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IS 511 2016

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FACULTY OF INFORATION TECHNOLOGY
INFORMATION SYSTEMS 511
YEAR 1
SEMESTER
1
Registered with the Department of Higher Education as a Private Higher Education Institution under the Higher Education Act, 1997.
Registration Certificate No. 2000/HE07/008
FACULTY OF INFORMATION TECHNOLOGY
LEARNER GUIDE
MODULE: INFORMATION SYSTEMS 511
(1ST SEMESTER)
PREPARED ON BEHALF OF
RICHFIELD GRADUATE INSTITUTEOF TECHNOLOGY (PTY) LTD
AUTHOR: NONHLANHLA NGOBESE
EDITOR: KHAUHELO MAHLAKENG
FACULTY HEAD: ISAKA REDDY
Copyright © 2016
Richfield Graduate Institute of Technology (Pty) Ltd
Registration Number: 2000/000757/07
All rights reserved; no part of this publication may be reproduced in any form or by any means, including
photocopying machines, without the written permission of the Institution.
MODULE: INFORMATION SYSTEMS 511 (1ST SEMESTER)
TOPIC 1: INTRODUCTION TO USING THE COMPUTER
TOPIC 2: SOFTWARE
TOPIC 3: THE SYSTEMS UNIT
TOPIC 4: INPUT AND OUTPUT
TOPIC 5: STORAGE
TOPIC 6: ADDENDUM 511(A): CASE STUDY FOR DISCUSSION
Prescribed / Recommended Books
Principles of Information Systems, 11th Edition
Ralph M. Stair Professor Emeritus 2013
ISBN-10: 1133629660 | ISBN-13: 9781133629665
Enhanced Discovering Computers (Shelly Cashman) 1st Edition
Misty E. Vermaat 2015
ISBN-13: 978-1285845500 ISBN-10: 1285845501
Discovering Computers Technology in a world of computers, mobile devices and the internet
1st Edition 2013
Cashman,S ISBN: 9781285161761, Cengage
3
LESSON PLAN ALIGNED TO MOBILE CONTENT [MOODLE]
SECTION
SUBJECT MATTER
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
2.16
2.17
2.18
2.19
3
3.1
3.2
3.3
INTRODUCTION TO USING THE COMPUTER
Computer Literacy & Information Literacy
What is Information Literacy?
Why is Information Literacy important?
How will I use Information Literacy?
What is an Information System?
Components of an Information Systems
Communication Networks
Categories of Computers
Types of PCs
SOFTWARE
Computer Software
Types of Software
The role of the Operating System & User Interface
Allocating System Resources
Monitoring System Activities
What is a User Interface?
What happens when you switch on a computer?
The Boot Process
Important Operating System Files
File & Disk Management
Single Program & Multitasking of Operating System
Common Operating Systems
The History of Windows
The Windows Operating Systems
Language Types
Introduction to Software Applications
Graphics & Multimedia Equipment
Software for Communication
Learning aids & support tools
THE SYSTEMS UNIT
Introduction to systems unit
The components of a system unit
Different types of memory
Lesson 1
Lesson 2-3
Lesson 4-6
Lesson 7-9
4
3.4
3.5
4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
5
5.1
How data is represented in a computer?
Storage Device
INPUT AND OUTPUT
Defining Input
Output Devices
Definition of Output
Display Devices
Video Adapter Cards
The Printer
Audio Output
DATA STORAGE & WAREHOUSING
Introduction to data storage
Lesson 10
Lesson 11
Lesson 12
5
INTERACTIVE ICONS USED IN THIS LEARNER GUIDE
Learning Outcomes
Study
Read
Writing Activity
Research
Glossary
Key Point
Case Study
Bright Idea
Problem(s)
Think Point
Review Questions
Multimedia Resource
Web Resource
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ONE | INTRODUCTION TO USING THE COMPUTER
Learning Outcomes
ONE | INTRODUCTION TO USING THE COMPUTER
1. Define and explain the difference between computer literacy &
information literacy
2. Know different components of an information system
3. Define what a computer is and list the various components of a
computer & their respective functions
4. Explain the operations of the information processing cycle,
namely: input, process, output & storage
5. List & discuss the factors that contribute to the processing power
of computers
6. Understand the key concepts of speed, reliability, accuracy,
storage & communications
7. List the various categories of computers
8. Know the differences between the different categories of
computers & their respective purposes
1.1 COMPUTER LITERACY AND
INFORMATION LITERACY
Computer literacy is being able to use a
computer for the required purpose to
produce required results.
LEARNER OUTCOME 1
is covered in Sections 1.1 to 1.5
[consider siting the book]
1.2 WHAT IS INFORMATION LITERACY?
Information Literacy is the ability to identify what information is needed,
understand how the information is organized, identify the best sources of
information for a given need, locate those sources, evaluate the sources
critically, and share that information. It is the knowledge of commonly used
research techniques.
1.3 WHY IS INFORMATION LITERACY IMPORTANT?
Information literacy is critically important because we are surrounded by a
growing ocean of information in all formats. Not all information is created equal:
some is authoritative, current, reliable, but some is biased, out of date,
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misleading, and false. The amount of information available is going to keep
increasing. The types of technology used to access, manipulate, and create
information will likewise expand.
1.4 HOW WILL I USE INFORMATION LITERACY SKILLS?
Information literacy skills are used for academic purposes, such as research
papers and group presentations. They're used on the job—the ability to find,
evaluate, use and share information is an essential skill. Consumer decisions,
such as which car or vacuum cleaner to purchase, are critical. You'll also use these
skills by participating fully in a democratic society as an informed citizen by
understanding issues and voting.
1.5 WHAT IS AN INFORMATION SYSTEM?
An information system is not only the technology that an organization uses, but
also the way in which the organization interact with the technology and the way
in which the technology works with the organization’s process such as gathering
raw data, storing it, processing this data and making information available to the
user or to an organization.
ONE | INTRODUCTION TO USING THE COMPUTER
1.6 COMPONENTS OF AN INFORMATION SYSTEM
1.6.1 End User
The aim of an information system is to
enable the end users to operate more
productively.
LEARNING OUTCOME 2
Is covered in section 1.6
1.6.2 Hardware
This is the physical equipment devices used by people to communicate with each
other such as Keyboard mouse, printer and Central Processing Unit.
1.6.3 Software
This is a program or a set of instructions that control the functioning of the
computer.
1.6.4 Data
Data is raw unprocessed facts and once the computer processes data it is then
called information.
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1.6.5 Information
Information is a collection of facts organized in such a way that they have
additional value beyond the value of the facts themselves.
1.6.6 Procedures
These are predetermined guidelines for users to follow when using the hardware
and software.
1.7 COMMUNICATION NETWORKS
ONE | INTRODUCTION TO USING THE COMPUTER
The purpose of a communications
network is to allow moving information
from one point to another inside the
LEARNING OUTCOME 3
organization. The information could be
Is covered in sections 1.7.1 and 1.7.2
stored on a device, such as a personal
computer in the network; it could be
generated live outside the network, such as speech, or could be generated by a
process on another piece of information, such as automatic sales transactions at
the end of a business day. The device does not necessarily have to be a
computer; it could be a hard disk, a camera or even a printer on the network.
Due to a large variety of information to be moved, and due to the fact that each
type of information has its own conditions for intelligibility, the computer
network has evolved into a highly complex system.
1.7.1 What Is A Computer?
A computer is an electronic device that manipulate data, process it to produce
information as output which is stored for later use.
1.7.2 The Four Functions Of A Computer
Every computer, whether microcomputer, mini-computer or mainframe has four
main functions, namely input, processing, output and storage, as indicated in the
figure on the next page:
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Figure 1 The four functions of a computer
As the Figure 1 above indicates, data about business transactions and other events are captured
into the computer through input devices such as the keyboard, the mouse, the microphone and
the modem, whereupon it is processed by the CPU (Central Processing Unit). Data entered into the
system is subjected to processing activities such as calculating, comparing, sorting, classifying and
summarizing. The above activities organize, analyze and manipulate data, thus converting it into
information for end-users. As the CPU is processing data it temporarily stores it in the Primary
Storage (also called the Main Memory). The data that has been
processed is presented to users in a way that they can
understand through output devices such as the monitor, the
printer, speakers and the modem. Here information is
IDEA
transmitted to end-users and made available to them by the
output activity. The goal of information systems is the
production of appropriate information products for end-users, You can start any program by
using the start button.
which can be messages, reports, forms, and graphic images. The
Complete the following three
phrase ‘in a way that they can understand’ is deliberately
steps to start a web browser.
inserted above, because computers talk only in terms of 1’s and
1. Click the start button
0’s, the so-called machine language.
2. Click all programs
Finally a computer stores its results for later use in storage
devices such as the hard disk drive (HDD), the floppy disk drive
(FDD), the CD Rom drive, the DVD Rom drive etc. This ability to
store results for future use and the ability to access these results
quickly gives the computer tremendous power in comparison to
a human being.
3. Click the internet
explorer
An internet explorer window
will be opened.
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ONE | INTRODUCTION TO USING THE COMPUTER
1.7.3 The Information Processing Cycle
The four functions of a computer discussed above also form what is called an
information processing cycle i.e., Input – Processing – Output – Storage. As the
dotted arrow in Figure 1 above indicates, it becomes a cycle when the Storage
devices are used as input devices to provide input to the computer. In other
words, the work that you did three days ago can become input today and the
whole cycle of Input – Processing – Output – Storage starts again.
The Figure 1 can be summarised as follows:
A. INPUT - This is the activity of
gathering and capturing raw data. For
example, in producing a payroll, the
LEARNING OUTCOME 4 & 5
number of hours every employee
Is covered in sections 1.7.3
works must be collected and captured
before the payroll is run.
B. PROCESSING
Involves
converting or transforming data into useful output, thus making calculations,
comparisons and taking alternative action and storing data for future use.
C. OUTPUT - Involves producing useful information, usually in the form of
documents and reports. For example pay slips, manager’s reports, etc.
D. STORAGE - Involves the keeping of the output for backup purposes. For
example filing the printed reports, saving the on USB, CDs etc.
E. FEEDBACK - is also very important in the above cycle. This feedback is the
output that is used to make changes to input or processing activities. For
example errors or problems might make it necessary to correct input data or
change a process.
1.7.4 Why A Computer Is So Powerful?
A computer’s power is derived from its capability of performing the information
processing cycle (input, process, output and storage) with amazing speed
reliability and accuracy; its capacity to store huge amounts of data and
information; and its ability to communicate with other computers.
1.7.4.1 Speed
Inside
the
system
unit,
LEARNING OUTCOME 6
operations
occur
through
Is covered in sections 1.7.4
electronic circuits. When data
and instructions, and information
flow along these circuits, they travel at close to the speed of light. This allows
billions of operations to be carried out in a single second.
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1.7.4.2 Reliability And Consistency
The electronic components in modern computers are dependable because they
have a low failure rate. The high reliability of the components enables the
computer to produce constant results.
1.7.4.3 Accuracy
Computers can process large amounts of data and generate error free results,
provided that the data is entered correctly. If inaccurate data is entered, the
resulting output will be incorrect. This computing principle is known as Garbage
in – Garbage out (GIGO) - points out that the accuracy of a computers output
depends on the accuracy of the input.
1.7.4.4 Storage Capacity
A computer can store huge amounts of data.
1.7.4.5 Communication
ONE | INTRODUCTION TO USING THE COMPUTER
Most computers today have the ability of communicating with each other.
Computers with this capability can share any of the four information processing
cycle operations- input, process, output and storage.
1.7.4.6 Programmability
A computer has also got the capability to be programmed.
1.8 CATEGORIES OF COMPUTERS
The six major categories of computers are personal computers, handheld
computers, Internet appliances, mid-range servers, mainframes and
supercomputers.
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1.8.1 Personal Computer
ONE | INTRODUCTION TO USING THE COMPUTER
A personal computer (PC) is any general-purpose computer whose size,
capabilities, and original sales price make it useful for individuals, and which is
intended to be operated directly by an end user with no intervening computer
operator. This is in contrast to the batch processing or time-sharing models
which allowed large expensive mainframe systems to be used by many people,
usually at the same time, or large data processing systems which required a fulltime staff to operate efficiently.
A personal computer may be a desk top computer, a laptop, a tablet PC, or a
handheld PC (also called a palmtop). The most common microprocessors in
personal computers are x86-compatible CPUs. Software applications for
personal computers include word processing, spreadsheet databases, Web
browsers and e-mail clients, games, and myriad personal productivity and
special-purpose software applications. Modern personal computers often have
high-speed or dial-up connections to the Internet allowing access to the World
Wide Web and a wide range of other resources.
A PC may be used at home or in an office. Personal computers may be connected
to a Local Area Networks (LAN), either by a cable or a wireless connection.
While early PC owners usually had to write their own programs to do anything
useful with the machines, today's users have access to a wide range of
commercial and non-commercial software, which is provided in ready-to-run or
ready-to-compile form. Since the 1980s, Microsoft and Intel have dominated
much of the personal computer market with the Wintel platform.
1.9 TYPES OF PCS
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1.9.1 Workstation
Processor from early 1990s
A workstation is a high-end personal computer designed for technical or scientific
applications. Intended primarily to be used by one person at a time, they are
commonly connected to a local area network and run multi-user operating
systems. Workstations are used for tasks such as computer-aided design, drafting
and modelling, computation-intensive scientific and engineering calculations,
image processing, architectural modelling, and computer graphics for animation
and motion picture visual effects.
ONE | INTRODUCTION TO USING THE COMPUTER
1.9.2 Desktop Computer
Prior to the wide spread of PCs a computer that could fit on a desk was considered
remarkably small. Today the phrase usually indicates a particular style of
computer case. Desktop computers come in a variety of styles ranging from large
vertical tower cases to small form factor models that can be tucked behind an LCD
monitor. In this sense, the term 'desktop' refers specifically to a horizontally14
oriented case, usually intended to have the display screen placed on top to save
space on the desk top. Most modern desktop computers have separate screens
and keyboards.
Single unit PCs (also known as all-in-one PCs) is a subtype of desktop computers,
which combine the monitor and case of the computer within a single unit. The
monitor often utilizes a touch screen as an optional method of user input;
however detached keyboards and mice are normally still included. The inner
components of the PC are often located directly behind the monitor, and many
are built similarly to laptops.
ONE | INTRODUCTION TO USING THE COMPUTER
1.9.3 Laptop
A laptop computer or simply laptop, also called a notebook computer or
sometimes a notebook, is a small personal computer designed for portability.
Usually all of the interface hardware needed to operate the laptop, such as USB
ports (previously parallel and serial ports), graphics card, sound channel, etc., is
built in to a single unit. Laptops contain high capacity batteries that can power the
device for extensive periods of time, enhancing portability. Once the battery
charge is depleted, it will have to be recharged through a power outlet. In the
interest of saving power, weight and space, they usually share RAM with the video
channel, slowing their performance compared to an equivalent desktop machine.
One main drawback of the laptop is sometimes, due to the size and configuration
of components, relatively little can be done to upgrade the overall computer from
its original design. Internal upgrades are either not manufacturer recommended,
can damage the laptop if done with poor care or knowledge, or in some cases
impossible, making the desktop PC more modular. Some internal upgrades, such
as memory and hard disks upgrades are often easy, a display or keyboard upgrade
is usually impossible. The laptop has the same access as the desktop to the wide
variety of devices, such as external displays, mice, cameras, storage devices and
keyboards, which may be attached externally through USB ports and other less
common ports such as external video.
15
A subtype of notebooks, called sub notebooks, are computers with most of the
features of a standard laptop computer but smaller. They are larger than handheld computers, and usually run full versions of desktop/laptop operating
systems. Notebooks are sometimes considered in this category, though they are
sometimes separated in a category of their own (see below).
ONE | INTRODUCTION TO USING THE COMPUTER
