"primitive microcode" is the wrong way of thinking about it. Microcoded CPUs had been around for ages by that point. It's a highly optimised microcode, designe

"primitive microcode" is the wrong way of thinking about it. Microcoded CPUs had been around for ages by that point. It's a highly optimised microcode, designed to produce the correct control signals in the minimum amount of space while not caring about the output for illegal opcodes.