2. Topics
Meanings of Computer
• Types of Computers
• Evolution/Generation of Computers
Computer System
Hardware
SoftwareSoftware
Data
Information
Procedure
People
Communication/ Connectivity
3. Meanings of Computer
Computer is a device that computes, especially a
programmable electronic machine that performs
high-speed mathematical or logical operations or
that assembles, stores, correlates, or otherwise
processes information. According to Collins English
Dictionary, Computer is “A device, usually
electronic, that processes data according to a set of
instructions”.
The actions carried by the computer are either
arithmetic or logical in nature.
4. Types of Computers
Computers are either analog or digital in nature. Computers
of yesteryears were analog in nature, but modern day
computers are digital in nature. Computers can be generally
classified by size and power as follows, though there is
considerable overlap:
Personal computer
Workstation
Minicomputer
Mainframe
Supercomputer
5. Types of Computers
Personal computer: A small, single-user computer based on a
microprocessor. In addition to the microprocessor, a personal computer
has a keyboard for entering data, a monitor for displaying information,
and a storage device for saving data. These are cost effective machines
which are used for general purpose computations.
Workstation: A powerful, single-user computer. A workstation is like a
personal computer, but it has a more powerful microprocessor and a
higher-quality monitor.
Minicomputer: A multi-user computer capable of supporting from 10 to
hundreds of users simultaneously. It is scaled down version of main
frame machines designed to meet the computing needs of small and
medium enterprise (SME). HP, IBM, SUN and Dell are some of the
major vendors of mini computers.
6. Types of Computers
Mainframe: A powerful multi-user computer capable of supporting many
hundreds or thousands of users simultaneously. They are usually installed
in very large organizations such as banks, meteorological office, defense
establishments etc. These machines have proprietary hardware and
software. The cost of acquisition and maintenance of these machines are
high.
IBM is the most popular maker of mainframe machines and some of the
models are 3090, ES/9000, and S/390
Supercomputer: An extremely fast computer that can perform hundreds
of millions of instructions per second. It works on massively parallel
architectures interconnecting more than one processor, has large quantity
of main memory and secondary storage devices. It supports multiple
users, use proprietary hardware and software, need special environment
for working and are very expensive in both procuring and maintaining.
Supercomputers are usually used for complicated computations such as
weather forecasting and other scientific research requiring massive
calculations.
7. Evolution/Generation of Computers
First Generation(1944-1958)
Most input and output media were punched cards and
magnetic tape.
Main memory was almost exclusively made up of
hundreds of vacuum tubes.
Computers were somewhat unreliable because the
vacuum tubes failed.
They could run only one program at a time.
ENIAC (Electrical Numerical Integrator And
Calculator) ,
8. Evolution/Generation of Computers
Second Generation(1959-1963)
Transistors and some other solid-state devices that
were much smaller than vacuum tubes.
Magnetic cores became the most widely used type
of main memory.
Removable disk packs were introduced as storage
device.
Smaller, more reliable and significantly faster than
first-generation computers.
9. Evolution/Generation of Computers
Third Generation(1964-1970)
Integrated circuit replaced traditional transistorized
circuit.
The use of magnetic disks for data storage became
widespread.
Multiprogramming and timesharing.
10. Evolution/Generation of Computers
Fourth Generation(1971-now)
LSI ,VLSI and ULSI circuits were developed.
Computers’ main memory capacity increased.
Software application like dBASE, electronic
spreadsheet became commercially available.
11. Computer System
A computer system comprises hardware
and software. A computer system processes
data into information according to instructions
provided by the user. Data are raw facts that
need to be processed, whereas information is
meaningful data. Instructions provided by the
user tell the computer hardware how to perform
a task are referred to as the computer software.
12. Computer System
It accepts data that is typed to it by the
user (input data).
The computer then processes this data
providing a result.
This result is then displayed on the screen or
printed on a sheet of paper (computer
output).
14. Basic Elements of a Computer System
Computer system includes hardware, peripheral devices, and software.
Hardware – the physical components that comprise the computer and
other devices connected to it, such as a keyboard or monitor.
Peripheral devices – expand the computer’s input, output, and storage
capabilities.
Input device is a hardware device that allows users to enter data or
commands into the computer.
Output device is any hardware device that makes information
available to a user.
Storage device is any device that can store data.
Software – programs containing instructions that direct the operation of
the computer system.
16. Basic Computer OrganizationBasic Computer Organization
ALU
Control
Unit
Input Devices Output
Devices
Memory
Central Processing unit
CPU3
8
9
5
2
1
4
67
11
10 12
T0
outside
world
From
outside
world
17. Computers Consist of Five Parts
Hardware
Software
Users
Data
Some authors treat
Communications as
fifth part
19. Types of Hardware
The Input hardware: used to enter
data and instructions into a computer.
The Output hardware: used to view
information produced by the computer.
The Processing hardware: used to
process data into information.
20. Types of Hardware
The Storage hardware: used to store
data, information and instructions
permanently on media.
The Communication hardware: used
to enable connections between
computers (i.e: modems, cable and fax
modems).
21. Software
Computer software is often regarded as anything
but hardware, meaning that the "hard" are the parts
that are tangible (able to hold) while the "soft" part
is the intangible objects inside the computer.
Software is made up of a group of related
programs. A program is a sequence of instructions
to the hardware components of a computer system
to perform a specific processing task.
22. Software
Software can generally be classified into application software or
systems software. Application software performs general-purpose tasks
for users, e.g. a payroll system, word processing, spreadsheets.
23. Software
Systems software, on the other hand, runs
basic computer operations, manages
computer resources and allows application
software to run on the computer. Systems
software includes operating systems, utility
programs and language translators.
24. Software
A software package is software to perform
a general business function, e.g. Microsoft
Office. The Microsoft Office programs
Word, PowerPoint, Excel and Access will
be studied in details in this course.
25. Data
As mentioned before, data is a
collection of raw facts, whereas
information is processed data.
In a computer system data is represented
using two binary digits: 1 ("on") and 0
("off"). This is referred to as the
binary system.
26. Data
During processing, 0 is represented by an
electrical current being off ( or at low voltage)
and 1 by the current being on (or at high
voltage).
When a letter is typed on the keyboard,
the character is automatically converted into
series of 1s and 0s that the computer can
understand.
27. Data
Letters, numbers and special characters are
represented within the computer system by
means of binary coding schemes. Two
common binary coding schemes are the
ASCII-8 and EBCDIC. Following, table lists
some examples of how some characters
are represented using the ASCII scheme.
28. Data
ASCII stands for American Standard Code
for Information Interchange and is typically
used to represent data in smaller computers
(microcomputers).
EBCEDIC stands for Extended Binary
Coded Decimal Interchange and is used to
represent data in larger computers.
29. Procedures
A procedure is a sequence of steps
describing how to carry out a particular
task on the computer. For example, to
logon the computer, to shut down the
computer, to save a file, etc.
30. People
People are the most important part of the
computer system because they design and
develop computer systems, operate computer
hardware, create computer software and
establish procedures for carrying out tasks.
31. People
People dealing with the computer can
mainly be classified into computer
professionals or end-users.
Computer professionals are people having
formal education in technical aspects of
using computers. Examples are computer
programmers, system analysts and network
administrators.
32. People
End-users, on the other hand, are people
who use a computer system to help them
carry out a task specific to their job or
profession or just for fun. End-users need
not have much technical knowledge about
the computer.
33. Communication/ Connectivity
Connectivity refers to using computers
for communication purposes, e.g.
sending messages from one computer to
another, sharing resources (such as
software) and sharing information.
