Colin Hobson: Weather, Wildlife and LEO Computers
Both LEO 1 and the LEO 2s were not installed in cosy, air-conditioned palaces. They went
into normal office accommodation and the heat, generated by the hundreds of thermionic
valves was conducted away by fans and overhead ducting. The operators were kept cool
only if they could open the office windows! This could cause a number of unexpected
problems:
On LEO 1 rain could be a problem. It was necessary to look outside before turning
anything on. If it was raining, or snowing, the heaters in the valves needed to be turned on
before the cooling fans. This built up enough heat to ensure that the water droplets sucked
in were vaporised before they hit a hot glass valve cover. Failure to do it this way round
would result in a series of high pitched squeaks as the glass, of the valves cracked. This
would be followed by the sound of engineers swearing! If there was no rain, it was better
to get the cooling up and running first.
On LEO 2 this was not a problem. The ventilation system didn’t cause the computer much
in the way of problems. The computer did provide a lot of heat, most of which was
conducted away by the ventilation system. However, there was still a lot of peripheral
equipment and human bodies churning out heat. The only option, certainly on LEO 2/1 was
to open the windows to the outside world. Mostly this worked well. However, there were
times when the outside world made its way into the operating area to cause chaos. Wildlife
was one such problem. The occasional visiting bird could provide some distracting
entertainment but the worst problem I can remember was a swarm of small insects which
came in through the open windows and settled on the paper tapes and punched cards. They
got squished into the holes in the cards and tapes changing the data.
Many years later I was working at a Post Office (now BT) site where a snake made its way
through one of the doors from the outside world, down a short corridor and then got stuck
between the automatic airlock doors into the air-conditioned computer hall.
