How it all began
On June 21st, 1948, at Manchester University, shortly after 11 o'clock in the morning, the world's first stored-program electronic digital computer successfully executed its first program. That program was written by Torn Kilburn who, along with Freddie Williams designed and built the machine. It was called the Small-Scale Experimental Machine, but was soon nicknamed "The Baby". On both sides of the Atlantic, teams had been working to produce the first true computer. Each immersed in their own very different projects, these teams of scientists, engineers and mathematicians may not have thought of themselves as being in a race to invent the modern computer. But with hindsight, that is exactly what they were doing and the race was won that June day in Manchester with the birth of the Baby. By the beginning of 1946 two major purely electronic digital computers had been built, the ENIAC in the USA and the Colossus in the UK. The first Colossus was designed and built at the Post Office Research Laboratories at Dollis Hill in North London in 1943, under Dr Tommy Flowers, for the code-breaking centre at Bletchley Park. In all 10 were built and they were extensively used in the last two years of the war to break the German "fish" codes.
The Colossus machines proved that large numbers of electronic valves (2,500) and supporting circuitry could be kept working for long enough to produce useful results in a fraction of the time it would take a mathematician. The Colossus operation at Bletchley Park was directed by M.H.A. (Max) Newman, who, after the war, moved to the University of Manchester as a professor in the Mathematics department. ENIAC (Electronic Numerator, Integrator, Analyzer and Computer) was built at the Moore School of Electrical Engineering, at the University of Pennsylvania, Philadelphia, for the US Army's Ballistics Research Lab. It was first working (in secret) in 1945, and was unveiled to the public in February 1946. It was built under John W. Mauchly and J. Presper Eckert, and the team was joined in 1945 by John von Neumann. ENIAC proved publicly that a large electronic digital machine was viable and useful, and the need for an effective electronic random access store to maker further progress was well understood. In 1945, work was already in hand to design EDVAC (Electronics Discreet Variable Automatic Computer), the successor to ENIAC. This would include an effective electronic Random Access Memory containing program as well as data, allowing for easy change of program and fast execution of programs. An early draft report was edited by John von Neumann, which resulted in the classic basic computer design being labelled the "von Neumann computer".
Much of the conceptual thinking behind the development of the computer had come from the British mathematician, Alan Turing, who published his ideas for a universal computing machine in 1936. Turing worked at Bletchley Park, designing a code-breaking machine that pre-dated Colossus, and after the ward he joined the National Physical Laboratory (NPL) in Teddington, Middlesex, where he began designing his own stored-program computer, the Automatic Computing Engine, or ACE. Turing would later, move to Manchester University, to join the staff of Max Newsman's Mathematics department, where they both contributed to Freddie Williams' project. Meanwhile, in November 1946 at Cambridge University, Professor Maurice Wilkes and his team began the design and construction of their own stored-program computing machine, EDSAC (Electronic Delay Storage Automatic Calculator), which was based on the EDVAC design.
As the various teams started to build from their designs, there was one main storage device accepted as the basis for the all important main electronic store, the Mercury Acoustic Delay Line. This had a major disadvantage in that it was not truly random-access, as you could only gain access to a block of words at a time.
Freddie who was then working at the UK Telecommunications Research Establishment (TRE) in Malvern, had the idea that he could build a better store based on the Cathode Ray Tubes he was so familiar with from his war works in Radar. By November 1946 he had shown how to store a single digit and provisionally patented this system in December 1946.
In January 1947 Freddie Williams moved to the University of Manchester to take up a chair in Electro-Technics in the Department of Engineering and continued to work on the system. Tom Kilburn, who had worked under him at TREE, was seconded to Manchester to continue the work width him.
By December that year, 2048 bits were being stored on a single 6-inch diameter CRT. The CRT storage system became known as the "Williams Tube".
Though the store could remember 2048 bits, an individual bit could only be reset by hand switches and it was necessary to test its capability of setting and reading any required bit at electronic Speeds and remembering its value indefinitely between settings.
Williams immediately wanted to develop a basic computer as the only way of fully besting his proposed storage mechanism.
Work on building the Baby took place in the first half of 1948 and was mainly carried out by Tom Kilburn with the assistance of G.C. (Geoff) Tootill, a Scientific Officer also seconded from TREE.
The finished machine filled a 20 foot square room in a Manchester side street across from the University.
In numerous trials, all the work of programming the computer produced no conclusive results. June 21st, 1948 seemed like many other routine days before it, until the display tube fit up with the answer the team had been waiting for.
It was the result of a program to determine the highest factor of a number and it proved that the world's first stored-program Computer had indeed been invented.
Freddie Williams later said of the first successful run:
"A program was laboriously inserted and the start switch pressed. Immediately the spots on the display tube entered a mad dance. In early trials it was a dance of death leading to no useful result, and what was even worse, without yielding any clue as to what was wrong. But one day it stopped, and there, shining brightly in the expected place, was the expected answer. It was a moment to remember. This was in June 1948, and nothing was ever the same again."