3 of 6Image
Cambridge University's Edsac, or Electronic Delay Storage Automatic Calculator, pictured above, is considered the first practical example of a machine holding program instructions in memory.
However, the significance of Edsac and the Manchester Mark 1 does not stop there. Both machines went on to form the basis of two milestone commercial systems: Edsac spawned Leo 1, while the Manchester computer was the immediate forerunner of the Ferranti Mark 1.
Leo 1 was the world's first business computer. From September 1951, it ran an application called Bakeries Valuations, organising logistics for catering company Lyons's famous tea shops and London Corner Houses.
The Ferranti Mark 1 became the world's first commercially available computer in February 1951, beating America's Univac 1 to market by as little as one month, according to some estimates.
Photograph © 2008 University of Cambridge Computer Laboratory. Reproduced by permission
From the control panel, pictured above, Leo 1's operators eventually ran applications on the 500kHz system that extended from weekly payroll calculations to accounts and management reports. The Edsac-based Leo — or Lyons Electronic Office — started out with punched card and paper tape readers, but later versions switched to magnetic tape.
Despite initial teething problems, the Leo 1 system became efficient enough for Lyons to offer computing services to other companies, including Ford UK, in what can be seen as a pioneering outsourcing service. Lyons also ended up building Leo machines for external organisations.
Photograph © 2008 Leo Computers Society
Based on the Manchester Mark 1, the Ferranti Mark 1, whose console is pictured above, is hailed today as the first commercially available business computer, but its 1952 sales brochure says much about the importance of commercial applications in that era.
In the Ferranti 1 brochure's section on applications, after a lengthy discussion of determinants and matrices, ordinary and partial differentials, problems of logical structure, tables of Laguerre polynomials and Laguerre functions, it casually mentions that the machine can be also be used for "commercial and industrial subjects".
According to Manchester University, early programming on the Ferranti Mark 1 was "horrific by modern standards". It required programmers to work in base 32 — a five-bit group — which meant remembering the 32-letter-shift keyboard characters of a teleprinter and their five-hole equivalents. However, some who have worked that close to the machinery say it gives a unique insight into the way the computer works, and encourages efficiencies unthinkable today.
Photograph © The University of Manchester 1998, 1999