1.9.4 Notebook
Notebooks (also called mini notebooks or sub notebooks) are a rapidly evolving
category of small, light and inexpensive laptop computers suited for general
computing and accessing web-based applications; they are often marketed as
"companion devices," that is, to augment a user's other computer access. At their
inception in late 2007 — as smaller notebooks optimized for low weight and low
cost— notebooks omitted key features (e.g., the optical drive), featured smaller
screens and keyboards, and offered reduced specification and computing power.
Over the course of their evolution, notebooks have ranged in size from below 5 in
to over 13 in, and from ~1 kg (2-3 pounds). Often significantly less expensive than
other laptops, by mid-2009, notebooks had been offered to users "free of charge",
with an extended service contract purchase. In the short period since their
appearance, notebooks have grown in size and features, now converging with
new smaller, lighter notebooks.
1.9.5 Tablet PC
A tablet PC is a Notebook or slate-shaped mobile computer, first introduced by
Pen Computing in the early 90s with their Pen Go Tablet Computer and
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popularized by Microsoft. Its touch screen or graphics tablet/screen hybrid
technology allows the user to operate the computer with a stylus or digital pen,
or a fingertip, instead of a keyboard or mouse. The form factor offers a more
mobile way to interact with a computer. Tablet PCs are often used where normal
notebooks are impractical or unwieldy, or do not provide the needed
functionality.
As technology and functionality continue to progress, prototype tablet PCs will
continue to emerge. The Microsoft Courier, a personal business device, has two
7" monitors that support multi-touch gestures, Wi-Fi capabilities and has a builtin camera. The device looks to be a replacement to traditional planners while
offering what most digital planners cannot, two pages and large writing spaces.
ONE | INTRODUCTION TO USING THE COMPUTER
1.9.6 Ultra-Mobile PC
The ultra-mobile PC (UMPC) is a specification for a small form factor of tablet PCs.
It was developed as a joint development exercise by Microsoft, Intel, and
Samsung, among others. Current UMPCs typically feature the Windows XP,
Windows Vista, Windows 7, or Linux and operating system.
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1.9.7 Pocket PC
A pocket PC is a hardware specification for a handheld-sized computer (personal
digital assistant) that runs the Microsoft Windows Mobile operating system. It
may have the capability to run an alternative operating system like NetBSD or
Linux. It has many of the capabilities of modern desktop PCs.
ONE | INTRODUCTION TO USING THE COMPUTER
1.9.8 Mid-range Servers
A mid-range server is more powerful and larger than a workstation computer.
Mid-range servers can often support up to 4000 connected computers at the
same time. Users often access a minicomputer via a terminal. A terminal is a
monitor and keyboard. Such terminals are known as dumb terminals because
they have no processing power – they cannot act as stand-alone computers and
they need the minicomputer connected to them at all times.
1.9.9 Mainframe Computers
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Mainframes (often colloquially referred to as Big Iron) are powerful computers used mainly by
large organizations for critical applications, typically bulk data processing such as census, industry
and consumer statistics, enterprise resource planning, and financial transaction processing.
The term originally referred to the large cabinets that housed the central processing unit and main
memory of early computers. Later the term was used to distinguish high-end commercial machines
from less powerful units.
Most large-scale computer system architectures were firmly established in the 1960s and most
large computers were based on architecture established during that era up until the advent of Web
servers in the 1990s. There were several minicomputer operating systems and architectures that
arose in the 1970s and 1980s, but minicomputers are generally not considered mainframes. (UNIX
arose as a minicomputer operating system; Unix has scaled up over the years to acquire some
mainframe characteristics.) Many defining characteristics of "mainframe" were established in the
1960s, but those characteristics continue to expand and evolve to the present day.
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Writing Activity
Now that you are familiar with basic knowledge on computers and
information literacy, you are ready to appreciate the many uses of
computers and information.
ONE | WRITING ACTIVITY
You are required to explain information systems, compare and
contrast between computer literacy and information literacy. You are
also expected to define the information process cycle.
20
Review Questions
ONE | REVIEW QUESTIONS
1.
2.
3.
4.
5.
6.
Explain why it is important to be Computer literate.
Define the terms computer.
Identify the component of the computer.
Explain why computer is so powerful tool.
Differentiate amongst the various categories of computers.
Discuss the application of computers in the categories
mentioned.
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KEY TERMS USED IN SECTION 1
All-in-one PC A sub-type of desktop computers, which combine the
monitor and case of the computer within a single unit. The monitor
often utilizes a touch screen as an optional method of user input;
however detached keyboards and mice are normally still included.
Application software allows end users to accomplish one or more
specific (not directly computer development related) tasks.
Arithmetic Logic Unit Performs the arithmetic comparison and
logical operations.
Cache memory Most of today’s computers improve their processing
time by using cache. Cache helps speed the process of the computer
by storing frequently used instructions and data. The rationale is that
the processor is likely to request these items over and over again.
When the processor needs an instruction it first searches cache.
ONE | GLOSSARY OF TERMS
Central Processing Unit (CPU) The CPU interprets and carries out
basic instruction that operates a computer. The CPU is also called a
processor, significantly impacts on overall computing power and
manages most of the computer operations. Most of the devices
connected to the computer communicate with the CPU in order to
carry out a task.
Complementary metal oxide semi-conductor (CMOS) Is used to
store configuration information about the computer e.g. type of disk
drives, keyboard, monitor, etc.
A Compact Disk (CD) is a flat round portable metal storage medium
that is usually 4.75 inches in diameter and less than one-twentieth of
an inch thick. Compact disks store items such as data instructions,
and information by using microscopic pits and land that are in the
middle layer of the disc. A high - powered laser light creates the pits.
A compiler program rewrites the program into machine language
that the CPU can understand. This is done all at once and the
program is saved in this new form. A compiled program is generally
considerably larger than the original.
Computer is an electronic device that manipulate data, process it to
produce information as output which is stored for later use.
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Computer Aided Design (CAD) is a sophisticated type of application
software that assists the user in creating engineering architectural
and scientific designs
Computer literacy being able to use a computer for the required
purpose to produce required results
Control Unit executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
Data Raw unprocessed facts and once the computer processes data
it is then called information.
Desktop The area on the display screen where icons are grouped is
often referred to as the desktop because the icons are intended to
represent real objects on a real desktop.
Desktop Computer horizontally-oriented case, usually intended to
have the display screen placed on top to save space on the desk top
Desktop Publishing Software allows you to create sophisticated
documents using a combination of text, graphics and brilliant
colours; professional graphic designers use it
Dot matrix printers are impact printers and they work much like the
typewriter. They produce characters on paper by impacting an inked
ribbon with a ‘matrix’ of tiny pins in their print heads. When a
particular pin in the print head receives a voltage it juts out and hits
the inked ribbon, which in turn comes in contact with paper. When
the voltage from the same pin mentioned above is switched off, the
pin retracts and another pin is given voltage and the process goes on
and on. Depending on the character being written on paper, different
sets of pins will receive voltage and others will not. Transistors on the
printer main board control the pins. Dot matrix printers are
becoming less popular, while inkjet and laser printers are becoming
more popular even for home users. Dot matrix printers are relatively
cheaper to purchase and operate, But they make a lot of noise,
produce documents of low quality, cannot print colour and are
extremely slow.
A graphical user interface (GUI) is a type of user interface item that
allows people to interact with programs in more ways than typing
such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office
equipment with images rather than text commands. A GUI offers
graphical icons, and visual indicators, as opposed to text-based
23
interfaces, typed command labels or text navigation to fully
represent the information and actions available to a user. The actions
are usually performed through direct manipulation of the graphical
elements
A hard disk usually consists of several inflexible, circular disks, called
platters, on which items are stored electronically. A platter in a hard
disk is made of aluminum, glass, or ceramic and is coated with a
material that allows items to be magnetically recorded on its surface.
Hardware referrers to the physical equipment devices used by
people to communicate with each other such as keyboard, mouse,
printer and Central Processing Unit.
Information A collection of facts organized in such a way that they
have additional value beyond the value of the facts themselves.
Information system The way in which the organization interacts with
its technology and the way in which the technology works with the
organization’s process such as gathering raw data, storing it,
processing this data and making information available to the user or
to an organization
Inkjet printers work by firing streams of ink from a cartridge directly
onto paper. The cartridge has tiny holes called nozzles through which
ink can be squirted out. The quality of the printout depends on the
dpi ratio (the dots per inch ratio is a measure of print resolution).
Both inkjet printers and laser printers are capable of printing highresolution text and graphics (300 dpi or more).
Input the activity of gathering and capturing raw data. For example,
in producing a payroll, the number of hours every employee works
must be collected and captured before the payroll is run
Keyboard It is the primary input devices on the computer. You enter
data into the computer by pressing the keys on the keyboard.
A laptop computer or simply laptop, also called a notebook
computer or sometimes a notebook, is a small personal computer
designed for portability. Usually all of the interface hardware needed
to operate the laptop, such as USB ports (previously parallel and
serial ports), graphics card, sound channel, etc., is built in to a single
unit.
24
Machine Languages The language of the CPU (The central processing
unit of the computer, which is the part that does the "thinking"). The
lowest level language. Composed of 0's and 1's
Mainframes (often colloquially referred to as Big Iron) are powerful
computers used mainly by large organizations for critical
applications, typically bulk data processing such as census, industry
and consumer statistics, enterprise resource planning, and financial
transaction processing.
A computer’s memory is used to store data, instructions and
information. The computer’s memory stores basically three things:
The operating system and other system software used to operate the
computer; Application programs designed to carry out a specific task
e.g. word processing; and The data being processed by the
application programs.
A mid-range server is more powerful and larger than a workstation
computer. Mid-range servers can often support up to 4000
connected computers at the same time. Users often access a
minicomputer via a terminal.
The computer monitor is the most important output device. Strange
as it may look, a computer can work without a monitor but we
cannot work with a computer without a monitor.
The motherboard / system board is the circuit board to which many
of the electronic components are attached to.
Mouse is an input device used to control the movement of the
pointer. The top of the mouse has one to four buttons, and some
have a wheel on it and the bottom of the mouse is flat and contains a
multi – directional mechanism usually a small ball.
Output Involves producing useful information, usually in the form of
documents and reports. For example pay slips, manager’s reports,
etc.
A personal computer (PC) is any general-purpose computer whose
size, capabilities, and original sales price make it useful for
individuals, and which is intended to be operated directly by an end
user with no intervening computer operator.
Pointing device A device, such as a mouse or trackball that enables
you to select objects on the display screen.
25
Printer The function of a printer is to take a soft copy (or electronic
copy) on your computer and transfer it onto paper (a hard copy).
Processing Involves converting or transforming data into useful
output, thus making calculations, comparisons and taking alternative
action and storing data for future use.
Random Access Memory (RAM) When the computer is powered on,
certain operating system files are loaded from storage devices onto
RAM. These files remain in RAM as long as the computer is running.
RAM is volatile, means items stored in RAM are lost when the
computer is turned off. For this reason any item that needed for
future use needs to be saved.
Read Only Memory (ROM) The name given to memory chips that
can store data that can only be read. The data stored on ROM chips
cannot be modified – hence the name read only. ROM is non-volatile
i.e. the contents of the computer is not lost when the computer is
turned off. ROM stores information such as the sequence of
instructions the computer follows to load the operating system and
other information when you first turn the computer on.
Scanners allow you to transfer pictures, photographs and text into
your computer. This is an example of going from a hard copy to a soft
copy (or digital image). You can then take that digital image (also
called a bitmap) and use it in a paint program like Paint, print it out
or send it out as a fax. With Optical Character Recognition (OCR)
software you can convert printed documents such as newspaper
articles to text that you can use in your word processor.
Software a program or a set of instructions that control the
functioning of the computer.
Storage Involves the keeping of the output for backup purposes. For
example filing the printed reports, saving the on USB, CDs etc.
A tablet PC is a Notebook or slate-shaped mobile computer, first
introduced by Pen Computing in the early 90s with their Pen Go
Tablet Computer and popularized by Microsoft. Its Touch screen or
graphics tablet/screen hybrid technology allows the user to operate
the computer with a stylus or digital pen, or a fingertip, instead of a
keyboard or mouse.
The ultra-mobile PC (UMPC) is a specification for a small form factor
of tablet PCs. It was developed as a joint development exercise by
Microsoft, Intel, and Samsung, among others. Current UMPCs
26
typically feature the Windows XP, Windows Vista, Windows 7, or
Linux and operating system.
The user interface (of a computer program) refers to the graphical,
textual and auditory information the program presents to the user,
and the control sequences (such as keystrokes with the computer
keyboard, movements of the computer mouse, and selections with
the touch screen) the user employs to control the program.
Windows You can divide the screen into different areas. In each
window, you can run a different program or display a different file.
You can move windows around the display screen, and change their
shape and size at will
A workstation is a high-end personal computer designed for
technical or scientific applications.
A Zip Disk is a type of portable magnetic media that can store from
100 MB to 750 MB of data. The larger capacity Zip disks hold about
500 times more than a standard floppy disk.
27
TWO | SOFTWARE
Learning Outcomes
1. Explain the uses and different types of widely used software
applications
2. Define and describe a User interface & a GUI
3. Define an operating system & describe its functions
4. List & describe the major operating systems being used today
5. Know the different types of computer languages
6. List software applications and communication software
2.1 COMPUTER SOFTWARE
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Computer software, or just software, is the collection of computer programs
and related data that provide the instructions telling a computer what to do.
The term was coined to contrast to the old term hardware (meaning physical
devices). In contrast to hardware, software is intangible, meaning it "cannot be
touched". Software is also sometimes used in a more narrow sense, meaning
application software only. Sometimes the term includes data that has not
traditionally been associated with computers, such as film, tapes and records.
Examples of computer software include:
 Application software includes end-user applications of computers such as
word processors or Video games, and ERP software for groups of users
 Middleware controls and co-ordinates distributed systems
 Programming languages define the syntax and semantics of computer
programs. For example, many mature banking applications were written in the
COBOL language, originally invented in 1959. Newer applications are often
written in more modern programming languages
 System software includes operating systems, which govern computing
resources. Today large applications running on remote machines such as
Websites are considered to be system software, because the end-user interface
is generally through a Graphical user interface(GUI), such as a web browser
 Test ware is software for testing hardware or a software package
28

