Untitled Lesson

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1.2.2 Second Generation Computers (1958 - 1964)

-The main technology used in this generation was that of transistors

-The transistor was smaller, cheaper and dissipated less heat than a vacuum tube.

-The second generation also saw the introduction of more complex arithmetic and logic units, the use of
high– level programming languages and the provision of system software with the computer.

-Transistors had higher operating speed. Manufacturing cost was also lower. Thus, the size of the
computer got reduced considerably

-It is in the second generation that the concept of Central Processing Unit (CPU), memory, programming
language and input and output units were developed.

-The programming languages such as COBOL, FORTRAN were developed during this period.

1.2.3 Third Generation Computers (1965 - 1971)

-The main technology used in this generation was that of an integrated circuit (IC). An IC is a set of
electronic circuits (resistors, diodes, capacitors, etc.) on one small flat piece (or "chip") of semiconductor
material that is normally silicon.

-The early integrated circuits are referred to as small-scale integration (SSI).

-Compared to the previous generations, computers of this generation were smaller in size, cost less, had
larger memory while processing speed was much higher.

1.2.4 Fourth Generation Computers (1972 - 1990’s)

-The main technology used in this generation was that of Large Scale Integrated (LSI) and Very Large Scale
Integrated (VLSI) circuit technology to construct computers.

-With LSI and VLSI, over 1,000 components can be placed on a single integrated-circuit chip.

1.2.5 Fifth Generation Computers

-These are computers of 1990s to present

-Use Very Large Scale Integrated (VLSI) circuit technology to build computers.

-The speed is extremely high in fifth generation computer. Apart from this, it can perform parallel
processing.

-The concept of Artificial intelligence has been introduced to allow the computer to make its own decision.

Artificial intelligence is a technology of developing computers or computer applications that have the
ability to imitate human intelligence (such as reasoning, learning, natural language processing, etc.)

NB: Each new generation is characterized by greater speed, larger memory capacity and smaller overall
size than the previous one.

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1.3 Classification of computers

-Computers can be classified using the following criteria (according to the following factors):

1.Functionality or type (Method/ mode of operation).

2.Purpose for which they are designed.

3.Physical size & processing power.

1.3.1 Classification according to functionality

-This is based on how the computer represents and processes the data.

-According to this criterion, we have three types of computers namely; digital computers, analog computers

and hybrid computers

Digital computers

-These are computers which process data that is represented in the form of discrete values by operating on
it in steps.

-Discrete data includes values like 0, 1, and 2.

-They are used for both business data processing and scientific purposes since digital computation results
in greater accuracy.

Analog computers

-These are computers which process data represented by physical variables and output physical magnitudes
in the form of smooth continuous graphs.

-They are used for scientific, engineering, and process-controlled purposes.

Hybrid computers

-These are computers that have the combined features of digital and analog computers. They offer an
efficient and economical method of working out special problems in science and various areas of
engineering.

1.3.2 Classification according to purpose

-This is a classification based on the use to which the computer is put. According to this criterion of
classification, we have two types of computers namely: special purpose and general purpose computers.

Special purpose computers

-These are used for a certain specific function like in medicine, engineering and manufacturing e.g., a
calculator is a special purpose computer (used for mathematical calculations only)

General-purpose computers

-These can be used for a wide variety of tasks e.g., accounting and word processing.

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1.3.3 Classification by power and size/ configuration

-According to this criterion, we have the following types of computers:

Supercomputers

-These are the largest, most powerful computers, fastest and most expensive computers. They are used to
process large amounts of data very quickly.

-They are mainly used in scientific research, simulation and meteorological or astronomical applications.

Mainframe computers

-They are less powerful and less expensive than super computers.

-They require a carefully controlled environment and specialist staff to operate them.

-Mainframes are commonly used in business and commerce and can be used applications such as payroll,
invoicing and stock control.

Minicomputers

-Minicomputers are typically smaller than the mainframes.

-They can support a number of concurrent users but are usually slower than mainframe computers

-Minicomputers are commonly used as network servers in the business industry.

Microcomputers

-They are smaller than minicomputers.

-They are cheaper, faster, smaller, energy-efficient, reliable and portable.

-They are commonly used in learning institutions, offices and homes.

-Examples of microcomputers include; Desktop computers, laptops, personal digital assistant (PDA),
tablets & smartphones

-The micro-computers are widely used and are specially designed for general usage like entertainment,
education and work purposes.

-Well known manufacturers of Micro-computer are Dell, Apple, Samsung, Sony & Toshiba.

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2.0 COMPUTER HARDWARE

2.1 Hardware concepts

–Hardware is a term used to describe all the physical and tangible devices that make up a computer
system. It consists of the parts that can be touched and felt. Figure 3.1 below shows a schematic
classification of the hardware components of a computer.

–A few of the hardware components of a computer system are shown in Figure 3.2 below:

Figure 3.2: Basic computer hardware parts

2.1.1 System Unit

–This is the casing (unit) that houses electronic components such as the Central processing Unit (CPU),
Motherboard, and internal storage devices.

–It has the computer’s power switch.

–The components inside the System unit include: -

Central Processing Unit (CPU), which is also referred to as the Processor.
Motherboard.
Power supply unit.
Memory storage devices.

–The system unit connects to all peripheral devices using ports.Peripheral devices (auxiliary devices)

refer to all hardware components that are attached to the system unit and can be easily removed or
plugged into the system.

–Peripheral devices are connected to the system unit using special cables called data interface cables
that carry data, programs and information to and from the processor.

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2.1.2 Ports

–A port is a docking point using which an external device can be connected to the computer.

–A port can also be a programmatic docking point through which information flows from a program to a
computer or over the internet.

–Examples of external devices attached via ports include the mouse, keyboard, monitor, microphone and
speakers.

–Some of the few important computer ports available include; Serial Port, Parallel Port, PS/2 Port,
Universal Serial Bus (or USB) Port, Video Graphics Array (VGA) Port, Digital Video Interface (DVI), High
Definition Multimedia Interface (HDMI) port, Fire wire Port, Modem Port, Ethernet Port, Game Port, Power
Connector, etc.

Serial Port

–This is a serial communication interface through which information transfers in or out sequentially one
bit at a time. It is a male connector port.

–It is commonly used for external modems and older computer mouse or printers

–It is the slowest of all ports on a computer, i.e. data travels at 115 kilobits per second. Modern
computers have replaced it with much faster USB ports.

Parallel Port

–This communication interface sends / receives multiple bits of data at once, as opposed to serial port. It
is a female connector port.

–It is commonly used for printers, scanners. In newer computers, it is getting replaced by the faster USB
and fire wire ports.

PS/2 Port

–It is also called the mouse port. It is (was) used in old computers for the keyboard and mouse.

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– The CPU itself has the following three main components that form its functional organization:

Control Unit (CU)
Arithmetic Logic Unit (ALU)
Main Memory Unit (MMU)

Control Unit

-It coordinates and controls activities of the different components of the computer system.

-The CU carries out the fetching, decoding and execution of the instructions. It fetches/ selects the
required instruction from Main storage, stores it, interprets the instructions, and causes the instruction to
be executed by sending appropriate signals to the appropriate hardware devices.

ALU (Arithmetic Logic Unit)

-This unit consists of two subsections namely;

Arithmetic section
Logic Section

Arithmetic Section

-This section performs arithmetic operations like addition, subtraction, multiplication and division. All
complex operations are done by making repetitive use of the above operations.

Logic Section

-This section performs logic operations such as comparing, selecting, matching and merging of data.

Main Memory Unit

–The main memory unit (MMU) is also known as main memory or primary memory or Random Access
Memory (RAM). The figure below shows a sample of RAM:

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–Its size affects speed, power and capability of a computer sytem.

–The functions of the main memory unit can be summarized as follows:

It stores all the data and the instructions required for processing.

It stores intermediate results of processing.

It stores final results of processing before these results are released to an output device.
All inputs and outputs are transmitted through main memory.
It supplies information to the other units of the computer when needed.

Characteristics of primary memory

Primary memory holds only those data and instructions on which computer is currently working.
It has limited capacity
It is usually volatile i.e. data is lost when power is switched off
It is faster than secondary memories but slower than cache memories.
A computer cannot run without primary memory.

2.2.3 Storage Hardware

– Generally, computer memory (also known as computer storage) is of two main types, namely:

Primary / Main memory
Secondary memory

Primary / Main memory

–Primary memory can further be classified into two;

(i)Random Access Memory (RAM) and;
(ii)Read Only Memory (ROM)

ROM

–This is memory from which we can only readbut cannot write on it (See Figure below).

–This type of memory is non-volatile. The information is stored permanently in such memories during
manufacture.

