Input/Output Telecommunication

The most popular devices that facilitate both input and output and allow computers to communicate are network adapter and modem.

A network adapter is a computer hardware component designed to allow computers to communicate over a computer network. It enables physical access to a networking medium and provides a low-level addressing system by means of MAC addresses.

Modem sends and receives information between computers over telephone lines. The modem con­verts the electrical signals from RAM in the computer into the type of electrical signals that can travel over telephone lines. In other words, the digital output from the computer must be modulated into an analog form before it can be sent over a telephone line, and the analog input received over the telephone line must be demodulated into digital form before it can be used for input into the computer.

The term modem is used because the device MOdulates/DEModulates sig­nals. With a modem, a computer terminal or a personal computer can be used to communicate with a mainframe or another personal computer. In either case, the modem acts as both an input device and an output device so the computer can send and receive information over the telephone lines. This is very useful for persons who wish to work at home, access a computerized information ser­vice to research some topic, or simply communicate with other computer users.

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THE FIRST COMPUTER

For a machine as important as the computer, it is strange to think that the question of who built the first computer was settled in court. A 1973 lawsuit invalidated early patents on the computer, because the judge decided the wrong persons had received credit for developing the first computer.

The early history of the computer involves three individuals, or groups of individuals, and the machines they built. One pair of individuals were John V. Atanasoff of Iowa State University and his graduate assistant, Clifford Berry, who began work on an electronic computer before World War II and finished a working prototype in 1942. Although there was a great deal of interest in computers that could compute artillery tables during the war, the Atanasoff-Berry Computer, or ABC, did not receive much attention. Iowa State did not even attempt to patent the device, and neither man followed up on this early work. The ABC was eventually forgotten and only a few parts of the original machine remain.

Another important individual in the development of the computer is Howard Aiken. In 1944, Aiken completed the MARK I computer for IBM in cooperation with Harvard University. Even though the MARK I had 760,000 electrical parts connected by 500 miles of wiring, it was not completely electronic, because it used 3,000 electromechanical relays as switches. It was so big that an entire building on Harvard's campus was set aside for it.

The pair of individuals who usually receive the credit for developing a purely electronic computer are J. Presper Eckert, Jr., and John Mauchly. Eckert was working on a government project to build a fast computing device when he visited Atanasoff at Iowa State to learn about the ABC. After his meeting, Eckert and Mauchly built the ENIAC (Electrical Numerical Integrator And Calculator) for the war effort. Unfortunately, it was not finished until 1946, after the war. The ENIAC contained 18,000 vacuum tubes and 80,000 resistors and capacitors, weighed 30 tons, and occupied over 15.000 square feet. It was much faster than the MARK I, because it could multiply two numbers in 0.0003 second, compared with over 0.05 second for the MARK I. However, ENIAC used so much electricity that the lights in the section of Philadelphia in which it was located supposedly dimmed each time the computer ran. The ENIAC, which ran for nine years, is now on exhibit at the Smithsonian Institution.

An important advance over the ENIAC was the EDVAC (Electronic Discrete Variable Automatic Computer) developed by John von Neumann. The EDVAC utilized the concept of the stored program, which meant the computer did not have to be rewired for each job as the ENIAC did.

The 1973 court decision named the Atanasoff-Berry team as the builders of the first computer, rather than Eckert and Mauchly. Aiken is best known for getting IBM interested in computers, but the MARK I contributed little to later developments of the computer. Von Neumann is remembered for adding the stored program concept to the computer

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