Firmware is low-level software often
stored on electrically programmable
memory devices. Firmware is given its name
LEARNING OUTCOME 1
because it is treated like hardware and run
Is covered in section 2.1 to 2.5
("executed") by other software programs
 Shrink ware is the older name given to
consumer bought software, because it was
often sold in retail stores in a shrink wrapped box
 Device drivers control parts of computers such as disk drives, printers, CD
drives, or computer monitors
Programming tools help conduct computing tasks in any category listed above.
For programmers, these could be tools for debugging, or reverse engineering
older legacy systems in order to check source code compatibility.
2.2 TYPES OF SOFTWARE
Practical computer systems divide software systems into three major classes:
system software, programming software and application software, although the
distinction is arbitrary, and often blurred.
2.2.1 System Software
System software helps run the computer hardware and computer system. It
includes a combination of the following:
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




Device Drivers
Operating Systems
Servers
Utilities
Window Systems
The purpose of systems software is to unburden the applications programmer
from the often complex details of the particular computer being used, including
such accessories as communications devices, printers, device readers, displays
and keyboards, and also to partition the computer's resources such as memory
and processor time in a safe and stable manner. Examples are - Microsoft
Windows, Linux, and Mac OS X.
2.2.2
Programming Software
Programming software usually provides tools to assist a programmer in writing
computer programs, and software using different programming languages in a
more convenient way. The tools include:
29





Compilers
Debuggers
Interpreters
Linkers
Text Editors
An Integrated development environment (IDE) is a single application that
attempts to manage all these functions.
2.2.3
Application Software
Application software allows end users to accomplish one or more specific (not
directly computer development related) tasks. Typical applications include:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Industrial Automation
Business Software
Video Games
Quantum Chemistry and Solid State Physics Software
Telecommunications (i.e. The Internet And Everything That Flows On It)
Databases
Educational Software
Medical Software
Molecular Modeling Software
Image Editing
Spreadsheets
Simulation software
Word Processing
Decision Making Software
2.3 THE ROLE OF THE OPERATING SYSTEM AND USER INTERFACE
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2.3.1 What is an Operating System?
Definition: An Operating System (OS) is software that governs the interaction
between application programs and hardware. The application programs cannot
communicate with the hardware directly and consequently, rely on the
Operating System to communicate with hardware on their behalf. The
Operating System also manages and controls the computer’s resources such as
the CPU, memory and the hard disk and handles the input and output of data.
It coordinates the operation of all the hardware and software components of
the computer system.
30
The Operating System is responsible for starting application programs running
and finding the resources that they need. When an application program is
running, the Operating System manages the details of the hardware for it. For
example, when you type characters on the keyboard, the Operating System
determines which application program they are intended for and does the
work of getting them there.
Modern Operating Systems usually come with a user interface that enables
users to interact with the Operating Systems themselves and with application
programs.
You could liken the Operating System of a computer to a shopkeeper who
keeps a shop in order by attending to customers, handling supplier deliveries,
stocking the shelves, doing the book keeping and so on. The Operating System
usually operates behind the scenes, thereby ‘protecting’ the user from the
mundane ‘housekeeping chores’. Consequently, the user does not have to
know all the complex low-level tasks that are involved in interacting with
hardware. In short, the purpose of the Operating System is to make it simpler
to use a computer.
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Computer users need only to know how to perform high-level functions, such
as opening and working with programs, copying and deleting files and so on.
However, they need not worry about low-level functions such as looking up
the physical location of the file in the disk’s file allocation table (FAT), finding
the pointer address of the first block and segment, positioning the read/write
head in the proper location, reading the data to the initial disk cache…Well, I
think you get the point!
All these complex low-level ‘housekeeping chores’ are transparent to the user,
i.e., for the user to operate a computer he does not need to know that all these
functions are taking place in the background.
31
Figure 2-1 Relationship between the user, applications, the OS and
hardware
2.3.2 Operating Systems
Between the hardware and the application software lays the operating system.
The operating system is a program that conducts the communication between
the various pieces of hardware like the video card, sound card, printer, the
motherboard and the applications.
2.3.3 Functions of Operating System
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Today most operating systems perform the following important functions:
1. Processor management, that is, assignment of processor to different tasks
being performed by the computer system.
2. Memory management, that is, allocation of main memory and other storage
areas to the system programmes as well as user programmes and data.
3. Input/output management, that is, co-ordination and assignment of the
different output and input device while one or more programmes are being
executed.
32
4. File management, that is, the storage of file of various storage devices to
another. It also allows all files to be easily changed and modified through the
use of text editors or some other files manipulation routines.
5. Establishment and enforcement of a priority system. That is, it determines
and maintains the order in which jobs are to be executed in the computer
system.
6. Automatic transition from job to job as directed by special control
statements.
7. Interpretation of commands and instructions.
8. Coordination and assignment of compilers, assemblers, utility programs,
and other software to the various user of the computer system.
9. Facilities easy communication between the computer system and the
computer operator (human). It also establishes data security and integrity.
2.4 ALLOCATING SYSTEM RESOURCES
The operating system directs the traffic inside the computer, deciding what
resource will be used and for how long.
Time
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Memory
Input
output
Time in the CPU is divided into time slices which are
measured in milliseconds. Each task the CPU does is
assigned a certain number of time slices. When time
expires, another task gets a turn. The first task must wait
until it has another turn. Since time slices are so small, you
usually can't tell that any sharing is going on. Tasks can be
assigned priorities so that high priority (foreground) tasks
get more time slices than low priority (background) tasks.
Memory must be managed also by the operating system.
All those rotating turns of CPU use leave data waiting
around in buffers. Care must be taken not to lose data!!
One way to help out the traffic jam is to use virtual
memory. This includes disk space as part of main memory.
While it is slower to put data on a hard disk, it increases
the amount of data that can be held in memory at one
time. When the memory chips get full, some of the data is
paged out to the hard disk. This is called swapping.
Windows uses a swap file for this purpose.
and Flow control is also part of the operating system's
responsibilities. The operating system must manage all
requests to read data from disks or tape and all writes to
these and to printers.
To speed up the output to printers, most operating
systems now allow for print spooling, where the data to
be printed is first put in a file. This frees up the processor
33
for other work in between the times data is going to the
printer. A printer can only handle so much data at a time.
Without print spooling you'd have to wait for a print job
to finish before you can do anything else. With it you can
request several print jobs and go on working. The print
spool will hold all the orders and process them in turn.
2.5 MONITORING SYSTEM ACTIVITIES
Time
Time in the CPU is divided into time slices which are measured in
milliseconds. Each task the CPU does is assigned a certain number of time
slices. When time expires, another task gets a turn. The first task must wait
until it has another turn. Since time slices are so small, you usually can't tell
that any sharing is going on. Tasks can be assigned priorities so that high
priority (foreground) tasks get more time slices than low priority
(background) tasks.
Memory
Memory must be managed also by the operating system. All those rotating
turns of CPU use leave data waiting around in buffers. Care must be taken
not to lose data!! One way to help out the traffic jam is to use virtual
memory. This includes disk space as part of main memory. While it is slower
to put data on a hard disk, it increases the amount of data that can be held
in memory at one time. When the memory chips get full, some of the data
is paged out to the hard disk. This is called swapping. Windows uses a swap
file for this purpose.
Input
and Flow control is also part of the operating system's responsibilities. The
output
operating system must manage all requests to read data from disks or tape
and all writes to these and to printers.
To speed up the output to printers, most operating systems now allow for
print spooling, where the data to be printed is first put in a file. This frees
up the processor for other work in between the times data is going to the
printer. A printer can only handle so much data at a time. Without print
spooling you'd have to wait for a print job to finish before you can do
anything else. With it you can request several print jobs and go on
working. The print spool will hold all the orders and process them in turn.
System
A user or administrator can check to see whether the computer or network
performance
is getting overloaded. Changes could be made to the way tasks are allocated
or maybe a shopping trip is in order! System performance would include
response time (how long it takes for the computer to respond when data is
entered) and CPU utilization (comparing the time the CPU is working to the
time it is idle.)
System security
Some system security is part of the operating system, though additional
software can add more security functions. For multiple users who are not
all allowed access to everything, there must be a logon or login procedure
where the user supplies a user ID and a secret password. An administrator
34
must set up the permissions list of who can have access to what programs
and what data.
2.6 WHAT IS A USER INTERFACE
In computer science and human-computer interaction, the user interface (of
a computer program) refers to the graphical, textual and auditory information
the program presents to the user, and the control sequences (such as
keystrokes with the computer keyboard, movements of the computer mouse,
and selections with the touch screen) the user employs to control the
program.
2.6.1 Graphical User Interface
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A graphical user interface (GUI) is a type of user interface item that allows
people to interact with programs in more ways than typing such as
computers; hand-held devices such as MP3 Players, Portable Media Players
or Gaming devices; household appliances and office equipment with images
rather than text commands. A GUI offers graphical icons, and visual indicators,
as opposed to text-based interfaces, typed command labels or text navigation
35
to fully represent the information and actions available to a user. The actions are
usually performed through direct manipulation of the graphical elements
Graphical user interfaces, such as Microsoft
Windows and the one used by the Apple
Macintosh, feature the following basic
components:
LEARNING OUTCOME 2
Is covered in section 2.6
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
Pointer
A symbol that appears on the display screen and that you move to select objects
and commands. Usually, the pointer appears as a small angled arrow. Text processing applications, however, use an I-beam pointer that is shaped like a
capital.
Pointing device

A device, such as a mouse or trackball that enables you to select objects on the
display screen.

Icons
Small pictures that represent commands, files, or windows. By moving the pointer
to the icon and pressing a mouse button, you can execute a command or convert
the icon into a window. You can also move the icons around the display screen as
if they were real objects on your desk.
Desktop

The area on the display screen where icons are grouped is often referred to as the
desktop because the icons are intended to represent real objects on a real
desktop.

Windows
You can divide the screen into different areas. In each window, you can run a
different program or display a different file. You can move windows around the
display screen, and change their shape and size at will.

Menus
Most graphical user interfaces let
you execute commands by selecting
a choice from a menu.
LEARNING OUTCOME 3
Is covered in section 2.7 to 2.9
2.7 WHAT HAPPENS WHEN YOU
SWITCH ON A COMPUTER?
When you switch on your computer, the computer locates the initial instructions
that start it up in the ROM BIOS instructions is to locate the device where the
Operating Systems resides and load it into main memory, a process called booting.
The process of booting was so named because it is analogous to someone ‘pulling
36
themselves up by the bootstraps’ (bootstraps is an old word for shoestrings).
Once the operating system is up and running, it can be used to start up any
other program.
If for any reason the Operating System cannot be loaded, you will not be able
to use your computer because you cannot communicate with it. Reasons for the
Operating System not being loaded vary from the Operating System being
corrupted by a virus, for example, to the hard disk crashing and so on.
When the computer has booted (loaded the OS) successfully, the Operating
System will then start running silently. Mostly it is managing the user interface,
waiting for some input to tell it what to do.
2.8 THE BOOT PROCESS
When you first turn your computer on, it locates the ROM BIOS chip on your
motherboard. This BIOS chip has a program that was burnt into it at the factory
and it is this program that knows where to look for and how to access, the
different hardware resources, and the Operating System.
The program code on the BIOS chip is loaded into main memory and the
computer sequentially executes the same instructions. It carries out a power on
self-test of several hardware devices such as the video adapter card and other
cards in the expansion slots. It copies their configurations into main memory,
and does a quick memory count.
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The program then compares the information it has gathered with the
information stored in the CMOS chip’s setup program. If there are any
discrepancies, it halts the boot process and informs the user.
Finally the computer has to locate the Operating System. It looks in the floppy
drive first. If there is a disk in drive a, it must have Operating System files on it.
If it does, the Operating System is loaded into main memory. If the disk does
not contain any system files, the computer will halt and display the following
error message:
Non-system disk. Insert boot disk and press any key when ready.
If there is no disk in the floppy drive, the computer checks the hard drive for the
Operating System files and, once found, continued to load the Operating
System into main memory.
37
2.9 IMPORTANT OPERATING SYSTEM FILES
The program mentioned in the above section, in loading the Operating System,
precisely locates and loads in memory a hidden system file on your boot disk,
called IO.SYS. After IO.SYS has been loaded in memory it also locates another
hidden system file called MSDOS.SYS and loads it as well. MSDOS.SYS in turn
locates a file called Command.com, the command interpreter, and loads it. This
file is the only Operating System file that is not hidden and is always located in
the root directory of your boot disk.
There are two other files worth mentioning, although they are not part of the
Operating System, namely, Config.sys and Autoexec.bat
Config.sys is a user-configurable text file that usually contains device drivers and
system setup values.
Autoexec.bat is another user-configurable text file that is used to set system
environment variables e.g. screen and memory settings. Autoexec.bat is the
right place to put commands that you want to be executed every time the
computer starts up. If these two files are not present the Operating System will
skip them, but as long as they are available, they are run every time your
computer starts up.
2.10 FILE AND DISK MANAGEMENT
2.10.1 What is a File?
A file is collection of characters or bytes or information treated as a single unit.
A file has a name and an extension e.g. sales.xls. Sales are the name of the file
and xls is the extension given by the application program MS Excel. It is the user
who decides on the name of the file and it is the program that gives the
extension to that file the different types of files and the extension determines
the type of file.
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2.10.2 Types of File