Advantages of ROM

Non-volatile in nature

Its contents cannot be accidentally changed
Cheaper than RAM

Its static and does not require refreshing

Its contents are always known and can be verified

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2.3 Operating computer hardware

Keyboard

–The Keyboard of a computer consists of keys similar to those of a typewriter. It contains the usual range
of alphabetic characters (A – Z), digits 0 – 9, and other symbols frequently used to represent data items.
However, it has some command keys for giving special instructions to the computer.

Category

Description /Examples

Function

Alphanumeric
keys

These consist of both alphabetic letters A to Z
and special character symbols like &, *, #, @,
!, %, etc.

These keys are also sometimes known as the
typing keys.

The alphabetic keys
help as to type or write
words in the computer

Number keys or

numeric keys

They have numbers 0 to 9 on them. Can be
found either in the top row above alphabet
keys or be found on a numeric pad (usually
the bottom right part of a computer)

They enable us to
write numbers in the
computer e.g. when
doing calculations

Navigation keys

They include Arrow keys,

Page up and Page down keys, Home key and

End key

The Arrow keys move
the cursor, on the
screen, in the four
different directions
(left, right, up, down)
accordingly. They are
also called direction
keys or cursor control
keys.

The Page up key and
Page down keys
respectively, move the
cursor one page up or
down if the document
has many pages.

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Printers

-A Printer is an output device that facilitates the transfer of information from a computer to a paper. It is
used when a permanent record of the output may be needed on paper.

-Printed output is usually referred to as Hardcopy output, which means that the document can be kept
indefinitely for future reference or use. The printed output can be distributed conveniently to reach the
recipients of such information/results.

Printers are of different types. The following figure shows some of them.

Dot matrix Printer

Daisy Wheel Printer

Laser Printer

Inkjet printer

Classification of Printers

-Printers are basically classified in 3 ways: -

(1). In terms of Print speed.

-Low-speed.

-High-speed.

(2). According to the amount of text it can print per given period of time.

-Character Printers.

-Line Printers.

-Page Printers.

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etc. In regard to resource management, the OS is responsible for:

 Memory management

Processor/process management

I/O device management

File management

Memory Management
-Main memory (RAM) is expensive and scarce, yet critical, hence needs proper management. It is
directly accessed by the CPU.
-For a program to be executed, it must be loaded into the main memory. The OS does the following
activities for memory management:

Keeping track of primary memory i.e. what part of it are in use, by whom and what part are
not in use.

Deciding which process will get memory, when and how much.

Allocating the memory when the process requests it to do so.

De-allocating the memory when the process no longer needs it or has been terminated.

Processor Management
-In a multiprogramming environment, the OS decides which process gets the processor, when and for
how long time. This function is called process scheduling.
-The Operating System does the following activities for processor management.

Keeps track of processor and status of process i.e. which program is using it, what is the state
of the process

 Allocates the processor (CPU) to a process.

De-allocates the processor when it is no longer required.

I/O device Management
-The OS manages device communication via their respective drivers. The OS does the following
activities for device management:

Keeps tracks of all devices. The program responsible for this task is known as the I/O
controller.

Decides which process gets the device, when and for how much time.

Allocates the device in the most efficient way.

De-allocates devices.

File Management
-A file system is normally organized into directories (folders) for easy navigation and usage. These
directories may contain files and other directories.

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-The OS does the following activities for file management:

Keeps track of information, location, uses, status of files. The collective facilities are often
known as file system.

Decides who gets the resources.

Allocates the resources.

De-allocates the resources.

Types of operating system

-There are several types of operating systems. These operating systems can be classified according to:-

a.User interface

b.Size of a computer

c.Number of tasks

d.Number of users

Classification according to user Interface

-User interface refers to the interaction between the user and a computer.
-User interfaces consist of the graphical design, the commands, prompts, and other devices that enable
a user to interact with a program. Microcomputers have three basic types of user interfaces (which
are not necessarily mutually exclusive):

a.Command-Line Interface

-It lets the user type a command at a command prompt. The computer reads the typed command from
the command line and executes it. For a command to be more user friendly, the words used should be
descriptive verbs e.g. print, copy, etc.
-Examples of command line interface are early versions of MS DOS, PC DOS, OS/2 and UNIX.
NB: One must press the enter key for each command to be executed.

b.The Menu-based interface (also called Menu-Driven interface)

-Used by many application programs such as Lotus 1-2-3, this interface offers the user a choice of
command words that can be activated by typing a letter, pressing a direction key, or pointing with a
mouse.

c.The Graphical user interface

-Characteristic of the Apple Macintosh and of windows programs, this interface presents the user with
a visual representation of some metaphor such as a desktop and allows the user to control not only
menuchoicesbutalsothesize,layout,andcontentsofoneormoreon-screen

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3.1.2 Managing files using the operating system

-The smallest data item on a computer is called a bit (with a value of 0 or 1). In a computer system,
data is systematically organized, often in a hierarchical form as follows:

Data fieldholds a single fact or attribute of an entity. Consider a date field, e.g. "September

19, 2004". This can be treated as a single date field (e.g. birthdate), or 3 fields, namely, month,
day of month and year.

A recordis a collection of related fields. An Employee record may contain a name field(s),

address fields, birthdate field and so on.

A fileis a collection of related records. If there are 100 employees, then each employee would

have a record (e.g. called Employee Personal Details record) and the collection of 100 such
records would constitute a file (in this case, called Employee Personal Details file).

Database– a group of related files

Characteristics of Files /File attributes

-Every file must have the following features:

1.Identifiers: the name a file can be addressed by.

2.Size: every file must have same size and this can be known by the number 'of bytes it
occupies.

3.Date of creation or modification:-refers to the age of the file.

4.Author/user:-the person who created the file or who the file was created for.

5.Organization:-this is the mode in which data can be retrieved from the file.

6.Type:-it can be a master file or a data file.

7.Size:-is the amount of data that is in the file, it may be expressed in terms of number of
records or character.

8.Growth:-files often grow in size as records are added or shrink as unwanted records are
deleted. Growth must be allowed for when planning to store a file. The increase or
decrease in the number of records that have been added or removed from the file or the
percentage increase or decrease of records in relation to existing records are referred to
as Growth.

9.Volatility:-is the frequency with which records are added or deleted from a file. If the
frequency is high the file is said to be volatile, a file that is not altered is said to be static
and if the frequency is low it is said to be semi-static.

10.Hit rate: Is the term use to describe the rate of producing master files in terms of active
records. It is a measure of file activity.

-The operating system is responsible for file management in a computer system.

Types of computer files

-The major file types in computer systems include:

1)Ordinary Files or Simple File

-Ordinary File may belong to any type of Application for example notepad, Songs etc. So all the Files
those are created by a user are Ordinary Files.

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i.Formula bar – this is where data or formula is displayed as the user enters it into a cell. It is also
used to edit a cell entry or a formula.

ii.Worksheet – this is the work area which is made up of rows and columns. Several worksheets
make up a workbook. The sheets can be added by clicking the new icon after the last worksheet
tab in the workbook.

iii.Rows – These are records that forma a worksheet. They are made up by lines running from right to
the left of a worksheet. They are labeled by numbers 1, 2, 3….

iv.Columns – These are fields that form a worksheet. They are made up of lines running from top to
bottom of the worksheet. They are labeled by letters A, B, C….

v.Cells – it is the intersection of rows and columns. Cells have an identification number which is
given by column number and row number e.g. the first cell in a worksheet is named as A1. This is
because it is in the first column A and first row 1

vi.Active cell pointer – this is the cell which is ready to accept an entry. It is highlighted with a dark
outline.

Types of Data in Spreadsheets

-Some of the data types used in spreadsheets include; labels, values, functions and formulae

(1). Labels (Text)

-Labels are texts consisting of alphanumeric characters that can be entered into a cell e.g., Item codes such
as Salary, Names such as John.

-Labels are made up of alphanumeric character strings. In Excel, Text is any combination of numbers,
spaces, & nonnumeric characters e.g., 10A19, 27AXY, 12-976, 208 4675.

(2). Values (Numbers)

-Values consist of numerals & mathematical formulas entered into a cell.

-In Excel, a number can contain only the following characters: digits 0 to 9 + - ( ) / $ %.

(3). Formulas

-A Formula is a sequence of values, cell references and arithmetic operators whose calculation results to a
numeric value. It is an equation that performs operations on worksheet data.

-Formulas can perform mathematical operations such as addition, subtraction, division and multiplication.
A Formula is used to tell Ms-Excel how you want a particular value to be computed. In Excel, a formula
must start with an equal sign (=).

(4). Functions

-It is a special command, which you can type into your formula to perform arithmetic operations.

-It is an inbuilt equation that is used for calculations. A Function is a short predefined (inbuilt) formula used
to perform a given specific task.

-Functions can be used to perform both simple and complex calculations.

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Cell References (Cell Addresses)

-A Cell reference is the identity of a cell in a worksheet. A Reference identifies a cell or a range of cells on a
worksheet and tells Ms. Excel where to look for the values or data you want to use in a formula.

