Download WESTNET COMPUTER HOUSE INTRODUCTION TO COMPUTER

WESTNET COMPUTER HOUSE
INTRODUCTION TO COMPUTER
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COMPUTER OVERVIEW
The word “computer” comes from the word “compute” which means to calculate. So a computer
is normally considered to be a calculating device that can perform arithmetic operations at
enormous speed. The original objective for inventing the computer was to create a fast
calculating machine. But more than 80% of the work done by computers today; is of nonmathematical or non-numerical nature. Thus defining a computer merely as a calculating device
is to ignore over 80% of its work.
Definition:
A computer therefore can be defined as device that operates upon information or data. Data can
be anything given and accepted by the computer as input. Data comes in various shapes and sizes
depending upon the type of computer application. A computer can store, process and retrieve
data as and when desired.
INFORMATION TECHNOLOGY.
"Information Technology," and is pronounced "I.T." It refers to anything related to computing
technology, such as networking, hardware, software, the Internet, or the people that work with
these technologies.
COMPUTER TERMINOLOGY
Data: data is the name given to basic facts e.g. the number of items sold by a business, the name
of a customer, a line of text, or the numerical values in mathematical formulae.
Information: a distinction is sometimes made between data and information. When data is
converted into a more useful of intelligible form then it is said to be processed into information.
Thus information is processed data.
Program: a program is a set of instructions that is written in the language of the computer. A
program is used to make the computer perform specific tasks such as calculating interest to be
paid to savings account holder4s or producing a payroll. (Note: The spelling program not
programme). The computer is only able to obey a program’s instruction if the program has been
first stored within the computer memory. This implies that the computer must be able to input
and store programs in addition to data. So the computer works under the control of stored
programs.
Hardware: is the general term used to describe all the electronic and mechanical elements of the
computer, together with those devices used with the computer.
Software: is the general term used to describe all the various programs that may be used on a
computer system together with their associated documentation.
Peripheral devices: this is any device that is connected to the computer.
User interface: it is the part of the software with which you interact with. It controls how data
and instructions are entered and how it is presented on the screen.
An icon: it’s a small image that presents a program, instruction or some object.
CHARACTERISTICTS OF COMPUTERS
1. Speed: a computer is a very fast device. It can perform in a few seconds the amount of work
that a human being could do in an entire year if he worked day and night and did nothing else.
Also a computer can do in one minute what would take a man his entire lifetime. The units of
speed used are microseconds, nanoseconds and even the picoseconds. A powerful computer can
manage 3 to 4 million arithmetic operations per second.
2. Accuracy: The accuracy of a computer is consistently high and the degree of accuracy of a
particular computer depends upon its design. But for a particular computer, each and every
calculation is performed with the same accuracy. Errors can occur in a computer but these are
mainly due to human rather than technological weaknesses; that is due to imprecise thinking by
the programmer or due to inaccurate data.
3. Diligence: unlike human beings, a computer is free from monotony, tiredness, lack of
concentration, etc., and hence can work for hours together without creating errors and without
grumbling. Due to this property, computers obviously score over human beings in doing routine
type of jobs which require great accuracy. If ten million calculations have to be performed, a
computer will perform the last calculation with exactly the same accuracy and speed as the first
one.
4. Versatility: versatility is one of the most wonderful things about the computer. One moment,
it is preparing the results of a particular examination, the next moment it is busy preparing
electricity bills, and in between it may be helping an office secretary to trace an important letter
in seconds. All that is required to change its talent is to slip in a new program into it.
5. Power of Remembering: as human being acquires new knowledge the brain subconsciously
selects what it feels to be important and worth retaining in its memory, and releases unimportant
details to the back of the mind or just forgets them. With computers this is not the case. A
computer can store and recall any amount of information because of its secondary storage
capability. every piece of information can be retained as long as required by the user. Even after
several years, the information recalled will be as accurate as on the day when it was fed to the
computer. A computer forgets or looses certain information only when it is asked to do so. So it
is entirely upon the user to make a computer retain or forget particular information.
6. No I.Q.: A computer is not a magical device. It can only perform tasks that a human being
can. The difference is that it performs these tasks with unthinkable speed and accuracy. It
possesses no intelligence of its own. Its I.Q. is zero at least till today. It has to be told what to do
and in what sequence. Thus only the user can determine what tasks a computer will perform. A
computer can not take its own decision.
