Combining the Elements

Konrad Zuse

In the 1930s, Konrad Zuse (pronounced zoo-zeh) developed a computing machine based on electromechanical relays.^[1] Zuse's machine could read instructions and data from punched tape (made from 35mm film stock). It could be instructed to move data from tape to memory registers (made from relays). It could perform Boolean functions on the data and punch holes in a new tape representing the results of the operations. It only lacked the conditional branch to make it a complete general-purpose computer by today's standards.

Zuse's machine introduced the final piece of the puzzle to make a modern general-purpose computer, performing Boolean logic by machine. Therefore, Zuse's machine could take data, move it, manipulate it mathematically or logically, and output the manipulated data. All of the functions of a modern computer except the conditional branch. If Zuse's machine had used vacuum tubes instead of mechanical relays, and were it able to perform a conditional branch, it would have been the first fully electronic, programmable general-purpose computer.

John Atanasoff

In 1942, John Atanasoff, with the assistance of his graduate student Clifford Berry, built a computer using vacuum tubes rather than electromechanical relays. It was the first all-electronic computer. The computer could not be readily reprogrammed, so it was not a general-purpose computer. The Atanasoff machine also used capacitor memory^[2] which, in integrated circuit form, is still used today as the main memory in most computers.

A replica of the Atanasoff-Berry Computer at Iowa State University

Atanasoff's machine didn't introduce any new elements to computing; all of the essential elements had already been introduced. However, it did introduce several significant refinements. The most important of which was being all electronic. Another was storing information in memory that was separate from the circuitry that did operations. Another was that it used a pure binary representation of data, rather than a decimal representation used by previous machines.