Commodore 64 (C64) DIY PLA Replacement (EPROM / OTP)
GadgetUK164
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A short video covering replacement of the PLA in a C64 with an AT27C512R OTP chip. A capacitor was required on the CASRAM line. Working rock solid on two different C64 motherboards.
Site I used for the diagram:- http://www.cbmfreaks.com/?p=563
NOTE: I’ve since tested Winbond W27C512-45 chips and they do not work at all, although I suspect the Winbond chips I’ve tested are fakes probably.
NOTE: There’s also a timing issues with sound if you use a Nano SwinSID. Works fine with MOS chips, but there’s a timing issue affecting the SwinSID. This can be fixed by adding ~68pF between the Nano CS pin and ground.
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