By Darwyn F. Kelley
What is the difference between a Computer and a Calculator? One the most satisfactory definition states,
"An automatic computer is a machine that manipulates symbols in accordance with given rules in a predetermined and self-directed
The most significant word here undoubtedly is "self directed". Any calculating device whether it be an abacus or an adding machine must be other-directed, that is, man directed.
An automatic computer, however has the ability to accept data and then work upon that data according to a preset program without human intervention, although human beings must, of course, devise the program which controls the automatic manipulation of the data. Regardless whether the computer is one of the special-purpose types for solving engineering and scientific problems or a general-purpose computer manufactured in large quantities, the principle remains the same.
How did computers come into being and why did anyone want to build one in the first place? Starting from crude methods of piling stones to represent numbers and proceeding
hrough such ingenious devices as the abacus, he has long been in pursuit of improved calculating methods. He has always been limited however, by the state of technology in the times in which he lived. As long ago as the 1820's Charles Babbage, in England made a "difference engine"., which was sound in principle, but which unfortunately was very unreliable due to the availability of only crudely machined parts.
The first true computer to be manufactured in any quantities was Ford Instrument Computer in
1915. A mechanical analog device. The Ford Computer was a marvel of gear trains, linkages, and differentials. It was difficult to keep in adjustment and very complicated to manufacture, but it did the job it was intended to do- find and keep the range for naval guns.
In 1930, the first general-purpose computer was built at MIT under the direction of
Dr. Vannever Bush. It to was a mechanical monster, but it could be disconnected and reconnected to solve different equations.
All of these devices were analog. That is they operated on real inputs such as voltages or the rotation of gears and they produced real
outputs, such as training of the guns of a main battery.
Analog computers have both advantages and disadvantages. They produce almost instantaneous output, but since they act upon analogies to numbers rather than on numbers themselves, their output is never perfectly accurate. They can be used to train a gun but not to calculate a payroll.
In 1939, a major breakthrough occurred when
Dr. Howard Aiken of Harvard completed the basic plans for a sequential, digital, electromechanical
computer. This computer was an unwieldy conglomeration of office calculating devices, but it embodied two
important concepts. First, it operated on real numbers, rather than on analogs of numbers, and, second it had the ability to make decisions. That is, it could compare two numbers when a partial result had been obtained and then follow one of two paths for further computation, depending upon the result of the comparison. All computers operate on this principle today.
Dr. Aiken's machine was still an electromechanical device and naturally was subject to failure through wear and tear and had such commonplace troubles as simply getting dirty. Also there were obvious physical limitation on the speeds which it could be operated.
The next major breakthrough came in 1946, when the first all-electronic, digital sequential computer was delivered. It was many times faster and far more reliable than any mechanical computer could be. It was an invention of
J. Presper Eckert and Dr. John Mauchly, who later formed a company which eventually became, the UNIVAC Division of Sperry Rand. The name of this first Electronic
Computer was ENIAC. (Acronym for :Electronic Numeric Integrated Automatic Computer). It was the father of all modern electronic computers.
Next, in rapid succession came BINAC, the first computer with serial
logic; Univac I , the first commercial computer, the Univac 1103A, the first computer to use core storage, the Univac Solid State, the first all Solid State Computer to be offered commercially, The Univac LARC, the world's most powerful computer at that time.