chad5200 Posted January 21 Share Posted January 21 I have two Coleco Adams. One is performing fine. However the other is misbehaving and I suspect RAM issues. I put "ADAM Final Test - Menu Version (198x) (Coleco).rom" on an AtariMax cartridge. I have run menu option 6 (TEST RAM) and the Adam that is performing fine passed the test. However this is the result of the other Adam that is misbehaving: 64K RAM TEST ----------------- LOWER 32K RAM BAD WROTE FF READ 00 AT 0100 UPPER 32K RAM OK Can anyone tell me where to go from here? I haven't opened up the Adam yet, but are there pictures or instructions somewhere as to which RAM chips are the "LOWER 32K RAM"? Any tips or suggestions would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
chad5200 Posted January 22 Author Share Posted January 22 @NIAD replied to a separate post I had made that lead me to the finding the bad RAM. He mentioned using "Gamma Debug to see if any system RAM errors are found". Gamma Debug returned this result: Which means I have to replace this U18 chip which according to schematics is 4164: The writing on that is R41250/6665. I have this in my supplies... was wondering if this would be a good replacement? Also, is there anything special I need to know about Coleco Adam RAM? Thanks, Chad Quote Link to comment Share on other sites More sharing options...
NIAD Posted January 23 Share Posted January 23 Beyond my skills and knowledge so hopefully someone like TekMan or ChildofCV will see this thread and can provide help. Quote Link to comment Share on other sites More sharing options...
chad5200 Posted January 23 Author Share Posted January 23 13 hours ago, NIAD said: Beyond my skills and knowledge so hopefully someone like TekMan or ChildofCV will see this thread and can provide help. Thanks. Hoping @Tekman or @ChildOfCv sees this. Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted January 23 Share Posted January 23 Well, one thing I can say is that Motorola's early chip marking SUCKS. I can't look up exact info on what your existing chip is. That said, your specimen is pin-compatible with it. The only remaining question is if it's fast enough. They make a MCM6665-20 and a MCM6665-15. Okay, I see another board that used Mostek (pronounced "mistake") memory. It has a -20 suffix. So that lends some confidence that your -20 memory should work. Quote Link to comment Share on other sites More sharing options...
chad5200 Posted January 23 Author Share Posted January 23 2 hours ago, ChildOfCv said: So that lends some confidence that your -20 memory should work. Thanks. I will report back after I replace it. Will socket it in case another RAM chip ends up being needed. Quote Link to comment Share on other sites More sharing options...
chad5200 Posted January 24 Author Share Posted January 24 Replaced the RAM at U18 and all is good! Thanks! 1 Quote Link to comment Share on other sites More sharing options...
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