RGBY-ROM reads data cartridges comprised of red, green, blue, and yellow acrylic squares where each square acts as 2 bits of program data.

The the program is then excuted on a custom simple CPU architecture instantiated on a FPGA to control a RGB LED and 8 LED indicators.

The executed program is assembled using a custom assembler to create the data cartridge's color pattern.

RGBY-ROM uses the TinyFPGA Bx as the FPGA board the Verilog is developed useing the ATOM IDE with the APIO extension.

Blog post: https://metaphasiclabs.com/rgby-rom-custom-fpga-retro-cpu/