That instruction set looks really weird, like some sort of obscure and long-forgotten 1960s experimental architecture. If I understand it correctly, the entire

That instruction set looks really weird, like some sort of obscure and long-forgotten 1960s experimental architecture. If I understand it correctly, the entire register file except for PC is effectively memory-mapped, it uses 16-bit word addressing and the peripherals (framebuffer + mouse) are accessed through dedicated instructions. Instructions are four words long, the first one only having 16 valid opcodes and the rest referencing either direct memory addresses or raw word values.