-A cell is identified by use of the Column letter heading and the Row number heading.

-To refer to a cell, enter the column letter followed by the row number. For example, B2 refers to the cell at
the intersection of column B & row 2.

Cell referencing is the act of using cell addresses especially in formulas and functions to identify cells. Two
types of references are used:

a)Single cell references – addressing a single cell [e.g. A1]

b)Range of cells – addressing a group of cells [e.g. A1:A5 (vertical), A1:F1 (horizontal)]

Ways of referencing

a)Relative referencing

b)Absolute referencing

Relative References

-A Relative reference is a cell reference, which changes automatically when the formula is copied to
another cell or range. It describes the location of a cell in terms of its distance (in rows and columns) from
another cell.

-When a formula is created using this type of referencing, the reference to the cells is based on their
position relative to the cell that contains the formulae. When the position of the cell that contains the
formula changes, the reference is changed.

Note: When you copy a formula containing relative references down or across from one cell to another,
Ms.Excel adjusts the references in the pasted formula automatically to refer to a different cell that is the
same no. of rows & columns away from the formula.

Example 1

-If the formula in cell B6 (i.e., =A5) (which is one cell above & one cell to the left of B6) is copied to cell B7.
Ms- Excel will adjust the formula in cell B7 to =A6, which refers to the cell that is one cell above and one
cell to the left of cell B7.

Example 2

-If cell A3 contains the formula =A1+A2, and you copy cell A3 to cell B3, the formula in cell B3 becomes
=B1+B2.

Absolute References

-In a formula, an Absolute cell reference is the exact address of a cell, regardless of the position of the cell
that contains the formula. The cell referenced is the same, no matter which cell refers to it.

-An absolute cell reference takes the form $A$1, $B$1, etc.

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-The table below shows the different types of references

Reference

Effect on a cell reference

A1

Relative reference.

$A$1

Both rows and column references are absolute

A$1, B$1

Absolute row reference, i.e., only the row reference is absolute.

$A1, $B1

Absolute column reference, i.e., only the column reference is absolute.

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3.2.3 PRESENTATION SOFTWARE

-A presentation program is a software package used to display information in the form of a slide show (a
sequence of words or pictures or both that tell a story or help support a speech or public presentation of
information).

-A presentation software has three major functions:

an editor that allows text to be inserted and formatted,
a method for inserting and manipulating graphic images,
a slide-show system to display the content.

-Presentation software is used to create presentations, quizzes, e-learning packages, information points
and many other multimedia products.

-Most presentation software packages allow you to create your multimedia product using a series of slides.
A slide is a frame or a page where text, images, video, animations, links and sound can be placed and
combined to create a sophisticated final product.

Examples of presentation software

Ms. PowerPoint (many versions) – This is the most widely used presentation software on the Windows
platform and is created by Microsoft.

OpenOffice.org Impress - created by Sun Microsystems Inc. OpenOffice Impress (as it is more commonly
known), is part of a suite of programs offered as a free download.

Windows Movie Maker - a desktop video program, created by Microsoft installed on every Windows
computer. Windows Movie Maker allows you to create and edit movies to use to accompany your
presentation, although you can also add still photos or graphics and create a slide show, just as in
PowerPoint and OpenOffice Impress.

Keynote - created by Apple Computer is the leader in presentation software on a Mac platform.

Common features of presentation software

Have slides that can contain any mixture of text, images, video, animations, links and sound.

Have Animation effects that allow the various elements on each slide to appear after a certain
amount of time or when a presenter presses a button.

An animation is a visual effect applied to text or graphics in a slide to define how these
elements move (are displayed) during presentation e.g. fly in, bounce, float, swivel, etc.

Have Transition effects – this is how the presentation software “moves” the display of one slide
to another.

A transition is a visual effect applied to a slide to define how the presentation moves
from one slide to another e.g. push, dissolve, reveal, curtain, etc. Transition effects signal
end of one slide and beginning of another.

Slide notes – when these are used, the presenter will see the current slide and any notes
associated with it on his/her display and the audience will see just the slide on another screen or
from a projector.

Slide Master – A master slide is one that is a part of every presentation that controls certain text
characteristics such as font type, size, and color, as well as background color and style.

Masters can affect all the slides in a presentation. There are masters that control the title slide, notes
pages, and handout pages. When you apply a template to a presentation, you apply a new set of masters
that control the presentation's look and format. There are four types of masters used in PowerPoint:

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Type of Master

Description

Slide Master

Stores information about the template, such as font styles, placeholder sizes
and locations, background design and color schemes

Title Master

Used to make changes to slides in your presentation that uses a Title Slide
layout. This enables you to give a title slide a different look from the rest of
your presentation.

Notes Master

Used to set the formatting for your notes pages.

Handout Master

Used to set the formatting of your handout pages.

Offers many printing options for a presentation. You can print slides, notes pages, handout pages, or outlines.
You can print the current slide, or select a range of slides.

Microsoft office features

1.Title Bar - Displays the name of the application followed by the title of the presentation

2.Formatting Toolbar - Provides quick access to commands you need for formatting

3.Outline and Slides Tab - The slides tab gives you a thumbnail view of all the slides in the
presentation and allows you to rearrange their order; the outline tab adds textual content to the slides
in an outline format.

4.Slide Pane - Area where you build the slides for your presentation

5.View Buttons - Change the way you view the presentation (Normal view, Slide sorter view, Slide
show vie, etc.):

Normal view: The main editing view for writing and designing a presentation. In this view,
you can see:

1.One selected slide displayed in the center

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2.Thumbnails of all slides at the left pane (on left side of the screen)

3.Speaker’s notes for the selected slide (displayed at the bottom of the screen)

Slide sorter view: Allows you to see your presentation as a whole and organize your
slides. You can see which slides are hidden, which ones have animations or transitions,
etc.

Notes page view: Enables you to view each of your slides on a separate page with all its
notes underneath.

Outline view: Enables you to view presentation text, removing any other distractions
(e.g. formatting, graphics, multimedia or animations)

Slide Show view: It displays one slide at a time in full-screen mode, including animations,
multimedia and links. This is the view that is used when delivering a presentation.

Presenter view: This is an extension of the Slide Show view. It enables you to view the
presentation in slide show mode with additional support elements such as the
presenter’s notes on your screen. The audience can only see the presentation slide
without the notes.

6.Drawing Toolbar - Provides all the tools you need to draw and format objects
7.Notes Pane - Adds notes for yourself for each slide in your presentation

8.Task Pane (Windows version) - Varies based on what you are currently working on; when you first start
PowerPoint, you see the New Presentation task pane; other possible tasks include Slide Layout, Slide Design,
and Effects

9.Menu Bar - Includes all of the PowerPoint menu choices

10.Placeholders - Designate the space that will be filled with titles, text, or other objects such as graphics or
charts

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3.5.4 COMPUTERIZED ACCOUNTING SOFTWARE

'Accounting Software' is software that assists bookkeepers and accountants in recording and reporting on
a firm's financial transactions. The functionality of accounting software differs from product to product.

Usage of Accounting Software

-Computerized accounting uses the concept of databases. For this purpose, accounting software is used to
implement a computerized accounting system. It does away the necessity to create and maintain journals,
ledgers, etc.

-Some of the commonly used accounting software is QuickBooks, SAGE, PASTEL, Tally, Cash Manager, etc.

Components of Accounting Software

1.Preparation of accounting documents: The software helps in preparing accounting documents like
Cash memos, Bills, Invoices, etc. and accounting vouchers.

2.Recording of Transactions: The software provides functionality for recording everyday business
transactions. Every account and transaction is assigned a unique code.

3.Preparation of Trial balance and financial statements: After recording of transactions, the data is
transferred automatically into ledger accounts. The trial balance is prepared by the computer to
check accuracy of the records and then with the help of this trial balance, other financial
statements (Trading and Profit and Loss account, Balance sheet, etc.) are prepared.

Desirable Features of accounting software

1.Should be simple and integrated in order to automate and integrate all business operations such as
sales, finance, purchases and inventory so as to provide up-to-date business information rapidly.

2.Transparency and control: These features increase data accessibility and enhance user satisfaction.
3.Scalability: The software should allow for change in the volume of data processing in tune with the
change in the size of the business (software can be used for any size of the business and type of
organization).

4.Accuracy and speed: The user-defined templates (data entry screens or forms) should facilitate
fast, accurate data entry of transactions.

5.Reliability: The software should ensure that critical information is accurate, controlled and secured.

