Note: This is currently "beta", and only tested on ASSY 326298 motherboard - but the project is unchanged from the original published by Daniel so should work on all except for the short board ASSY 250469

"SlimPLA" - The compact version of PLA20V8

replacement PLA chip for Commodore 64 computer.

This is a compact version of the very popular PLA20V8 project. I created it as I didn't like the look of the original design. In my design, one of the GAL chips is installed at the bottom of the PCB, the other at the top. Construction is a bit more complicated as it requires soldering one of the chips from the top, but as you will see from my results, it's possible and it's simple. The "end product" looks nice and compact. Here is how to build it (YouTube link to a full video here)

1) Gather all the parts: you will need the PCB, 2 of the GAL20V8B-25LP chips, and some pin headers (the best is to use the precision round pin headers).

2) Make sure you mark your GAL chips "R" and "L" as per the original project, and program the chips, I use the following files to program my chips:

Right - 906114-01_20V8_R.jed

Left - 906114-01_20V8_L_alt2.jed

3) Before soldering anything we must prepare the "L" chip by trimming pins 13-24. We temporarily insert the chip into the PCB like this but DO NOT SOLDER THE CHIP YET:

4) Trim the pins of the "L" chip using side cutters:

The chip should look like this after trimming:

Keep the "L" chip for later.

5) Insert the "R" chip at the bottom of the PCB, make sure pin one is facing up this way:

6) Solder the "R" chip from the top:

7) After soldering the "R" chip, you should also "trim" the pins this way:

The PCB should look like this, at this point only the "R" chip is soldered at the bottom of the PCB:

8) Now you can insert the "L" chip to the top side of the PCB:

9) Solder one row of the pins from the bottom:

10) Now we can solder the pin headers, I use a "breadboard" to help keep the pins straight:

11) Solder the pin headers:

12) Now is the critical part of the project, we still have one row of pins for the "L" chip to solder:

It is a bit "tricky" so I add some flux, and solder from the top of the PCB, you will see the solder flow into the space where the pins are:

13) After soldering I clean with a bit of flux cleaner, and the project is ready to use:

And here is side by side comparison of the "Fat" and the "Slim" version of PLA20V8