silly question:
how many instructions and registers would a minimal RISC be?
load, store, move, add, sub, nop, jump, beq, blt, and, or, xor, not, shift left, shift right, mul, div, rem, min, max, call, ret, sys, int?
general purpose, return addr, stack pointer, func args(x?), saved registers(x?),
maaaybe a time register and identity register, an interrupt masks register that can only be written by a privileged process... so a ring register?