New uses for oscilloscopes
The 3-day week is fading from my memory
now. Many readers will never even have heard of it!
At the time we were developing a computer
in the corner of the laboratory.
As we'd only been given 9 months to
think about it, design it, build three prototypes and to demonstrate
a working system to the Australian Government it was hard enough
without having only three days a week to contend with.
The restrictions were imposed just after
the first prototype had been delivered to the lab.
Those in Industry may remember the hardships.
We were completely disconnected from
the mains, or if deemed a special case, allowed only a limited
amount of power for all but three days.
This meant that you couldn't work weekends
or two days of the normal week.
That is unless one could invent a way
of getting round the ban.
Our factory had been fitted with a special
device installed at the mains input board.
This operated on our "off"
days, and I believe in our case was set to deliver a current
of 13 amps, any more than this and the device tripped and all
power was removed.
The 13 amps was a figure agreed to cover
the minimum security aspects which were agreed to be necessary
for a "List X" site (whatever that was).
We had to have a company policeman permanently
manning the foyer; or strictly speaking, there were three of
them working in shifts.
This wasn't really enough because, during
the period, someone broke in and emptied all the cigarette machines.
Fortunately they didn't take any cryptographic equipment or secret
documents for which they could have got a lot more than a few
Being engineers we had worked out exactly
how much power was available to us if we were to come in during
the off days.
During the day we could operate the
computer and one small oscilloscope.
An AVO, connected to the special mains
lead that came several hundred feet from the front door and up
the lift shaft, registered the number of amps of power we were
Ten Amps was our limit after about 6pm
and 5 Amps was our limit during the day.
We worked in two shifts, 12am to 12pm
and 12pm to 12am with an hours overlap so we could pass on details
of progress, if any, to our colleagues. I worked the former shift
with a fellow engineer and a couple of other engineers did the
It was very cold and snow lay on the
After 6pm it got really cold in the
The floor was bare concrete and too
cold to stand on, so we had large pieces of fibre insulating
board laid in front of the computer.
We had no heating at first but being
resourceful we realised that the Tektronix valve oscilloscopes
could be pressed into service for this purpose.
We arranged four of these, back-to-front,
with their cooling fans blowing warm air over us.
The AVO read just under 10 Amps and
things weren't too bad.
About 11pm, everything suddenly went
The two anglepoise lamps went out, the
computer display stopped flashing and the oscilloscope fans all
We found our torches and went down to
We were on the fourth floor of the "old
building", which had once been a margarine factory, and
we made towards the front door of the "new building"
which had been added in the 50s.
It took us about ten minutes to thread
our way through the ghostly factory.
Finally, we met the security man who
sheepishly owned up to having plugged in his ILLICIT electric
We went home.