PLA replacement circuit for Commodore 64. Based on dodgyPLA https://github.com/desaster/c64-dodgypla
I showed the design to some friends and they said "neat". Hence the name neatPLA :)
What is changed compared to dodgyPLA:
- 3.6V voltage regulator. Better for logic levels. Still within XC9536XL specs
- Cool looking PCB
- Changed pin mapping code to mach the new schematic & PCB.
- CASRAM delay increased to 30ns. Fixes timing issues with motherboard 326298
- Added extra delay to all outputs. Fixes a timing issue with motherboard 250425 + SwinSID
Now it is one of the most compatible PLA replacements.
This project includes:
- A Xilinx ISE project written in Verilog for Xilinx XC9536XL
- A Xilinx iMPACT project file (I use this SW and Xilinx Platform cable USB for programming)
- .jed and .svf file for programming the CPLD chip (subfolder original_dodgyPLA_fix got fixed files for the original dodgyPLA and compatible versions)
- Gerber design files for ordering your own PCBs
- BOM and CPL files for SMD assembly service
- Schematic PDF
Part list:
| Definition | Designator | Quantity | Manufacturer | Manufacturer PN | Alternative |
|---|---|---|---|---|---|
| CAP CER 2.2uF 16V X7R 0805 | C1, C2 | 2 | Samsung Electro-Mechanics | CL21B225KOFNNNE | Any 2.2uF 16V X7R 0805 ceramic capacitor |
| CAP CER 220nF 50V X7R 0805 | C3 | 1 | Samsung Electro-Mechanics | CL21B224KBFNNNE | Any 220nF 50V X7R 0805 ceramic capacitor |
| IC CPLD 36MC 10NS 44VQFP | U1 | 1 | AMD | XC9536XL-10VQG44C | XC9536XL-10VQG44I |
| IC REG LIN 3.6V 250MA SOT23-3 | U2 | 1 | Microchip Technology | MCP1702T-3602E/CB | MCP1700T-3602E/TT |
| CONN HEADER 2.54MM MALE-MALE ROUND 14 PINS | J1 | 1 | - | - | long leg female headers |
| CONN HEADER 2.54MM MALE-MALE ROUND 14 PINS | J2 | 1 | - | - | long leg female headers |
| PCB | - | 1 | JLCpcb / PCBway | - |
Long leg female headers makes a lower profile but are only compatible with leaf spring sockets. Round pin headers gives a taller profile but are compatible with all sockets.
PCBs can be ordered with the provided gerber files. You can also buy the PCBs from PCBway.
If you want a ready assembled PCB check my Amibay sales posts. I charge 17€ + shipping for it.
See programming guide for how to program the CPLD ICs with a cheap FT232H board.