EDSAC

EDSAC. The Electronic Delay Storage Automatic Calculator was the world's first practical stored-program computer to enter regular service. Designed and built under the leadership of Maurice Wilkes at the University of Cambridge Mathematical Laboratory, it executed its first program on 6 May 1949. EDSAC's operational success provided a vital computational resource for scientists across the University of Cambridge and pioneered foundational concepts in computer architecture and software engineering.

History and development

The project was initiated by Maurice Wilkes shortly after he attended the seminal lectures on computer design at the Moore School of Electrical Engineering, which detailed the EDVAC design. Construction began in 1947 within the University of Cambridge Mathematical Laboratory, with key contributions from engineers like William Renwick. The design was influenced by the von Neumann architecture and the earlier Manchester Baby, but focused on delivering a reliable, usable machine. Funding and components were secured from various sources, including J. Lyons and Co., which later used the experience to develop the LEO I business computer. EDSAC was officially unveiled and began solving real problems for researchers in fields like radio astronomy and X-ray crystallography in mid-1949, marking a pivotal moment in the history of computing.

Technical specifications

EDSAC was a serial computer utilizing mercury delay line memory for both storage and processing, with an initial capacity of 512 words, later expanded. Each word was 17 bits plus a sign bit. Its instruction set comprised about 18 basic instructions, and it operated at a clock speed of 500 kHz, achieving an addition time of 1.5 milliseconds. Input was via punched tape and output was delivered by a teleprinter. The machine's arithmetic logic unit was built from approximately 3,000 vacuum tubes and consumed around 11 kW of power. Its physical construction, featuring large racks of electronic equipment, was housed in the Mathematical Laboratory and became a landmark in early British computer science.

Programming and software

Programming EDSAC was a hands-on process involving low-level machine code, initially entered via punched tape. A major breakthrough was the development of the first assembly language and assembler, conceived by David Wheeler, who also invented the concept of the subroutine for EDSAC. The team created a comprehensive library of subroutines, effectively establishing one of the first software libraries. Early significant programs included a table of squares and calculations for John C. Kendrew's work on myoglobin. This environment made the Cambridge University computer lab a nurturing ground for pioneering programmers and influenced subsequent systems like the IBM 701.

Impact and legacy

EDSAC's immediate impact was profound, providing unprecedented computational power for post-war British science, notably supporting Martin Ryle's radio interferometry and the crystallography research of Dorothy Hodgkin. It demonstrated the viability of the stored-program concept for practical scientific and commercial work, directly inspiring the development of the business computer LEO I. The machine and its successor, EDSAC 2, trained a generation of influential computer scientists, including Seymour Cray and Peter Naur. The principles of its design and its software innovations were disseminated through Wilkes's 1951 textbook and shaped the evolution of later machines like the IBM 704. EDSAC is commemorated by a replica project at the National Museum of Computing in Bletchley Park.

See also

* Manchester Mark 1 * UNIVAC I * Whirlwind (computer) * Timeline of computing 1950–1979 * History of compiler construction

Category:Early computers Category:University of Cambridge Category:1949 introductions