7. No Feelings: computers are devoid of emotions. They have no feelings and no instincts
because they are machines. Although men have succeeded in building a memory for the
computer, but no computer possesses the equivalent of a human heart and soul. Based on our
feelings, taste, knowledge and experience, we often make certain judgments in our day to day
life. But computers cannot make such judgments on there own. Their judgment depends on the
instructions given to them in the form of programs.
HISTORY OF COMPUTING
The history of computing development is often referred to in reference to the different
generations of computing devices. Each generation of computer is characterized by a major
technological development that fundamentally changed the way computers operate, resulting in
increasingly smaller, cheaper and more powerful and more efficient and reliable devices that we
use today. Otherwise computer history dates back to 1647 when Frenchman Blaise Pascal
invented the mechanical calculator.
First Generation 1940-1956: vacuum tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were
often enormous, taking up entire rooms. They were very expensive to operate and in addition to
using a great deal of electricity, generated a lot of heat, which was often the course of
malfunctions. First generation computers relied on machine language to perform operations, and
they could only solve one problem at a time. Input was based on punched cards and paper tape,
and output was displayed on printouts. The UNIVAC and ENIAC computers are examples of
first generation computing devices. The UNIVAC was the first commercial computer delivered
to a business client, the U.S Census Bureau in 1951.
Second generation- 1956-1963: transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers. The
transistor was invented in 1947 but did not see wide spread use in computers until the late 50s.
The transistor was far superior to the vacuum tube, allowing computers to become smaller,
faster, cheaper, more energy efficient and more reliable than their first-generation predecessors.
Though the transistor still generated a great deal of heat that subjected the computer to damage,
it was a vast improvement over the vacuum tube. Second generation computers still relied on
punched cards for input and printouts.
Second generation computers moved from cryptic binary machine language to symbolic or
assembly languages which allowed programmers to specify instructions in words. High-level
programming languages were also being developed at this time, such as early versions of
COBOL and FORTRAN. These were also the first computers that stored their instructions in
their memory, which moved from a magnetic drum to magnetic core technology. The first
computers of this generation were developed for the atomic energy industry.
Third generation- 1964-1971: integrated circuits
The development of the integrated circuits was the hallmark of the third generation of computers.
Transistors were miniaturized and placed on silicon chips, called semiconductors, which
drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through
keyboards and monitors and interfaced with an operating system, which allowed the device to
run many different applications at one time with a central program that monitored the memory.
Computers for the first time became accessible to a mass audience because they were smaller
and cheap than their predecessors.
Fourth generation-1971-1990: microprocessors.
The microprocessor brought the fourth generation of computers, as thousands of integrated
circuits were built onto a single silicon chip. What in the first generation filled an entire room
could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the
components of the computer- from the central processing unit and the memory to input/output
controls on a single chip.
In 1981 IBM introduced its firs computer for the home user, and in 1984 Apple introduced the
Macintosh. Microprocessor also moved out of the realm of desktop computers and into many
areas of life as more and more everyday products began to use microprocessors.
As these computers became more powerful, they could be linked together to form networks,
which eventually led to the development of the internet. Fourth generation computers also saw
the development of GUIs, the mouse and the hand held devices.
Fifth generation-1990 to present: artificial intelligence.
Fifth generation computing devices, based on artificial intelligence, are still in development,
though there are some applications, such as voice recognition, that are being used today. The use
of parallel processing and superconductors is helping to make artificial intelligence a reality.
Quantum computation and molecular and nanotechnology will radically change the face of
computers in years to come. The goal of the fifth generation computing is to develop devices that
respond to natural language input and are capable of learning and self-organization.
COMPUTER TYPES
A computer may be classified by technology (electronics), purpose, and size.
Basic types according to technology (electronics)
a. Digital: digital computer process data that is represented in the form of discrete values
(e.g. 1, 2, 3, 4) by operating on it in steps. Discrete values occur at each step in the
operation. Counting on one’s fingers is probably the simplest digital operation we know.
