Technology History | 590 Madison Avenue — The Computer in the Shop Window

IBM put a computer in a shop window and let the public watch it work.

The room was on the ground floor at the corner of 57th Street and Madison Avenue, behind glass, in a space that had recently been a women's shoe shop.

The machine was the Selective Sequence Electronic Calculator, dedicated and demonstrated to the public on 27 January 1948.

Pedestrians stopped to stare at it through the window, and gave it a nickname that the sources record as both Poppa and Poppy.

Thomas Watson Sr. called it a calculator rather than a computer on purpose, because in 1948 a computer was a person doing arithmetic for a living, and he did not want the machine read as a replacement.

It was built at IBM's Endicott plant across 1946 and 1947, under the direction of the Columbia astronomer Wallace Eckert, and it ran on roughly 12,500 vacuum tubes alongside thousands of electromechanical relays.

Installed on three sides of a room about sixty feet by thirty, it worked until August 1952.

The claim usually attached to it needs care.

The SSEC could operate on its own instructions as data, which is why it is often called the first operational stored-program machine, and Brian Randell put it that way with an "almost certainly" attached.

John Backus, who worked on it, later said flatly that calling it the first stored-program computer was an extreme stretch.

Backus is the other reason this address matters.

He walked in off the street with a mathematics degree, took the tour, mentioned to the guide that he wanted a job, and was hired onto the machine — 1949 by Columbia's account, 1950 by IBM's own.

Nine years later his team shipped Fortran.

IBM built the SSEC partly because Howard Aiken's press release for the Harvard Mark I had given the company almost no credit.

Watson wanted a machine that was unmistakably IBM's, and unmistakably public.

The 1938 building that held it was demolished from 1977.

What stands here now is the 41-storey tower IBM developed on the site, opened in October 1983 and sold by IBM in 1994.

Its ground floor is a glass atrium of bamboo and movable chairs, a privately owned public space anyone may walk into, running through the block from 56th Street to 57th.

Seventy-five years after IBM gave this corner's ground floor to the public as a spectacle, the ground floor is public again, and the machine is the part that has gone.

Note on the images: no freely licensed photograph of the SSEC appears to exist. The cover shows the present atrium; the second image is the machine's block diagram from IBM's patent filing, a drawing rather than a photograph.

Sources: IBM Heritage; Columbia University Computing History; Brian Randell, The Origins of Digital Computers; The Cultural Landscape Foundation; APOPS, Municipal Art Society.

Photos: Jim.henderson, public domain, and Joseph Robbins for IBM, public domain, both via Wikimedia Commons.