Computing’s early days are full of stories about great technical leaps forward.  But sometimes what matters most isn’t a shift in technology so much as a change in the way it is used.  The “Electronic Delay Storage Automatic Calculator” (EDSAC)—64 years old today—is a stellar example.

Entry from log book marking the first day that EDSAC was in operation: “May 6th 1949.  Machine in operation for first time. Printed a table of squares (0-99), time for programme 2 mins, 35 sec. Four tanks of battery 1 in operation”. Reproduced with kind permission of Computer Laboratory, University of Cambridge


EDSAC is noteworthy for marking the transition from “test to tool” in civilian computing.  Maurice Wilkes, EDSAC’s designer, sought to build a multi-purpose, reliable workhorse that would bring unrivalled calculating power to University of Cambridge researchers.  His aim wasn’t to be at the cutting edge of engineering; rather to be at the forefront of delivering a computer-powered general calculation service.  Above all else, Wilkes wanted EDSAC to be a practical computer, useful and accessible to a wide range of researchers.   


Short film celebrating the work of EDSAC’s team, led by Maurice Wilkes, produced by Google

In May 1949 EDSAC became the world’s first general purpose stored program computer to enter regular service, transforming scientific research at the University of Cambridge by making it possible to speedily tackle analyses of previously impractical scale, across disciplines as varied as astronomy, economics, biology and more.

But EDSAC’s legacy stretches far further. Subroutines—a central tenet of programming today—were invented by David Wheeler to make it easier to program EDSAC by re-using lines of existing code. The world’s first computer science diploma had EDSAC as its foundation. The world’s first business computer was built with EDSAC as a prototype.

Sadly, little remains physically of EDSAC today. That’s why a team of U.K. volunteers have embarked on an ambitious project to construct a working replica of the original EDSAC, in partnership with The National Museum of Computing. We’re delighted to support the EDSAC Rebuild Project, and we look forward to welcoming it back to regular service—as a reminder of the U.K.’s illustrious computing past.