[Coco] Attempting to upgrade a CoCo2

[Chad H]

Yes, you are on the right track as far as the ram goes.

However...

The 2716's are usually 16K (2kb x 8) and this is in "kilobits" not
"kilobytes" so divide by 8 and you get >> 2KB, not enough to hold DECB ROM
which takes 8KB.

Recommend 2764's at a MINIMUM as they are  64 Kbit (8Kb x 8) divided by 8 ==
8KB  (kilobytes).

Could do 27128's or something and use bank switching if you have such a
board for the cart slot. And "select" which ROM to boot.

-Chad

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
Behalf Of Mike Craig
Sent: Friday, October 04, 2013 8:55 PM
To: coco at maltedmedia.com
Subject: [Coco] Attempting to upgrade a CoCo2

Hi Everyone. I recently got my paws on a CoCo2 16k 26-3134. I'm going to
hunt down a 2716 Eprom and program it with ECB tomorrow. I'm lucky in the
fact that I have a surplus company around the corner from with with parts of
all kinds. Question I have is about the RAM upgrade. The eight RAM chips are
8040517's and from what I understand, I have to replace them with 4164 chips
of 200 ns or better access time, and to solder a wire between the two pads
labeled J1. I'm assuming that all eight chips need to match speed wise. I
did a search on Ebay and see lots of them listed. I have my eye on these
'NEC Dynamic RAM Memory 64K x 1-Bit UPD4164C-15'. Would those work? And am I
barking up the right tree so far? :D

Thanks,

Mike


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