13 Dec
2022
13 Dec
'22
2:31 p.m.
Douglas McIlroy <douglas.mcilroy(a)dartmouth.edu> wrote:
Apropos of accessing rotating storage, John Kelly used
to describe the
Packard-Bell 250, which had a delay-line memory, as a machine where
addresses refer to time rather than space.
The PB 250 had two instruction-sequencing modes. In one mode, each
instruction included the address of its successor. In the other mode,
whatever popped out the delay line when the current instruction
completed would be executed next.
Doug
For us (relative) youngsters, can you explain some more how delay
line memory worked? The second mode you describe sounds like it
would be impossible to use if you wanted repeatable, reproducible
runs of your program.
Thanks,
Arnold