Application or Programme Files
Driver Files
Systems Files
Document or Text Files
Sound Files
Video or Animation Files
Graphic or Image Files
38
Keeping track of what files are where is a major job. If you can't find a file, it
doesn't help to know that it is safe and secure somewhere. So an operating
system comes with basic file management commands. A user needs to be able
to create directories for storing files.
(Dumping everything in one pile soon becomes the needle-in-the-haystack
story.) A user needs to copy, move, delete, and rename files. This is the category
of operating system functions that the user actually sees the most. A more
technical task is that of disk management. Under some operating systems your
hard disk can be divided up, or partitioned into several virtual disks. The
operating system treats each virtual disk as though it were a physically separate
disk. Managing several physical and/or virtual disks can get pretty complex,
especially if some of the Disks are set up with different operating systems.
(Some folks are never satisfied with just one of anything!)
2.11
SINGLE PROGRAM AND MULTITASKING OF OPERATING SYSTEM
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The first allows only one program to run at a time. This means that if you are
working in a spreadsheet and want to write a memo, you must shut down the
spreadsheet application and open up a word processor. This is annoying,
especially if you need to quote some data from the spreadsheet in your memo!
So new operating systems were designed that allowed multiple programs to
run at the same time.
The simplest form is multi-tasking. What this really means is that the programs
are taking turns with the processor. It allows a single user to have the
spreadsheet and the word processor open at the same time, and even more.
Now the user can see to copy data from one to the other. Much better!!
The computer must decide on how many time slices each program gets. The
active program gets the most. Next is a program that are doing things but which
aren't the foreground program. Last is a program that is open but aren't doing
39
anything. They need a little bit of time every now and then to see if they are
supposed to do something yet.
The next step up in complexity is multiple users. On a network several users can
be using the same computer or even the same program on that computer. This
is called time-sharing.
If a computer has multiple CPUs, it can do multiprocessing. Rather than a single
CPU giving out turns to various programs, the different CPUs can work
simultaneously. Speed increases immensely. Of course cost does, too!
It is possible for a computer to use more than one operating system through
the use of virtual machines. "Virtual" means it's not really there. But programs
written for different operating systems are fooled into thinking their required
operating system is present.
2.12
COMMON
SYSTEMS
OPERATING
LEARNING OUTCOME 4
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Originally the operating system
Is covered in section 2.12 to 2.14
was created by each company that
manufactured a processor and
motherboard. So each operating system was proprietary, that is, unique to each
manufacturer. Problem: changing to a new computer meant your software had
to be replaced! Not good marketing. So there was pressure early on to
standardize things so that software could be transferred to the new (and of
course better!) computer. This required more standardization in operating
systems.
The winner in the PC market was MS-DOS, Microsoft's Disk Operating System,
and its twin at IBM, PC-DOS, also written by Microsoft. Now it's hard to recall
those days when each computer had its own unique operating system. More on
DOS Commands.
2.13 THE HISTORY OF WINDOWS
When Microsoft Windows was developed, about two decades ago, it was not
really an Operating System; it was more of an operating environment. Windows
would rely on DOS to boot the system and was then launched through a
statement that the user had to include in his Autoexec.bat file, i.e.
C:\Windows\Win.com
40
Windows came of age in the early 90s with the release of Windows for
Workgroups version 3.11, the first version of Windows to have networking
capability. The author still recalls this version of Windows with fond memories.
In December 1995, Microsoft launched a version of Windows that was truly an
Operating System in its own right. It did not need DOS to boot the computer for
it, it would accomplish that own its own. However, DOS still existed within it.
This new Operating System included a fully-fledged Web Browser called
Internet Explorer.
Hitherto, Netscape Navigator had been the dominant Web Browser, but by
releasing Windows 95 bundled with Internet Explorer, Microsoft had placed a
fatwa on Netscape’s head. Throughout its history, Microsoft has demonstrated
its vision, strong survival instincts, and an uncanny ability to forecast what the
market wants. In line with this philosophical
observation, Microsoft has a proven track
record as a super-efficient killer of
competitors.
IDEA
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2.14 THE WINDOWS OPERATING SYSTEM
Please Note: The Windows
Boot Process is very
similar to the DOS Boot
Process, except that apart
from IO.SYS, MSDOS.SYS
and COMMAND.COM,
Windows loads additional
files such as
DRVSPACE.BIN,
SYSTEM.DAT, USER.DAT,
SYSTEM.INI, WIN.INI and
others. Refer to the DOS
Boot Process.
The Windows Operating System boasts a GUI
(pronounced gooey) interface. The user
interacts with Windows by clicking on small
graphic images on the screen called icons.
With Windows there is no need to ‘carry’
commands in your head any more (Contrast
DOS)? Most of the icons are designed in such a
way that they are suggestive of their function.
The computer icon, for example, is an image
depicting a desktop computer and the My
Briefcase icon in an image of a real brief case.
As a result of this, Windows is several times
more user-friendly than DOS. Through Windows, Microsoft has managed to demystify computers. In the Old days of cryptic Operating Systems like UNIX,
computers were solely for power users like Engineers and Scientists. With
Windows computers are truly for everyone, including the semi-literate.
Windows 95 and Windows 98 are actual operating systems on their own. The
previous versions of Windows use DOS as the operating system and adding a
graphical user interface which will do multitasking. But with Windows 95,
Microsoft released an operating system that can take advantage of the 32-bit
processors.
41
Windows Me (Windows Millennium Edition) is an upgrade of Windows 98,
release date Sept. 14, 2000. The system resources required for this operating
system are significantly higher than previous versions of Windows.
Windows NT (the NT apparently came from New Technology) is an operating
system for client-server type networks. The latest version of NT has a user
interface that is practically identical to Windows 95. Since Windows NT is
designed for the higher demands of networks, it has higher demands itself for
disk space and memory.
Windows 2000 is an upgrade of Windows NT rather than of Windows 98
Windows XP an upgrade to Windows 2000. It comes in two versions - Home
and Professional. The Professional version contains all the features of the Home
version plus more business features, like networking and security features.
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Windows CE is for small devices like palmtop and handheld computers. Late
versions of a number of major applications are available to run on these devices.
You can link your small computer to a regular one to synchronize documents
and data.
Windows 7 is the latest public release version of Microsoft Windows, a series
of operating systems produced by Microsoft for use on personal computers,
including home and business desktops, laptops, notebooks, tablet PCs, and
media centre PCs. Windows 7 was released to manufacturing on July 22, 2009,
and reached general retail availability on October 22, 2009, less than three
years after the release of its predecessor, Windows Vista. Windows 7's server
counterpart, Windows Server 2008 R2, was released at the same time. Unlike
its predecessor, who introduced a large number of new features, Windows 7
was intended to be a more focused, incremental upgrade to the Windows line,
with the goal of being fully compatible with applications and hardware with
which Windows Vista is already compatible. Presentations given by Microsoft
in 2008 focused on multi-touch support, a redesigned Windows Shell with a new
taskbar, referred to as the Super bar, a home networking system called Home
Group and performance improvements. Some applications that have been
included with prior releases of Microsoft Windows, including Windows
Calendar, Windows Mail, Windows Movie Maker, and Windows Photo Gallery,
are not included in Windows 7; most are instead offered separately as part of
the free Windows Live Essentials suite.
2.15 LANGUAGE TYPES
Programming has changed a lot since the
first computers were created. The original
LEARNING OUTCOME 5
Is covered in section 2.15
42
programs were very simple and straight forward compared to today's elaborate
databases, word processors, schedulers, and action games.
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Different computer languages have been created with which to write these
increasingly complex computer programs. They can be categorized based on how
close to normal speech they are, and thus how far from the computer's internal
language.
Machine Languages
The language of the CPU (The central processing
unit of the computer, which is the part that does
the "thinking"). The lowest level language.
Composed of 0's and 1's.
Assembly Languages
Abbreviations for machine language.
High-Level Languages
Use program statements - words and algebra-type
expressions. Developed in the 50's and 60's.
After a program is written in one of the high-level
languages, it must be either compiled or
interpreted.
A compiler program rewrites the program into
machine language that the CPU can understand.
This is done all at once and the program is saved in
this new form. A compiled program is generally
considerably larger than the original.
An interpreter program translates the program
statements into machine language one line at a
time as the program is running. An interpreted
program will be smaller than a compiled one but
will take longer to execute.
4th Generation Languages 4GL. Very high-level languages. These are results
oriented and include database query languages.
There are fewer options for programmers, but the
programs are much easier to write than in lower
level languages. These too must be compiled or
interpreted.
Natural Languages
5th Generation Languages. We don't really have
any programming languages yet that use natural
language. In such a language you would write
statements that look like normal sentences. For
example, instead of odd-looking code you would
write "Who are the salesmen with sales over
$20,000 last month?"
43
2.16 INTRODUCTION TO SOFTWARE APPLICATIONS
Scientists. With Windows computers are truly for everyone, including the semiliterate.
Application software can be used for the
following purposes:
LEARNING OUTCOME 6
Is
covered
in sections 2.16 to 2.18
(1) As a productivity/business tool
(2) To assist with graphics and multimedia
projects
(3) To support household activities for personal business, or for education
(4) To facilitate communication
Home/
Personal/
Educational
Computer Aided
 Integrated
Design
Software
Desktop
 Personal Finance
Publishing
Paint/Image
 Legal
Editing
Video and Audio
 Tax Preparation
Editing
Multimedia
 Desktop
Authoring
Publishing
Graphic
Productivity/Business
Design/Multimedia



Word
Processing
Spread Sheet

Database


Presentation
Graphics
Personal
Information
Manager
Software Suite


TWO | SOFTWARE



Project
Management
Accounting



Web Page
Authoring




Paint/Image
Editing
Home Design/
Landscaping
Educational/
Reference/
Entertainment
2.16.1 Productivity/Business Software Packages
This software is designed to make people more effective and efficient while
performing daily activities. Table below lists some of the more popular
Productivity Software.
44
Software
Application

