Page 7 - Handout Digital Electronics

LECTURE 1 HISTORY OF COMPUTERS

1.1 Introduction
History of computers is generally referred to as computer generation. The term generation will be used
throughout this module to refer to the history of computers. Each computer generation is
differentiated from the other by technological development (i.e. the technology used to
implement/build the computer). This in turn changed how the computers operated. To date, five (5)
computer generations are known, and these are based on the characteristics of computers developed
from time to time. A computer generation is roughly a period of ten years.

Computer

Generations

First Second Third Fourth Fifth
Generation Generation Generation Generation Generation

1946-1959 1959-1965 1965-1971 1971-1980 1980-onwards

Figure 1: Computer Generations

Authors differ on the dates (years) of computer generations, but the best classification is using the
technology used to implement computers in each generation. Previously, only the technology was used
to define a computer generation but presently both the technology and software are used to
characterize computer generations ((Computer generations n.d. www.tutorialspoint.com).

1.2 First Generation (1946-1954).

These digital computers were using electronic valves (Vacuum tubes). The vacuum tubes were costly,
and this prevented their use for main memory. They stored information in the form of propagating
sound waves. The vacuum tube by its nature consumes a lot of power and these computers were large
and writing programs on them was difficult. Some of the images of electronic vacuum tubes or valves:

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