HISTORY OF THE COMPUTER

HISTORY OF THE COMPUTER ABSTRACT
This paper takes a keen look at the history of computer technology with a view to 
encouraging computer or electrical electronic engineering students to embrace and learn the 
history of their profession and its technologies. Reedy (1984) quoted Aldous Huxley thus: 
“that men do not learn very much from the lessons of history is the most important of all the 
lessons that history has to teach.” This paper therefore emphasizes the need to study history 
of the computer because a proper study and understanding of the evolution of computers will
undoubtedly help to greatly improve on computer technologies. 
INTRODUCTION
The word ‘computer’ is an old word that has changed its meaning several times in the last
few centuries. Originating from the Latin, by the mid-17th century it meant ‘someone who 
computes’. The American Heritage Dictionary (1980) gives its first computer definition as “a 
person who computes.” The computer remained associated with human activity until about 
the middle of the 20th century when it became applied to “a programmable electronic device 
that can store, retrieve, and process data” as Webster’s Dictionary (1980) defines it. Today, 
the word computer refers to computing devices, whether or not they are electronic, 
programmable, or capable of ‘storing and retrieving’ data. 
The Techencyclopedia (2003) defines computer as “a general purpose machine that processes 
data according to a set of instructions that are stored internally either temporarily or 
permanently.” The computer and all equipment attached to it are called hardware. The 
instructions that tell it what to do are called "software" or “program”. A program is a detailed 
set of humanly prepared instructions that directs the computer to function in specific ways. 
Furthermore, the Encyclopedia Britannica (2003) defines computers as “the contribution of
major individuals, machines, and ideas to the development of computing.” This implies that 
2the computer is a system. A system is a group of computer components that work together as 
a unit to perform a common objective. 
The term ‘history’ means past events. The encyclopedia Britannica (2003) defines it as “the 
discipline that studies the chronological record of events (as affecting a nation or people), 
based on a critical examination of source materials and usually presenting an explanation of 
their causes.” The Oxford Advanced Learner’s Dictionary (1995) simply defines history as 
“the study of past events.…” In discussing the history of computers, chronological record of 
events – particularly in the area of technological development – will be explained. History of 
computer in the area of technological development is being considered because it is usually
the technological advancement in computers that brings about economic and social 
advancement. A faster computer brings about faster operation and that in turn causes an 
economic development. This paper will discuss classes of computers, computer evolution 
and highlight some roles played by individuals in these developments. 
CLASSIFICATION OF COMPUTERS 
Computing machines can be classified in many ways and these classifications depend on their 
functions and definitions. They can be classified by the technology from which they were 
constructed, the uses to which they are put, their capacity or size, the era in which they were 
used, their basic operating principle and by the kinds of data they process. Some of these 
classification techniques are discussed as follows: 
Classification by Technology
This classification is a historical one and it is based on what performs the computer operation, 
or the technology behind the computing skill. 
3I FLESH: Before the advent of any kind of computing device at all, human beings 
performed computation by themselves. This involved the use of fingers, toes and any 
other part of the body. 
II WOOD: Wood became a computing device when it was first used to design the 
abacus. Shickard in 1621 and Polini in 1709 were both instrumental to this 
development. 
III METALS: Metals were used in the early machines of Pascal, Thomas, and the 
production versions from firms such as Brundsviga, Monroe, etc 
IV ELECTROMECHANICAL DEVICES: As differential analyzers, these were present 
in the early machines of Zuse, Aiken, Stibitz and many others 
V ELECTRONIC ELEMENTS: These were used in the Colossus, ABC, ENIAC, and 
the stored program computers. 
This classification really does not apply to developments in the last sixty years because
several kinds of new electro technological devices have been used thereafter. 
Classification by Capacity
Computers can be classified according to their capacity. The term ‘capacity’ refers to the 
volume of work or the data processing capability a computer can handle. Their performance
is determined by the amount of data that can be stored in memory, speed of internal operation 
of the computer, number and type of peripheral devices, amount and type of software 
available for use with the computer. 
The capacity of early generation computers was determined by their physical size - the larger 
the size, the greater the volume. Recent computer technology however is tending to create 
smaller machines, making it possible to package equivalent speed and capacity in a smaller 
format. Computer capacity is currently measured by the number of applications that it can
4run rather than by the volume of data it can process. This classification is therefore done as 
follows: 
I MICROCOMPUTERS
The Microcomputer has the lowest level capacity. The machine has memories that are 
generally made of semiconductors fabricated on silicon chips. Large-scale production of 
silicon chips began in 1971 and this has been of great use in the production of 
microcomputers. The microcomputer is a digital computer system that is controlled by a 
stored program that uses a microprocessor, a programmable read-only memory (ROM) and a 
random-access memory (RAM). The ROM defines the instructions to be executed by the 
computer while RAM is the functional equivalent of computer memory. 
The Apple IIe, the Radio Shack TRS-80, and the Genie III are examples of microcomputers 
and are essentially fourth generation devices. Microcomputers have from 4k to 64k storage 
location and are capable of handling small, single-business application such as sales analysis,
inventory, billing and payroll. 
II MINICOMPUTERS 
In the 1960s, the growing demand for a smaller stand-alone machine brought about the 
manufacture of the minicomputer, to handle tasks that large computers could not perform 
economically. Minicomputer systems provide faster operating speeds and larger storage 
capacities than microcomputer systems. Operating systems developed for minicomputer
systems generally support both multiprogramming and virtual storage. This means that many 
programs can be run concurrently. This type of computer system is very flexible and can be 
expanded to meet the needs of users. 
5Minicomputers usually have from 8k to 256k memory storage location, and a relatively 
established application software. The PDP-8, the IBM systems 3 and the Honeywell 200 and 
1200 computer are typical examples of minicomputers. 
III MEDIUM-SIZE COMPUTERS 
Medium-size computer systems provide faster operating speeds and larger storage capacities
than mini computer systems. They can support a large number of high-speed input/output 
devices and several disk drives can be used to provide online access to large data files as 
required for direct access processing and their operating systems also support both 
multiprogramming and virtual storage. This allows the running of variety of programs 
concurrently. A medium-size computer can support a management information system and 
can therefore serve the needs of a large bank, insurance company or university. They usually 
have memory sizes ranging from 32k to 512k. The IBM System 370, Burroughs 3500 
System and NCR Century 200 system are examples of medium-size computers. 
IV LARGE COMPUTERS 
Large computers are next to Super Computers and have bigger capacity than the Mediumsize computers. They usually contain full control systems with minimal operator
intervention. Large computer system ranges from single-processing configurations to 
nationwide computer-based networks involving general large computers. Large computers 
have storage capacities from 512k to 8192k, and these computers have internal operating 
speeds measured in terms of nanosecond, as compared to small computers where speed is 
measured in terms of microseconds. Expandability to 8 or even 16 million characters is 
possible with some of these systems. Such characteristics permit many data processing jobs 
to be accomplished concurrently. 
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