1822. Many attempts were made to improve the reliability of the machines invented by Pascal and Leibniz, but the engineering techniques available could not produce the precisions required. The first machine to perform the basic arithmetic operations suitable for commercial use was the Arithmometer built by Charles Xavier Thomas in 1822. Only about 1600 Thomas machines were actually constructed.
1887. Leon Bollee of France designed the first machine to perform multiplication directly rather than by repeated additions. The device had a multiplying piece consisting of a series of tongued plates representing the ordinary multiplication table up to multiples of 9. The milliner, a popular commercial calculating machine based on the principles developed by Bollee, was manufactured in Switzerland. It required only one turn of the handle for each figure of the multiplier and provided for automatic shift to the next position.
1934. The first prototype electronic computer, with vacuum tubes replacing electromagnetic relays, was conceived in 1934 by Dr. John Vincent Atanasoff at Iowa State University. After concluding that none of the ten available calculating devices was adequate for his needs, Atanasoff decided to build his own machine. He teamed up with Clifford Berry, his graduate assistant, and began the task of building the first electronic computer. This computer, called the Atanasoff-Berry computer (ABC), was completed five years later.
Atanasoffs attempts to get either IBM or Remington Rand interested in his invention and to obtain patent rights for himself failed. Although he conceived and designed the first electronic digital computer, his invention was for many years credited to others. In 1974 a federal judge ruled that Atanasoff was the true inventor of the concepts required for a working electronic digital computer. It is now generally agreed that the design of the ABC and the use of electronics in that computer provided the foundation for the developments of electronic digital computers.
1937. Howard Aiken of Harvard University began working on an automatic calculating machine called the Mark I, a relay machine. With the help of graduate students and IBM engineers, Aiken's automatic machine was completed in 1944. The Harvard Mark I was 51 feet long and
8 feet high, contained 760,000 parts, used 500 miles of wire, and weighed about 5 tons. It used a program to guide it through long series of calculations. It could add, subtract, multiply, divide, compute trigonometric functions, and perform other complicated calculations. Addition and subtraction were accomplished in 0.3 seconds, multiplication in less than 6 seconds, and division in less than 16 seconds.
1938. Several early electromechanical computers using relays for switching purposes were built at Bell Telephone Laboratories, starting in 1938. These special-purpose computers were based initially on the work of Dr. George R. Stibitz. The first one, called the complex calculator, is said to be the first computer to employ binary components. This machine, put into operation in 1940, could be remotely controlled and performed arithmetic operations on two numbers. Models II and III were built to solve military problems and were placed in operation in 1943 and 1944, respectively. Model IV could handle trigonometric functions, such as sine and tangent. Model V contained 9000 relays and 50 pieces of Teletype equipment, weighed 10 tons, and occupied 1000 square feet of floor space. Model VI, the last of the family, was built for Bell Laboratories' own use and featured many improvements, including magnetic tape storage units.
1941. A relay computer was built in Germany in 1941 by Konrad Zuse. Called the Z3, its logical operations were alterable by changing the interconnections among the relays. The Z3 was the world's first working general-purpose program-controlled computer.
UNIT 2
