Isn't the KA10 basically asynchronous? (I know, it has a clock, but I'm not sure how much it is used for.) The thing is I recall reading (where, I don't now remember) that the CPU is organized with 'go' pulses leading from one block of circuity to another, and it uses delay lines to time out the passage of these pulses, so if you wanted the CPU to be as fast as possible, you went around to each delay line and tweaked them down until things started to fail, and then backed off a bit. Other CPUs of that era might be the same. There's an amusing description of the Multics CPU here: http://www.multicians.org/mga.html#6180 "The 6180 processor was among the last of the great non-microcoded engines. Entirely asynchronous, its hundred-odd boards would send out requests, earmark the results for somebody else, swipe somebody else's signals or data, and backstab each other in all sorts of amusing ways which occasionally failed (the 'op not complete' timer would go off and cause a fault). Unlike the PDP-10, there was no hint of an organized synchronization strategy: various 'it's ready now', 'ok, go', 'take a cycle' pulses merely surged through the vast backpanel ANDed with appropriate state and goosed the next guy down." Noel