Hey everyone,
Lately I've worked on the CAT702 security chip on ZN systems in order to perform a ZN2 conversion (EX2 -> Tetris TGM). And today I've managed to succeed.
This is a picture of my current ultra-janky-af-breadboard implementation and a proof that the game is actually running in the original hardware.
Here's what I had to deal with:
So I recreated the algorithm in FPGA. It took me quite a while to have an operation which was perfectly accurate. After, spending some time setting up random inputs sent to the actual chip and a bunch of simulation, I was able to recreate a 100% accurate implementation using a TinyFPGA A1.
So, what's next? I know that @Hammy spent a lot of time on the ZN system. And with everything collected I think it opens up the way to multi ZN2 (maybe ZN1, not sure) without BIOS/ROM hacks. If you want to do such things, DM me so I can share the project with you.
For fun, I also have worked on a PCB to make this with proper dipswitches to select which key you want (it requires a MachXO2 1200 or TinyFPGA A2 otherwise you don't have enough space in the FPGA).
However, please note that I don't produce PCB professionally, I have no plan on producing it and shipping it to people.
But, if someone interested in this want to do it, I'd be glad to share the WIP design and the FPGA code. Please DM me here or through my twitter.
Enjoy!
Lately I've worked on the CAT702 security chip on ZN systems in order to perform a ZN2 conversion (EX2 -> Tetris TGM). And today I've managed to succeed.
This is a picture of my current ultra-janky-af-breadboard implementation and a proof that the game is actually running in the original hardware.
Here's what I had to deal with:
- Write the roms (duh)
- Fortunately, this games uses only 32Mbit roms which are compatible with 27c322 chips. I'm able to write them using the arduino project I created a while back to write cps2 roms check it out here
- If you want to burn EX2 / Strider 2 / Star Gladiator 2 / Tech Romancer, you might need to deal with 64Mbit DIP42 roms which are really rare afaik
- Deal with the jumpers
- Thanks to the works of @twistedsymphony, everything has been listed previously in this google doc. Thanks a lot!
- Note: those jumpers in the end select if you want to transmit A21 address line to pin 11 (usually it's the /CS line). This line is useful only if you have a 64Mb roms which is okay here so we need to pull this to low here.
- Recreate the PAL
- Everything has been dumped and tested by @Hammy and @twistedsymphony so I was able to recreate BANK02 using a standard ATF16V8. Thank you guys!
- Recreate the CAT702 for CP11 instead of CP08
So I recreated the algorithm in FPGA. It took me quite a while to have an operation which was perfectly accurate. After, spending some time setting up random inputs sent to the actual chip and a bunch of simulation, I was able to recreate a 100% accurate implementation using a TinyFPGA A1.
So, what's next? I know that @Hammy spent a lot of time on the ZN system. And with everything collected I think it opens up the way to multi ZN2 (maybe ZN1, not sure) without BIOS/ROM hacks. If you want to do such things, DM me so I can share the project with you.
For fun, I also have worked on a PCB to make this with proper dipswitches to select which key you want (it requires a MachXO2 1200 or TinyFPGA A2 otherwise you don't have enough space in the FPGA).
However, please note that I don't produce PCB professionally, I have no plan on producing it and shipping it to people.
But, if someone interested in this want to do it, I'd be glad to share the WIP design and the FPGA code. Please DM me here or through my twitter.
Enjoy!