Facilities/ Functions of accounting software

-A typical accounting software does a variety of jobs some of which include;

1.Online input and storage of accounting data.
2.On-screen input and physical output generation of sales invoices, vouchers, etc.
3.Updating of customers’ accounts in Sales Ledger and suppliers’ accounts in Purchase Ledgers.
4.Automatic updating of general ledger.
5.Recording of suppliers’ invoices.
6.Recording of Bank Receipts
7.Making payments to suppliers and for the expenses.
8.Maintenance of Stock Accounts

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9.Generation of Aged debtor summary (who owes what and since when)
10.Preparation of Trial Balance, Profit and Loss Accounts and Balance sheet.
11.Stock valuations.
12.Payroll analysis
13.Statutory returns (such as VAT, Service tax, etc.)

-When using computerized accounting system on the computer, the input screens have been designed for
ease of use. The main advantage is that each transaction needs to be input only once, unlike a manual
double entry system where two or three entries are required.

Advantages of computerized accounting software

1.Better quality work: The accounts prepared with the used of accounting software are usually
uniform, neat, accurate and more legible than those prepared manually.

2.Lower operating costs: Capitalizing on the speed of a computer, the volume of work handled with
the help of an accounting software results in economy and lower operating costs compared to
manual accounting.

3.Improved efficiency: Using computerized accounting software in preparing records and accounts
results into improved employee efficiency due to the computer’s speed and accuracy
characteristics.

4.Greater accuracy: Computerized accounting software ensures accuracy in accounting records and
statements by preventing clerical errors and omissions in records.

5.Relieves monotony: Computerized accounting reduces the monotony of carrying out repetitive
accounting tasks which can be tiresome and time-consuming.

6.Facilitates better control: From the management point of view, there is greater control possible
and more information may be available with the use of computerized accounting software.

7.Facilitates standardization: Accounting routines and procedures are standardized thus ensuring
standardization in accounting records.

8.Quality reports: The inbuilt checks and features of data capturing and handling facilitate production
of quality, highly objective and reliable reports.

9.Accuracy: Provided data is correctly entered, while doing mathematical operations with computers,
errors are virtually eliminated.

10.The ability to deal in multiple currencies easily – many computerized accounting packages now
allow a business to trade in multiple currencies with ease. Problems associated with exchange rate
changes are minimized.

Disadvantages of computerized accounting software

1.Unemployment: The number of employees in an organization reduces with the introduction of
accounting software leading to unemployment.

2.High initial cost: The installation and maintenance costs to start computerized accounting is high
for small firms with little amount of accounting work.

3.Require special skills: Computerized software requires skilled operators. The availability of such
personnel is very scarce and very costly.

4.Disruption: Power failure, computer viruses, etc. can disrupt an organization’s accounting

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functions.

5.Staff opposition: Resistance resulting from technophobia is a common problem whenever an
organization decides to use computerized accounting software for its accounting functions.

Categories of accounting software

-Accounting software can be categorized into: readymade software, customized softwareand tailor-made
software.

Readymade software

-They are developed not for any specific user but for users in general. Examples include Tally, Professional
Accountant, etc.

-These software has its own advantages and disadvantages:

Advantages of readymade software

1.They are economical because they are made for general users hence the price of the software is
determined on the basis of number of pieces expected to be sold.

2.Are available off-the-shelf and require only installation and are ready to use. This saves time that
could be incurred in development of new software.

3.Developed by a group of experienced professionals hence addresses problems that may be
overlooked if user-specific software is developed.

4.After sales maintenance for readymade software is less time consuming and costs less.

Disadvantages of readymade software

1.A majority of these software support specific printers whose printing costs are high.
2.Normally, they do not have a facility for secondary backup which implies in case of data loss,
recovery may not be possible.

Customized software

-These are made by making changes to readymade software to suit the specific requirements of the user
i.e. making it user-specific. The user bears the costs of such changes.

-Customized software is one, which is developed on the basis of the requirement specifications provided
by the business unit. A feasibility study is done in order to ascertain the requirements of the unit.

-Based on these requirements, a requirement specification report is prepared for submission to the top
management for approval. After approval, the designing process starts. After testing, it is implemented.

Advantages

1.It covers all functional areas as per requirement,
2.For ease of data entry, the input screens would be tailor-made to match input documents,
3.The reports would be as per the specifications of the business unit,
4.Bar-code scanners can be used as input devices suitable for its specific needs.

Disadvantages

a)If requirement specification or documentation is incomplete or control measures are inadequate,
the system may work defectively,

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b)Inadequate testing may result in bugs in the software,
c)Vendor may not give full support for the operation of the software.

Tailor-made software

-These are designed and developed for a specific user on the basis of discussion between the user and
developers. They have advantages and disadvantages too.

Advantages of tailor-made software

1.Being user-specific, it takes care of the accounting reports that may be required by the user and
management of the enterprise.

2.A software engineer can be engaged to maintain it i.e. the problem faced can be countered
immediately.

3.Well-trained users use the software hence can maximize software utilization.

Disadvantages of tailor-made software

1.Development cost is higher than the cost of readymade or customized software.
2.Requires fresh training in case the one conversant with it leaves the job. This wastes time and is
also costly.

3.Maintenance costs are higher than in readymade and customized software.

Factors to Consider when choosing an Accounting software

-The requirements of the particular business should match with the available solutions. The software that
fulfills the maximum requirement should be selected. Some of the factors to consider include;

1.Flexibility: It must be flexible in terms of data entry, information retrieval and in generating
designs of reports.

2.Portability: The software should be able to run on a variety of computer environments (e.g. on
different operating systems) and machines (hardware).

3.Installation and maintenance costs: The costs for installation, maintenance (upgrading,
updating) and training should be negotiable and within an organization’s ability to afford.

4.Ease of adaptation and training needs: Some software is user-friendly and requires simple
training to the users while others are complex and require intense training. The software chosen
should be able to attract users.

5.Size of the organization: The volume of business transactions and multi-user requirements
influence the software chosen. The software must be according to the size of the organization.

6.Exporting / importing data facility: The software should allow easy data transfer option for
flexible reporting and data entry.

Stages of Computerized Accounting System

Transaction Processing System [TPS]

-The first stage of a computerized accounting system is transaction processing. Its purpose is to record,
process, validate and store transactions that occur in various functional areas of a business for subsequent
retrieval and usage.

-The following steps are involved in processing a transaction:

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4.0. COMPUTER NETWORKS

4.1 Computer network concepts

A computer network is a group of two or more computers interconnected, alongside other communication
devices so that they can communicate with each other to share resources (data, hardware, software, and
processing power).

Computer that are not hooked up to each other or to the internet are simply referred to as stand-alone
computers.

The interconnection of the computers in a network is done through cables or in a wireless manner using
radio signals.

Key terms

Node – any device connected to a network such as a computer, printer or data storage device.

Server – a computer that allows its resources to be used by other computers on a network. It may
be called a file server, printer server, communication server, web server or database server.

Client – a node that requests and uses resources available from other nodes / the server (e.g. a
microcomputer).

Network Operating System (NOS) – the operating system (of the server) that controls and
coordinates the activities between computers on a network.

Bandwidth – the maximum amount of information (in bits per second) that can be transmitted
along a communication channel.

4.2 Advantages and disadvantages of computer networks

Businesses and organizations heavily rely on computer networks to get messages and information across
essential channels. Not only has it benefited establishments, but also individuals, as they also need to share
important information every day. Equally, there are drawbacks in the use of computer networks.

Networks are used to improve communication between departments, foster customer relationships, and share
data
throughout the world.

4.2.1 Advantages of computer networks

1. It enhances communication and availability of information

With computer networks, governments and government agencies, businesses entities and individuals can
communicate faster and get instant feedback through instant messaging (e-mails), video calls, etc. This
makes communication more effective. Businesses can reach their customers through online advertisements
faster.

2. It reduces operating costs for organizations / businesses

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With a computer network, resources such as printers, scanners and photocopy machines can be shared across
multiple users. This resource sharing is important for organizations as it leads to reduction of operating
costs.

3. It makes file sharing easier
Computer networking allows easier accessibility for people to share their files. This greatly helps them with
saving more time and effort.

4. It enhances telecommuting / remote working

People can work remotely (or telecommute) without having to physically be in the office while they are
working by simply logging on to the home computer and work from their own computer. They can also send
documents from their computer to the office and receive information from the office on the same computer.

5. It boosts storage capacity
Organizations have an abundance of data that needs to be stored. For that purpose, they are required to store
them in a central server. A central server is a remote server that is accessible to each and every employee so
that in case one loses the data, others have it.

6. It enhances collaboration

With a network, businesses / individuals can collaborate with others. Two companies / organizations with a
shared interest can share information about their different projects and problem-solve. Tasks can be
delegated and distributed among various workers.

7. Provides better data security

When data is stored on a computer that is part of a network, the data is more secure because it can be stored
in different places. For example, when the data is stored on a server, it can be protected against hackers and
viruses. The data can also be backed up. If something happens to the computer, the data can be sent to
another computer with the click of a button.

