[Coco] 64 K upgrade for COCO 1 gives ?OM ERROR

John E. Malmberg wb8tyw at qsl.net
Sat May 2 18:00:12 EDT 2020

I have a COCO 1 later grey case with the non-chicklet keyboard.

It was has a 16K memory badge.

While the computer had 16 K memory in it, I was able to verify that it 
had BASIC 1.1 ROM in addition to the ECB ROM.

I tried to put 64 K using 2164 memory chips.

The circuit board had 4 jumpers to move to go from 16 K to 32 K, which I 
moved to the correct locations.

The circuit board has a jumper set labeled high / low.

The computer boots, displays the sign-on for Extended Color Basic 1.0.

It reports ?OM ERROR for any command given.

Any ideas?


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