Google has a nice post with a short video commemorating today's 50th birthday of the Ferranti Atlas, the UK's first "supercomputer". Although it wasn't the first computer I programmed, Cambridge University's Atlas 2 prototype, called Titan, was the machine I really learned programming on, starting in 1968. It was in production from 1966 to 1973 with a time-sharing operating system using Teletype KSR33 terminals, a device-independent file system and many other ground-breaking features. I got access to it late at night as an undergraduate member of the Archimedeans, the University Mathematical Society. I wrote programs in machine code (as I recall there was no mnemonic assembler, you had to remember the numeric op-codes), in Atlas Autocode, and in BCPL. Best of all, it was attached to a PDP-7 with a DEC 340 display, which a friend and I programmed to play games.