Digital watches have special tiny, digital computers within them.
b. Analog: analog computers are similar to measuring instruments such as thermometer and
voltmeter which points on circular dials. They process data in the form of electrical
voltages, which are variable like the variable positions of a pointer on a dial. The output
from ad analog computer is often in the form of smooth graphs from which information
can be read.
c. Hybrid: hybrid computer, as their name suggest, are computers that have the combined
features of digital and analog computers.
Computers by purpose
a. Special purpose computer: as their name they are designed for a particular job only; to
solve problems of a restricted nature. Examples are computers designed for use in digital
watches, in petrol pumps or in weapons guidance systems.
b. General purpose computers: they are designed to solve a wide variety of problems.
Within the limitations imposed by their design capabilities, they can be adapted to
perform particular tasks or solve problems by means of specially written programs.
Examples of computes
a. Home computer: is a low-cost microcomputer of limited capability designed for
domestic use with programs that typically are used for such things as computer games or
controlling family finances.
b. A personal computer (pc): it is a microcomputer designed for independent use by an
individual at work or in the home mainly for business purposes. Some PC’s are portable.
Many can be connected to minicomputers and mainframe computer so that the PC can
also gain access to the facilities offered by the larger machine.
c. A desktop computer: is any computer designed for use on a desk in an office
environment. Therefore home computers and PCs are types of desktop computers.
d. A workstation: is another kind of computer. Although larger more powerful PCs are
sometimes called workstations the term is normally used to imply the presence of
advanced features not provided by all PCs. These include in-built capabilities for their
interconnection and operation in conjunction with other computers, and for them to
process pictorial data as well as that presented in the form of text.
e. Laptop: is a computer sufficiently small for the user to comfortable use it on his or her
lap. A typical lap-top operates on mains electricity or by rechargeable batteries and is
small enough to fit inside a briefcase still leaving room for other items. They have inbuilt flat screens called liquid crystal displays (LCDs)
f. An embedded computer: is one that is within some other device or system but is not
accessed directly. For example there are embedded computers operating within petrol
pumps, watches, switches, cameras, video recorder and many types of domestic and
industrial equipment.
Classification by power and size
Further classification is done in order of decreasing power and size.
a. supercomputer
b. mainframe computer
c. minicomputers
d. microcomputers
e. laptops/notebooks
Super computers are high capacity machines that require special air-conditioned room and are
the fastest calculating devices ever invented. Supercomputers use “non-von Neumann designs”
multiprocessor systems with simultaneous or “parallel” processing.
They are used for complex scientific applications like weather forecasting, where large amount
of data need to be manipulated within a very short time.
Mainframe computers are very large, often filling an entire room. They can store enormous of
information, can perform many tasks at the same time, can communicate with many users at the
same time and are very expensive. The price of a mainframe computer frequently runs into the
millions of shillings. Mainframe computers usually have many terminals connected to them.
These terminals look like small computers but they are only devices used to send and receive
information from the actual computer using wires. Terminals can be located in the same room
with the mainframe computer but at times can also be located in different rooms, buildings, or
cities. Large businesses, government agencies and universities usually use this type of computer.
Minicomputers are much smaller than mainframe computers and they are also much less
expensive. The cost of these computers can vary from a few thousands shillings to several
hundreds thousands shillings. They possess most of the features found on mainframe computers,
but on a more limited scale. They can still have many terminals, but not as many as the
mainframes. They can store a tremendous amount of information but again usually not as much
as the mainframe. Medium and small businesses typically use these computers.
Microcomputers are the type of computers we are using in our labs. They are limited in what
they can do when compared to the larger models discussed above because they can only be used
by one person at a time, they are much slower than the larger computers, and they can not store
nearly as much information but they are excellent when used in small business, homes and
schools. These computers are inexpensive and easy to use. Two main categories of
microcomputers are:
i.
Laptops/notebooks. These are portable computers equipped with a flat display
screen and are smaller in size. The expandability and the number of peripheral
devices used by the laptop are also limited. However as technology advance more
and more features are being incorporated into the system.
ii.
Handheld computers. Are small PC designed to fit in your hand eg personal
digital assistant (PDA) which can handle personal information like calendar.
Servers
Servers are not designed to be used directly. They make programs and data available for people
hooked up to a computer network, a collection of computers connected together so that they can
exchange data.
THE COMPUTER SYSTEM UNIT
The computer system unit contains many parts.
Motherboard - The motherboard is the main circuit board of a microcomputer. It is also
known as the main board or system board.
