My speciality. Шепелева М.А - 25 стр.

      The First Generation: Vacuum Tubes BVMC

         AC (Electronic Numerical Integrator And Computer), designed by and
constructed under the supervision of John Mauchly and John Presper Eckert at the
University of Pennsylvania„was the world's first general-purpose electronic digital
computer.
       The project was a response to U.S. wartime needs. The Army's Ballistics
Research Laboratory (BRL), an agency responsible for developing range and
trajectory tables for new weapons, was having difficulty supplying these tables
accurately and within a reasonable time frame. Without these firing tables, the new
weapons and artillery were useless to gunners. The BRL employed more than 200
people, mostly women, who, using desktop calculators, solved the necessary
ballistics equations. Preparation of the tables for a single weapon would take one
person many hours, even days.
Mauchly, a professor of electrical engineering at the University of Pennsylvania,
and Eckert, one of his graduate students, proposed to build a general-purpose
computer using vacuum tubes to be used for the BRL's application. In 3943, this
proposal was accepted by the Army, and work began on the ENIAC. The resulting
machine was enormous, weighing 30 tons, occupying 15,000 square feet of floor
space, and containing more than 18,000 vacuum tubes. When operating, it
consumed 140 kilowatts of power. It was also substantially faster than any
electromechanical computer, being capable of 5000 additions per second.
       The ENIAC was a decimal rather than a binary machine. That is, numbers
were represented in decimal form and arithmetic was performed in the decimal
system. Its memory consisted of 20 "accumulators," each capable of holding a 10-
digit decimal number. Each digit was represented by a ring of 10 vacuum tubes. At
any time, only one vacuum tube was in the ON state, representing one of the 10
digits. The major drawback of the ENIAC was that it had to be programmed
manually by setting switches and plugging and unplugging cables.
         The ENIAC was completed in 1946, too late to be used in the war effort.
Instead, its first task was to perform a series of complex calculations that were used
to help determine the feasibility of the H-bomb. The use of the ENIAC for a
purpose other than that for which it was built demonstrated its general-purpose
nature. Thus, 1946 ushered in the new era of the electronic computer, culminating
years of effort. The ENIAC continued to operate under BRL management until
1955, when it was disassembled.

      The Second Generation: Transistor

       The first major change in the electronic computer came with                the
replacement of the vacuum tube by the transistor. The transistor                    is
smaller, cheaper, and dissipated. Less heat than a vacuum tube but can             be
used in the same way as a vacuum tube to construct computers. Unlike              the