A SNES CPU Replacement Via FPGA

Let’s say you had a SNES with a busted CPU. What would you do? Your SNES would be through! That is, unless, you had a replacement based on an FPGA. [leonllr] has been developing just such a thing.

The project was spawned out of necessity. [leonllr] had purchased a SNES which was struck down with a dead CPU—in particular, a defective S-CPU revision A. A search for replacements only found expensive examples, and ones that were most likely stripped from working machines. A better solution was necessary.

Hence, a project to build a replacement version of the chip using the ICE40HX8K FPGA. Available for less than $20 USD, it’s affordable, available, and has enough logic cells to do the job. It’s not just a theoretical or paper build, either. [leonllr] has developed a practical installation method to hook the ICE40HX8K up to real hardware, which uses two flex PCBs to go from the FPGA mainboard to the SNES motherboard itself. As for the IP on the FPGA, the core of the CPU itself sprung from the SNESTANG project, which previously recreated the Super Nintendo on Sipeed Tang FPGA boards. As it stands, boards are routed, and production is the next step.

It’s nice to see classic hardware resurrected by any means necessary. Even if you can’t get a whole bare metal SNES, you might be able to use half of one with a little help from an FPGA. We’ve seen similar work on other platforms, too. Meanwhile, if you’re working to recreate Nintendo 64 graphics chips in your own basement, or something equally weird, don’t hesitate to let us know!