Cambridge University established a Mathematical Laboratory in 1937. This was designed to both develop new computational techniques and provide a computing service for general staff and student use. In 1945 its sole full-time employee, Maurice Wilkes, assumed its directorship.
Wilkes was captivated when a friend visiting Cambridge in 1946 brought a document back from America called First Draft on a Report on the EDVAC, by the Manhattan Project mathematician John von Neumann. Wilkes was able to attend an important series of lectures on computers at the University of Pennsylvania later that year, and returned to the UK with a mission to design a practical computer based on von Neumann's principles to be used by the Cambridge community.
By focusing on reliable and proven design features rather than revolutionary architecture, the EDSAC was up and running by May 1949. The processing unit was made up of racks of vacuum tubes, and the memory consisted in mercury delay tubes, a technology with origins in radar.
Data was compressed into sound waves and sent into a medium, mercury, which slowed them down until the computer was ready to read them and translate the wave back into an electric signal. The EDSAC 2 (Image 1), which began operation a decade later, used magnetic memory similar to that still in use today along with programming and storage innovations to expand its memory and processing capacities.
One of the biggest innovations brought about by the EDSAC was the way it was used. In 1951 Wilkes and his colleagues, including David Wheeler, published one of the first programming texts, which explained how a computer program could be constructed using a relocatable subroutine.
Rather than coding out the instructions for repeated operations sequentially on a single strip of paper, Wilkes and his colleagues described a way of giving instructions to link operations (described as 'sub-routines') in what they called a load module. This increased efficiency, allowing computer time to be shared out to University staff and students. In 1950 EDSAC was the first computer to be used to solve a problem in the field of biology, when Wilkes and Wheeler collaborated with Ronald Fisher to solve a differential equation relating to gene frequencies.
