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27xx <--> 28xx

Posted: Sat Jan 18, 2020 2:36 pm
by JannievanZyl
How compatible is a 28xx EEPROM with its equivalent 27xx EPROM?

They are pin-compatible, but can one drop a 2864 in the place of a 2764, for example?

I wrote two different 28C64s and tested them in place of a 2764 (in a C64 cartridge) and they seem to work but are definitely unstable.

So, not sure if I have flaky 2864s or if they're not electrically compatible.

Any ideas?