CPU - The CPU is the central electronic chip that determines the processing power of the
computer.
Memory - Memory is the part of the computer that temporarily stores applications, documents,
and stem operating information.
Bus - A bus is an electronic line that allows 1s and 0s to move from one place to another.
Expansion Slots - Expansions slots appear on the motherboard. They are sockets into which
adapters are connected.
Ports and Connectors - A port is a connector located on the motherboard or on a separate
adapter.
Bays - A bay is a space inside the computer case where a hard drive, floppy drive or CD-ROM
drive sits
Power Supply - A power supply changes normal household electricity into electricity that a
computer can use.
Sound Components - A sound card lets a computer play and record high quality sound.
The basic elements that make up the computer system are:
a. Input.
b. Storage.
c. Control.
d. Processing.
e. Output.
INPUT: Most computers cannot accept data in forms customarily to human communications
such as speech or hand-written. The data is presented to the computer through devices like the
keyboard, which converts the data into machine-sensible forms. Data finally enters storage.
STORAGE: Data and instructions enter main storage, and are held until needed to be worked
on. The instructions dictate action to be taken on the data. Results of action will be held until
they are required for output. Main storage is supplemented by auxiliary storage, also called
backing storage, e.g. hard disks for mass storage purposes. Backing storage serves an important
role in holding “maintained data”, i.e. data held by the computer so that it can provide
information to the user when required to do so.
CONTROL: The processor controls the operation of the computer. It fetches instruction from
main storage, interprets them and issues the necessary signals necessary in obeying the
instructions.
PROCESSING: Instructions are obeyed and the necessary arithmetic operations are carried out
on the data. The part of the processor that does this sometimes is called the Arithmetic Logic
Unit (ALU). Although in reality, as for the control unit, there is often no physical separate
component that performs this function. In addition to arithmetic the processor also performs what
is called logical operations. These operations take place at incredible high speeds, e.g. 10 million
numbers may be totaled in one second.
OUTPUT: Results are taken from main storage and fed onto an output device. This may be
printed text, sound, charts, and graphs displayed on a computer screen.
Data &
programs
STORAGE UNIT
INPUT
UNIT
OUTPUT
UNIT
CONTROL UNIT
Results
C.P.U
ARITHMETIC LOGIC UNIT
KEY: Instruction flow
Command/signal
The functional components of a computer
From the above figure
Data normally flows from input devices or backing storage into main storage main storage to
output devices.
The processor performs operations on data from main storage and returns the results of
processing to main storage.
In some cases, data flows directly between the processor and input or output devices.
The arithmetic logic unit (ALU) and control unit combine to form the processor.
NB: Unit – is a distinctive function and not a separate hardware component.
There are two types of flow shown in fig. above solid lines carry data or instructions but broken
lines carry commands or signals.
Data held on backing storage may be input into main memory during processing, used and
brought up to date using newly input data and then returned to backing storage.
Input units
This unit consists of devices that translate data into a form the computer can understand. Divided
into three types:
 Keyboard hardware
 Pointing devices
 Source data-entry
Keyboard hardware: This is a device that converts letters, numbers, and other characters into
electrical signals that are machine-readable by the computers processors. It looks like a
typewriter keyboard, and contains alphabetical and alphanumeric characters, numbers and other
functional keys.
Pointing devices: control the position of the cursor or pointing on the screen. E.g. mice, lightpens, touch pads etc.
Source data-entry devices: these refer to menu forms of data-entry devices that are not
keyboards or pointing devices. They create machine-readable data on magnetic media or paper of
feed it directly into the computer’s processor. They include: scanning devices, sensors, etc.
CENTRAL PROCESSING UNIT
The brain of a computer system is the Central Processing Unit; which is generally referred to as
the C.P.U or sometimes mainframe. The CPU is the computer. It is the CPU that processes the
data transferred to it from one of the various input devices, and then transfers either the
intermediate or final results of the processing to one of many output devices. A central control
section and work areas are required to perform calculations or manipulate data. The CPU is the
computing center of the system. It consists of a control section, internal storage section (main or
primary memory), and arithmetic logic section. Each of the sections within the CPU serves a
specific function and has a particular relationship to the other sections within the CPU.
