The EDSAC was an early computer in the mathematics laboratory at Cambridge in the UK. I have just read an old article on the machine and how it was programmed, from a 1998 issue of the IEEE Annals of the History of Computing.
There are many fascinating aspects to the machine and its utter simplicity, but one that struck me as I read the paper was that so many of the fundamental ideas of programming and practical computing were invented then and there. Indeed, the EDSAC was designed as a machine to experiment with programming, rather than as a machine for maximal computing performance.