4.2.2 Disadvantages of computer networks

1. Lack of robustness

Computer networks rely on the central server. If the central server malfunctions or there is an issue in the
central server, then the entire network would stop functioning. So, this is a major disadvantage due to
dependency on a single server.

2. Spread of computer viruses

As computers in a network are interconnected, there is a high probability that if one of the computers is
infected by a virus, others too can get infected. This spread can actually damage the entire system.

3. Independence issues

The entire networking system is based on a centralized server, individual users lack the freedom to use the
computer as per their wish.

4. Lack of productivity

Since a network has a lot of advantages and applications, it is certain that it results in simultaneous use of
many services that cause distraction. Thus, due to employees focusing on a number of tasks, productivity
issues are quite common.

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5. Health issues

Computer networks provide access to a range of services including entertainment, gaming, and movies.
These result in making you addicted to the content and thus results in overuse of these services. This
excessive screen time can cause eye strain and body pain.

6. Criminal activities
Computer networks have presented with us an online environment that has facilitated crime to grow.
Criminals such as cyber bullies and predators have used computer networks to go after teens to harass them
sexually or take advantage of them in some other way.

7. Erosion of social morals
Computer networks have facilitated sharing of age inappropriate content such as pornography which has
contributed to sexual immorality. Social media has been used as a tool to spread hate and threats. The fact
that the message is put over the network by someone far away makes them even more courageous to do bad
things because they think they can easily get away with it.

8. High implementation costs

The initial cost incurred in setting up a computer network is high. The cost of setting such a network
especially for small businesses or organizations may outweigh the benefits.

4.3 Types of computer networks

Different communication channels allow different types of networks to be formed (Wired or wireless).
Telephone lines may connect communications equipment within the same building. You can also create
your own network in your home or apartment. Communication networks also differ in geographical size.

Modern computer networks can be classified into one of four broad categories centering on the connection
and geographic configuration strategy used with the physical devices. These network categories are:

LANs, MANs, PANs and WANs.

4.3.1 Local Area Networks (LANs)

A LAN is a group of computers and associated devices connected to each other in a small area (up to 1 km
radius) such as an office or a commercial establishment. Minicomputers, mainframes or optical disk storage
devices can be added to the network.

The following are some of the characteristics of LANs:

The equipment in this network is located geographically close together e.g. within a building.
They are privately owned i.e. they belong to individuals or particular organizations.
The speed of LANs is higher compared to that of WANs
There is little congestion in LANs hence propagation delay is short.
Their design and maintenance is easy
They are less costly compared to WANs
They provide higher security.

Wireless networkrefers to technology that allows two or more computers to communicate (using standard
network protocols),without network cabling. They are most often referred to as wireless local area
networks (WLANs).

This technology has produced a number of affordable wireless solutions that are growing in popularity with
businesses and schools, or when network wiring is impossible, such as in warehousing or point-of-sale
handheld equipment. Wireless networking hardware requires the use of technology that handles data

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•

Network problems are easier to diagnose.

Disadvantages

•

The cost of installation and maintenance is high (more cable is required than any other
configuration)

4.6 User Accounts

-User accounts are the backbone of network security administration. Through the use of user accounts, you
can determine who can access your network, as well as what network resources each user can and cannot
access.

- Every user account is associated with a username (sometimes called a user ID), which the user must enter
when logging in to the network. Each account also has other information associated with it (user password,
restrictions, group membership, etc.).

4.7 Network Resources

-Network resources are elements of hardware (printers, scanners and storage devices), software and files that
can be easily accessed from a remote computer through a network e.g. a LAN.

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1.0. FOUNDATIONAL CONCEPTS OF COMPUTERS

1.1 Definition of terms

1.1.1 Computer

A computer is an electronic device that takes data (as input from the user) and processes the data under
the control of a set of instructions (called a program) to produce information (as output) and saves it for
future use. It can process both numerical (arithmetic) and non-numerical (logical) calculations. Examples
of computers include desktop computers, laptops, tablets, smartphones, smart watches, etc.

1.1.2 Data

Data refers to raw and unorganized facts entered into a computer (as input). It is a collection of letters,
numbers, images, symbols and graphs. On its own, data is not sufficient for decision making. Examples of
data include; date of a transaction, price of an item, etc.

1.1.3 Information

Information refers to processed, organized and structured data. That is, data that has undergone
transformation in order to be meaningful to the user. Information is sufficient for decision-making. For
example, a single customer’s sale at a shop is data but it becomes information when the business is able
to identify the most popular or least popular product.

1.1.4 Computing

This is the process of using computer technology to complete a given goal-oriented task. The fundamental
question that computing seeks to answer is ‘What can be successfully automated?’.

One form of computing is cloud computing. Cloud computing is the delivery of on-demand computing
services (such as applications, storage and processing power) over the internet and on a pay-as-you-go
basis.

1.1.5 Computerization

This is the process of starting to use a computer to do tasks or activities that were done by people or other
machines before.

Advantages of computerization

1.Response time is greatly reduced

2.Very large data are stored for information and decision-making

3.Accuracy of information is considerably improved, thereby improving the quality of the decision

4.Problems are handled more easily by using various operation research models

5.The cost involved in the decision-making process is reduced

6.More secrecy is observed as compared to manual file system

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2.2 Types of computer hardware

Computer hardware is generally divided into four major categories namely; input hardware, processing
hardware, output hardware and storage hardware.

2.2.1 Input Hardware

–Input hardware enables the computer user to enter data into the computer. It also enables the user to
issue commands to the computer.

Functions of input devices

1.Accepts data and instructions from the user into the computer system.
2.Converts the human-readable data into electronic/machine-readable form.
3.Accepts commands for running, halting or aborting a program from the user.

–Once the data is entered into the computer, it finally enters the Main storage.

Classification of Input devices

–Input devices can be classified according to how they are used to enter data into a computer. These
include:

(a)Keying devices.
(b)Pointing devices.
(c)Touch screens and digitizers.
(d)Speech recognition or Voice input devices such as Microphones.
(e)Scanning and other data capture devices.

Data capture devices are those devices that automatically capture data from the source.

(a) Keying Devices

-These devices use a set of buttons or keys to enter data or instructions into the computer. Examples include
keyboards and keypads.

Keyboard

Keypad on a calculator

Keypad on a feature phone

Keypad is a mini-keyboard. It has fewer keys than the ordinary keyboard and is meant to
be used for a specific devices or for specific purposes.

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Secondary memory / Secondary storage

–This type of memory is also known as external memory or non-volatile memory. It is used for long term
storage / permanent storage.

–This memory has the following characteristics:

1.It is slower than main memory.
2.It is non-volatile
3.It is not accessed directly by the CPU. Instead it is accessed via input-output routines.
4.It can save huge amounts of data in the range of gigabytes (GB’s) or Terabytes (TB’s)

–Secondary memory is further classified into three categories, namely; magnetic storage,optical storage
or solid-state storage

–Examples of magnetic storage devices include the floppy disk, magnetic tapes and hard disks (HDD).

–Examples of optical storage devices include;

1.Compact Disks (CD’s)

Compact Disk Recordable (CD-R) – Can be read from many times but written on only once
Compact Disk Re-writable (CD-RW)- Can be read from and written on many times

2.Digital Versatile Disks (DVD’s)

DVD Recordable (DVD-R)
DVD Re-writable (DVD-RW)

-Solid state memory devices are very fast compared to magnetic and optical storage media. Examples of
such devices include memory sticks (cards), Flash disks (drives), Solid State Drive (SSD)

2.2.4 Output Hardware

-When the computer processes the data, it displays the results (or communicates the solution to whoever
posed the question) by use of output hardware /an output device.

Functions of Output Units

1.Transmit the intermediate results & final results to the users

2.Convey messages, e.g. error messages, to the operators

3.Accept the results produced by the computer (which are in coded form & hence cannot be easily
understood) & convert these coded results to human readable form.

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-With the help of Ordinary Files, we can store the information which contains text, database, any
image or any other type of information.

2)Directory files/Folders

-A directory / folder is a place where files or other directories are saved.

Goals of directory organization

•Efficiency - locating a file quickly

•Naming - convenient to users

•Two users can have the same name for different files.

•The same file can have several different names.

•Grouping; logical grouping of files by properties (e.g. all Pascal programs, all games…)

3)Special Files/System files

-The Special Files are those which are not created by the user or the files that are necessary to run a
System. These files must be on the computer for it to function well.

Types of File Operations

-Files are not made for just reading the Contents. We can also perform some other operations on the
Files such as:

1)Read Operation: Meant To Read the information which is Stored into the Files.
2)Write Operation: For inserting some new Contents into a File.
3)Rename or Change the Name of File.
4)Copy the File from one Location to another.
5)Sorting or Arrange the Contents of File.
6)Move or Cut the File from One Place to Another.
7)Delete a File
8)Execute.
9)Share
10)Print

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transmission over radio frequencies. Wireless devices have become extremely popular because of the
mobility they provide.