This is to say the CPU;
 Does all of the work for the computer
 Does all of the mathematics, mainly addition
 Does all the logical comparisons of values
 Directs the flow of data in a computer
 Controls the operation of the parts of the computer
Today, all CPUs are microprocessors
A microprocessor is a complete computer on a silicon chip
A microprocessor does all of the functions of a computer
 Stores data and instructions waiting to be used
 Follows changeable instructions
 Does input, processing, and output
CPUs have the following basic parts
1. The control section (Control unit)
2. The arithmetic logic section (ALU)
3. The Output units
4. The Storage unit
Control section
The control section may be compared to a telephone exchange because it uses the instructions
contained in the program in much the same manner as the telephone exchange uses telephone
numbers. When a telephone number is dialed, it causes the telephone exchange to energize
certain switches and control lines to connect the dialing phone with the phone having the number
dialed. In similar manner, each programmed instruction, when executed, causes the control
section to energize certain control lines, enabling the computer to perform the function or
operation indicated by the instruction.
The program may be stored in the internal circuits of the computer (computer memory), or it
may be read instruction by instruction from external media. The internally stored program type
of computer, generally referred to as a stored-program computer, is the most practical type to use
when speed and fully automatic operations are desired.
Computer programs may be so complex that the number of instruction plus the parameters
necessary for program execution will exceed the memory capacity of a stored-program
computer. When this occurs, the program may be sectionalized, i.e. broken down into modules.
One or more modules are then stored in the computer memory and the rest in an easily accessible
auxiliary memory. Then as each module is executed producing the desired results, it is swapped
out of internal memory and the next succeeding module read in.
In addition to the commands that tell the computer what to do, the control unit also dictates how
and when each specific operation is to be performed. It is also active in initiating circuits that
locate any information stored within the computer or in an auxiliary storage device and in
moving this information to the point where the actual manipulation or modification is to be
accomplished.
The four major types of instruction are:
1. Transfer
2. Arithmetic
3. Logic
4. control
Transfer instructions are those whose basic function is to transfer (move) data from one
location to another.
Arithmetic instructions are those that combine two pieces of data to form a single piece of data
using one of the arithmetic operations.
Logic instructions transform the digital computer into a system that is more than a high-speed
adding machine. Using logic instructions, the programmer may construct a program with any
number of alternate sequences. E.g. through the use of logic instructions, a computer being used
for maintenance inventory will have one sequence to follow if the number of a given item on
hand is greater than the order amount and another sequence to follow if it is smaller.
The choice of which sequence to use will be made by the control section under the influence of
the logic instruction. Logic instructions, thereby, provide the computer with the ability to make
decisions based on the results of previously generated data. The logic instructions permit the
computer to select the proper program sequence to be executed from among the alternatives
provided by the programmer.
Control instructions are used to send commands to devices not under direct command of the
control section, such as input/output units or devices.
Arithmetic logic-section
The arithmetic-logic section performs all arithmetic operations-addition, subtraction,
multiplication and division. Through its logic capability, it tests various conditions encountered
during processing and takes action based on the result. Data flows between the arithmetic logic
section and internal storage section during processing. Specifically, data is transferred as needed
from the internal storage section to the arithmetic logic section, processed and returned to the
internal storage section. At no time does processing take place in the storage section. Data may
be transferred back and forth between these two sections several times before processing is
completed. The results are then transferred from internal storage to an output unit, as indicated
by the solid arrows.
Output units
These are output devices that translate information processed by the computer into a form that
human can understand. They are divided into:
1. Softcopy output
2. Hard copy output
3. Other output devices.
Soft copy output devices: these are devices that show programming instructions and data as
they are being fed to the computer and information after it is processed. E.g. monitor, flat panel
displays, etc.
Hard copy output devices: these are devices that print characters, symbols and perhaps graphics
on paper or another hard copy medium. E.g. printers, plotters, etc.
Other output devices: these refer to output hardware for sound output, voive output, video
output, virtual reality, and simulation devices. E.g. speaker.
Storage unit
These refer to devices used for storing data or computer instructions. They are divided into three:
a) Main memory (primary memory)
b) Secondary memory
c) Registers
Main memory: this is used for holding data and instructions required immediately by the CPU.
