DEVELOPMENT OF COMPUTERS.
- Before 1900, most data processing was done manually using
simple tools like stones & sticks to count and keep records.
Around 2000 years ago, Asian merchants came up with a
special calculating tool called Abacus
that could be used to calculate large figures.
An Abacus is made up of a rectangular frame and a crossbar
at the middle. It is fitted with wires
or strings running across from the frame to the crossbar.
How to represent a number using an Abacus.
- Each bead in the lower row has a value of 1, while each bead
in the upper row has a value of 5. To
represent a number, the bead is moved to the crossbar. Those beads away from the crossbar represent
The Figure below represents the number 6908 (Six thousand
nine hundred and eight).
- After Abacus, the first machine that is usually regarded as
the forerunner of modern computers was named the Analytical Engine, and was developed by an English mathematician
called Charles Babbage.
In 1939, Professor
Howard Aken of Horrard
University designed the
first computer-like machine named Mark 1. Since then, a series of advancements in
electronics has occurred. With each
breakthrough, the computers based on the older form of electronics have been
replaced by a new “generation” of computers based on the newer form of
- A Computer generation
is a grouped summary of the gradual developments in the computer
technology. The historical events are
not considered in terms of individual years, but are classified in durations (a
period of more than a year).
1ST Generation computers (1946 – 1956).
- The 1st generation of computers used thousands of
electronic gadgets called Vacuum tubes or Thermionic valves to store & process
- The tubes consumed a lot power, and generated a lot of heat
during processing due to overheating.
The computers constantly broke down due to the excessive
heat generated, hence were short-lived, and were not very reliable.
They also used Magnetic
Cards were used to enter data into the computers.
Their internal memory capacity was limited. The maximum memory size was approx. 2 KB
The computers used big physical devices in their circuitry;
hence they were very large in size, i.e. the computer could occupy several
office blocks. For example, ENIAC
occupied an area of about 150m2 - the size of an average 3-bedroom
They were very slow - their speed was measured in Milliseconds. E.g., ENIAC (the earliest electronic
computer) could perform 5,000 additions per second & 300 multiplications
The computers were very costly - they costed millions of
Examples of 1ST
- ENIAC (Electronic Numerical Integrator And Calculator) built in 1946 for use in World War II. It contained 18,000 Vacuum tubes.
(Electronic Discrete Variable Automatic Computer) developed in 1945 by Dr. John Von Neumann. It was the first computer that used instructions
stored in memory.
- UNIVAC (UNIVersal Automatic Computer).
- IBM 650.
- LEO (Lyon’s Electronic Office).
2ND Generation computers (1957 – 1963).
- The 2nd generation computers used tiny,
solid-state electronic devices called Transistors. The transistors were relatively smaller, more
stable & reliable than vacuum tubes.
- The computers consumed less power, produced less heat, were
much faster, and more reliable than those made with vacuum tubes.
They used Magnetic
RAM Memory size expanded to 32 KB.
Their operation speed increased to between 200,000 – 300,000
instructions per second. Their speeds
were measured in Microseconds. E.g., a computer could perform 1 million
additions per second, which was comparatively higher than that of the 1st
The computers were smaller in size & therefore, occupied
less space compared to the 1st G computers.
They were less costly than the 1st G computers.
Examples of 2nd
- ¨ NCR
501, IBM 300, IBM 1401, IBM 7070, IBM 7094 Series & CDC-6600 Mainframe
- ¨ ATLAS
LEO Mark III.
- ¨ UNIVAC
- ¨ HONEYWELL
3RD Generation computers (1964 – 1979).
- Used electronic devices called Integrated Circuits (ICs), which were made by combining
thousands of transistors & diodes together on a semiconductor
called a Silicon chip.
4TH Generation computers (1979 – 1989).
- The 4th generation computers used Large Scale Integrated (LSI) circuits & Very Large Scale Integrated (VLSI) circuits. These circuits were made by compressing more
tiny circuits and transistors into even smaller space of the silicon chip.
