[Coco] Memory upgrade TRS-80?

mike delyea mdelyea at gmail.com
Mon Jul 30 12:18:53 EDT 2012

Found this re. upgrading the Model 4 (Model 4P in this case but also works
for the 4).

"Last month I mentioned my desire to upgrade the RAM in my TRS-80 Model 4P
to 128KB. To that end, I ordered a TRS-80 Model 4 RAM upgrade kit from
computernews80 ($28, available via their eBay store).

The upgrade comes as a nicely packaged kit of eight Tandy-badged 8040665
64K x 1 DRAMs (essentially 4164 DRAMs with a Tandy part number) carefully
inserted in a anti-static foam block. It also includes detailed
installation instructions covering all revisions of the Model 4/4P series
as well as a 5.25” memory test/diagnostic diskette.

The installation process was quite easy on my gate-array Model 4P and only
took about ten minutes - I spent a little more time as I took this
opportunity to clean the case plastics in the bathtub. In a nutshell, open
the case, remove the logic carrier pan and simply plug the eight chips into
the empty sockets on the logic board. Next, move the memory enable jumper
from the E2/E3 pins to E1/E2."

However I was unable to locate the ebay store.  their webpage does have
instructions for doing it yourself.


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