It’s characterized by fast accessing information, low capacity and high costs. They are of two
types:
 RAM
 ROM
RAM: Random access memory
They can both be read, to retrieve information or written into, to store information. The contents
of RAM remain stable as long as power is available i.e. it is volatile and has a short time
response. Two types of RAM exist; Dynamic RAM and Static RAM.
R.A.M. Stores data and instructions that are used by the CPU to perform some task. These
instructions are usually loaded into RAM from a secondary storage device. RAM is also used to
store instructions that tell the CPU how to work with its parts. These instructions are usually
called drivers. The instructions in RAM are constantly changing, depending on the needs of the
CPU. When the computer is turned off the information in RAM disappears. Access to
information is random access.
ROM: Read only memory
They provide permanent or semi permanent storage only. Their contents can be read but cannot
be rewritten during normal computer operations. They are non-volatile i.e. they retain their
information even when power is off.
ROM stores instructions that are used by the CPU
Tells the CPU how to be the kind of computer it is, for example a Windows, Macintosh, or Play
Station computers. Tells the CPU how to work with the different parts of the computer
ROM can also hold programs that are directly accessed by the CPU. One such program is the
self-test when the computer is first turned on. The self-test tests to see if all the parts on the main
circuit board (mother board) are working correctly. The instructions in ROM can not be changed
The instructions are built into the electronic circuits of the chips. These instructions in ROM are
called firmware. To change the instructions in ROM you need to usually change the chips or do
some other special process that is normally not available to an average user. Access to
information is random access.
Random access means that any piece of information in ROM can be accessed at any given time
without access other information first. It is a lot like the tracks on a music CD. You can access
any track at any time and in any order. The other kind of access is sequential access. You must
access the information in the order that they are located. This is a lot like a music tape. You
must play the songs in order, or you have to fast forward past songs to get to the one you want.
Secondary memory: it is used for storing backup information that is not needed immediately by
the CPU. They are characterized by slow access of information, higher capacity and lower cost.
E.g. hard disk, floppy, etc
Registers: High speed circuits which are a staging area for temporary storing data during
processing. Size of the registers can affect the speed and performance of the processor
COMPUTER HARDWARE
Computer hardware refers to the physical parts of a computer and related devices. Internal
hardware devices include motherboards, hard drives, and RAM. External hardware devices
include monitors, keyboards, mice, printers, and scanners.
The internal hardware parts of a computer are often referred to as components, while external
hardware devices are usually called peripherals. Together, they all fall under the category of
computer hardware
COMPONENTS
Power Supply - The power supply comes with the case, but this component is mentioned
separately since there are various types of power supplies. The one you should get depends on
the requirements of your system.
Motherboard - This is where the core components of your computer reside which are listed
below. Also the support cards for video, sound, networking and more are mounted into this
board.

Microprocessor - This is the brain of your computer. It performs commands and
instructions and controls the operation of the computer.

Memory - The RAM in your system is mounted on the motherboard. This is memory that
must be powered on to retain its contents.

Drive controllers - The drive controllers control the interface of your system to your
hard drives. The controllers let your hard drives work by controlling their operation. On
most systems, they are included on the motherboard; however you may add additional
controllers for faster or other types of drives.
Hard disk drive(s) - This is where your files are permanently stored on your computer. Also,
normally, your operating system is installed here.
CD-ROM drive(s) - This is normally a read only drive where files are permanently stored.
There are now read/write CD-ROM drives that use special software to allow users to read from
and write to these drives.
Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4
Megabytes of memory capacity.
Other possible components devices include DVD devices; Tape backup devices, sound cards,
graphic card, Fans, Heat sinks, Coolers and some others.
PERIPHERALS
Monitor - This device which operates like a TV set lets the user see how the computer is
responding to their commands.
Keyboard - This is where the user enters text commands into the computer.
Mouse - A point and click interface for entering commands which works well in graphical
environments.
Track ball - basically an upside down mouse
Joystick
Scanner
A scanner allows you to scan documents, pictures, or graphics and view them on the computer.
You can also use software to edit the items you scan.