Word
Processing

Spread Sheet

Database

Presentation
Graphics

Personal
Information
Manager

Software Suite

Project
Management

Accounting
Popular Packages





























Microsoft Word
Corel Word Perfect
Lotus Word Pro
Microsoft Pocket Word
Microsoft Excel
Corel Quattro Pro
Lotus 1-2-3
Microsoft Pocket Excel
Microsoft Access
Corel Paradox
Lotus Approach
Microsoft Visual FoxPro
Oracle
Microsoft Power-point
Corel Presentations
Lotus Freelance Graphics
Microsoft Outlook
Corel CENTRAL
Lotus Organizer
Microsoft Pocket Outlook
Palm Desktop
Palm Multi-Mail
Microsoft Office
Corel WordPerfect Office
Lotus Smart Suite
Microsoft Project
Primavera Sure-Track Project Manager
Intuit Quick Books
Peachtree Complete Accounting
TWO | SOFTWARE
2.17 GRAPHICS AND MULTIMEDIA EQUIPMENT
In addition to productivity software, many individuals also work with software
designed specifically for their field of work. Power users such as engineers,
architects, desktop publishers, and graphic artists for example use powerful
software that allows them to work with graphics and multimedia.
45
Here is a list of the popular graphics and multimedia equipment:
 Computer Aided Design (CAD) is a sophisticated type of application
software that assists the user in creating engineering architectural and
scientific designs
 Desktop Publishing Software allows you to create sophisticated
documents using a combination of text, graphics and brilliant colours;
professional graphic designers use it
 Image Editing Software allows you to create images and edit existing
images as well as the one you have created
 Video and Audio editing Software allows you to edit segments of audio
and video clips
 Multimedia Authoring Software also called auto ware, allows you to
combine text, graphics, audio, video and animation into an interactive
presentation
 Web Page Authoring Software helps users of all skill levels create web
pages that include graphical images, video, audio, animation and other special
effects
2.18
SOFTWARE FOR COMMUNICATION
One of the most valuable aspects of software is its capability of supporting
communication. Certain applications are specifically designed to facilitate
communication thus allowing you to share information with others.
TWO | SOFTWARE
The following is a list of some communication software:
 Groupware identifies any type of software that helps groups of people on
the network collaborate on projects and share information
 E-mail is the transmission of messages via a computer network such as a
local area network or internet
 FTP is a method of downloading and uploading the files to the internet.
 Web browser allows you to access or view web pages
 Chat rooms permit users to chat with each other via the computer.
 Newsgroups also called a discussion, is an online area on the web where
users conduct written discussions about a particular subject.
 Instant messaging (IM) is a real-time communications service that notifies
you when one or more people are online and then allows you to exchange
messages or files with them or join a private chat room.
 A videoconference is a meeting between two or more geographically
separated people who use a network on the Internet to transmit audio and
video data.
46
Case Study
In 2000, Crystal Flash decided to revamp its outdated sales
practices that led to customers being called on by more than one
salesperson, creating heavy administrative workloads. A
committee consisting of representatives from sales, marketing and
information systems was formed to determine how to establish a
more uniform and efficient set of sales processes. The group
focused on implementing a sales management software
application. After six months of work, they decided that a custom
sales management application would be too expensive due to the
required consulting, hardware, ongoing maintenance and licensing
fees. They spend the next six months reviewing and evaluating
existing sales management software packages. The solution they
chose was Salesnet Sales Force Automation, a software application
that runs on saver hardware owned and operated by Salesnet, a
sales software application service provider.
TWO | CASE STUDY
The Salesnet Process Builder software module enables sales
organizations to define and build their own sales processes. Crystal
Flash was able to define a set of standard sales processes that will
reinforce effective selling and closing behaviors among all its sales
reps. No longer are Crystal Flash’s sales reps spending time
completing unnecessary paperwork. They are able to use the
software’s calendar, scheduling, and contact management
features to support greater teamwork. In addition, use of the
software enables Crystal Flash’s managers to access real-time
information about sales team activities and to obtain sales reports,
forecasts and customer information.
Sales reps can access the Internet-based application through
desktop PCs, by dialing up through notebook computers or
wirelessly on smaller devices. Because Salesnet is a hosted
application, there is no upfront capital investment in software,
hardware, IT resources, or ongoing maintenance fees. As a result
Crystal Flash saved up to $100,000 over other solutions. (Source:
Principles of Information Systems (2003) by Ralph M Stair and
George W Reynolds).
47
Review Questions
TWO | REVIEW QUESTIONS
1.
Which problems did Crystal Flash face before they engaged
Salesnet Sales Force Automation software?
2.
What are the benefits of this new system for Crystal Flash?
3.
What is a User Interface? Describe how Crystal Flash would
interface with this new software for effective communication?
4.
Why did Crystal Flash abandon the use of a custom sales
management application software?
48
KEY TERMS USED IN SECTION 2
4th Generation Language 4GL. Very high-level languages. These are
results oriented and include database query languages. There are
fewer options for programmers, but the programs are much easier to
write than in lower level languages. These too must be compiled or
interpreted.
Application software allows end users to accomplish one or more
specific (not directly computer development related) tasks.
Arithmetic Logic Unit (ALU) Performs the arithmetic comparison and
logical operations.
Cache memory Most of today’s computers improve their processing
time by using cache. Cache helps speed the process of the computer
by storing frequently used instructions and data. The rationale is that
the processor is likely to request these items over and over again.
When the processor needs an instruction it first searches cache.
CMOS (Complementary metal oxide semi-conductor) Is used to
store configuration information about the computer e.g. type of disk
drives, keyboard, monitor, etc.
TWO ||GLOSSARY OF TERMS
A compiler program rewrites the program into machine language
that the CPU can understand. This is done all at once and the
program is saved in this new form. A compiled program is generally
considerably larger than the original.
Computer Aided Design (CAD) A sophisticated type of application
software that assists the user in creating engineering architectural
and scientific designs
Control Unit Executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
Desktop Publishing Software Allows you to create sophisticated
documents using a combination of text, graphics and brilliant
colours; professional graphic designers use it
E-mail The transmission of messages via a computer network such as
a local area network or internet
A graphical user interface (GUI) is a type of user interface item that
allows people to interact with programs in more ways than typing
49
such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office
equipment with images rather than text commands. A GUI offers
graphical icons, and visual indicators, as opposed to text-based
interfaces, typed command labels or text navigation to fully
represent the information and actions available to a user. The actions
are usually performed through direct manipulation of the graphical
elements
A hard disk usually consists of several inflexible, circular disks, called
platters, on which items are stored electronically. A platter in a hard
disk is made of aluminum, glass, or ceramic and is coated with a
material that allows items to be magnetically recorded on its surface.
High-Level Languages use program statements - words and algebratype expressions. Developed in the 50's and 60's. After a program is
written in one of the high-level languages, it must be either compiled
or interpreted.
Icons Small pictures that represent commands, files, or windows. By
moving the pointer to the icon and pressing a mouse button, you can
execute a command or convert the icon into a window. You can also
move the icons around the display screen as if they were real objects
on your desk.
Image Editing Software Allows you to create images and edit existing
images as well as the one you have created
Instant messaging (IM) A real-time communications service that
notifies you when one or more people are online and then allows
you to exchange messages or files with them or join a private chat
room.
An interpreter program translates the program statements into
machine language one line at a time as the program is running. An
interpreted program will be smaller than a compiled one but will take
longer to execute.
Machine Languages The language of the CPU (The central processing
unit of the computer, which is the part that does the "thinking"). The
lowest level language. Composed of 0's and 1's
Menus Most graphical user interfaces let you execute commands by
selecting a choice from a menu.
50
Multimedia Authoring Software Also called auto ware, allow you to
combine text, graphics, audio, video and animation into an
interactive presentation.
An Operating System (OS) is software that governs the interaction
between application programs and hardware. The application
programs cannot communicate with the hardware directly and
consequently, rely on the Operating System to communicate with
hardware on their behalf. The Operating System also manages and
controls the computer’s resources such as the CPU, memory and the
hard disk and handles the input and output of data. It coordinates
the operation of all the hardware and software components of the
computer system.
Pipelining In some Computers the CPU executes only one instruction
at a time. The second instructions wait until completion of first
instruction. With Pipelining the CPU begins executing the second
instruction before it completes the first instruction thus results in
faster processing
Pointer A symbol that appears on the display screen and that you
move to select objects and commands. Usually, the pointer appears
as a small angled arrow. Text -processing applications, however, use
an I-beam pointer that is shaped like a capital
Pointing device A device, such as a mouse or trackball that enables
you to select objects on the display screen.
Programming software usually provides tools to assist a programmer
in writing computer programs, and software using different
programming languages in a more convenient way.
System software helps run the computer hardware and computer
system.
Terminal A monitor and keyboard. Such terminals are known as
dumb terminals because they have no processing power – they
cannot act as stand alone computers and they need the
minicomputer connected to them at all times.
The user interface (of a computer program) refers to the graphical,
textual and auditory information the program presents to the user,
and the control sequences (such as keystrokes with the computer
keyboard, movements of the computer mouse, and selections with
the touch screen) the user employs to control the program.
51
Video and Audio editing Software Allows you to edit segments of
audio and video clips
Web Page Authoring Software Helps users of all skill levels create
web pages that include graphical images, video, audio, animation
and other special effects
Wikipedia for Kids The search box above searches Wikipedia "Simple
Edition" for kids and those learning English.
52
THREE | THE SYSTEM UNIT
Learning Outcomes
1.
2.
3.
4.
5.
6.
7.
8.
Define a systems unit and identify its components
Describe the use and functions of these components
Describe how a CPU processes data
Differentiate between RAM and ROM; and explain their uses and
characteristics
Explain what a machine language is and its purpose
Define a bit and explain how data is represented in a computer
Explain how different bit patterns are used to represent characters
Explain the use of the binary, decimal and hexadecimal number
systems
THREE | THE SYSTEM UNIT
3.1 INTRODUCTION TO THE SYSTEM UNIT
A system unit is sometimes called a box or
main unit /the main part of a personal
computer. The system unit includes the
chassis, microprocessor, main memory, bus,
and ports, but does not include the keyboard
or monitor, or any peripheral devices. The
LEARNING OUTCOME 1
Is covered in sections 3.1 to 3.2
53
system unit which houses electronic components is a box-like case that is made
of plastic or metal and is designed to protect the components from damage. On
a desktop computer, the electronic components and storage devices are inside
the unit and the peripherals are situated on the outside. However, on a laptop
most of the components are housed inside.
3.2 THE COMPONENTS OF A SYSTEM UNIT
3.2.1 The Motherboard
THREE | THE SYSTEM UNIT
The motherboard / system board is the
circuit board to which many of the
electronic components are attached to.
LEARNING OUTCOME
One of the components attached to the
Is covered in sections 2.16 to 2.18
motherboard is a chip. A chip is a small
piece of semi-conductor on which one or
more integrated circuits (IC) are attached.
An IC is a microscopic pathway that can carry electrical current and may contain
millions of transistors. The motherboard contains different types of chips and
one of the most important chips is the Central Processing unit (CPU).
54
3.2.2
Central Processing Unit (CPU)
The CPU interprets and carries out basic
instruction that operates a computer. The
CPU is also called a processor, significantly
impacts on overall computing power and
manages most of the computer operations.
Most of the devices connected to the
computer communicate with the CPU in
order to carry out a task.
3.2.3
LEARNING OUTCOME 3
Is covered in section 3.2.2
Components of the CPU
 Control Unit: Executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
 Arithmetic Logic Unit: Performs the arithmetic comparison and logical
operations.
 Pipelining: In some Computers the CPU executes only one instruction at a
time. The second instructions wait until completion of first instruction. With
Pipelining the CPU begins executing the second instruction before it completes
the first instruction thus results in faster processing.
THREE | THE SYSTEM UNIT
 System Clock: The CPU relies in a small chip called the System Clock to
control the timing of all computer operations. Title and number of the figure
below?
Think Point
Since the dawn of the computing age,
people have wondered if a computer will
ever be capable of thoughts. As
computer processors and software
become more powerful, the questions is
debatable more hotly. Can computers
think? Why or why not? If computers
cannot think right now, might they be
able to think in the future? Why? How
important are common sense and the
ability to think?
55
THREE | THE SYSTEM UNIT
3.2.4 Memory
While performing a processing operation, a processor needs a place to temporarily
store instructions to be executed and the data to be used with those instructions.
A computer’s memory is used to store data, instructions and information. The
computer’s memory stores basically three things:

The operating system and other system software used to operate the
computer
56

Application programs designed to carry out a specific task e.g. word
processing

The data being processed by the application programs.
3.3
DIFFERENT TYPES OF MEMORY

Random Access Memory (RAM) - When the computer is powered
on, certain operating system files are loaded from storage devices onto RAM.
These files remain in RAM as long as the computer is running. RAM is volatile,
means items stored in RAM are lost when the computer is turned off. For this
reason any item that needed for future use needs to be saved.
THREE | THE SYSTEM UNIT

Cache – Most of today’s computers improve their processing time by
using cache. Cache helps speed the
process of the computer by storing
frequently used instructions and
data. The rationale is that the
LEARNING OUTCOME 5, 6, 7, 8
processor is likely to request these
Is covered in sections 3.4 and 3.5
items over and over again. When
the processor needs an instruction it
first searches cache.

Read Only Memory (ROM) - is the name given to memory chips that
can store data that can only be read. The data stored on ROM chips cannot
be modified – hence the name read only. ROM is non-volatile i.e. the contents
of the computer is not lost when the computer is turned off. ROM stores
information such as the sequence of instructions the computer follows to
load the operating system and other information when you first turn the
computer on.

Complementary metal oxide
semiconductor (CMOS) - is used to store
configuration information about the
computer e.g. type of disk drives,
keyboard, monitor, etc.
3.4
LEARNING OUTCOME 4
Is covered in section 3.3
HOW DATA IS REPRESENTED IN A COMPUTER
To fully understand the way a computer processes data, it is important to
understand the way the data is represented in the computer. Computers are
digital i.e. they understand only two discrete states: on and off. This is
because electronic goods only have two states i.e. on and off. These two
states can be represented easily by using two digits 0 for off and 1 for on.
57
The number system referred to above is called the binary system, because
of its two digits 0 and 1. Each on or off digit is called a bit (binary digit) and
represents the smallest unit of data a computer can handle. By itself a bit is
not very informative but when 8 bits are grouped together as a unit they are
called a byte. A byte is very informative because it contains enough different
combinations of 0s and 1s to represent 256 individual characters including,
numbers, upper and lower case letters of the alphabet, punctuation and
other characters such as the Greek alphabet.
3.5
STORAGE DEVICES
3.5.1 What are Bits?
Every computer has electronic devices called transistors inside it. A
transistor is basically an electronic switch that is either on or off. In the
computer world the on is represented by a 1 (one) and the off is
represented by a 0 (zero). If it were possible to peer inside the bowels of a
computer, one would see millions of transistors in different states, some on
and some off. Binary mathematics was chosen to model what takes place in
the bowels of a computer because the electronic devices that make up a
computer are bi-stable (two states). Just as unary stands for one, binary
stands for two.
THREE | THE SYSTEM UNIT
The 0’s and 1’s that are used to represent information inside a computer are
called binary digits or bits for short. One bit can represent only two unique
states, i.e., on and off.
A good analogy would be a light bulb. It is either on or off. If you wanted to
use one light bulb in your bedroom to communicate a message to a friend
who lives across the street you would only be able to communicate two facts
i.e.
On means ‘I am in and I am reading’ and off means ‘I am out’.
In the above scenario you would not be able to communicate a third fact like
‘I am in and I am playing poker.’ So once your friend sees the light on, he
would assume (wrongly off course) that you are in and you are reading.
Therefore, with only one bit we would not be able to represent the alphabet,
for example, because we have twenty-six uppercase letters and twenty-six
lowercase letters, which give fifty-two unique states.
To avoid confusion in the computer industry, the American National
Standards Institute (ANSI), developed a code to represent keyboard
characters, called the ASCII code. ASCII stands for American Standard Code
for Information Interchange.
58
For example the letter A is 01000001 in ASCII code. The original ASCII code
used 7 bits to represent characters and one bit for error correction. The bit
used for error correction is called the parity bit.
IDEA

A byte is a group of 8 bits.
A Kilobyte (KB) is 1024
bytes of information
(Approx. 1000 bytes).
 A Megabyte (MB) is 1024
Kilobytes or 1024 X 1024
bytes (Approx. a million
bytes)
 A Gigabyte (GB) is 1024
Megabytes or 1024 X 1024
X 1024 bytes (Approx. a
billion bytes).
 A Terabyte (TB) is 1024
Gigabytes.

