Commodore C64 8K ROM Cartridge PCB
- Product Review (submitted on 6 December 2020):
I bought this as a pseudo challenge to better understand the C64 memory and cartridge relationship, and I did learn a few things.
- This is a 8k cartridge so you are limited to 8k
- Depending on the size of the EPROM you can put multiple 8k programs/games on the IC and use the jumpers to reconfigure the cartridge for their use
- The Tynemouth Software user guide link has been pulled down for some curious, perplexing, reason which I don't understand, but if you take the link and look for historical records you will find it; use WaybackMachine to find the link as of September 28, 2020, alternatively look for other similar guide to relate
- I used an ST M27C256B EPROM and put 4 8k bin programs on it. I found that there are some odd things with either the 256 IC, the Cartridge PCB layout, or one of the bin. I was able to use the jumpers to switch the PCB to use 3 of the 4 bins
- It seams that how you lay out the 8k bins on the EPROM is in reverse expected order; eg $0000-$2000 is considered ROM4 and not ROM1 (A13,A14,A15) jumpers are set.
- C64C responds to this IC whether A15 is set or not. By the guide from Tynemouth A15 should always be set for a 256 IC
- TFW8b also has a note regarding the 256 ICs for which is not clear, and presuming to be inaccurate; (to tie A14 high and select from A13 & A15); advising anyone to double check
- If you are looking for a 16k cartridge there are a few more circuits and traces needed for a new/different PCB for which I hope TFW8b issue.
- Consider adding pin headers, jumpers, and an IC socket to make an experimental board. Then after learning, get other PCBs and solder jumper points, solder IC to PCB, and put it in a nice case
All-in-All a wonderful adventure in learning, and a great tool for just that purpose