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HP21 uses same RAM chip as HP25?
05-21-2019, 01:53 AM
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HP21 uses same RAM chip as HP25?
I was wondering if the HP21 uses the same RAM chip (HP PN 1820-1564 or AMI/Mostek MK6220N). I have a HP25 which has a flaky RAM chip that stopped working and only will operate briefly after one or more pins have been heated with a soldering iron. After a few minutes of working again perfectly, once the chip cools down the chip stops working and its back to no registers or programming. Very frustrating.

Just wondering if a parts donor HP21 could be used, or does have to be a HP25?

Thanks for any leads.
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HP21 uses same RAM chip as HP25? - calc-calcs - 05-21-2019 01:53 AM



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