Seven bits gave the original ASCII
code the ability to represent 2
characters i.e., 128 characters. IBM,
however, later developed another
code called the extended ASCII code,
which uses all the 8 bits in a byte to
represent characters (no parity bit is
employed). This extended ASCII code
is able to represent 256 characters,
i.e. 2.The 8 bits that form one
character constitute a byte. Inside a
computer, the word ACE, for
example will be represented as
follows:
010000010100001101000101
THREE | THE SYSTEM UNIT
So the word ACE is made up of 3
bytes and will obviously occupy 3
bytes of storage space on a
secondary storage device, provided
it is typed as pure text. Secondary
storage devices such as floppy disks and hard disks store information on
them permanently (Contrast RAM). Even if power is switched off data stored
on a secondary storage device will not be erased. It will remain there and can
be accessed days, weeks, months or even years later.
Please do not confuse memory with storage space on a secondary storage
device. Memory refers to the amount of RAM installed in your system,
whereas storage space refers to the capacity of your hard disk or floppy disk,
whichever the case maybe. The capacity of a floppy disk or hard disk is
measured in bytes, kilobytes, megabytes or even gigabytes. But what are
these bytes? Do they bite?
Please Note: 1024 = 210
1024 X 1024 =220
1024 X 1024 X 1024 =240
Do not confuse Kilobyte (KB) with Kilobit (Kb) and Megabyte (MB) with
Megabit (Mb). Speeds over networks and modem speeds for example are
measured in Kilobits per second or Megabits per second (Kbps or Mbps).
59
THREE | THE SYSTEM UNIT
Data is stored on secondary storage devices in the form of files. A file is a
related set of bytes that has been given a name and is stored on a storage
device such as a floppy disk, a hard disk or CD ROM.
60
THREE | REVIEW QUESTIONS
Review Questions
1.
What is System Unit? Explain the components of System Unit
2.
What is Central Processing Unit? Explain the components of
Central Processing Unit?
3.
What is Memory? Explain different types of Memory?
4.
Explain how data is represented in a Computer?
5.
Define terms:
a.
Motherboard
b.
Control Unit
c.
Arithmetic Logic Unit
d.
Pipelining
e.
System Clock
f.
RAM (Random Access Memory)
g.
Cache
h.
ROM (Read Only Memory)
i.
CMOS (Complementary Metal Oxide Semi-conductor)
j.
Bit
k.
Byte
61
KEY TERMS USED IN SECTION 3
Application software allows end users to accomplish one or more
specific (not directly computer development related) tasks.
Arithmetic Logic Unit (ALU) Performs the arithmetic comparison and
logical operations.
Cache memory Most of today’s computers improve their processing
time by using cache. Cache helps speed the process of the computer
by storing frequently used instructions and data. The rationale is that
the processor is likely to request these items over and over again.
When the processor needs an instruction it first searches cache.
CMOS (Complementary metal oxide semi-conductor) Is used to
store configuration information about the computer e.g. type of disk
drives, keyboard, monitor, etc.
A compiler program rewrites the program into machine language
that the CPU can understand. This is done all at once and the
program is saved in this new form. A compiled program is generally
considerably larger than the original.
THREE | GLOSSARY OF TERMS
Computer Aided Design (CAD) A sophisticated type of application
software that assists the user in creating engineering architectural
and scientific designs
Control Unit Executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
Desktop Publishing Software Allows you to create sophisticated
documents using a combination of text, graphics and brilliant
colours; professional graphic designers use it
E-mail The transmission of messages via a computer network such as
a local area network or internet
A graphical user interface (GUI) is a type of user interface item that
allows people to interact with programs in more ways than typing
such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office
equipment with images rather than text commands. A GUI offers
graphical icons, and visual indicators, as opposed to text-based
interfaces, typed command labels or text navigation to fully
represent the information and actions available to a user. The actions
62
are usually performed through direct manipulation of the graphical
elements
A hard disk usually consists of several inflexible, circular disks, called
platters, on which items are stored electronically. A platter in a hard
disk is made of aluminum, glass, or ceramic and is coated with a
material that allows items to be magnetically recorded on its surface.
High-Level Languages use program statements - words and algebratype expressions. Developed in the 50's and 60's. After a program is
written in one of the high-level languages, it must be either compiled
or interpreted.
Icons Small pictures that represent commands, files, or windows. By
moving the pointer to the icon and pressing a mouse button, you can
execute a command or convert the icon into a window. You can also
move the icons around the display screen as if they were real objects
on your desk.
Image Editing Software Allows you to create images and edit existing
images as well as the one you have created
Instant messaging (IM) A real-time communications service that
notifies you when one or more people are online and then allows
you to exchange messages or files with them or join a private chat
room.
An interpreter program translates the program statements into
machine language one line at a time as the program is running. An
interpreted program will be smaller than a compiled one but will take
longer to execute.
Machine Languages The language of the CPU (The central processing
unit of the computer, which is the part that does the "thinking"). The
lowest level language. Composed of 0's and 1's
Menus Most graphical user interfaces let you execute commands by
selecting a choice from a menu.
Multimedia Authoring Software Also called auto ware, allow you to
combine text, graphics, audio, video and animation into an
interactive presentation.
An Operating System (OS) is software that governs the interaction
between application programs and hardware. The application
programs cannot communicate with the hardware directly and
63
consequently, rely on the Operating System to communicate with
hardware on their behalf. The Operating System also manages and
controls the computer’s resources such as the CPU, memory and the
hard disk and handles the input and output of data. It coordinates
the operation of all the hardware and software components of the
computer system.
Pipelining In some Computers the CPU executes only one instruction
at a time. The second instructions wait until completion of first
instruction. With Pipelining the CPU begins executing the second
instruction before it completes the first instruction thus results in
faster processing
Pointer A symbol that appears on the display screen and that you
move to select objects and commands. Usually, the pointer appears
as a small angled arrow. Text -processing applications, however, use
an I-beam pointer that is shaped like a capital
Pointing device A device, such as a mouse or trackball that enables
you to select objects on the display screen.
Programming software usually provides tools to assist a programmer
in writing computer programs, and software using different
programming languages in a more convenient way.
System software helps run the computer hardware and computer
system.
Terminal A monitor and keyboard. Such terminals are known as
dumb terminals because they have no processing power – they
cannot act as stand-alone computers and they need the
minicomputer connected to them at all times.
The user interface (of a computer program) refers to the graphical,
textual and auditory information the program presents to the user,
and the control sequences (such as keystrokes with the computer
keyboard, movements of the computer mouse, and selections with
the touch screen) the user employs to control the program.
Wikipedia for Kids The search box above searches Wikipedia "Simple
Edition" for kids and those learning English.
64
FOUR | INPUT AND OUTPUT
Learning Outcomes
1. List the various types of input and how the computer uses them
2. Define input and output
3. Explain how to use the various function keys of a keyboard and
describe its features
4. Know how a mouse and the various other pointing devices are used
and how they operate
5. Describe the different methods of source data automation
6. List and describe the various types of output devices
7. Describe the various types of printed output
8. Recognize and identify different types of display devices
9. List and explain the differences between impact and non – impact
printers
FOUR | INPUT AND OUTPUT
4.1 DEFINING INPUT
Input is any data or instructions you enter into the memory of the computer.
Once input is in memory, the CPU can access it and process the input into
output.
There are four types of inputs:
 Data is a collection of unorganized facts that can include words, numbers
and pictures. A computer manipulates and processes data into information
 Program, is a series of instructions that tells a computer how to perform the
tasks necessary to process data into information
 Command, is an instruction given to a computer program. A command is
issued when typing in a keyword or pressing any special keys on the keyboard
 User response, is an instruction you give to the computer by replying to the
question posed by the computer program, such as Do you want to save the
changes made?
4.1.1 Input Devices
An input device is any hard ware device that allows you to enter data, programs
or commands, and user responses into the computer. Input devices include
keyboard, pointing devices, scanners, reading devices, and digital cameras,
audio and video input devices.
65
 Keyboard
It is the primary input devices on the
computer. You enter data into the
computer by pressing the keys on
the keyboard.
LEARNING OUTCOME 1, 2, 3 & 4
Is covered in section 4.1 to 4.3
There are different types of
keyboards for Personal Computers,
Handheld Computers and Computer appliances.
1) Enhanced Keyboard: This is a normal keyboard for personal computers having
12 functions keys on the top, 2 ctrl keys, 2 alt keys etc.
2) Cordless Keyboard: This is a battery-powered device that transmits data using
wireless technology
3) Inbuilt Keyboard: This is a like enhanced keyboard but it is built in for Laptops,
Notebooks etc
4) Portable Keyboard: This is a pocket sized portable keyboard, which can attach
and remove from a handheld computer.
FOUR | INPUT AND OUTPUT
 Pointing Devices
A pointing device is any input device that allows you to control a pointer on the
screen. In a graphical user interface a pointer is a small symbol on the screen.
Types of pointing devices:
 Mouse is an input device used to control the movement of the pointer. The
top of the mouse has one to four buttons, and some have a wheel on it and the
bottom of the mouse is flat and contains a multi – directional mechanism
usually a small ball.
As the mouse is moved over a horizontal surface a pointer moves on the
computer screen. In most programs you will use the left mouse button to make
a selection. The right mouse button is used to bring up a context-sensitive submenu of special commands.
Types of Mice
PS/2 Mouse – the PS/2 connector used by this type of mouse is the same as
the PS/2 connector used by the keyboard.
Serial Mouse – this type of mouse connects to the System Unit using a DB-9
female connector.
USB Mouse – a newer type of mouse connects to the System Unit using a USB
port.
Cordless Mouse – another new type of mouse is the cordless type, which has
no cable connecting it to the system unit but uses infrared light to communicate
66
with the System Unit.
Bus Mouse – this type of mouse is virtually obsolete. It used to come with its
own expansion card and would connect to the motherboard through this
expansion card. The rationale behind the introduction of this mouse was to
free up a COM port for use with another serial device, such as a modem. It
became obsolete however because it would waste a whole expansion slot
and it would take up an Interrupt Request-channel (IRQ)
 The Microphone
The microphone is another input device. It allows the computer to receive and
record sound. The microphone is necessary for voice recognition software and
any type of software that needs to record sound.
FOUR | INPUT AND OUTPUT
 The Scanner
Scanners allow you to transfer pictures, photographs and text into your
computer. This is an example of going from a hard copy to a soft copy (or
digital image). You can then take that digital image (also called a bitmap) and
use it in a paint program like Paint, print it out or send it out as a fax. With
Optical Character Recognition (OCR) software you can convert printed
documents such as newspaper articles to text that you can use in your word
processor.

Trackball is a stationary
pointing device with a ball
mechanism on the top. To move
the pointer using the trackball you
Think Point
rotate the ball mechanism using
you thumb, finger or the palm of
A biometric face recognition system
your hand
recognizes the customer’s face. At

Touch Pad is a small, flat,
large sporting events, airports, and
rectangular pointing device that is
other public areas, face recognition
systems scan visitors’ faces and
sensitive to pressure and motion.
compare their faces to wanted or
To move the pointer you slide your
known criminals.
finger across the surface of the pad
Would you mind constant monitoring

Pointing Stick is a
by face recognition systems? Why?
pressure sensitive pointing device
Which types of criminals should face
shaped like a pencil eraser.
recognition systems be used to locate?
Because of its small size the device
Why? How would you react if you
was positioned between the
were improperly detained due to a
keyboard keys. To move the
mistake made by a face recognition
pointer you push the pointing stick
system?
to the direction you want the
pointer to move with your finger

Joystick and Wheel used
mostly for games. It is a vertical lever mounted on a base. You move the lever
in different directions to control the action of the vehicle or player
67

Light Pen is a handheld input device that can detect the presence of
light. Some light pens require a specially designed monitor

Touch Screen, interaction with the computer is done through
touching areas of the screen with your fingers, which in turn acts as the input
device

Stylus, electronic pen is used to input data into the computer. The
pen can be used to point at onscreen objects and write or draw objects and
many handheld computer supports handwriting input through a stylus
 The Modem
A modem, sometimes classified as a communication device, is an input as well
as an output device. The word modem is actually a contraction of the words
Modulator-Demodulator.
The function of a modem is to connect computers to the Internet. The reason
why a modem is required is that computers use digital signals (1’s and 0’s)
whereas telephone lines use analogue signals. A modem is therefore required
to convert digital signals to analogue signals.
A process called modulation for placement on the telephone wire. Before the
signals reach the computer on the receiving end, they need to be converted
from analogue to digital again.
FOUR | INPUT AND OUTPUT
A process called demodulation. Every modem is capable of doing both
modulation and demodulation.
Modem speeds started at 2.4 Kbps (Kilobits per second) and progressed as
follows: 4.8 Kbps, then 9.6 Kbps, then 19.2 Kbps, then 33.6 Kbps up to 56
Kbps, which is the fastest analogue modem speed to date. The Kbps unit is
usually abridged to K, so you may hear of a ‘56 K modem’ more often than a
’56 Kbps modem’. In the old days the unit of measurement of modem speed
was the baud rate, so 2.4 Kbps was referred to as 2400 baud.
 The Digital Camera
Digital cameras allow you to take digital photographs. The images are stored
in the memory of the camera and can be later downloaded into the computer.
Some cameras can also capture sound and video.
 Scanners and Reading Devices
Some devices make the input process more efficient by eliminating the
manual entry of data. Instead of the person entering the data using a
keyboard or pointing device, these devices capture data from the source
document, which is the original form of the document.
Types of Scanners and Reading devices:
68

Optical Scanner, simply called a scanner, is a light sensitive input
device that reads printed text and graphics and then transmits the results into
a form the computer can understand.
FOUR | INPUT AND OUTPUT

Optical Character recognition is technology that involves reading
typewritten, computer printed or handwritten characters from ordinary
documents and translating them into a form that the computer can
understand.

Optical mark recognition (OMR) devices read hand- drawn marks
such as small circles or rectangles.

Bar Code Scanner uses laser beams to read barcodes. A bar code is a
set of vertical lines and spaces of different widths.

