These little projects are such a good way to illustrate principles in a concrete way, even if they aren't "useful" in any other regard.

Back in 1983 or so, I had a TI/99 computer and found a BASIC program called "PicoProcessor" in one of the home computing magazines. It emulated a 4-bit microprocessor. It only had a handful of instructions, 16 bytes of memory, and a couple of registers but it was enough to illustrate the concepts of how a processor runs machine code, in a way that was much more understandable than just reading about it.

I love this 4bit "isa" with 12 simple instructions. It makes me want to dig out my old 74x chips from storage and make one. That said, thank God for FireFox Reader mode, on mobile at least the add popups make this excellent blog post unreadable..

it would be remiss to not mention the most excellent ben-eater's 8bit-computer https://eater.net/8bit and ofcourse the nand-to-tetris book + resources (https://www.nand2tetris.org/)

where can I find the full list of instructions?

Nice!