Second Lecture

Computer Hardware and Software

INPUT DEVICES

Input devices are used to capture data into the computer or an information processing system

An input device is any piece of computer hardware equipment used to capture data into the computer system.

EXAMPLES OF INPUT DEVICES

Compact Disc (CD) - CDs store information.  The CD can then be put into another computer, and the information can be opened and added or used on the second computer. Note:  A CD-R or CD-RW can also be used as an OUTPUT device. Keyboard - The keyboard is a way to input letters or numbers into different applications or programs.  A keyboard also has special keys that help operate the computer.

• Mouse - The mouse is used to open and close files, navigate web sites, and click on a lot of commands (to tell the computer what to do) when using different applications. Digital Camera - A digital camera can be used to take pictures.  It can be hooked up to a computer to transfer the pictures from the camera to the computer.  Some digital cameras hold a floppy disk, and the floppy disk can be taken out of the camera and put directly into the computer.

• Drawing Tablet - A drawing tablet is similar to a white board, except you use a special pen to write on it and it's connected to the computer.  Then the word or image you draw can be saved on the computer.

Examples cntd• Microphone - A microphone is used to record

sound. The sound is then saved as a sound file on the computer. Scanner - A scanner is used to copy pictures or other things and save them as files on the computer. Disk Drive - A disk drive can hold a CD or a floppy disk. It reads the information on the disk so that the computer can use it.

• Joystick - A joystick is used to move the cursor from place to place, and to click on various items in programs.  A joystick is used mostly for computer games. Touch Screen - A touch screen is a computer screen or other screen that you can touch with your finger to enter information.  Examples of touch screens include a smart board, a microwave, a dishwasher, or an ATM at a bank. Bar Code Scanner - A bar code scanner scans a little label that has a bar code on it.  The information is then saved on the computer.  Bar code scanners are used in libraries a lot.

The Central Processing Unit ( CPU)

– Performs the actual processing of data.

– Often referred to as the “brain” of the computer.

– Responsible for controlling all activities of the computer system.

– Motherboard: The place where most of the electronics including the CPU are mounted.

The major components of the CPU are:

1. Arithmetic Logic Unit (Computations performed)

performs mathematical computations on Data (additions, subtrations, multiplication etc)

It can also perform simple logical tests for equality and greater than and less than between operands.

2. Control Unit

• controls the fetching of instructions from the main memory and the subsequent execution of these instructions.

• Among other tasks carried out are the control of input and output devices and the passing of data to the Arithmetic/Logical Unit for computation.

Main/Primary Memory• The primary memory of CPU is the place where

computer program and data is stored during processing.

• This storage unite is often called either main memory or primary memory.

• There two types primary memory

RAM (Random Access Memory)

ROM (Read Only Memory)

RANDOM ACCESS MEMORY(RAM)

• This is the section of the memory that is used to store data and information currently in use and it the memory that is immediately accessible to the user

• This type of memory enhances the speed of the computer

• The computer cannot function without RAM

RAM• Since RAM is volatile, as soon as the power

is switched off, all the information in the RAM is lost

Features OF RAM• It holds the data and instructions currently

in use

• Information in this memory can be read, written, and changed

• It is volatile

READ ONLY MEMORY(ROM)

• READ ONLY MEMORY CAN ONLY BE ACCESSED BUT CANNOT BE CHANGED.

• ROM IS USED TO STORE INSTRUCTIONS TO START UP THE COMPUTER AND CANNOT BE CHANGED BY THE USER.

Size of Memory

• The computer represents all data using just two numbers – 1s and 0s. These are called binary digits, or bits.

• A byte is a group of 8 bits.• An example of a byte could be 0 1 1 0 0 0 1 1.

Computer memory can store lots of bytes of data – the table below summarises the different memory sizes.

Unit Value Also equals . . .

bit 1 or 0

byte 8 bits

Kilobyte 1024 bytes

Megabyte 1024 Kilobytes 1,048,576 bytes

Gigabyte 1024 Megabytes 1,073,741,824 bytes

Output devices

• Output devices are basically used to get Information from the Computer.

• These are devices that display or output work done by a computer in a meaningful or readable format

Examples of output devices• Monitor - A monitor is the screen on which words, numbers,

and graphics can be seem. The monitor is the most common output

• Compact Disk - Some compact disks can be used to put information on. This is called burning information to a CD. NOTE: A CD can also be an input device.

• Printer - A printer prints whatever is on the monitor onto paper. Printers can print words, numbers, or pictures.

• Speaker - A speaker gives you sound output from your computer. Some speakers are built into the computer and some are separate.

• Disk Drives - A disk drive is used to record information from the computer onto a floppy disk or CD.

• Floppy Disk - A floppy disk is used to record information on. The information is stored on the floppy disk and can be used later or used on another computer.

• Headphones – Headphones give sound output from the computer. They are similar to speakers, except they are worn on the ears so only one person can hear the output at a time.

