[Coco] Downgrading form 64kRAM to 16KRAM

CoCoList for Color Computer Enthusiasts coco at maltedmedia.com
Sat May 10 21:55:19 EDT 2014


Have an E board that I bought lured by the 16K RAM badge on the case, once
I opened for a general inspection and clean up I found it had been modified
for 64K, power up tests confirmed.

Having a spare set of 16K chips I am set to downgrade this E board back to
its stock RAM. Looking at the board and following a write up for a 64 K
upgrade on an article on July 1983 Hot CoCo, I see that all wires to U29
(7402) need to be removed, one bend pin on U11 (74138) needs to be de-wired
and bent back into the socket, all RAM size jumpers moved to 16K, a solder
blob on the HIGH-LOW jumper remains on the LOW side, one R83 resistor
(22ohm) needs to be removed and all 4164 chips replaced by 4116s.

Question is: all the caps removed to do the 64K upgrade by the RAM chips...
what's the impact on the performance of the CoCo if I leave them off? I
would prefer to re-install them all but wondered what would happen if I
forego the task. If they're a must on the board, what is the value and type
of cap?

Thanks!

-- Rogelio Perea



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