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

[Bruce W. Calkins]

----- 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 
> 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.

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.

Bruce W.