Magnetic Ink Character Recognition (MICR) reader is used to read
text printed with magnetized ink. MICR is exclusively used in the banking
industry for check processing.
4.2
OUTPUT DEVICES
An output device is a device that is used to get data out of the computer
system to the outside world (the human world).
69
 The Monitor
The computer monitor is the most important output device. Strange as it may
look, a computer can work without a monitor but we cannot work with a
computer without a monitor.
 Audio and Video Input
 Audio Input is the process of entering music, speech or sound effects. To
record high quality personal sound your computer must have a soundcard.
Sound is entered via a device such as a microphone, tape player, or audio CD
player which plugs into the port of your computer.
 Video Input is the process of entering a full motion recording into a
computer and storing the video onto a hard disk or some other medium. To
capture the video you must plug a video camera into a video capture card which
is an expansion card that converts analogue signal into digital signal so that the
computer can understand.
FOUR | INPUT AND OUTPUT
 Input Devices for Handheld Computers
The primary input data method on most is the stylus. A handheld computer
typically includes a basic stylus. With the stylus you can enter data in two ways:
use an on screen keyboard or use hand writing recognition software.
 Another way of input to handheld computer is you can attach a full sized
keyboard to your handheld computer (Portable keyboard)
 Another way is you can type on the desktop and you can transfer the data
to the handheld computer
4.3 DEFINITION OF OUTPUT
Output is data that has been processed into a useful form called information.
You may choose to view this information on a monitor, print it on a printer, or
listen to it through speakers or headsets. There are four common types of
outputs:
 Text consists of characters that are used to create words, sentences or
paragraphs
 Graphics are digital representations of non-text information such as
drawings, charts and photographs. Graphics can also be animated, giving them
the illusion of motion
 Audio is music speech or any other sound
 Video consists of images that are played back at speeds that provide the
appearance of full motion
70
4.4
DISPLAY DEVICES
Display device is an output device that visually conveys text, graphics and
video information. Information shown on a display device is called soft copy,
because the information exists electronically and is displayed for a temporary
period only. Display devices include:
CRT Monitors: Cathode Ray Tube monitors (CRT) are popular for desktop
computers.
Flat – Panel Display Devices: Flat-panel Liquid Crystal Display (LCD) models
are used mostly for portable computers but are also starting to be used with
desktop computers. They are expensive but take up less desk space, give out
no radiation and do not flicker. Laptops, Notebooks, Handheld Computers,
eBooks, Mobile Phones comes under LCD models
High Definition Television
The monitor receives signals from a video display adapter card inside the
computer and it gives the user a graphical or textual display. A complete
display system consists of a video display adapter and a monitor. A video
display adapter (also called video card) is an expansion card that provides a
data pathway from the motherboard to the monitor.
FOUR | INPUT AND OUTPUT
A computer monitor looks somewhat like a TV screen and displays images
composed of dots called pixels or picture elements. The numbers of dots that
make up an image, determine the sharpness and clarity or resolution of the
image. For example, a resolution of 800 pixels x 600 pixels will give a sharper
and clearer picture than a resolution of 640 pixels x 480 pixels.
Whereas Cathode Ray Tube
monitors (CRT) are popular for
desktop computers, flat-panel
LEARNING OUTCOME 6 & 7
Liquid Crystal Display (LCD) models
are covered in section 4.4
are used mostly for portable
computers but are also starting to
be used with desktop computers.
They are expensive but take up less desk space, give out no radiation and do
not flicker. Monitors can be monochrome or colour, though colour is almost
universal these days except in palm-size computers.
When choosing a monitor, you want a high-resolution, Non-Interlaced
monitor (NI). The so-called NI monitor does not flicker when it refreshes or
redraws the image on the screen. The most common monitor size is 14”
(measured diagonally). However, if you can afford it, a 15” or better still a 17”,
is recommended.
71
4.5 VIDEO ADAPTER CARDS
FOUR | INPUT AND OUTPUT
In the old days PC Monitors were basically monochrome in nature, i.e.
capable of producing only one colour. Subsequent to the monochrome
monitor a video adapter card called a Colour Graphics Adapter (CGA)
introduced colour to the personal computer. It could achieve resolutions of
320 x 200 and had a palette of 16 colours. With the introduction of the
Enhanced Graphics Adapter (EGA) by IBM, monitors were able to achieve a
resolution of 650 x 350 pixels and could display 16 colours from a palette of
64.
For some time in the computer industry, colours were produced digitally by
the use of three electron guns,
one red, one green and one blue
(RGB). These monitors were
driven by 8 bit adapter cards and
could produce a total of 16
Think Point
Digital billboards often display public
colors. Shortly after this, IBM
service advertisements, amber alerts
came up with the idea of
or other valuable information’s.
developing an analogue display
Are digital billboards any more of a
system that could produce 64
distraction than other driving
different levels of intensity. This
distractions? Should the government
new Video Graphics Array
regulate digital billboards? What type
(VGA) adapter was capable of a
of regulations, if any, should
resolution of 640 x 480 pixels
governments apply to digital
and could display up to 256
billboards and which level of
colours from a palette of 26
government should regulate them?
000.This
technology
soon
Have you seen a digital billboard, and
if so, do you feel that the billboard
became the de facto standard
was a distraction?
for almost every video adapter
card and monitor being
developed.
The Super Video Graphical Array (SVGA) standard later succeeded the VGA
standard. More features and enhancements were added to the VGA
technology.
72
73
FOUR | INPUT AND OUTPUT
Standard
Suggested
Resolution
Maximum
Possible Colors
Monochrome
Display
Adapter (MDA)
Video Graphics Array
(VGA)
Extended Graphics Array
(XGA)
Super Video Graphics
Array (SVGA)
Beyond SVGA
FOUR | INPUT AND OUTPUT
SVGA could achieve resolutions of 800 x 600 with 256 colours or 1024 x 768
with 16 colours. However, with further enhancements, SVGA cards are now
capable of resolutions of up to 1280 x 1024 with a palette of over sixteen million
colours.
IBM also developed another video
technology
called
extended
Graphics Array (XGA) that could
LEARNING OUTCOME 9
perform better than both VGA and
Is covered in section 4.6
SVGA.
However,
this
video
technology was proprietary i.e. it
could
only
work
on
one
manufacturer’s computer architecture, i.e. IBM’s, and this limited its survival
and growth.
4.6
THE PRINTER
Another very important output device is the printer. The function of a printer
is to take a soft copy (or electronic copy) on your computer and transfer it
onto paper (a hard copy).
Without a printer you would be able to type your curriculum vitae (CV) on the
computer, for example, but you wouldn’t be able to carry it to show a
prospective employer. Imagine! There are three main types of printers i.e. dot
matrix, inkjet and laser.
Dot matrix printers are impact printers and they work much like the typewriter.
They produce characters on paper by impacting an inked ribbon with a ‘matrix’
of tiny pins in their print heads. When a particular pin in the print head receives
74
a voltage it juts out and hits the inked ribbon, which in turn comes in contact
with paper. When the voltage from the same pin mentioned above is switched
off, the pin retracts and another pin is given voltage and the process goes on
and on. Depending on the character being written on paper, different sets of
pins will receive voltage and others will not. Transistors on the printer main
board control the pins. Dot matrix printers are becoming less popular, while
inkjet and laser printers are becoming more popular even for home users. Dot
matrix printers are relatively cheaper to purchase and operate, but they make
a lot of noise, produce documents of low quality, cannot print colour and are
extremely slow.
Inkjet printers work by firing streams of ink from a cartridge directly onto
paper. The cartridge has tiny holes called nozzles through which ink can be
squirted out. The quality of the printout depends on the dpi ratio (the dots per
inch ratio is a measure of print resolution). Both inkjet printers and laser
printers are capable of printing high-resolution text and graphics (300 dpi or
more).The main advantages of inkjet printers are:
 They make very little noise and are therefore suitable for an office
environment
 They are relatively cheaper than laser printers
 The most popular laser printer manufacturer is Hewlett Packard.
FOUR | INPUT AND OUTPUT
Laser Printer: The main advantages of a laser printer are:
 They produce a very high print quality
 They can print colour of high quality (although colour laser printers are still
very Pricey)
 They are very quiet in their operation
 They print with a very high printing speed
On the other hand however, laser printers have the following notable
disadvantages:
 They are very expensive to purchase
 They are also expensive to operate
A printer is an output device that produces text and graphics on a physical
medium such as paper or transparency film. Printed information is called
hardcopy because the information exists physically and is a more permanent
form of output than that presented on a display device. There are basically two
types of printers:
Impact Printers form characters and graphics on a piece of paper by striking a
mechanism against an ink ribbon that physically contacts the paper. Because
of the striking activity, impacts printers are generally are noisy. There are two
types of impact printers i.e. Dot Matrix and Line Printers.
75
Non-impact Printers forms characters and graphics on a piece of paper without
actually striking the printer. Some spray ink, while others use heat and pressure to
create images. Because these printers do not strike the paper they are generally
quieter then the impact printers. The three commonly used non-impact printers
are Ink-jet, Photo Printers, laser, thermal printers, Portable Printer, Label and
Postage Printers and Wireless Printers.
4.6.1
Viewing the Progress of Printing
If you have sent a number of documents to be printed, you may wish to review
their progress. You can do this from the desktop Print Manager. There are two
ways to do this:
 Open the printer’s window (start- printers and faxes) and select the printer
that you are currently using and open it. A window appears which shows you the
progress of the various print jobs you have sent to this printer
 When you start to print, a printer icon opens in the Taskbar at the bottom
right of your screen (next to the clock in the most cases). The icon remains on
the Taskbar as long as there are files being printed. When printing is complete, it
disappears
4.6.2 Pausing, Restarting, or Deleting a Print Job
From the Print Manager screen, you can also pause or purge printing. This can be
useful if, for example, you have a long print queue and suddenly have something
urgent to print, or if the printer jams and you need to stop printing. To do this,
either click the printer menu or right click a specific file. In either case, select
what you want to do.
FOUR | INPUT AND OUTPUT
4.6.3 Installing a Printer
If you’re new printer is plugged and play, then if you plug it into the correct port
and turn it on, windows automatically defects it and installs it. The different types
of printer port are outside the scope of this book, but the documentation with
your printer should make clear which port to use- the plug and sockets are
different for each kind of port. If you do not have a plug and play printer, you can
use Add Printer Wizard. Choose start – printer and faxes-window has the option
Add a printer at the top. If you using the Classic view, you see an Add new printer
icon.
In either case, click the option to open the Add Printer Wizard and follow the
instructions. You will be asked for the manufacturer and model of printer. You
may also be asked to insert the installation disk that came with your printer. You
may also ask if you want to share the printer with other networks users, and you
will be given the option to print a test page.
76
4.6.4 Changing the Default Printer
Your system always has a default printer, but you can change this by taking the
following steps:
 Choose start- printers and faxes. The printers and faxes window will open.
Which printers are listed depends on how your system and network has been
set up.
 Select the printer that you want to make the default. (Perhaps you have
changed your printer, installed another, or want to run a series of jobs on a
printer that is currently not the
default.)
 Choose File- Set as default printer
or right click the printer icon and
LEARNING OUTCOME 8
Is covered in section 4.7
select Set as a default printer from
the menu that displays. If there is a
tick alongside this, then this printer
is already the default printer.
 Close the printer’s window. The next time you print from an application,
your new default printer will be highlighted.
FOUR| |INPUT
INPUTAND
ANDOUTPUT
OUTPUT
FOUR
4.7
AUDIO OUTPUT
Audio is music, speech or any other, sound. Audio Output Devices are the
components of the computer that produces music, speech or any other sounds
such as beeps.
Most personal computers only have small internal speakers that output only
low quality sound. For this reason, many personal computer users add higher
quality stereo speakers to their computers.
77
Review Questions
FOUR | REVIEW QUESTIONS
1.
2.
3.
4.
5.
6.
7.
8.
What is input? Explain the types of input.
What is input device? What are the kinds of input devices?
What is keyboard? Describe the different types of keyboards.
What are the various types of pointing devices? Explain.
What is output? Define the common types of output?
What is the display device? Explain with examples.
What is a printer? What are the types of printers? Explain.
Define the terms:
a.
Data
b.
Program
c.
Command
d.
User response
e.
Keyboard
f.
Enhanced keyboard
g.
Portable keyboard
h.
Cordless keyboard
i.
Inbuilt keyboard
j.
Trackball
k.
Touch pad
l.
Pointing stick
m.
Joystick and wheel
n.
Light pen
o.
Touch screen
p.
Stylus
q.
Microphone
r.
Modem
s.
Digital camera
t.
Impact printer
78
KEY TERMS USED IN SECTION 4
Application software allows end users to accomplish one or more
specific (not directly computer development related) tasks.
Arithmetic Logic Unit (ALU) Performs the arithmetic comparison and
logical operations.
Cache memory Most of today’s computers improve their processing
time by using cache. Cache helps speed the process of the computer
by storing frequently used instructions and data. The rationale is that
the processor is likely to request these items over and over again.
When the processor needs an instruction it first searches cache.
CMOS (Complementary metal oxide semi-conductor) Is used to
store configuration information about the computer e.g. type of disk
drives, keyboard, monitor, etc.
A compiler program rewrites the program into machine language
that the CPU can understand. This is done all at once and the
program is saved in this new form. A compiled program is generally
considerably larger than the original.
Computer Aided Design (CAD) A sophisticated type of application
software that assists the user in creating engineering architectural
and scientific designs
FOUR | GLOSSARY OF TERMS
Control Unit Executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
Desktop Publishing Software Allows you to create sophisticated
documents using a combination of text, graphics and brilliant
colours; professional graphic designers use it
E-mail The transmission of messages via a computer network such as
a local area network or internet
A graphical user interface (GUI) is a type of user interface item that
allows people to interact with programs in more ways than typing
such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office
equipment with images rather than text commands. A GUI offers
graphical icons, and visual indicators, as opposed to text-based
interfaces, typed command labels or text navigation to fully
represent the information and actions available to a user. The actions
79
are usually performed through direct manipulation of the graphical
elements
A hard disk usually consists of several inflexible, circular disks, called
platters, on which items are stored electronically. A platter in a hard
disk is made of aluminum, glass, or ceramic and is coated with a
material that allows items to be magnetically recorded on its surface.
High-Level Languages use program statements - words and algebratype expressions. Developed in the 50's and 60's. After a program is
written in one of the high-level languages, it must be either compiled
or interpreted.
Icons Small pictures that represent commands, files, or windows. By
moving the pointer to the icon and pressing a mouse button, you can
execute a command or convert the icon into a window. You can also
move the icons around the display screen as if they were real objects
on your desk.
Image Editing Software Allows you to create images and edit existing
