PLA replacement circuit for Commodore 64. Based on dodgyPLA https://github.com/desaster/c64-dodgypla
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 MCP1700T-3602E/TT 3.6V LDO
C1, C2 2.2uF X7R 0805 ceramic capacitor
C3 220nF X7R 0805 ceramic capacitor
At the time of writing there have been a huge price jump for the XC9536XL chip. Usually they were about 1$. Now Digikey, Mouset etc. suppliers sell for 7$. I hope this is a temporary price jump caused by corona or other short term issue.
PCBs can be ordered with the provided gerber files. You can also buy the PCBs from PCBway