Can you replace your C64 PLA for under $3?

Adrian's Digital Basement2 minutes read

Replacing the common failure PLA chip on a Commodore 64 with modern replacements like Platinum and GAO PLA, which are affordable and effective, requires specific components such as GAL chips, sockets, and pin headers, alongside a TL866 Mini Pro EEPROM programmer for programming. The process involves soldering the components onto a PCB with careful attention to detail and configuration to ensure proper functionality and compatibility, resulting in a cost breakdown of $6.46 per board.

Insights

  • The PLA chip failure on Commodore 64 often results in a black screen due to its role in regulating communication on the data bus and acting as a gatekeeper for peripherals.
  • The GAO PLA project offers an affordable and accessible solution to replace the original 82S100 chips by utilizing modern replacements like the Platinum and GAO PLA, which are effective and compatible with components like Lattice GAL 20V8 chips, providing a cost-effective alternative for users.

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Recent questions

  • What is PLA failure on Commodore 64?

    PLA failure on Commodore 64 results in a black screen due to a malfunction in the chip that regulates communication on the data bus.

  • What are modern replacements for PLA?

    Modern replacements for the PLA chip on Commodore 64 include the Platinum and GAO PLA, which are affordable and easily obtainable alternatives to the original 82S100 chips.

  • How is GAO PLA constructed?

    The GAO PLA project utilizes Lattice GAL 20V8 chips and requires components like PCBs, GAL chips, sockets, and pin headers for construction, with a TL866 Mini Pro EEPROM programmer essential for programming the GAL chips.

  • How to assemble GAO PLA?

    To assemble the GAO PLA, solder the pin headers onto the PCB after cutting them to length, ensuring the longer part is for the motherboard socket and the shorter part for soldering onto the PCB, and program the GAL chips using JED files with a programmer.

  • What is the cost breakdown for GAO PLA?

    The cost breakdown for making GAO PLA boards includes PCBs, GAL chips, pin headers, and sockets, totaling $64.62 for ten boards or $6.46 each, excluding the programmer, making it a cost-effective replacement option for Commodore 64.

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Summary

00:00

"Replacing Commodore 64 PLA with GAO"

  • PLA is a common failure on Commodore 64, leading to a black screen.
  • The PLA chip is crucial and regulates communication on the data bus.
  • The PLA is a gatekeeper for peripherals on the computer.
  • Original 82S100 chips are no longer available for replacement.
  • The Platinum and GAO PLA are modern replacements for the PLA.
  • The GAO PLA project offers an affordable and easily obtainable replacement.
  • The GAO PLA uses Lattice GAL 20V8 chips for compatibility.
  • Testing with Super Zaxxon and Easy Flash 3 shows GAO PLA's effectiveness.
  • Components needed for building a GAO PLA include PCBs, GAL chips, sockets, and pin headers.
  • A TL866 Mini Pro EEPROM programmer is essential for programming the GAL chips.

15:30

"Assembly and Programming of PCB Boards"

  • The PCB has two sockets and two GAL chips, with pin headers on the bottom for connection to the motherboard.
  • Cut the pin headers to length for insertion into the longer set of holes on the PCB.
  • The headers have a longer part for the motherboard socket and a shorter part for soldering onto the PCB.
  • To keep the headers straight, insert them into a socket before soldering onto the PCB.
  • Solder a couple of pins onto the PCB first to keep the headers steady, then solder the rest.
  • Install the pin header before the sockets to facilitate assembly.
  • Program the GAL chips using JED files, ensuring to differentiate between left and right chips.
  • Use a programmer to load the JED files onto the GAL chips, ensuring correct configuration and programming.
  • The cost breakdown for making the boards includes PCB, GAL chips, pin headers, and sockets, totaling $64.62 for ten boards, or $6.46 each, excluding the programmer.
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