MIT PDP-6 photo timeline

Photos of the MIT Project MAC / AI lab PDP-6, arranged in a timeline.

Project MAC previously had a PDP-1 that was traded in for a PDP-6 in 1964. There was also a second PDP-6 used by MIT’s Dynamic Modeling group.


Photo of the first PDP-6 room 914 at the 9th floor of Technology Square 545 building.
No loudspeakers visible here. The source dates this to April 1966.

Loudspeakers added.

The moby memory has been added last in the row.
MacHack VI playing in a chess tournament.

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Still the old room 914. Same papers taped to the paper tape panels.
Richard Schroedinger and Michael Speciner.

New room with raised floor. Memory boxes are now in a separate row to the left, not visible here.
David Waltz at the console.


One chess trophy has been added, standing between the speakers.
Photo from Computer Design, October 1967. Caption mistakenly says PDP-8.

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Chess plaque and “NO SMOKING” sign added.

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Egyptian cartouche added. Spacewar consoles (game controllers) in the background.
Gerald Sussman, maybe editing an assembly language program in TECO?


Number of chess trophies are up to two. To the back row has been added the Systems Concepts DC-10, DK-10.
Barthold Horn.

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Photo from Harvard Magazine, October 1973.
Michael Speciner; his MLIFE program displaying on the CRT.


Bill Gosper, LIFE hacker extraordinaire.


Photo from 1974/75. PDP-6 visible in the background.
Joel Moses and Patrick Winston with GT40.

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Very nice! Just by way of orientation, Wikipedia says

The PDP-6 was DEC’s first “big” machine. It used 36-bit words, in common with other large computers at the time from companies like IBM, Honeywell and General Electric. … Memory was implemented using magnetic cores; a typical system included 32,768 words

Also I found this photo on the chessprogramming wiki PDP-6 page, captioned “First tournament game by a computer, Carl Wagner (2190) - Robert Q, January 21, 1967”

(Which I now notice matches your MacHack VI photo - but gives it a date.)

Great, thanks for the added information!

Great photo series!

To add a bit of my own special expertise, those Spacewar control boxes look exactly like the original ones for the PDP-1. It’s also an interesting detail, as it allows to get an idea of the size of these control boxes.

(These are not the original ones, since the color of the wooden body is much lighter. Compare Also, I’m not sure, if those would have been still in best working condition, about 5 years later. It seems, there was a small serial production going on…)

Greenblatt said the original first consoles were the best.

Mike Beeler (of HAKMEM fame) made the new ones for the PDP-6, probably what we see in the photos in this thread. Here’s his story:

Here is some history on the Spacewar consoles. I wish I knew who made the original ones at the PDP-1. Greenblatt is correct, they were great. I heard that one of the officials at the PDP-1 came in one morning and found several MIT students who were not qualified PDP-1 users hanging around playing Spacewar. So it was banned, and the consoles were hidden. I don’t know what ever happened to them; perhaps they were thrown out. Some time later, Spacewar was ported to the AI Lab PDP-6. Clearly we needed some consoles. So I designed as good a replica of the original ones as I could, and made them. Pine sides, masonite top, telephone switchboard toggle switches and pushbuttons from TMRC. Slightly improved by a rubber strain relief sleeve. As close to the dimensions and sloping top as I could remember. Cinch-Jones plugs on the end of the cables, that plugged into sockets in the general purpose devices interface.

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According to common lore, the original ones were by Alan Kotok and Robert A. Saunders (compare “The Origin of Spacewar!” by Martin Graetz). The quality of those control boxes probably comes down to the leaf switches used. Robustness and silience of operation (in order to not to give away any hints by noises) were explicit design goals.
Thomas Tilley once held a class on a reconstruction of these controllers and even had Dan Edwards for a talk on the subject. See this page for details: Spacewar! Controllers - Thomas Tilley

Bonus content (not wanting to hijack this thread, but anyways): Even before this, there had been a set of original push button controllers, which are apparently remebered by Steve Russell only. (So gamepads came before joysticks!)


The version that I remember quite clearly, and nobody else does, so I think they must have died very early — there was a 1930s design, 4-pushbutton block that was used for buzzing buzzers in an office; so you’d have a receptionist who had maybe one or two or three lines on a phone and when one of them rang, she’d pick it up, find out who it was and then buzz the buzzer to get that person to pick up the phone. Those were nice because you could hold them in one hand and play them like a flute. But they died very quickly; they were designed for being pushed a few times a day, and it turned out that there was a fatigue problem when they were pushed hundreds of times a day. And so they died fairly early.

(Oral History of Steve Russell, interviewed by Al Kossow, rec. 9 Aug 2008, CHM catalog no. 102746453, p.16)

According to Dan Edwards (source: Thomas Tilley), Spacewar! on the PDP-1 also went into full joystick mode, namely utilizing the entire left control panel of a surplus BOMARC missile controller with a joystick on it. (Spacewar 4.8 uses some weird decoding for the input, which is probably why. There is also a left-over comment hinting at a [lost] version featuring dual speed aceleration.)
So whatever is your favorite controller, there’s an early reference.