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Pyestock Diaries

Computer Building (574)

Built: 1961
Decommissioned: 2002

The Computer Building was well positioned within the Pyestock site. Believed built in 1961 (along with the Air House and Cell 3) it was placed almost equidistant from the major testing cells (Cells 1 & 2, Cell 3 and the then future Cell 4). This minimised the amount of data and control wiring required between each cell and the computer.

Given the size of the building and the size of early computers, the Computer Building was probably designed to house only one machine. The first computer was believed to be a first-generation valve based Atlas (and the engineers had to change approximately a dozen valves a day to keep it going). It was later joined by an Elliot 803B machine.

In 1963/64, the ageing Atlas was replaced by the second-generation (and probably far more reliable) solid-state SDS9300. As the decade continued, it was joined by a DEC PDP-7 (SN#41) and then a DEC PDP11/20 in the mid 1970s.

These machines would've required specialised environmentally controlled rooms. The interior of the Computer Building still reflects this requirement, with two large, windowless rooms situated in the middle of the building, one on each floor. These were surrounded by corridors with offices and workshops on the periphery.

The north and west sides of the Computer Building.
05|05|07 © Simon Cornwell 2007

One of the more novel features was a tunnel leading from a trapdoor in the Computer Building to the underground passage connecting Cell 3 and Cell 4. Named Monks Tunnel (the nomenclature determined by a warning board placed near the trap door) this passage was probably used to route data and control cabling from the computer through to the cells.

South eastern view across the Cell 3 control room.
05|05|07 © Simon Cornwell 2007

It appears the exterior of the building was altered in the 1980s with smart brick cladding, new window frames, new staircases and a pitched roof. New offices extended the west of the building but weren't added at the same height thus creating a mezzanine floor. This remodelling was prompted by the arrival of the microcomputer, so there was no need for a purpose built computer building. This rebuilding also involved the repositioning of Cell 3's control room, which was moved into the empty first floor computer room. (And required the addition of more cabling distributed through Monks Tunnel.)

Despite the removal of the huge mainframe and minis, the Computer Building never really lost its connection with computers. Now closed and standing largely empty, we found one ground floor office full of redundant PCs and monitors, all awaiting their fate. And despite lacking the architectural massiveness of the test cells, the Computer Building was built to a more human scale, and offered some wonderful views of the huge buildings and piping networks which it one controlled.

Computer Building Walkthrough...

The north and eastern sides of the Computer Building Northern ground floor workshop, looking south Southern view of north western ground floor office Close-up of the computers in the north western ground floor office Detail of wallpaper in one of the central ground floor rooms Western staircase Mezzanine walkway. Moving south towards the southwest mezzanine office Looking northwest towards Cell 4 from the southwest mezzanine office Northern view of the mezzanine floor in the stairwell First floor of the western staircase looking towards Cell 4
Northwest mezzanine office looking north Northwest mezzanine office looking south west towards the Air House Labels on the keyhooks in the northwest mezzanine office First floor corridor moving eastwards  small first floor office in the Computer Building. The trees to the north of the site can be seen through the window Detail of miscellaneous keys in a first floor office The eastern staircase with view to Cell 1 & 2 Door to the Cell 3 control room. The eastern stairwell is just behind me South eastern view across the Cell 3 control room Eastern view across the Cell 3 control room
Northeast view across banks of controls in the Cell 3 control room Southern first floor office with view towards the Plant House East-West corridor in the ground floor of the Computer Building. View west Entrance to Monk's Tunnel situated in the northern corridor from the western stairwell

Further Reading