c0pperdragon

The modifications to the bios are done and available in the github releases section. Autodetection will work for RAM sizes of 512KB, 1MB, 2MB, 4MB. The detection algorithm assumes that...

Using 2 ICs to get 4 MByte in total would also have been my choice. But you probably need to invert A21 for one of the chips. You can again...

I did a quick check on mouser and it seems that there are no parts bigger than 1MByte that run on 5V. So if you want to have 4MB and...

3.3V should also work. I once had a similar board running on 3.3V and I think with 10MHz this is probably OK. I am mainly using 5V to directly run...

The things you did not try 1 - 3 should not make any difference. Especially 2 and 3 are totally unrelated to the FPGA. But actually it would make sense...

This security bit may indeed be something. I actually never used it and I could not even check it anyways, so I never bothered. Same as you, I don't even...

Congratulations! Building the boards successfully is no easy task.

Summary on how to hack the mod intended for a C64 (as sold by videogameperfection.com) to fit a C128DCR: 1. The FPGA board could somehow fit in the space of...

For information on the new LumaCode modification, please have a look at https://github.com/c0pperdragon/LumaCode . @scorpio-ny Please open an issue in this repo to discuss a possible C128 variant.

Yes, they also pay me a small fee for my designs.