The DEC PDP-12

Sure looks " mini", huh? But we're getting ahead of our story.

One of the earliest attempts to build an all-electronic (that is, no gears, cams, belts, shafts, etc.) digital computer occurred in 1937 by J. V. Atanasoff, a professor of physics and mathematics at Iowa State University. By 1941 he and his graduate student, Clifford Berry, had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. This machine was the first to store data as a charge on a capacitor, which is how today's computers store information in their main memory (DRAM or dynamic RAM). As far as its inventors were aware, it was also the first to employ binary arithmetic. However, the machine was not programmable, it lacked a conditional branch, its design was appropriate for only one type of mathematical problem, and it was not further pursued after World War II. It's inventors didn't even bother to preserve the machine and it was dismantled by those who moved into the room where it lay abandoned.

The Atanasoff-Berry Computer [photo © 2002 IEEE]

Another candidate for granddaddy of the modern computer was Colossus, built during World War II by Britain for the purpose of breaking the cryptographic codes used by Germany. Britain led the world in designing and building electronic machines dedicated to code breaking, and was routinely able to read coded Germany radio transmissions. But Colossus was definitely not a general purpose, reprogrammable machine. Note the presence of pulleys in the two photos of Colossus below:

НАЗИМ

The Harvard Mark I, the Atanasoff-Berry computer, and the British Colossus all made important contributions. American and British computer pioneers were still arguing over who was first to do what, when in 1965 the work of the German Konrad Zuse was published for the first time in English. Scooped! Zuse had built a sequence of general purpose computers in Nazi Germany. The first, the Z1, was built between 1936 and 1938 in the parlor of his parent's home.