When young families with children visit, they are always amazed how big the systems from the 50s, 60s and 70s really were. Their knowledge of computing today may typically be the desktop or tablet they have at home, work and school - or the smartphone in their pocket which has many times more processing power than all the systems on display.

It’s fitting that our First Generation Gallery is our largest. Here you can see just how big those early computer systems really were.

In our First Generation Gallery you will see the original Harwell Dekatron computer, also known as the WITCH, from the early 1950s, the prototype Hollerith Electronic Computer (HEC) from about the same period and the ongoing reconstruction of the Electronic Delay Storage Automatic Calculator (EDSAC) that dates back to 1949.

For visitors who actually worked on or maintained the systems on display, we often bring back fond memories of yesteryear which they frequently share with our room guides. They are very complimentary and often amazed that we have them working today!


Harwell Dekatron Computer, or the WITCH

This is the world's oldest original working digital computer.

In 1949 plans were drawn up for a machine to automate the tedious work performed by teams of bright young graduates using mechanical calculators. Simplicity, reliability and unattended operation were the design priorities. Speed was of a lower priority.

This pioneering computer first ran in 1951 and by 1952 was using 828 Dekatron tubes for program and data storage, relays for sequence control and valve-based electronics for calculations. It was its geographical location of Harwell and these valves that gave it its first name.

A tortoise not a hare

The Harwell Dekatron computer was pitched against a human mathematician to check the machine’s operation. The human kept pace for 30 minutes, but then retired exhausted as the machine carried on remorselessly. The computer once ran unattended for ten days over a Christmas/New Year holiday period.

It was used at Harwell until 1957, when a competition was held for colleges to see who could make best use of it. The competition was won by Wolverhampton and Staffordshire Technical College (later becoming Wolverhampton University) and they gave it its second name of the WITCH (Wolverhampton Instrument for Teaching Computation from Harwell). The WITCH was used in computer education for over 15 years until 1973.

After a period on display at Birmingham Museum of Science and Industry, the computer was disassembled and stored at Birmingham City Council Museums’ Collection Centre.

In 2009 the machine was spotted dismantled in storage and recognised by TNMOC volunteers who made a plan to bring it to TNMOC for restoration in full public view.

You can follow the technical story of how the Harwell Dekatron / WITCH computer was restored here.

When it was rebooted on 20 November 2012 the Harwell Dekatron computer / WITCH became the world's oldest original working digital computer. You can find out more about it in This short BBC video.

We aim to keep the Harwell Dekatron computer / WITCH working but because of its great age, we can't always guarantee it so occasionally you may find it is down for maintenance.

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EDSAC

The EDSAC Replica Project aims to reconstruct one of the most important early British digital computers.

Designed in 1947 by a team lead by Maurice Wilkes, the original EDSAC computer operated for almost 10 years, starting from its first successful program run on 6th May 1949, at the Cambridge University Mathematical Laboratory.

The goal is to have a working reconstruction of EDSAC as it was in May 1949, built and operational by the end of 2019.

You can also see A video record of the EDSAC Project, by the renowned TV film maker David Allen.

You can also see EDSAC in the news.

Follow the link below for the full story of the EDSAC Replica Project.

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Hollerith Electronic Computer (HEC)

The HEC was the prototype for the range of computers that were to become Britain’s best-selling first-generation computer and, as the first computer installed in many countries including India, New Zealand and East Africa, the machine played a key role in starting the global computer revolution.

Today, the first version of the two by three metre HEC with its highly innovative magnetic drum store can be seen by visitors to the First Generation Gallery at TNMOC where it stands alongside other machines of the period

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