[Coco] CoCo 1 64K upgrade failed :(.
Bruce W. Calkins
brucewcalkins at charter.net
Fri Sep 26 20:40:13 EDT 2008
----- Original Message -----
From: "Ryan Pritchard"
>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
> 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
> MA0 - MA7 according to CoCo Technical Manual.
With the addition of a few logic chips and the upgraded CoCo 2 variant SAM
chip all of those 256k RAM chips can be used. I need to understand a bit
more to get it to work with NitrOS9 though since nobody has yet figured out
exactly what needs to be tweaked. It works under OS-9 level 1 and RS Disk
Basic as a RAM disk, or 32K paged memory.
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