An Overview of the Histoy of Computers

Only once in a lifetime will a new invention come about to touch every aspect of our lives. Such a device that changes the way we work, live, and play is a special one, indeed. A machine that has done all this and more now exists in nearly every business in the US and one out of every two households (Hall, 156). This incredible invention is the computer. The electronic computer has been around for over a half-century, but its ancestors have been around for 2000 years. However, only in the last 40 years has it changed the American society. From the first wooden abacus to the latest high-speed microprocessor, the computer has changed nearly every aspect of people's lives for the better.

The very earliest existence of the modern day computer's ancestor is the abacus. These date back to almost 2000 years ago. It is simply a wooden rack holding parallel wires on which beads are strung. When these beads are moved along the wire according to "programming" rules that the user must memorize, all ordinary arithmetic operations can be performed (Soma, 14). The next innovation in computers took place in 1694 when Blaise Pascal invented the first "digital calculating machine". It could only add numbers and they had to be entered by turning dials. It was designed to help Pascal's father who was a tax collector (Soma, 32).

In the early 1800's, a mathematics professor named Charles Babbage designed an automatic calculation machine. It was steam powered and could store up to 1000 50-digit numbers. Built in to his machine were operations that included everything a modern general-purpose computer would need. It was programmed by--and stored data on--cards with holes punched in them, appropriately called "punchcards". His inventions were failures for the most part because of the lack of precision machining techniques used at the time and the lack of demand for such a device (Soma, 46).

After Babbage, people began to lose interest in computers. However, between 1850 and 1900 there were great advances in mathematics and physics that began to rekindle the interest (Osborne, 45). Many of these new advances involved complex calculations and formulas that were very time consuming for human calculation. The first major use for a computer in the US was during the 1890 census. Two men, Herman Hollerith and James Powers, developed a new punched-card system that could automatically read information on cards without human intervention (Gulliver, 82). Since the population of the US was increasing so fast, the computer was an essential tool in tabulating the totals.

These advantages were noted by commercial industries and soon led to the development of improved punch-card business-machine systems by International Business Machines (IBM), Remington-Rand, Burroughs, and other corporations. By modern standards the punched-card machines were slow, typically processing from 50 to 250 cards per minute, with each card holding up to 80 digits. At the time, however, punched cards were an enormous step forward; they provided a means of input, output, and memory storage on a massive scale. For more than 50 years following their first use, punched-card machines did the bulk of the world's business computing and a good portion of the computing work in science (Chposky, 73).

By the late 1930s punched-card machine techniques had become so well established and reliable that Howard Hathaway Aiken, in collaboration with engineers at IBM, undertook construction of a large automatic digital computer based on standard IBM electromechanical parts. Aiken's machine, called the Harvard Mark I, handled 23-digit numbers and could perform all four arithmetic operations. Also, it had special built-in programs to handle logarithms and trigonometric functions. The Mark I was controlled from prepunched paper tape. Output was by card punch and electric typewriter. It was slow, requiring 3 to 5 seconds for a multiplication, but it was fully automatic and could complete long computations without human intervention (Chposky, 103).

The outbreak of World War II produced a desperate need for computing capability, especially for the military. New weapons systems were produced which needed trajectory tables and other essential data. In 1942, John P. Eckert, John W. Mauchley, and their associates at the University of Pennsylvania decided to build a high-speed electronic computer to do the job. This machine became known as ENIAC, for "Electrical Numerical Integrator And Calculator". It could multiply two numbers at the rate of 300 products per second, by finding the value of each product from a multiplication table stored in its memory. ENIAC was thus about 1,000 times faster than the previous generation of computers (Dolotta, 47).

ENIAC used 18,000 standard vacuum tubes, occupied 1800 square feet of floor space, and used about 180,000 watts of electricity. It used punched-card input and output. The ENIAC was very difficult to program because one had to essentially re-wire it to perform whatever task he wanted the computer to do. It was, however, efficient in handling the particular programs for which it had been designed. ENIAC is generally accepted as the first successful high-speed electronic digital computer and was used in many applications from 1946 to 1955 (Dolotta, 50).

Mathematician John von Neumann was very interested in the ENIAC. In 1945 he undertook a theoretical study of computation that demonstrated that a computer could have a very simple and yet be able to execute any kind of computation effectively by means of proper programmed control without the need for any changes in hardware. Von Neumann came up with incredible ideas for methods of building and organizing practical, fast computers. These ideas, which came to be referred to as the stored-program technique, became fundamental for future generations of high-speed digital computers and were universally adopted (Hall, 73).

The first wave of modern programmed electronic computers to take advantage of these improvements appeared in 1947. This group included computers using random access memory (RAM), which is a memory designed to give almost constant access to any particular piece of information (Hall, 75). These machines had punched-card or punched-tape input and output devices and RAMs of 1000-word capacity. Physically, they were much more compact than ENIAC: some were about the size of a grand piano and required 2500 small electron tubes. This was quite an improvement over the earlier machines. The first-generation stored-program computers required considerable maintenance, usually attained 70% to 80% reliable operation, and were used for 8 to 12 years. Typically, they were programmed directly in machine language, although by the mid-1950s progress had