4.3.2 Wide Area Networks (WANs)

A WAN is a computer network that may be countrywide or worldwide. A network is considered a wide area
network (WAN)based on characteristics that are opposite those for a LAN. The following are some of the
characteristics of WANs:

Equipment in this network is geographically dispersed.
Ownership of WANs may be private or public. Mostly, the connection services, and possibly equipment,
are leased from telecommunications providers such as phone companies or Internet service providers (ISPs).

They run at much lower speeds compared to LANs.
Propagation delay in WANs is longer than in LANs.
Their design and maintenance is difficult
They are costly compared to LANs.

The internet is an example of a WAN (The largest of all WANs). The internet refers to a worldwide
interconnection of computers that allows for communication among these computers. Some of the services
that the internet providesinclude:

Email.

Worldwide web (www) – a collection of websites with a variety of services or information

Web-enabled audio/video conferencing services.

Online movies and gaming.

Data transfer/file-sharing, often through File Transfer Protocol (FTP).

Instant messaging.

Internet forums.

Social networking.

Online shopping.

Financial services.

Terms associated with the use internet

Browser – application software that enables you to view web pages / content in websites. Examples of
browsers include; Mozilla Firefox, Chrome, Opera Mini, Microsoft Edge, etc.

Search engine – a software / program that enables you to look for (search) information on the internet.
Examples of search engines include; Google.com, Bing, Ask.Com, Baidu, Yandex, DuckDuckGo, etc.

Surfing / browsing – the acting of moving from one website / web page to another when using the internet.

4.3.3 Metropolitan Area Networks (MANs)

A metropolitan area network (MAN) is smaller than a wide area network (WAN) but larger than a LAN.
MANs connect computers within a metropolitan area, which could be a single large city, multiple cities and
towns, or any given large area with multiple buildings. MANs combine characteristics of both LANs and
WANs.

The following are some of the characteristics of MANs:

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(b) Pointing devices

–These are the input devices that enter data or instructions by controlling a pointer (cursor) on the screen.
Examples of pointing devices are; Mouse, Trackball, Stylus, Joystick and Light pen.

Trackball

Laptop touchpad

Joystick in use-used for
playing computer games

Mouse

Light Pen

–A Light Pen is similar in shape to a ball-point pen, and has a light sensitive point. It consists of a pen-
like device called a stylus connected by a cable to a computer terminal. It is used together with a graphic
VDU that is able to sense light shining on the screen using special hardware and software.

–A Light pen provides a direct input mode. It can be used to read data directly from the source document.

(c) Touch-sensitive screens and digitizers

Touch-sensitive screens

–A Touch-sensitive screen uses the human finger as the input medium, (i.e. one can select items or options
from a given list by touching the screen with a finger).

–Touch screens are mostly used in public places like banking halls, hotels, in airports (to provide guidance
information), etc.

Capacitive touchscreen on a
smartphone

Infrared touchscreen on a bank’s
ATM.

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Computer File Types by Extension

-When you create a file in a computer system, you specify its name and its extension. The extension
associates the file with the application program responsible for the file e.g.

Extension

Associated Program

DOC/DOCX

Microsoft Word

PDF

Adoble Acrobat Portable Document

XLS

Microsoft Excel Spreadsheet

JPG

Image

MP3

Audio

AVI

Animated Video

BMP

Bitmap Graphic

DLL

Dynamic Link Library

GIF

Image

- A file should be organized in such a way that the records are always available for processing with no
delay. This should be done in line with the activity and volatility of the information.

- Files need to be properly arranged and organized to facilitate easy access and retrieval of the
information.

-A program that uses a file needs to know the structure of the file and needs to interpret its contents.

Utility software

-It is a special program that performs commonly used services that make certain aspects of computing
go on smoothly.

-Such services include sorting & merging, copying, file handling, backup, file defragmentation, disk
repair, virus protection etc.

-The two broad categories of utility software are:

1.System-level utility: - These help the user to work with the operating system and its functions.

2.Application-level utility: - These make application programs run more smoothly and efficiently.
They are commonly purchased separately or may be part of an operating system.

Sort and merge utility

-Sort utility is used to arrange the records within a file according to some predetermined sequence.
Arrangements can either be in ascending or descending order of the alphabetic characters or
numerals.

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Ownership can be private or public

Their speeds are average

Propagation delay is moderate

4.3.4 Personal Area Network (PAN)

This is a computer network that connects computers or devices within the range of an individual person
(typically within a range of 10 meters).

One of the most common examples of a PAN is the connection between a Bluetooth earpiece and a
smartphone. When a PAN is created using wireless technology like this, it is called a wireless personal area
network (WPAN) and it serves multiple users.

Note: While devices within a PAN can exchange data with each other, PANs typically do not connect to
the Internet directly.

Advantages and disadvantages of PAN

Some of the Advantages of PANs include:

They are relatively flexible and provide high efficiency for short network ranges.

They are easy to set up and are relative cheaper.

Do not require frequent installations and maintenance

They need fewer technical skills to use.

Some of the disadvantages of PANs include:

Low network coverage area/range.

Limited to relatively low data rates.

Devices are not compatible with each other.

Inbuilt WPAN devices are a little bit costly.

4.4 Network Devices

Networking devices may also be known as network equipment or network hardware. Some of the most
commonly used network devices include:

Hub
Switch
Router
CAT 6 cable

4.4.1 Hub

-This is an unintelligent network device that sends one signal to all of the stations connected to it.

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Digitizers

–The Digitizers are input devices that convert graphical drawings or images on the paper or other
material into digital data and convey them to the computer memory.

–Digitizers are slow, but easy to handle and errors are hardly present.

–A graphics tablet is the most commonly used digitizer. It has a board used to detect the position of a stylus
on its surface.

The images that are sketched on it are displayed on the computer screen. It is commonly used in graphics
design and in creating computer animations.

(d) Voice Input Devices (Speech Recognition Devices - SRD)

–Voice recognition is a type of input method where a Microphone connected to a computer system
(through some extra circuitry) is used to enter data in form of spoken words into the computer.

–The SRD accepts spoken commands & convert them into electronic pulses/ signals, which can be
processed by the computer.
–The user must train the system to recognize his/her voice by repeating each word in the vocabulary
several times. Each word is analyzed & filed for identification.

Uses of Voice Input devices

In Security and Access control – Each person has a unique ‘Voiceprint’ that can be used for
identification. This approach could be used in electronic money transfer, house/ car security using
voice activated locks and office security for room access.

In Voice-activated toys and games.
In Quality control and automation (computerization/mechanization) in factories.
In Automated materials handling – in airports, handler’s give spoken commands that direct the
luggage to the appropriate conveyor belt.

In Computer-Aided Design (CAD) – A designer, e.g. of buildings, working at a terminal can call up
design patterns which are frequently used, instead of having to punch catalogue nos. into a Keyboard.

Limitations (disadvantages) of Speech Input/Recognition devices found Today

1.Homophones – some words have same sounds.
2.Word separation.

–The speech must be “clipped” i.e. each word must be followed by a short period of silence. This
enables the device to recognize the end of each word.

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Soft-copy output devices

VISUAL DISPLAY UNIT (VDU)/ MONITOR

-Visual display unit (or a Monitor) is a television-like screen which displays the data that is being typed at a
Keyboard. It also displays the information that has been processed by the computer in a human-sensible
form.

-The display is meant to provide a means of visually checking whether the information that has been
entered is correct.

VOICE OUTPUT DEVICES (Audio Response Units -ARU)

-ARU converts data/ information from the computer memory (which is in electronic form) through various
specialized additional circuitry into waveforms/ sound for the receiver to hear.

-The sound can be spoken language, musical notes or beeps. This output is obviously Softcopy.

-Voice output is useful where reading is not necessary or is impossible and where fast output is required.

-For example, Voice output is used:

As a learning aid.

In emergency situations for messages.

In answering services, e.g. Post office talking clock.

-When an ARU is used to produce speech, it is called a Speech Synthesizer.

GRAPH PLOTTERS

-These are output devices that produce graphics such as diagrams, maps, images, statistical charts etc. on
paper.

-Plotters use pens of different types, varying thickness & different colours, in order to plot. T

Uses/ applications of Graph Plotters.

-Graph Plotters are used: -

In Computer Aided Design (CAD) – are mainly used for printing large architectural or engineering
drawings. In this case, the computer is used to form the graphical design & the Plotter produces the
output.

In Weather forecasting for drawing Isobars on weather maps.

In Statistical work for producing graphs or complicated mathematical formulas.

In Cartography to produce contour maps.

In Craft & Textile industry for drawing designs.

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-Merge utility is used to influence the combining of the contents of two or more input files to produce
one output file.

Language translator

-Used to convert the source codes, the program statements coded in any of the computer
programming languages to their computer language equivalent.

