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.
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.