History of Computers

The earliest existence of a modern day computer's ancestor was 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. 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.

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 1,000 50-digit numbers. Built into his machine were operations that included everything a modern computer would need. It was programmed by, and stored data on, cards with holes punched in them, appropriately called "punch cards". But his inventions became failures because of the lack of precision machining techniques used at the time and the lack of demand for such a device.

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. The Mark I was controlled from pre-punched paper tape. The outbreak of World War II produced a desperate need for computing capability, especially for the military. 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.

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 re-wire it to perform whatever task he wanted the computer to do. It was 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.

The first wave of modern programmed electronic computers 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. These machines had punched card or punched-tape input and output devices and RAMs of 1000-word capacity. The first generation of "stored program" computers required considerable maintenance. Typically, they were programmed directly in machine language, although by the mid-1950s progress had been made in several aspects of advanced programming. This group of machines included EDVAC and UNIVAC, the first commercially available computers.

Early in the 1950s two important engineering discoveries changed the electronic computer field. The first computers were made with vacuum tubes, but by the late 1950's computers were being made out of transistors, which were smaller, less expensive, more reliable, and more efficient. In 1959, Robert Noyce, a physicist at the Fairchild Semiconductor Corporation, invented the integrated circuit, a tiny chip of silicon that contained an entire electronic circuit. Gone was the bulky, unreliable, but fast machine; now computers began to become more compact, more reliable and have more capacity. Memory storage capacities increased 800% in commercially available machines by the early 1960s and speeds increased by an equally large margin. In the 1960s efforts to design and develop the fastest possible computers with the greatest capacity reached a turning point with the completion of the LARC machine for Livermore Radiation Laboratories by the Sperry-Rand Corporation, and the Stretch computer by IBM. The LARC had a core memory of 98,000 words and multiplied in 10 microseconds. Stretch was provided with several ranks of memory having slower access for the ranks of greater capacity, the fastest access time being less than 1 microseconds and the total capacity in the vicinity of 100 million words.

During this time the major computer manufacturers began to offer a range of computer capabilities, as well as various computer-related equipment. These included input means such as consoles and card feeders; output means such as page printers, cathode-ray-tube displays, and graphing devices; and optional magnetic tape and magnetic-disk file storage. The trend during the 1970s was, to some extent, away from extremely powerful, centralized computational centers and toward a broader range of applications for less-costly computer systems.