CBM-II solderless memory expansion

From: Michał Pleban <*lists_at_michau.name*> Date: Thu, 12 Apr 2018 22:05:15 +0200 Message-ID: <5ACFBBFB.4040400@michau.name> · lists_at_michau.name

Hello!

The widely known method of expanding a CBM-II memory requires soldering
several things on the motherboard, which is doable but not for the faint
of the heart.

Alternatively you can also use the expansion port to connect a big SRAM
chip which could expand the memory for the 6509, but it would not be
seen by the 8088 card.

So I thought about an easier way to expand the memory. The standard
method uses 41256 chips instead of 4164. But how about using 4464
instead of 4164? The memory banks would still be 64kB in size, which
means that all that is needed is a custom PLA; PLA is socketed on most
motherboards so it could be a straightforward expansion.

Just to test the waters, I replaced a row of 4164's today with two
4464's and it works fine. Did anybody go down this route before?

Regards,
Michau.