What RISC cpu has the smallest instruction set?

Question

I'm currently writing an 8086 emulator however the task is prooving to be more time consuming then i first anticipated.

So... I'm plannnig on putting that project on hold and writing a smaller emulator based around a simpler CPU. My question is which one? I know there are a number of reduced instruction set computers out there but i dont know which of the RISC CPUs have the smallest instrucion sets.

I seem to recall from a while ago reading about a CPU that only had something like 12 instructions. This would certainly make for an easier time building an emulator!

Anybody know of a CPU with a really small instruction set?

Answer 1

The Universal Turing machine has I believe only four instructions. Forth or LISP both can be implemented very small as a CPU. If you need more powerful functions then you just load libraries that implement higher level functions.