5TH Generation computers (1990 – Present).
- In this generation fall today’s computers.
The technologies used are Parallel architectures, 3-Dimensional
circuit design & super conducting
These technologies have led to the development of computers
referred to as Supercomputers, which
are very powerful, and have very high processing speeds. Their speeds are measured in Nanoseconds & Picoseconds.
They are able to perform parallel (or multiprocessing)
whereby a single task is split among a number of processors.
The memory sizes range between 1 Gigabyte & 1 Terabyte.
The computers are designed using VLSI and the Microchip technology that has given rise to the
smaller computers, known as Microcomputers used today.
The computers have special instruction sets that allow them
to support complex programs that mimic human intelligence often referred to as Artificial
Intelligence. Such programs can
help managers to make decisions and also provide critical expert services to
users instead of relying on human professionals.
//Register as a member to attempt development of a computers questions. click here to learn more on membership
PARTS OF A COMPUTER
A computer is made up of a collection of different
components that are interconnected together in order to work as a single
A Computer consists of the following parts/devices: -
The System Unit.
This is the casing (unit) that houses electronic components
such as the ‘brain’ of the computer
called the Central processing Unit (CPU) and storage devices.
The components in the System unit include: -
Processing Unit (CPU), which is also referred to as Processor.
drives, which are used to store, record and read data.
There are two makes of System units:
This system unit is made to stand
alone. They are designed to be placed on
style units have more space for expansion than the typical desktop units.
Desktop units lie on the desk with
the monitor resting on top of the system unit.
Features of the System
- It houses
connects to all peripheral devices using ports.
- It has the
computer’s Power switch.
The Central processing unit (CPU)
- This is the brain of the computer, and carries out all the
processing within the computer
- These are the devices used to enter/put data into the
- They accept data for processing & convert it
into a suitable form that the computer can understand.
Examples: Keyboard, Mouse, Joysticks, Light pen, Scanner, etc.
The keyboard looks like a typewriter, and has letters,
numbers and other keys through which data is entered into the computer.
To enter data & instructions into the computer, the user
should press the required keys.
It is a pointing device that enables the user to issue
instructions to the computer by controlling a special mouse pointer displayed
on the screen.
- Output devices are
used to give the end results of data that was entered into the computer.
extract/ disseminate processed data (information) from the computer.
accept data from processing devices & convert it into human sensible form.
- Examples: Screens (Monitors), Printers, Graph plotters, Speakers, etc
It is a television like screen used for displaying
output. When you type a letter or number
on the keyboard, it shows up on the monitor.
Note. The monitor enables the user to monitor/track
or see what is going on in the computer.
Printers are used to create permanent copies of output on
A computer is basically made up of a system unit and other
devices connected to the system unit called Peripheral devices.
Peripheral devices are the elements (components) connected to
the system unit so as to assist the computer satisfy its users.
Peripheral devices are connected to the System unit using
special cables called data interface cables that carry
data, programs & information to and from the processor. The cables are connected to the system unit
using connectors called Ports.
Examples of peripheral devices
//Register as a member to attempt computer program questions. click here to learn more on
Characteristics / Features of a Computer.
Before 20th century, most information was
processed manually or by use of simple machines. Today, millions of people are using computers
in offices and at home to produce and store all types of information
The following are some of the attributes that make computers
widely accepted & used in the day-to-day activities in our society:
- Computers operate at very high
speeds, and can perform very many functions within a very short time.
- Unlike human beings, computers are
very accurate, i.e., they never make mistakes.
- A computer can work for very long
periods without going wrong. However,
when an error occurs the computer has a number of in-built, self-checking
features in their electronic components that can detect & correct such
- Usually errors are committed by
the users entering the data to the computer, thus the saying Garbage in Garbage Out (GIGO).
This means that, if you enter
incorrect data into the computer and have it processed, the computer will give
you misleading information.
- The computer can be relied upon to
produce the correct answer if it is given the correct instructions &
supplied with the correct data.
