Tuesday, 30 September 2014

Pillowcases and air freshener - the unexpected world of classic computers

On the day of his retirement, Pete Turnbull introduces us to his museum of computing.

If you walked along the ground floor corridor of the Fairhurst Building last summer, you would have seen a display cabinet reflecting five decades of computing artefacts. The contents came from my collection of 'classic computers'.

5 decades of computing at the University - click for key
Pete and his SGI 2000
My collection is quite small, comprising perhaps 65 machines, whereas my friend Jim has over 600. My smallest and probably cheapest computer is a single-board microcomputer only about 10cm square. The largest and most expensive is a Silicon Graphics Origin 2000, a 'supercomputer' once used by the Dutch weather bureau. It's almost identical to (though half the capacity of) a $1,000,000 system owned by Computer Science in the late 1990s. Luckily I only had to pay for beer when mine was donated. If that makes the CompSci outlay seem a little OTT, understand that the two acquisitions were six years apart.

Why do people collect these things? Well, they aren't all static museum pieces. Most run, and some have practical use in data recovery. There's also a movement to preserve history and heritage. Of course the real reasons for my collection are just nostalgia and entertainment.

Many of the machines have needed repair, restoration or 'improvement', and that's part of the fun. I designed and built the single-board micro mentioned above, loosely based on magazine articles of the day. I recall a trip to Cambridge to collect pre-production Zilog Z8 parts for it in 1984. Cutting edge stuff, 32K memory on a single chip. Fault diagnosis too can be a rewarding intellectual exercise, though ideally away from children easily confused by short 'technical' words.

The PDP-8 - now fresh and clean
Many machines I own came with stories, or the acts of collection did. One PDP-8 had to be treated in the 'circuit board cleaner'. As it was carried out to my car, a small round pink object fell out. "Ah yes," said the donor. "I meant to tell you about that, you'll need it." Apparently Mrs Donor refused to allow the machine in her house because when switched on and warmed up it smelled strongly of cat's pee. The pink object was the optional, somewhat non-standard and fairly ineffectual air freshener upgrade.

A common method of cleaning circuit boards in small production houses is to put them in a domestic dishwasher, so that's what happened. (If you try this, don't use caustic detergent and don't use the hot drying cycle.) Actually I own a number of useful pieces of equipment for computer care, and as several are located in the kitchen, my wife uses them too. For example, our large high temperature paint dryer also produces excellent cakes and roast meats, while the small-parts cleaner and drier can both be used for laundry. Just remember to photograph the keyboard layout before you remove the keycaps and put them in the pillowcase...


  1. I remember building a wire-wrapped Z8 based computer with an NEC 7220 graphics chip. Was certainly a lot smaller than the dumb terminal I had plugged into the serial port!

  2. Good luck, Pete. I expect to see you down at the pigsheds much more frequently now. :-)

  3. 32K memory! Luxury! It was ZX81s with 1K for us

  4. Enjoy your retirement Pete. I finally turned off the last SGI here about 18 months ago.

    And Arthur, be careful with that line of thought, you might run into some Yorkshiremen around here...


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