[Coco] FW: Attempting to upgrade a CoCo2

[Kip Koon]

Hi Mike!
You will have to find someone who either has a 24 pin mask programmed rom
from Tandy for ECB 1.1 or program an MCM68766 8K x 8 bit eprom with ECB 1.1
or get a 24 pin to 28 pin eprom adapter and program a 2764 8K x 8 bit eprom.

 I found my Color Burner which can burn MCM68764s, but I have never burned a
68766 yet.  I need to see how close to a 68764 the 68766 is.  I bought some
recently, so I plan to play with them and see how it goes.  
I also just created a 24 pin to 28 pin eprom adapter that will hold a 2764
8K x 8 bit eprom.  I haven't tested it yet in my disk controller to hold
HDB-DOS.  It is designed to replace the MCM68364 mask programmed roms Tandy
used on the motherboards, disk controllers and some rom cartridges.
If you'd like, I'll go ahead and test it and see how it does.  It should
work as the circuit is pretty simple.  I have been exploring making PCBs of
late and this is my third or fourth PCB I've made.  I'm having a lot of fun
with it.  Take care my friend.
Kip

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
Behalf Of Mike Craig
Sent: Friday, October 04, 2013 9:55 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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