Although once little more than an academic endeavor, the RISC-V architecture is slowly supplanting applications that would have normally gone to ARM. Even a few microcontrollers have chips running this open-source instruction set now, and we expect it to grow in the future since it doesn’t require the licensing of an ARM or x86 chip. [M_Jagadeesh97] is getting ahead of the curve with this retro gaming system built on a custom-designed RISC-V system.
Most of us, presumably including [M_Jagadeesh97], don’t have access to chip fabrication tools, but what we can get is any of various FPGAs. This RISC-V CPU is built on a Terasic DE0-Nano board with 32 MB of RAM available to it, and boots to a launcher with 32 games available. There are a few limitations with this low-power system which was largely solved by limiting the display to 64×32, which lets it maintain the same aspect ratio as the original DOOM as well as the same aspect ratio for many of the older games, while still maintaining 45 FPS.
The project writeup goes deep into the design of a system like this, from the bare metal, the CPU design, the timing of the video signals, and how to implement a Wolfenstein-like raycaster. After adding a small display it looks to be fairly portable as well and is an excellent demonstration of how powerful inexpensive boards like this FPGA can be with the proper amount of effort.