- Therefore, if you want to add two numbers, but by mistake, give
the computer a “Multiply”
instruction, the computer will not know that you intended to “ADD”; it will
multiply the numbers supplied.
- Computers are usually consistent. This means that, given the same data &
the same instructions, they will produce the same answer every time that
particular process is repeated.
- A computer
is capable of storing large amounts of data or instructions in a very small
- A computer
can store data & instructions for later use, and it can produce/ retrieve
this data when required so that the user can make use of it.
stored in a computer can be protected from unauthorized individuals through the
use of passwords.
- Unlike human beings, a computer
can work continuously without getting tired or bored. Even if it has to do a million calculations,
it will do the last one with the same speed and accuracy as the first one.
- A computer is an automatic device. This is because, once given the instructions,
it is guided by these instructions and can carry on its job automatically until
it is complete.
- It can also perform a variety of
jobs as long as there is a well-defined procedure.
- A computer can be used in
different places to perform a large number of different jobs depending on the
instructions fed to it.
of a formal approach to working methods:
- Because a computer can only work
with a strict set of instructions, it identifies and imposes rigid rules for
dealing with the data it is given to process.
//Register as a member to attempt characteristics of a computer questions. click here to learn more on
- Information is the
data which has been refined, summarized & manipulated in the way you want
it, or into a more meaningful form for decision-making.
information must be accurate, timely, complete and relevant.
Comparison between Data and Information.
(raw) facts or figures.
not have much meaning to the user.
be used for decision-making.
is the end-product of data processing (processed data)
into a meaningful format.
meaningful to the user.
be used to make decisions.
//Register as a member to attempt information questions. click here to learn more on
Data is a collection of raw facts, figures or instructions that
do not have much meaning to the user.
be in form of numbers, alphabets/letters or symbols, and can be processed to
There are two types/forms of data:
Digital (discrete) data:
- Digital data is discrete in nature.
It must be represented in form of numbers, alphabets or symbols for it
to be processed by a computer.
- - Digital
data is obtained by counting. E.g. 1, 2, 3 …
Analogue (continuous) data:
- Analogue data is continuous in nature. It must be represented in physical nature in
order to be processed by the computer.
data is obtained by measurement. E.g.
Pressure, Temperature, Humidity, Lengths or currents, etc
output is in form of smooth graphs from which the data can be read.
is the process of collecting all items of data together & converting them
- Processing refers to the way the data is
manipulated (or handled) to turn it into information.
The processing may involve calculation, comparison or any
other logic to produce the required result.
The processing of the data usually results in some meaningful
information being produced.
//Register as a member to attempt data questions. click here to learn more on
A Computer Program:
computer Program is a set of related
instructions written in the language of the computer & is used to make the
computer perform a specific task (or, to direct the computer on what to do).
set of related instructions which specify how the data is to be processed.
set of instructions used to guide a computer through a process.
//Register as a member to attempt computer program questions. click here to learn more on
Definition of a
Computer is an electronic device
that operates (works) under the control of programs stored in its own memory
computer is an electronic machine that processes raw data to give information
electronic device that accepts data
as input, and transforms it under the influence of a set of special
instructions called Programs, to
produce the desired output (referred to as Information).
- A computer automatically accepts data & instructions as
input from an Input device, stores them temporarily in its memory, then
processes that data according to the instructions given, and finally transfers
the processed data (Information) to an Output device.
computer is described as an electronic
device because; it is made up of electronic components and uses electric energy (such as electricity)
computer has an internal memory, which stores data & instructions
temporarily awaiting processing, and even holds the intermediate result
(information) before it is communicated to the recipients through the Output devices.
- It works on the data using the instructions
issued, means that, the computer cannot do any useful job on its own. It can only work as per the set of instructions
A computer will accept data in one form and produce it in
another form. The data is normally held
within the computer as it is being processed.
//Register as a member to attempt definition of a computer questions. click here to learn more on membership