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Colin Hobson: Reminiscence

Weather, Wildlife and LEO Computers

Both LEO I and the LEO IIs 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.

Colin Hobson adds" I was worked on LEO I and subsequent machines but am not sure about recordings.  LEO I certainly did make a noise but I have a vague recollection that the speaker was not in the original hardware but in the dexion operators console, which was a later addition.

LEO Iwas on a platform at one end of the room (hall). There was an engineer’s console up there which the operators did not use. The dexion operators console was down on the parquet flooring along with all the peripherals. The peripherals were aligned in two rows with shallow metal cable runs going back to the main frame platform. The room was not air conditioned and at times it was necessary to open several windows to allow the operators to breathe!  A warm wet day was a real problem as we had to make sure the heat in the room was enough to evaporate the rain before we could open the windows!  Another side effect, on the operators, was the smell of cooking which often wafted up from below!

Note: Colin Hobson was interviewed by Marie Hicks for her book Programmed Inequality and provides one of her case studies noting the story of LEO.

Date : Unknown

Creator : LEO

This exhibit has a reference ID of CH53407. Please quote this reference ID in any communication with the Centre for Computing History.

Colin Hobson: Reminiscence

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