[Coco] MPROM woes
tonym at compusource.net
Sat Nov 15 19:24:10 EST 2008
You DID notice that it came with a harness for (3) 9V batteries, right?
As I said - I have NO idea on the condition of that unit.
It was in a box I got from Art before he moved, hence why I wouldn't "sell" it to you.
Wouldn't have been right...
From: Roger Taylor operator at coco3.com
Sent 11/15/2008 7:09:37 PM
To: cocolist for Color Computer Enthusiasts coco at maltedmedia.com
Subject: [Coco] MPROM woes
I can't for the life of me figure out why my MPROM board will do
everything it's supposed to do except WRITE the EPROMs.
The voltage regulator is showing Ground, 12.5v, 21v, and the source
voltage. I haven't checked the EPROM socket VCC pin yet. I guess I
need to reheat the solder joints.
The EPROMs are reporting blank and I've tried 27128, 27256, and some
2764 clones, using the 12.5v jumper setting then the 21v, but I have
60+ EPROMs and I doubt all of them are bad. Most are new, so
obviously something is going wrong on the board.
The software gets to the first write of address $0000 and reports
"Not programmed properly" and quits. In other words, the write
didn't take. Checking the EPROM again reports it to still be
completely blank with $FF's.
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