Mainframes & large systems
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Mainframes arrived in the 1950s. They are still with us!
Whenever families with children visit, they are always amazed just how big the systems from the 50s, 60s and 70s really were. Their only knowledge of computing might be the PC or laptop they have at home, or the iPhone in their pocket (which has many times more processing power than all the systems on display). We have many visitors with memories of working with these machines and they are usually amazed that we have them working!
- a TAC from the late 1950s
- three Elliotts from the 1960s
- PDP-11s from the 1970s
- and the monster ICL 2966 from the 1980s.
TAC - Transistorised Automatic Computer
Dating to around 1958/60. this is one of the more unusual systems we have on display. Contained within four large cabinets and a control desk, it was one of the first transistorised computers made in the UK. Ours was used as a monitoring system for a nuclear power station. It gave sterling service for many years from its installation in the early 1960s to finally being decommissioned in 2004 - that's over 40 years! That is amazing considering the technology being used. It was kindly donated to the museum.
This is a fully functioning machine from around 1962 which, when it was donated to the museum, had spent about 15 years in a farm barn. The restoration was lead by John Sinclair, and the machine has been running with little need for attention for many years. It has recently had two upgrades: The addition of a Calcomp drum plotter and some additional input/output features. As well as the system on display here at TNMOC, John has also restored and maintained an 803B system for the Science Museum in London.
As with any good system we have it working hard each Saturday. Members of the project team keep their programming skills sharp by developing programs for the 803 using the original software tools. These programs play music, draw graphs or solve mathematical problems. One recent program calculates the cost of a shopping list in pounds, shillings and pence (£sd, the UK's currency pre-decimalisation in 1971). This is a far cry from its original use for planning bakery delivery routes or accounting, but it does allow the system to be shown working and in doing so ensures its continued operation.
Three Elliott machines from the 800 and 900 series are on display at TNMOC.
The PDP-11, first launched by Digital Equipment Corporation in 1970, was one of the most popular mini-computers in the world throughout the 1970s and 1980s. Models were still being made in 1990.
The first PDP-11 machines were transistorised, but by the end of the line the whole machine would fit on a chip. They could be configured as a system as small as a paperback book and built into a machine or be a huge multi-user system. PDP-11 systems could be found being used to run experiments in university laboratories, controlling production equipment in factories, and even on US Navy warships.
It was widely copied, particularly behind the Iron Curtain. One the first official versions of UNIX ran on PDP-11 machines.
In the Museum is the IRIS Air Traffic Control System and the Blacknest PDP-11 designed to distinguish seismic events from nuclear explosions.
Since the advent of the PC, the imminent demise of "big iron" has been predicted, but they are still here - alive and well in the cloud.
The Museum's largest computer, the huge ICL 2966 from around 1985/7, is coming back to life. It is by far the largest system we have on display at the museum, taking up almost a third of the floor space in the large systems gallery. What is more surprising is that we did not actually have room for all of it.
This system uses a lot of power - you can't run this from a 13A plug - so we had to have a separate mains supply fitted to enable the restoration to continue. At least we know that on cold winter days the large systems gallery will probably be the warmest room in the museum (assuming our resident ICL Mr fixit can get it going!)
The system itself was used up until 1999 at TARMAC, who after having decommissioned the system, donated it to the museum where it was put in storage. It was not until late 2007 that we had enough floor space to put it out on display and it certainly is impressive to see.
The long and difficult process of restoring the system to full working order is now well under way. We are lucky to have help and advice from the ICL/Fujitsu engineer who maintained the system during it's working life at TARMAC and actually decommissioned it.
Restoration work takes place on most Saturdays.
You can follow the latest technical developments in restoring the ICL 2966 computer here.