Backup

-It allows one to make a duplicate copy of every file on a hard disk or any other secondary storage
media.

Disk repair

-The disk repair utility scans a hard disk for bad sectors (defective areas) and makes repairs to these
sectors or marks the defective area so that the operating system will not store any data in that
location.

3.2 Computer Application Software

-Application software is also known as application packages.

-They are programs designed to help end users solve particular problems using the computer or to
perform specific tasks.

-There are quite a number of application packages / application software that are of use in business and
accounting. These include:

Word processing software
Spreadsheet software
Presentation software
Computerized accounting software

-The table below outlines some examples of application software and their uses;
Software

Uses

Examples

Word processors

Typing documents like letters,
reports etc.

Word processor, Lotus WordPro,
OpenOffice Writer,
WordStar etc.

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-Traditionally, hubs are used for star topology networks but they are often used with other configurations to
make it easy to add and remove computers without bringing down the network.

4.4.2 Switch

-This device splits large networks into segments, decreasing the number of users sharing the same network
resources and bandwidth.

-It helps prevent data collisions and reduces network congestion, increasing network performance.

4.4.3 Router

-This device connects any number of LANs. It connects networks of different types (for example, star and
token ring).

-It is commonly used in Local Area Network and Metropolitan Area Network (MAN).

-It manages traffic by forwarding data packets to their proper destinations. Traffic between these networks
may be managed.

-It determines the best path to send packets.

4.4.4 CAT 6 Cable

Cabling is an important component of any network because this is how the data will travel from machine to
machine (unless the network is wireless). Several types of network cabling are available. The three main types are
coaxial,twisted pair, and fiber optic.

Some of the factors to consider before choosing the type of cableto use include:

Bandwidth rating

Interference susceptibility

Cost of the cable

Installation costs

Maximum number of segments per network

Maximum number of devise per segment.

Twisted-pair cable is used in most of today’s network topologies. Twisted pair cabling is either unshielded twisted
pair (UTP) or shielded twisted pair (STP).

UTP is popular because it is inexpensive and easy to install. The following figure shows an example of UTP cable.

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3.Speaker variability.

–The speed, tone (quality of sound), accent, loudness and pronunciation of an individual speaker can
vary

–Voice input does not take care of speech related problems such as accents and tone.

4.Limited vocabulary understood & the no. of speakers they can recognize.

5.Most speech systems can recognize a limited, standard vocabulary of spoken words. The simplest SRD
can recognize the voice of only one speaker. The response rates of these devices are still relatively
slow.

–When you compare the no. of words in English and the total no. of words that can be said at a given
point, it shows that speech recognition is slow.

6.Speech input is complex to develop and is still at the early stages of development.

(e) Scanning and Other Data Capture Devices

–These are devices that enter (capture) data into the computer directly.

Image Scanners

–A Scanner is used to input pictures or photographs into the computer. This is because a Keyboard or a
Mouse cannot perform these tasks.

–Scanners are usually used to capture existing documents in an electronic form into the computer for
further processing or incorporating into other documents.

–It converts text and graphics into machine sensible format. Once the text and graphics are scanned, the
images can be manipulated by changing the colors, the sharpness and contrast.

–There are two main types of Scanners namely; page scanners and hand scanners: -

Page scanner

–This is a desktop machine that looks like a small photocopier. It scans a whole page at a time. An
example is the Flatbed scanner.

–Using this scanner, one can scan text, a real object or a picture by placing it on a glass plate exactly
the way a photocopying machine works. The text or the picture scanned is displayed on the screen or
saved so that one can edit or print it.

Hand scanner

–A Hand scanner is held in the hand and passed over a document.

–Scanners are very useful when large amounts of existing documents need to be converted into electronic
form for feeding into a computer system.

Digital Cameras

–A Digital camera stores its images in digital form. These images can then be streamed (entered) directly
into a computer for editing or printing by connecting the camera to a computer using a special cable.

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There are seven types of UTP cable (Category 1 (Cat1), Category 2 (Cat2), Category 3 (Cat3), Category 4 (Cat4),
Category 5 (Cat5) and Category 6 (Cat6) )

-Category 6 cable (Cat 6) is the 6th generation of twisted pair Ethernet cabling that is used in home and
business networks.

- Cat 6 cable contains four pairs of copper wire and uses all the pairs for signaling to obtain its high level of
performance.

-Cat 6 cables support Gigabit Ethernet data rates of 1 gigabit per second.

4.5 Network Topologies

-Network topology is also called computer network configuration. It refers to the physical layout of the
network (how the nodes are connected) and the method of communication.There are four principal network
topologies:

a)Star

b)Bus

c)Ring

d)Hierarchical (hybrid)

e)Mesh topology Completely connected (mesh)

4.5.1 Star topology

-In a star network, there are a number of small computers or peripheral devices linked to a central unit
called a main hub.

-All communications pass through the central unit and control is maintained by polling.

Advantages of star topology

Centralized management of the network through the use of the central computer, hub, or switch.

Easy to add another computer to the network.

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(f) Document Readers

–A Document reader is an input device, which can read data directly from source documents, such as
bank cheques and convey it to the computer in form of electronic signals.

–Types of codes on documents that can be recognized by a Document reader include: -

(i).Marks – short lines made by hand, usually in pencil on a document.
(ii).Characters – hand-written (e.g. on meter-reading) or printed in magnetic ink on cheques.
(iii).Printed lines –the bar codes.

–Document readers can be classified into; Optical readers and Magnetic Readers.

Optical Readers

–Optical readers use the principles of light to sense the document contents or to capture data. The reader
converts the data into digital form, and then passes it to the computer for processing.

–There are two types of optical readers: Optical Character Reader (OCR) & Optical Mark Reader (OMR).

Optical Character Reader (OCR)

–Optical Character Recognition (OCR) is a data capture technique, which enables the computer to read
printed or hand-written documents directly.

–Handwriting can also be recognized if the characters have been carefully/well formed.

–The reading is done by OCR, which can be connected directly to the computer. An OCR is able to
distinguish one character from another by its shape.

Uses of Optical Character Recognition devices

–OCR devices are used by companies that do a large amount of processing on a regular basis. For
example, Public utility companies, Insurance companies, Airlines, Banks and the Postal service (for
reading postal codes).
Used in Sales Order forms.

–The forms can be printed by the computer with standard data, e.g. Stock codes, Account code, etc. The
Salesman then enters details of the order form and returns it for OCR processing.

Used in Stock-taking sheets.

–The computer can print out stock sheets in OCR characters. The stock checker then enters the actual
stock quantities on the form in careful handwriting. The sheet can then be optically read into the
computer for amending the stock records.

Disadvantages of OCR

(i). The document should be handled carefully (should not be folded or creased) for accurate reading.

(ii). Document size and type area may be limited for accurate reading.
(iii)It requires special typing and character formation and a paper with the required quality.
(iv)The user must make sure that characters are well-formed; if they are not, reading errors may arise.

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The Home key moves
the cursor to the
beginning of the
current line and the
End key moves the
cursor to the end of the
current line.

Editing keys

They include the Delete key, Backspace key
and Insert (Ins) key.

Note: The backspace key, in some keyboards,
does not have the name Backspace on it but
has a backward arrow marked on it.

The Backspace key is
used to erase (delete)
characters from right
to left of the cursor

The Delete (Del) key
is used to erase
(delete) characters
from left to right of the
cursor.

When pressed, the
Insert (Ins) key helps
one to insert text in the
middle of a sentence
or replace a character
the cursor position

Function keys

They are found above the alphanumeric keys
and are numbered from F1 to F12

These keys are used to
perform special or
specific functions or
tasks.

For example, in many
programs, pressing F1
will display a ‘Help’
menu.

Note: The functions of
Function keys vary
from one program to
another.

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Optical Mark Reader (OMR)

The documents are pre-printed with predefined data positions. These positions can then be marked by, let
say, a pencil.

–The OMR detects the presence or absence of a mark on a form by sensing the reflected light of these
positional marks. The reader is then used to convert the marks into computer-readable data and sends the
value of the sensed data into the computer in form of electronic signals.

–The accuracy of an OMR depends on the marks being made properly. If a mark is too light or not solid
enough, it may be misread, giving rise to errors.

Uses of OMR

–OMR forms are used in situations where the data to be input is simple, or the volume of data is large
enough since using other methods would be more expensive.

Used in marking Multiple-choice examination papers where the answers are filled in a form with special
pencils.

–The OMR can sense the presence of a pen or pencil mark. The person taking the test makes a pencil
mark in the box, which he/she thinks corresponds to the answer. An ‘OMR’ is then used to ‘read’ the
answers given by sensing the marks made. This data is then relayed to the computer, which can then
check the answers given and grade the paper.

In Insurance premium collection.
To read marked research questionnaires.
In Supermarkets for stock recording.
Traffic surveys.

