Page 12 - DCAP101_BASIC_COMPUTER_SKILLS

Unit 1: Computer Fundamentals

and used 18,000 vacuum tubes it could add two numbers in 200 microseconds and Notes
multiply them in 2000 microseconds.
4. The EDVAC (1946-52). A major drawback of ENIAC was that its programs were
wired on boards that made it difficult to change the programs. Dr. John Von
Neumann later introduced the “stored program” concept that helped in overcoming
this problem. The basic idea behind this concept is that a sequence of instructions
and data can be stored in the memory of a computer for automatically directing
the flow of operations. This feature considerably influenced the development of
modern digital computers because of the ease with which different programs can
be loaded and executed on the same computer. Due to this feature, we often refer
to modern digital computers as stored program digital computers. The Electronic
Discrete Variable Automatic Computer (EDVAC) used the stored’ program concept
in its design. Von Neumann also has a share of the credit for introducing the idea
of storing both instructions and data in binary form (a system that uses only two
digits—0 and I to represent all characters), instead of decimal numbers or human
readable words.

5. The EDSAC (1947-49). Almost simultaneously with EDVAC of U.S.A., the Britishers
developed the Electronic Delay Storage Automatic Calculator (EDSAC). The machine
executed its first program in May 1949. In this machine, addition operations took 1500
microseconds and multiplication operation: took 4000 microseconds. A group of scientists
headed by Professor Maurice Wilkes at the Cambridge University Mathematical
Laboratory developed this machine.
6. The UNIVAC I (1951). The Universal Automatic Computer (UNIVAC) was the first
digital computer that was not “one of a kind”. Many UNIVAC machines were produced,
the first of which was installed in the Census Bureau in 1951 and was used continuously
for 10 years. The first business use of a computer, a UNIVAC I, was by General Electric
Corporation in 1954. In 1952, the International Business Machines (IBM) Corporation
introduced the IBM-701 commercial computer. In rapid succession, improved models
of the UNIVAC I and other 700-series machines were introduced. In 1953, IBM produced
the IBM-650, and sold over 1000 of these computers. UNIVAC marked the arrival of
commercially available digital computers for business and scientific applications.

Some of the well-known early computers are the MARK 1 (1937-44), the
ATANASOFF-BERRY (1939-42), the ENIAC (1943-46), the EDVAC
(1946–52), the EDSAC (1947-49) and the UNIVAC I (1951).

1.3 Computer Generations

Generation in computer talk is a step in technology. It provides a framework for the growth
of computer industry. Originally, the term “generation” was used to distinguish between
varying hardware technologies but it has now been extended to include both hardware and
software that together make up a computer system.

The custom of referring to computer era in terms of generations came into wide use only
after 1964. There are totally five computer generations known till today. Below we describe
each generation along with its identifying characteristics. Although there is a certain amount
of overlap between different generations, the approximate period shown against each are
normally accepted.
During description of various computer generations, you will come across several new
terminologies and computer jargons that you may not be able to understand properly.
However, the idea here is to provide you an overview of the major developments and
technologies during the five generations of computers. Subsequent chapters will cover these

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