images as well as the one you have created
Instant messaging (IM) A real-time communications service that
notifies you when one or more people are online and then allows
you to exchange messages or files with them or join a private chat
room.
An interpreter program translates the program statements into
machine language one line at a time as the program is running. An
interpreted program will be smaller than a compiled one but will take
longer to execute.
Machine Languages The language of the CPU (The central processing
unit of the computer, which is the part that does the "thinking"). The
lowest level language. Composed of 0's and 1's
Menus Most graphical user interfaces let you execute commands by
selecting a choice from a menu.
Multimedia Authoring Software Also called auto ware, allow you to
combine text, graphics, audio, video and animation into an
interactive presentation.
An Operating System (OS) is software that governs the interaction
between application programs and hardware. The application
programs cannot communicate with the hardware directly and
80
consequently, rely on the Operating System to communicate with
hardware on their behalf. The Operating System also manages and
controls the computer’s resources such as the CPU, memory and the
hard disk and handles the input and output of data. It coordinates
the operation of all the hardware and software components of the
computer system.
Pipelining In some Computers the CPU executes only one instruction
at a time. The second instructions wait until completion of first
instruction. With Pipelining the CPU begins executing the second
instruction before it completes the first instruction thus results in
faster processing
Pointer A symbol that appears on the display screen and that you
move to select objects and commands. Usually, the pointer appears
as a small angled arrow. Text -processing applications, however, use
an I-beam pointer that is shaped like a capital
Pointing device A device, such as a mouse or trackball that enables
you to select objects on the display screen.
Programming software usually provides tools to assist a programmer
in writing computer programs, and software using different
programming languages in a more convenient way.
System software helps run the computer hardware and computer
system.
Terminal A monitor and keyboard. Such terminals are known as
dumb terminals because they have no processing power – they
cannot act as stand-alone computers and they need the
minicomputer connected to them at all times.
The user interface (of a computer program) refers to the graphical,
textual and auditory information the program presents to the user,
and the control sequences (such as keystrokes with the computer
keyboard, movements of the computer mouse, and selections with
the touch screen) the user employs to control the program.
Wikipedia for Kids The search box above searches Wikipedia "Simple
Edition" for kids and those learning English.
81
FIVE | STORAGE
Learning Outcomes
1. Define storage
2. Identify the major storage devices
3. Describe how special purpose storage devices such as smart cards
are used.
5.1 INTRODUCTION TO DATA STORAGE
Storage refers to the media on which data, instructions and information are
kept as well as the devices that record and retrieve these items. This section
explains various storage media and storage devices. Following completion of
this chapter you will have an understanding of all four operations in the
information processing cycle: input, processing, output and storage.
FIVE | STORAGE
Storage also called secondary storage
or auxiliary or mass storage holds
LEARNING OUTCOME 1, 2 &3
items such as data, instructions and
Is covered in section 5.1
information for future use. Storage is
non-volatile, which means that items
in storage are retained even when
power is removed from the computer. A storage medium is the physical
material on which items are kept. One commonly used storage medium is a
disk, which is a round, flat piece of metal or plastic with a magnetic coating on
which items can be written. A storage device is the mechanism used to record
and retrieve items to and from a storage medium.
5.1.1
Floppy Disk
For some time in the computer world, floppy disks were the best way of
transporting data from one computer to another. However, this has changed as
the threat of computer viruses being transported along with the data, has
become significant.
Floppy disks come in two different sizes 51/4 inch (almost obsolete) and 31/2
inch. The 51/4 inch disk is quite flexible (like a floppy hat), hence the name floppy
disk. The 31/2 inch disk is a bit more rigid than its 51/4 inch counterpart and some
82
people have resorted to calling it a ‘Stiffy’ disk. However this term is nonstandard and is not used in well-respected international text books, so use it
with caution.
The following table summarizes floppy disks sizes and capacities:
Disk Size & Density
Capacity
5.25” DSDD
5.25” DSHD
3.5” DSDD
3.5” DSHD
CD
DVD
360 KB
1.2 MB
720 KB
1.44 MB
700 MB
4.5 GB
Equivalent 8.5” X 11”
Printed Pages
180
600
360
720
A small library
A feature length movie
DSDD – stands for Double Sided Double Density
DSHD – stands for Double Sided High Density
FIVE | STORAGE
At the moment, the 3.5” DSHD 1.44 MB floppy disk has been adopted as a de
facto industry standard. If you were to buy a PC today, most likely it will come
with this floppy disk drive size and capacity.
5.1.2
Zip Disk Storage
A Zip Disk is a type of portable magnetic media that can store from 100 MB to
750 MB of data. The larger capacity Zip disks hold about 500 times more than a
standard floppy disk.
5.1.3
Hard Disk Storage
When personal computers were first introduced, software programs and their
related files required relatively small amounts of storage space which could easily
fit onto a floppy
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disk. As software became more advanced and included graphical user
interfaces and multimedia, file sizes and storage requirements increased.
Today’s hard disks- provide far larger storage capacities and much faster
access times then any floppy disk. A hard disk usually consists of several
inflexible, circular disks, called platters, on which items are stored
electronically. A platter in a hard disk is made of aluminum, glass, or ceramic
and is coated with a material that allows items to be magnetically recorded
on its surface. On hard disks the platters, the read/write heads and the
mechanism for moving the head across the surface of the disk are enclosed
in an airtight container to prevent it from contamination. The hard disk in
most desktop computers is housed inside the systems unit. Such hard disks,
which are not portable, are considered fixed disks. Nowadays hard disks are
also removable.
5.1.4 The Hard Disk Drive (HDD)
A hard disk drive (usually called hard disk) is a high-capacity, high-speed,
magnetic storage device that is housed inside the system unit of your
computer.
FIVE | STORAGE
A typical hard disk can be accessed in about 10 milliseconds, whereas a floppy
disk can take several seconds to be accessed. Of course a hard disk is much
slower than main memory, which has a typical access time of 60 nsec. A hard
disk is much slower than main memory because whereas the operation of
main memory involves electronic processes, a hard disk’s operation involves
mechanical motion.
Hard disks store the majority of information on today’s modern computer.
All other storage devices play an ancillary role.
5.1.5
Compact Disk Storage
A Compact Disk (CD) is a flat round portable metal storage medium that is
usually 4.75 inches in diameter and less than one-twentieth of an inch thick.
Compact disks store items such as data instructions, and information by using
microscopic pits and land that are in the middle layer of the disc. A high powered laser light creates the pits.
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The compact discs operate by reflecting light through the bottom of the discs,
which is either solid gold or silver in color. The reflected light is converted into
a series of bits that the computer can process.
Land causes the light to reflect, which is read as
binary digit 1. Pit absorbs the light; this absence
of light is read as binary digit 0.
Think Point
At an ever increasing rate, companies
and individuals store Web sites and
data in the cloud.
Should data kept in the cloud be
treated the same way as items that
are kept in one’s home? Why? Should
the government be able to access your
data in the cloud without your
knowledge or permission? Why or
why not? What types and amount of
personal data are you comfortable
storing in cloud? Why?
A Compact Disc stores items in a single track that
spirals from the center of the disc to the edge of
the disc. As with a hard disc, this single track is
divided into evenly sized sectors in which items
are stored. A CD ROM is used to read the
information from a CD.
Although CD ROMs have huge storage capacities,
but nowadays even a CD is not large enough for
many of today’s software. To meet these
tremendous storage requirements some software
moved from the CD to the DVD.
A capacity compact disc is capable of storing from
4.7GB to 17GB. Not only is the capacity of a DVD
greater than a CD but the quality of the DVD surpasses that of a CD. In order to
read a DVD you need a DVD ROM drive.
5.1.6
Other Types of Storage
Although the majority of data, instructions, information are stored on floppy
disks, hard disks, compact disks and PC cards, other more specialized means for
storing these items are also used. These include smart cards, micro-films and
microfiche. Each of these media is discussed below.
FIVE | STORAGE
 Smart Cards
A smart card which is similar in size to a credit card, stores data on a thin
microprocessor embedded in the card.
 Microfilm and Microfiche
Microfilm or Microfiche are used to store microscopic images of documents on
roll or sheet film. The images are recorded onto the film using a device called
computer output microfilm (COM) recorder. The stored images are so small,
microfilm or microfiche reader can only read them.
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Review Questions
FIVE | REVIEW QUESTIONS
1.
2.
3.
4.
5.
6.
7.
What is Data Storage?
What are the devices for Data Storage? Explain
Differentiate between Storage and Memory
What is a floppy? How do you take care about floppies?
Explain how data is stored on a floppy disk?
Explain how data is stored on compact disks?
Define terms:
a. Storage
b. Storage Medium
c. Floppy
d. Zip Disk Storage
e. Hard Disk
f. Compact Disk (CD)
g. Digital Versatile Disk (DVD)
h. Smart Cards
i. Microfilm
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KEY TERMS USED IN SECTION 5
Application software allows end users to accomplish one or more
specific (not directly computer development related) tasks.
Arithmetic Logic Unit (ALU) Performs the arithmetic comparison and
logical operations.
Cache memory Most of today’s computers improve their processing
time by using cache. Cache helps speed the process of the computer
by storing frequently used instructions and data. The rationale is that
the processor is likely to request these items over and over again.
When the processor needs an instruction it first searches cache.
CMOS (Complementary metal oxide semi-conductor) Is used to
store configuration information about the computer e.g. type of disk
drives, keyboard, monitor, etc.
A compiler program rewrites the program into machine language
that the CPU can understand. This is done all at once and the
program is saved in this new form. A compiled program is generally
considerably larger than the original.
Computer Aided Design (CAD) A sophisticated type of application
software that assists the user in creating engineering architectural
and scientific designs
FIVE | GLOSSARY OF TERMS
Control Unit Executes the instructions given to the computer, it coordinates and directs most of the activities in the computer
Desktop Publishing Software Allows you to create sophisticated
documents using a combination of text, graphics and brilliant
colours; professional graphic designers use it
E-mail The transmission of messages via a computer network such as
a local area network or internet
A graphical user interface (GUI) is a type of user interface item that
allows people to interact with programs in more ways than typing
such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office
equipment with images rather than text commands. A GUI offers
graphical icons, and visual indicators, as opposed to text-based
interfaces, typed command labels or text navigation to fully
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represent the information and actions available to a user. The actions
are usually performed through direct manipulation of the graphical
elements
A hard disk usually consists of several inflexible, circular disks, called
platters, on which items are stored electronically. A platter in a hard
disk is made of aluminum, glass, or ceramic and is coated with a
material that allows items to be magnetically recorded on its surface.
High-Level Languages use program statements - words and algebratype expressions. Developed in the 50's and 60's. After a program is
written in one of the high-level languages, it must be either compiled
or interpreted.
Icons Small pictures that represent commands, files, or windows. By
moving the pointer to the icon and pressing a mouse button, you can
execute a command or convert the icon into a window. You can also
move the icons around the display screen as if they were real objects
on your desk.
Image Editing Software Allows you to create images and edit existing
images as well as the one you have created
Instant messaging (IM) A real-time communications service that
notifies you when one or more people are online and then allows
you to exchange messages or files with them or join a private chat
room.
An interpreter program translates the program statements into
machine language one line at a time as the program is running. An
interpreted program will be smaller than a compiled one but will take
longer to execute.
Machine Languages The language of the CPU (The central processing
unit of the computer, which is the part that does the "thinking"). The
lowest level language. Composed of 0's and 1's
Menus Most graphical user interfaces let you execute commands by
selecting a choice from a menu.
Multimedia Authoring Software Also called auto ware, allow you to
combine text, graphics, audio, video and animation into an
interactive presentation.
An Operating System (OS) is software that governs the interaction
between application programs and hardware. The application
programs cannot communicate with the hardware directly and
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consequently, rely on the Operating System to communicate with
hardware on their behalf. The Operating System also manages and
controls the computer’s resources such as the CPU, memory and the
hard disk and handles the input and output of data. It coordinates
the operation of all the hardware and software components of the
computer system.
Pipelining In some Computers the CPU executes only one instruction
at a time. The second instructions wait until completion of first
instruction. With Pipelining the CPU begins executing the second
instruction before it completes the first instruction thus results in
faster processing
Pointer A symbol that appears on the display screen and that you
move to select objects and commands. Usually, the pointer appears
as a small angled arrow. Text -processing applications, however, use
an I-beam pointer that is shaped like a capital
Pointing device A device, such as a mouse or trackball that enables
you to select objects on the display screen.
Programming software usually provides tools to assist a programmer
in writing computer programs, and software using different
programming languages in a more convenient way.
System software helps run the computer hardware and computer
system.
Terminal A monitor and keyboard. Such terminals are known as
dumb terminals because they have no processing power – they
cannot act as stand-alone computers and they need the
minicomputer connected to them at all times.
The user interface (of a computer program) refers to the graphical,
textual and auditory information the program presents to the user,
and the control sequences (such as keystrokes with the computer
keyboard, movements of the computer mouse, and selections with
the touch screen) the user employs to control the program.
Wikipedia for Kids The search box above searches Wikipedia "Simple
Edition" for kids and those learning English.
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SIX | ADDENDUM: CASE STUDY FOR DISCUSSION
CASE STUDY FOR DISCUSSION
You work as an intern in the Information Technology department for the
Star Journal, a local newspaper. The newspaper’s board of directors
recently approved a budget for redesigning the interior of its century-old
building as part of an inner-city rehabilitation project. Your manager has
been asked to recommend the type of transmission media (hardwire or
wireless) to use for the newspaper’s local area network. He has asked you
to submit a feature/benefit report that summarizes the advantages of
wired versus wireless transmission for the building.




Which transmission media would have a greater startup cost?
Which transmission media do you think is most secure?
Do the walls in the building present a problem for a wireless
network?
Does a wireless network present any health hazards?
SIX | CASE STUDY
Be prepared to discuss your findings in a class. (Source: Shelly, Cashman
and Vermaat, 2012).
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