Comparative advantages of OMR vs OCR

(i).Speeds up data input. They ensure faster and more accurate processing of data.

They read data directly from the source document and enable data to be given directly to the
computer for processing.

With an OCR it is possible to read up to 10,000 A4 sized documents in 1hr.

(ii).They read data directly from the source document & therefore, no data preparation is required.
(iii).Errors are easily corrected.
(iv).The documents can be re-used, thus saving on stationery.
(v).The contents of the documents are both human & machine sensible, hence reliable.
(vi).The sensitivity of an OMR can be altered to allow for different surface, pencils and inks.
(vii).OMR has a better recognition rate than OCR.

(viii). With an OCR, no typing or transcription/recording process is involved and therefore, not prone to
transcription errors.

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Special PC
operating keys

They include Escape (Esc) key, Caps Lock
key, SHIFT key, CONTROL (Ctrl) key,
Windows key, ALT key

The Shift key, Control
key, Windows key and
ALT key are usually
used in combination
with other keys to give
special instructions to
the computer.

For example, if you
press the key labeled 5
while pressing down
the SHIFT key, the
percentage sign (%)
will be displayed
rather than the number
5.

Escape key is used, in
some programs, to quit
a particular task

The Control (Ctrl) key
is used in controlling a
number of functions
when used in
conjunction with other
keys e.g. in a text
writing program,
Pressing the Control
key and the key with
letter S (CTRL+S) will
lead to saving the
document and its
contents.

CAPS Lock key is
used to switch between
uppercase (capital
letters) and lowercase
(small letters).

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Comparative disadvantages of OMR and OCR

(i).They are expensive methods of input, because they require specialized techniques & equipment.
(ii).Verification of marked data is difficult.
(iii).Documents may be difficult to design, understand and fill in.
(iv).The document reader will have to be reprogrammed for each new document design.

Magnetic Readers

–They use the principles of magnetism to sense the document characters that have been written using
magnetized ink.

–Example; Magnetic Ink Character Reader (MICR).

Magnetic Ink Character Reader (MICR)

–This is the machine recognition of characters printed with Magnetic Ink.

–The document characters are typed or printed in ink containing Iron (II) Oxide that gives them a
magnetic property.

Uses/ applications of MICR

Used in banks to process the many cheques being written each day.

In Local Authorities for payment of rates by installment.

Advantages of MICR over OCR

(i).A MICR can read data faster & accurate since the information on the document is usually pre-printed.
(ii).Difficult to forge.
(iii).Document can still be read when folded, written on, etc. This means that, MICR is more ‘robust’.
(iv).Faster than OCR. It is possible to read about 2,400 A4 sized documents 1 minute.

(g) Point-Of-Sale (POS) Terminals

–This is a general class of Input devices of which a Bar-code reader is an example.

–A POS terminal can be used as an Input device when online processing is required. Data arising out of a
transaction (e.g. item purchase) is entered on the terminal and is immediately processed by the computer.

–POS terminals are widely used in the Banks and in wholesale or retail industries, such as Supermarkets.
Each item in the store has a code; Universal Product Code (UPC) printed on it, which identifies the item.

–The POS terminal consists of a Numeric keypad & a few Control (Functional) keys for entering data, a
Screen and a Printer to print out the list of items and price for the customer.

–The Item code, Quantity & Price of the goods purchased by the customer is entered into the POS
terminal directly by the operator. The terminal produces the customer receipt. The details of the sales are
then entered directly into a backing storage device and the Stock level is also automatically decreased.

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Bar-Code Reader

–This is a device used to read the bar-codes printed on many items in Supermarkets & Pharmacies.

–Each item is given a code known as Bar-code (a Bar-code is a set of parallel bars of varying thickness &
spaces of varying widths representing a number code). A space represents a “0” while a bar represents a
“1”. The coded data can be read by using the principles of light.

–A computer is used to store the code of the items, item description, price, amount in stock, etc.

–When a Bar-code reader is moved across the bars by the Cashier, the reader scans the bar codes printed
on the item using a laser beam, which is then converted to a number (which is the code for the item).

–The interpreted data is sent to the computer memory and compared with standard codes stored in the
computer and is used to look up the price of the item. The details of the price and description are printed
out on a receipt for the customer. The Store Inventory may also be updated at the same time.

–Bar codes are also used in Library lending Systems.

Advantages of using a Bar-code reader

(i).They are very fast & accurate provided that the bar-code has been printed clearly. For example, if the
bar- code is soiled by dirty hands or has broken bars, errors may occur when an attempt is made to
read the code.

(ii).It is a cost-saving method.

(iii).Saves time. The prices do not have to be attached to each item in the store because the items details
are already held in a master file.

(iv).Does not require special skills to operate.
(v).It improves customer convenience.

Disadvantages of using a Bar-code reader

(i).Requires standby facilities.

(ii).Requires very expensive equipments.

(iii).The prices are not stamped on the product, and therefore, high chances of incorrect data being
entered.

(h) Direct Input from Instruments

–Sensors are devices that can be connected to computers & are used to record physical quantities like

Temperature, light, humidity.

–Examples of direct input instruments: -

(a).Sensors used to record temperature, light, humidity in a Green house to ensure the best conditions for

plant growth.

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4).A Cable - connects the mouse to the System unit.

–The mouse is mostly used with Graphical User Interfaces (GUIs). It issues commands to the computer
by activating certain simple graphic images called Icons displayed on the screen.

Using the Mouse

–To use a mouse, hold it in your hand and move it across a flat surface or on top of a table. When you
move the mouse, an arrow-shaped pointer called the Mouse pointer moves across the computer screen in
the same direction. The pointer is usually controlled by moving the mouse.

–To select an option/ item on the screen;

Position the tip of the pointer (cursor) over the item to be selected;

Press a button on the mouse to make your selection.

–When using the mouse, observe the following rules:

a).Place the mouse on a flat smooth surface.

b).Gently hold the mouse with your right hand, using the thumb and the two rightmost fingers.
c).The index finger should rest on the left button, while the middle finger rests on the right button.

Terminologies associated with the use of a Mouse

Point: - this means moving the mouse until the tip of the pointer on the screen is over the item you want
to select.
–To select an item on the screen, point the item, then press a mouse button. Use the Left button (Primary
button) for most tasks or the Right button (Secondary button) to quickly accomplish common tasks.

Clicking: - pressing & releasing the left mouse button once. A click usually selects an object/item on the
screen.

Double-clicking: - pressing the left button twice in a row (in a quick succession) without moving the
mouse. Double-clicking usually opens a file or starts a program.

Right-clicking: - pressing the right mouse button once (or, selecting an item by use of the right mouse
button).

–A right click usually displays a list of commands from which the user can make a selection. This list of
commands is called a Shortcut menu or Context-sensitive menu. This is because; the commands on this
menu apply to the specific item that has been right-clicked.

Drag and drop: This is whereby the user moves an item from one location on the screen to another.
–To move an item on the screen by dragging;

1.Point to the item you want to drag.
2.Press & hold down the left mouse button.
3.Slide the mouse until the pointer reaches the desired position on the screen while still holding down the
mouse button.

4.Release the mouse button to ‘drop’ the item in its new location.

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Examples of the commonly used Spreadsheet packages

-Some of the most common spreadsheet packages/application programs include:

Microsoft Excel (Ms. Excel).

VisiCalc – this was the 1st type of spreadsheet to be developed for PCs.

Lotus 123 – this is integrated software with spreadsheet module, graphs, and database.

Corel Quattro-Pro

Application areas of spreadsheets (Areas where Spreadsheets are used)

-Spreadsheets find their application in the following areas;

Accounting

-Spreadsheets provide an easy and streamlined means of financial management. They are mostly used by
Accountants to record their daily transactions and also to keep financial records.

-For example; a spreadsheet can be used to do the following:

Record sales and purchases.

Calculate profits.

Produce Invoices and also compile financial statements.

Prepare budgets.

Assist the management of an organization to monitor the current state of payments from
customers in relation to goods delivered.

Detect aged debtors (i.e. those who owe you for more than the allowed period).

Track the value of assets over time (i.e., Appreciation and Depreciation).

Note: Most spreadsheet programs come with inbuilt functions such as SUM, AVERAGE, PRODUCT, etc.,
which enable the Accountant to carry out his/her daily accounting tasks easily.

Data management

-A spreadsheet enables you to store large amounts of data in workbooks that contain one or more
worksheets. For example;

It enables the user to create, edit, save, retrieve and print worksheet data and records.

It enables data to be arranged neatly in tabular structure.

Related data can be typed on the same worksheet. If the data is on different worksheets, the
worksheets can be linked so that the data can be accessed easily.

-Some of the data management functions in spreadsheet programs include:

Sorting (i.e., arranging worksheet records in a particular order so as to easily access the data
items).

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