Used to put printed pictures and text into a computer
Converts an image into dots that the computer can understand
To scan text, optical character recognition (OCR) software is needed
Digital Camera
Used to take electronic pictures of an object
The pictures taken by a digital camera can be used directly by a computer
Microphone
Used to put sound into a computer
Need sound recording software
Others include: Backup devices, Card readers, TV tuner card, controller card, Game controller
OUTPUT DEVICES
An output device displays information on a screen, creates printed copies or generates sound. A
monitor, printer, and speakers are examples of output devices. Some Common Output Devices:
Monitors and Displays
Shows the processed information on a screen
A monitor uses a Picture Tube like a television with the image displayed on the front of the tube,
which is called the screen.
Displays are flat and use plasma, LCD, active-matrix, or some other technology.
Monitors used to be called Cathode Ray Tubes (CRTs) because of the picture tube, which is a
large vacuum tube.
A monitor or display, produces a soft copy. When the device is turned off the information goes
away. Monitors are slowly being replaced by flat panel displays.
Printers
Printers produce a hard copy
The information is printed on paper and can be used when the device is off.
It is also called a printout
Dot-matrix printers (impact printer)
Uses metal pins to strike an inked ribbon to make dots on a piece of paper.
Can see the dots that make up the letters or images. Lowest print quality of all of the printers.
Very low in cost per page to use. Rarely used today because of the poor print quality, but still
used in business to print multi-part forms.
Ink jet printers (non-impact printer)
Use drops of magnetic ink to produce dots on a page to produce text or images.
The print quality is almost the same as a laser printer's. Problems with the ink
The ink is very expensive. The ink is water soluble and will run if the paper gets wet.
Highest cost per page of all the printers. For producing color documents, it has the highest
quality at a reasonable price.
Laser printers (non-impact printer)
How the laser printer produces an image
A laser or LEDs make dots on a light sensitive drum
Toner (very tiny particles of plastic) stick to the drum where the dots where made
Paper is pressed against the drum and the toner is placed on the paper
The paper is heated and the toner melts into the paper
Produces the highest quality printout
For black and white printouts, very low cost per page
Printout is permanent
Color laser printers are still fairly expensive ($3,000 to $10,000)
Speakers
Used to output sound
COMPUTER SOFTWARE
Software comprises instruction that tell the computer what to do. Generally software is divided
into:
a) System software
b) Application software
c) Software development tools
Common features of software
There are some common features of software which include:
 Features of the keyboard
 The user-interface
 Tutorial and documentation.
Features of the key board: even though keyboard is an input device, it is used in manipulating
software to some extent. Besides letters, numbers, and punctuation keys, the keyboard has
special purpose and function keys.
Special purpose keys are used to enter, delete, and edit data and to execute commands. E.g. ESC,
Enter, Ctrl, etc.
Function keys, labeled F1,F2….F12 are used to execute command specific to the software being
used.
Macros (keyboard shortcuts), are a series of keystroke or commands used to automatically issue
a longer predetermined series of keystrokes or commands.
E.g. ALT + F4 which is used for closing.
The user interface: it is the user controllable part of the software that allows users to
communicate, or interact with the software. These include GUIs (graphical user interfaces),
menu (a list of available commands presented on the screen), windows (rectangular area that
appears on the screen and displays information from a particular part of a program), icons
(pictures used in GUI to represent a command, a program, o file or even a task), buttons
(simulated on-screen button that is activated by a mouse or other pointing device to issue a
command), dialog box (a box that appears on the screen and display a message requiring a
response from a user), etc
Tutorial and documentation: most commercial packages come with tutorials and
documentation. A tutorial is an instruction book or program that takes a user through a
prescribed series of steps to help in learning how to use the product. Documentation is a user
guide or reference manual that is narrative and graphical description of a program.
System software
It controls the location and usage of hardware resources and enables the application software to
run. Include operating system, assemblers, etc.
Application software
Software that has been developed to solve a particular problem, to perform a useful work on
specific task or to provide entertainment. They may be custom or packaged. E.g. Ms-Office.
Software development tools
These are software used to develop system software, or application software. They include
programming languages e.g. C, C++, JAVA etc.
System software- The operating system
Operating system is system software that interfaces between the user and the computer hardware.
Functions of operating system
 Loads programs
 Allocates memory
 Provides scheduling and accounting
 Manages computer resources
 Performs I/O control
 Provides user interface
Computer application software Categories
They may be classified as:
1. Entertainment software
2. Home/personal software
3. Education/reference software
4. Productivity software
5. Specialty software
Entertainment software: these are software mainly used for entertainment purposes e.g. games,
music, video, etc.
