On May 6th, 1949 EDSAC (or Electronic Delay Storage Automatic Calculator) ran its first programs, calculating a table of squares and generating a list of prime numbers. The massive vacuum-tube-powered machine was put into service at the University of Cambridge and almost immediately changed how research was done at the school. It was among the first general-purpose computers capable of storing programs in rewritable memory, which took the form of mercury delay lines. Maurice Wilkes, the designer of the EDSAC, certainly earned his place in computing history, but David Wheeler's later contributions were equally important. Using the EDSAC he invented subroutines, an essential component of modern programming that allows developers to reuse bits of existing code to simplify the act of writing software. This milestone piece of machinery is little more than scraps at this point, but a team at the UK's National Museum of Computing is working to build a working replica. The hope is to have the computer up and running by May of 2015. For some more insight into how the EDSAC changed the face of computing, check out the video after the break.
[Image credit: University of Cambridge]