14 Jul
2015
14 Jul
'15
6:36 p.m.
On 07/14/2015 07:44 PM, William Donzelli wrote:
On the system 360 CPUs, they did not use flip-flops like we
are used to, today. They used latches, making it a
requirement that there be at least two clock phases in most
of the CPU, so that data into the ALU, for instance,
remained stable when some register at the output was
clocked. Since these were discrete transistor
implementations, a real flip-flop was too expensive, but a
latch could be implemented in about 6 transistors, I think.
The 11/45 used TTL ICs, so real FFs were available in that
technology, although they may have used latches as well.
Jon
IIRC, the KB11
processors used in the DEC 11/45 and 11/70 (and other
related systems) used five "clocks delayed from each other" (more
commonly known as clock phases).
IBM used this method as well on many of their
machines.