Home/personal software: these are software on CD-ROM disks that are used for personal
activities e.g. software featuring recipes for exotic foods.
Education/reference software: these are software used to supplement learning. E.g. CD-ROM
containing encyclopedia, maps, mailing lists, phone books, etc.
Productivity software: these are software that consists of programs that assist users in achieving
a particular task. Include word processing, spreadsheet, database software, financial software and
communication software.
 Word processing: allows a user to create, edit, format, print and store text materials
amongst other things. E.g. Ms-word, etc.
 Spreadsheet: allows a user to create tables and financial schedules by entering data and
formulas into rows and columns arranged as a grid on a display screen. E.g. MS-excel.
 Database software: a program that controls the structure of the database and access the
data. The principal features of database software include: organization of database, data
retrieval and display, sort and built-in mathematical formulas e.g. Ms-Access, oracle, etc.
 Financial software: is a growing category that ranges from personal-finance to managers
to entry-level accounting programs to business financial-management packages. E.g.
QuickBooks, lotus organizer, etc
 Communication software: manages the transmission of data between computers. E.g.
electronic mail software like Pegasus mail, Eudora mail, Ms-outlook, web browsers (IE).
Specialty software
These are software designed to assist the user I performing a particular task. E.g. desktop
publishing, presentation graphics, project management, computer aided design, drawing and
painting programs.
Desktop publishing: used for mixing text and graphics to produce high quality output for
commercial printing. E.g. PageMaker.
Presentation graphics: uses graphics and data/information form other software tools to
communicate or make a presentation of data to others. E.g. Ms-PowerPoint.
Project management: a program used to plan, schedule, and control the people, cost, and
resources required to complete a project in time. E.g. Ms-project.
Computer aided design: used for the design of products, structure, civil engineering drawings
and maps. E.g. corelCAD.
Drawing and painting programs: a drawing program is a graphic software that allows users to
design and illustrate object and products e.g. CorelDraw, Adobe illustrator. Painting program are
graphic programs that allow users to simulate painting on the screen e.g. Adobe Photoshop,
Corel PhotoPaint, etc.
Drawbacks of application software
There is a couple of significant drawback that often characterizes new software;
Bloatware or featuritis: this means software having too many features that computer users
don’t understand how to use all of them e.g when Ms- Office 97 came on the market, it contained
4500 commands- far more than the few dozen or even few hundreds that most people will use.
Shovelware: this is where software made is full of flaws due to incompatibility standards with
other parts of the computer system.
Ethic and intellectual property rights
Intellectual property consists of the products, tangible or intangible, of the human mind. One of
the major methods of protecting intellectual property is copyright.
Copyrights: exclusive legal rights that prohibit copying of intellectual property without the
permission of the copyright holder. It protects the expression of an idea but not the idea itself.
There are three important copyright related matters viz:
Software and network piracy: software piracy is the unauthorized copying of copyrighted
software and network piracy is using electronic network materials in digitized form.
Plagiarism: the expropriation of another writer’s text, findings, or interpretations and presenting
it as one’s own.
Ownership of images and sound: this involves the use of computers, scanners, digital cameras
and the likes to make it possible to alter images and sound.
NOTE: Apart from these types of software, there are some other well-known forms of computer
software like inventory management software, ERP, utility software, accounting software and
others.
Inventory Management Software: This type of software helps an organization in tracking its
goods and materials on the basis of quality as well as quantity. Warehouse inventory
management functions encompass the internal warehouse movements and storage. Inventory
software helps a company in organizing inventory and optimizing the flow of goods in the
organization, thus leading to an improved customer service.
Utility Software: Also known as service routine, utility software helps in the management of
computer hardware and application software. It performs a small range of tasks. Disk
defragmenters, systems utilities and virus scanners are some of the typical examples of utility
software.
Data Backup and Recovery Software: An ideal data backup and recovery software provides
functionalities beyond simple copying of data files. This software often supports user needs of
specifying what is to be backed up and when. Backup and recovery software preserve the
original organization of files and allow an easy retrieval of the backed up data.
Multimedia applications for playing multimedia.
Firmware which is software programmed resident to electrically programmable memory devices
on board main-boards or other types of integrated hardware carriers.
Middleware which controls and co-ordinates distributed systems.