26 May
2008
26 May
'08
9:11 p.m.
branchuk wrote:
I think fatten your mac had you piggy back your 64K
drams and
bring out CS? to the address decoder.
Nope. DRAMs don't have a CS signal, they have RAS and CAS. Also, there
wasn't any decode for another bank of 64K DRAMs. The upgrade was to
replace the DRAMs with newfangled expensvie 256K parts, and add a
74S257 multiplexer for A8. I don't recall whether the board had
pin 1 of the DRAMs wired together; if not you'd have to do that
as well.
Eric