It wasn't fast. But if you were really concerned about performance on the CPC you wouldn't be using the firmware anyway. Standard practice to do a delay on the

It wasn't fast. But if you were really concerned about performance on the CPC you wouldn't be using the firmware anyway. Standard practice to do a delay on the CPC was a loop around CALL &BD19 - that paused until frame flyback, i.e. 1/50th of a second.