07 October 2008


entrance I took a long side trip from my family business in the Sacramento area to visit the Computer History Museum in Mountain View, spang in Silicon Valley. The donation-funded museum was relocated a few years ago from digs in Massachusetts.

steampunk calculatordifference engine detailUntil early next year, the highlight of the collection is Difference Engine No. 2, constructed from Charles Babbage's plans for Nathan Myhrvold and on loan to the museum. Like everything else in the museum, this machine is vounteer-powered , one staffer taking a turn at the crank while the other explains the workings. Though the gear is equipped for printing (see detail at right), that part of its operation is not part of the demo, as it takes four hours to clean up every time.

expensive benchMost of the equipment is hands-off, but you can have a seat on this Cray-1, located just outside the main exhibit hall.

Another highlight of the visit is the demonstration of a reconstructed PDP-1, Digital Equipment's first commercial system, docented by John Bohner and Peter Samson when I visited. The PDP-1, introduced in the early 1960s, was the first machine to feature a symbolic debugger, an amenity no doubt appreciated by Samson. As part of the restoration, he reverse-engineered paper-tape music files that had been serendipitously preserved in order to recreate a music synthesizer that he wrote while an undergraduate at MIT. The synthesizer resides in 4K of memory, which is also a good thing, because this model holds all of 12K 18-bit words.

grad school daysfull circleMost all of the other boxes are not powered up, but rather are displayed warehouse-style in the main hall. (Imagine the heat generated by all of these boxes were they all running!) My graduate school days were brought back by the sight of a DECSystem-10 (at left). Those panels of switches are perhaps the only attractive industrial design to come out of the 1970s. And most of us, in one way or another, have crossed paths with an IBM System/360 (at right).

There are lots of smaller, newer, and older items, as well: a rack of HP calculators, Herman Hollerith's tabulation equipment, a rack of tubes from ENIAC, some game consoles, a Sage air-defense system (tube-based and inexplicably still in service through 1983), a Norden bombsight, an Enigma machine.

Except for a side exhibit of computer chess (and the PDP-1 demo), there isn't a lot of emphasis on software; for now, the museum is largely a repository of hardware. But, we hope, forthcoming fundraising will increase the level of interactivity at this gem of a museum.

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