The STC ZEBRA and CPU meters

From: Derek Peschel <dpeschel_at_eskimo.com>
Date: Mon Jan 14 01:50:05 2002

Thread crossing alert...

Since the ZEBRA used a drum for storage, most instructions had to wait for
the drum to rotate into position, so one instruction takes a variable
amount of time.

And so the computer had a moving-needle efficiency meter on the front panel,
which presumably integrated a series of pulses (similar to the circuit
Tony described earlier). Or I suppose it could have divided the rate
of instruction execution by the rate of drum rotation (since there was
a timing track on the drum anyway). 100% efficiency was attainable
but only by simple programs such as a parity check of the drum.

It also had a telephone dial, sense switches, the usual memory-tweaking
switches, and a register display. In the second-generation (transistor)
machine, the register display was a CRT. In the first-generation (tube)
machine the register display was a bunch of Magic Eye units IIRC.

-- Derek
Received on Mon Jan 14 2002 - 01:50:05 GMT