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
- Schematic PDF
Part list:
- PCB
- "long leg female headers" or "round pin headers" for pins
- U1 XC9536XL-10VQG44C CPLD
- U2 MCP1702T-3602E/CB 3.6V LDO
- C1, C2 2.2uF X7R 0805 ceramic capacitor
- C3 220nF X7R 0805 ceramic capacitor
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 14€ + shipping for it.
Programming guide for cheap FT232H board https://github.com/1c3d1v3r/neatPLA/tree/master/programming