Bletchley Park boffins start trailblazer EDSAC computer rebuild
First replica parts go into production
Physical production of a replica of EDSAC, aka the Electronic Delay Storage Automatic Calculator, has at last begun at The National Museum of Computing, located at World War II crypto centre Bletchley Park. EDSAC is an early computer originally put together at Cambridge University in the late 1940s.
The initial work on the replica focused on punching out 20 chassis units based on the three that survive from the original EDSAC’s 140, each home to a selection of the computer’s 3,000-odd thermionic valves. These helped it process up to 650 instructions per second, not many by today’s standards, but two orders of magnitude more than the electromechanical computers that preceded it.
“Over the past year we have researched EDSAC’s design and original construction, so this week marks the exciting transition from research to production,” said Andrew Herbert, the EDSAC reconstruction project lead. “With this important step accomplished we are confident that we can complete the daunting task of replicating EDSAC as it was in 1949."
EDSAC in the 1940s
Source: Cambridge Computer Lab
The machine was designed in 1947 by Maurice Wilkes (1913-2010) after his appointment two years previously as the second director of what was then called the University of Cambridge Mathematical Laboratory. Wilkes’ team took their lead from John von Neumann’s plan for an electronic computer called EDVAC (Electronic Discrete Variable Automatic Computer), itself an evolution of ENIAC (Electronic Numerical Integrator And Computer), the machine built by John Mauchly and J. Presper Eckert of the University of Pennsylvania at the behest of the US Army.
EDSAC, which occupied a space 5 x 5 x 2m, ran its first program on 6 May 1949 and was used for the following nine years. . It formed the basis for LEO (Lyons Electronic Office) built for the Lyons food company and widely regarded as the world’s first business computer. In 1958, having been succeeded by EDSAC 2, EDSAC was dismantled.
The goal of the reconstruction project - which was launched two years ago this Friday and is backed by likes of the Computer Conservation Society, Acorn co-founder Hermann Hauser and Google UK - is to have a working replica of EDSAC up and running by March 2015. ®
Re: Delay lines
"A long-standing question for the project has been the reconstruction of the mercury delay lines used by the original. These are problematic for several reasons: the precision engineering required to manufacture them is demanding, the operational, maintenance and durability aspects of mercury delay lines are challenging, especially for a museum rather than laboratory environment, and the cost of buying the mercury is significant. After investigations by Peter Linington into other storage technologies we have decide that the main store will be constructed using nickel delay lines. These were the immediate successor to mercury delay lines, follow similar physical principles, and are known to be reliable and long-lived in operation. That said, the techniques used in constructing them are essentially lost so Peter has mostly recently been investigating these and has been able to demonstrate a first proof of concept prototype.
Given the importance of mercury delay lines in the history of early computers, the project has given itself the objective of, at a minimum, building a small stand-alone demonstration rig showing a mercury delay line in operation. One route to this might be to experimentally refill the surviving short delay line."
http://www.cs.man.ac.uk/CCS/res/res60.htm#b (Was reading it in the bath last night)
EDSAC ran a version of noughts and crosses displayed on a cathode ray tube. It might well have been the world's first video game console.
More seriously, the subroutine was also invented on EDSAC.
EDSAC web simulator
As a student at Cambridge we were tasked with writing a web-based emulator of the EDSAC as part of the 50th anniversary celebrations. Our group got some original code to run - including the OXO game, as well as developing some latter day examples, such as Conway's life.
Amazingly it still runs 13 years later . Our simulator is available here:
"It's not very fucking useful."
And yet, still more useful than your post.
There are a lot of good reasons for going back to first principles, not least of which is because it gives a better understanding of those principles. Considered in that light EDSAC-2015 is not a computer, it's a map. If the writing is in big letters and it only shows main roads, that's to help you read it better.
Hats off guys
Every time we turn around, the british are rebuilding another historical computer. Great job!