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PDP-1 Multimedia

April 5th, 2008 by Multimedia Mike

I got to see a demonstration of a restored, 45 year old DEC PDP-1 computer today at the Computer History Museum in Mountain View, CA, USA. Does that sound interesting in the context of multimedia hacking? The thing could be hooked up to some kind of dot-plotting video device, and it didn’t feature any sound audio. At least, no sound hardware out of the box. Thing is, the unit was highly mod-able.

The PDP-1 hosted what is widely believed to be the first video game ever– Spacewar!. I have already written up that aspect of the experience in my Gaming Pathology blog.

Sound, however, was possible through a hardware mod. The computer had an array of LEDs and one clever hacker thought to wire 4 of these up to square wave generators, thus producing 4-channel music. This was originally programmed in the early 1960s and was demoed today. The hacker who had originally written the music engine on a PDP-1 at MIT found himself on the restoration committee many decades later. It seems MIT had donated paper tape sequences that contained musical data that played on his music engine– but the engine code had been lost. Still, he was able to reverse engineer the audio format and reimplement the engine on the original PDP-1 hardware. Sounds familiar. He even made the same point that I like to make in my multimedia technology presentations — data is more important than code.

It almost made me feel young again. Here I am, studying multimedia formats that largely only date back about 15 years to around 1993.

Posted in Reverse Engineering | 2 Comments »

2 Responses

  1. mat Says:

    Did you know that some people [1] manage to play back old Phonautogram [2] sound from 1860 with a computer :)

    [1] http://www.firstsounds.org/sounds/index.php
    [2] http://en.wikipedia.org/wiki/Phonautogram#The_phonautograph

  2. Ian Farquhar Says:

    I believe that the earliest report of computer music was in either 1950 or 1951, on CSIRAC. CSIRAC was the fourth stored program computer. Apparently the computer had a speaker attached to a register, originally intended to generate a tone to indicate process completion. More info here:

    http://www.csse.unimelb.edu.au/dept/about/csirac/music/