:32 EDT 2008


On Fri, 2008-09-26 at 21:46 +0100, Phill Harvey-Smith wrote:

> My answer to that would have to be 'maybe' I have done this on a Dragon 
> 32 board and it did seem to work ok, however it is out of spec as the 
> 74LS783 SAM can only do 128 cycle refresh, where as the 41256 type chips 
> need 256 cycle refresh however like I said I tried it and it did seem to 
> work, so may be worth a shot.

Ah, but if you're only using the lower half, only the lower half needs a
refresh, no? :)

Talking out of my ass here, don't remember the innards of DRAMs anymore,
but I don't see the need to recharge the caps in the unused
rows/columns.

C.





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