On May 19, 2004, only seven months after starting the project, a team of Computer History Museum volunteers flipped the 'on' switch on this 1963 Digital Equipment Corporation (DEC) PDP-1 computer. Nearly 45 years after it was made, the machine jumped to life!
As in all restorations, the key principle was to ensure that all work undertaken was reversible. This made the restoration more challenging but preserved the historical integrity of the machine.
The first step of the project, and one of the most time-consuming, was the repair and testing of the machine's power supplies. This ensured that once power was applied it would not damage the computer's circuitry. Next, the team began work on the Central Processing Unit (CPU)–the 'brain' of the computer. To the team's surprise, the PDP-1 worked almost perfectly right away.
The machine's peripherals, however, took more effort. To interact with the PDP-1, users originally used a paper tape reader and punch, a screen with a light pen, and a typewriter. Each of these peripherals took a great deal of effort to bring back to working order.
Once all of these devices were working, the team began testing its original software, preserved in the Museum’s permanent collection. For example, on March 1, 2005, the team ran the 1962 game Spacewar!–originally developed on the PDP-1 at MIT.
The PDP-1 Restoration Project is now in its maintenance phase during which it will be demonstrated to the general public and periodically examined for problems.