[cctalk] Re: Z80 vs other microprocessors of the time.

Might well be, I don't remember. Or moving the SB3 (the loop counter) to be right after the loads is probably helpful. The full answer depends on understanding the timing, both of the instructions and of the memory references that are set in motion by them. I never had my hands on a 6600, only a 6400 which is a single unit machine. So I had to do some thinking to understand why someone would do a register transfer with L (shift operation) rather than B (boolean operation) when I first saw that in my code reading. The answer is that both instructions take 300 ns, but they are in different functional units on the 6600 so they can start 100 ns apart. paul