PDP 1s and Model Trains

Elsewhere on the Internet last week, people were solving a mystery about a PDP-1 running a model train. People who know about such things acknowledge that the “Tech Model Railroad Club” (TMRC) at MIT used a PDP-1 to operate its layout for a few years. The photo at the left, along with a similar one, are tagged in various archives as portraying the TMRC. Greybeards who remembered the TMRC layout disputed this attribution. Then someone stumbled over an ancient paper I wrote about the evolution of computer architecture, which contained the correct attribution.

People don’t cite my ancient papers very often, so it’s satisfying when they do, even for peripheral reasons. And it was a fun paper to write. The Babbage Institute gave me a summer fellowship to write it when I was a grad student. I still want to turn it into a Coursera course one of these days.

I had written the paper for the Annals of the History of Computing and included a handful of diagrams and tables. JAN Lee was the editor-in-chief at the time, and he spruced up my article by adding historic photos, including the one above. Lee also provided the citation to go along with the photo: a review he wrote for the Annals about Steve Levy’s book Hackers. Levy talked about the TMRC and PDP-1 in his book, and Lee took the opportunity to point out a different model railroad run by a different PDP-1 at the University of Massachusetts, Amherst. The companion photo showed Lee himself sitting at the PDP-1.

While I like adding hackish touches to academic papers, I can’t remember exactly how the reference to Lee’s review ended up in the final paper.