PLAster™/128 (PLA replacement for C128)

(1 customer review)

$29.00 USD

PLAster/128 allows your C128 to work in fast mode with the BackBit cartridge, and functions as a general MOS 8721 replacement as well.

Not currently manufactured by BackBit, but available as open source here:

Out of stock

SKU: PL8 Category:


Replace your MOS 8721 PLA with PLAster™ for Commodore 128:

  • Acts as fully compatible replacement for the MOS 8721 chip;
  • Connected pins logic is 100% identical to original chip (over 10 million input combinations);
  • “Compatibility Mode” allows FAST mode programs to work properly with the BackBit cartridge (and possibly other devices, too);
  • “Private Eyes” test functionality (via DIP switch) to enable in-circuit testing with BackBit Chip Tester;
  • When used in conjunction with BackBit cartridge, allows for software controlled C64 and/or C128 KERNAL replacement (with DIP switch setting);
  • Includes socket for soldering to motherboard;
  • Thanks to Johan Grip for his work reverse-engineering the die (see CC BY 4.0;
  • Note: requires insulation to prevent shorting from motherboard shielding (see picture). Recommended to use 2-3 layers of electrical tape.

Additional information

Weight 2 oz
Dimensions 1 × 1 × 1 in

1 review for PLAster™/128 (PLA replacement for C128)

  1. Abelardo (verified owner)

    This is a great replacement. Works great with every program I’ve thrown at it.

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