There's not really much risk. Because the S/360 was built from gates (SLT) rather than an integrated circuit, they could easily change the design if needed. (Ev

There's not really much risk. Because the S/360 was built from gates (SLT) rather than an integrated circuit, they could easily change the design if needed. (Even at a customer site!) It's not like a microprocessor chip that would require an expensive re-spin if something went wrong. So if they discovered they needed another micro-operation, they could just add it to the design. There are a few micro-operations that seem rather contrived, as if they realized it would really help performance to do this random combination of things.