STORAGE DEVICES

• Storage devices are used to keep or store information for later use. Information processed by the CPU is saved onto a storage device.

• The Information can then be retrieved later for use again

• There are two types of storage devices used in computers;

primary storage device secondary storage device.

Secondary Storage Devices

• the devices of computer that store information such as software and data permanently are called secondary storage device .

• there are many types of secondary storage devices such as ,magnetic disk,Hard disk floppy disk , CD Rom , magnetic tape etc

EXAMPLES OF SECONDARY STORAGE DEVICES

Hard disksFloppy DisksData CartridgesCD-ROMMagnetic DisksZip DisksFlash Memory/Memory stick

Interface Devices• An interface device (IDF) is a

hardware component or system of components that allows a human being to interact with a computer, a telephone system, or other electronic information system

Centralised Computer System

• In a centralised Computer system, the central computer does all the processing and storage of data.

• The centralised computer controls all operations and workstations are for data input and output

Centralized data processing. • All data processing operations and

calculations are executed by the central computer.

• The different departments have terminals, linked to the central computer.

• Centralized data. Data is stored in a centralized data storage under the control of the central computer.

Example of a Centralised Computer System• Airplane ticket reservation service is a typical

example of a centralized system.

• There is one central computer that serves a lot of ticket sell desks.

• It keeps up data about all flights and vacancies.

• All ticked reservation activities are performed in the central computer, while there are terminals only at the sell desks for order input and printing of the results.

ADVANTAGES OF A CENTRALISED SYSTEM

• The main advantages are:

• easy to manage, less personnel costs.

• one computer is enough to support several information systems in the company

• Centralised management of all users, processes, applications, backups and security

• Has lower costs of ownership

• Centralised file storage

Disadvantages of A centralised system

• When the Central Computer goes down, everyone in the company will be down as well.

• There is also risk of data loss when data is controlled at the central position

DISTRIBUTED SYSTEMSWhat is a distributed system?

• Andrew Tannenbaum defines it as follows:

• A distributed system is a collection of independent computers that appear to its users as a single coherent system.

• A simpler definition would be as follows

• A distributed system is a collection of independent computers that are used jointly to perform a single task or to provide a single service.

THE ADVANTAGES OF DISTRIBUTED SYSTEMS

• Cost. Better price/performance

• Performance. By using the combined processing and storage

• capacity of many nodes, performance levels can be reached that are out of the scope of centralised machines

Advantages cntd.

• Scalability. Resources such as processing and storage capacity can be increased incrementally

• Reliability. By having redundant components, the impact of hardware and software faults on users can be reduced

THE DISADVANTAGES OF DISTRIBUTED SYSTEMS

• New component: network. Networks are needed to connect independent nodes, are subject to performance limits, and constitute another potential point of failure

• Security. It is easier to compromise distributed systems

Disadvantages cntd.

• Software complexity. Distributed software is more complex and harder to develop than conventional software hence, it is more expensive and harder to get right

• Distributed systems are hard to build and understand

Client Server System

• A computing system that is composed of two logical parts:

• a server, which provides services, and • a client, which requests them.

• The two parts can run on separate machines on a network, allowing users to access powerful server resources from their personal computers.

Advantages Of Client/Server Systems• Reduction of responsibilities and cost

overhead at centre

•  Better local cost control of operations  and development

• Faster response time to requests for processing

• Greater access to corporate data and knowledge otherwise maintained in a highly protected and centralized data structure

• Enable distribution of processing from centralized to desktop computing.

• Offers cooperative processing between individuals and group departments across organizational  boundaries, geographies and time zones

• Security

+  One machine can secure entire network +  One central login.

• Scalability

+  Easy to add new resources

• Offers more friendly interfaces for end users – especially knowledge workers and customers.

• Greater involvement of end users in IT implementation

• Centralised Resources +  All data stored in one location +  Easier to backup files and data +  Easier to find files and data

• Efficient

+  Software optimised for multiple users +  Hardware optimised for multiple users

Disadvantages of Client Server

+ If the server goes down, it takes part or the whole network with it.

+ It is more expensive to install.

+ Needs to be maintained by staff with high IT skills.

COMPUTER SOFTWARE

Computer Software

• The term “Computer Software” refers to a set of instructions given to the computer to perform a specific task.

• The set of instructions is called a computer program.

• The user needs to understand some software concepts to be able to interact with the computer

Categories of Software

There are two types of Software:

• SYSTEMS SOFTWARE

• APPLICATIONS SOFTWARE

Computer Components (Software)Computer Components (Software)

– System SoftwareSystem Software• Programs that control the operations of the

computer and its devices• Example is the Operating Systems e.g.

Microsoft XP

– Application SoftwareApplication Software• Specific programs that are used to perform

specific tasks• Examples are Microsoft Word, Microsoft

PowerPoint etc

SYSTEMS SOFTWARE

SYSTEM SOFTWARE OVERVIEW

• System software consists of programs that manage and support a computer system and its information processing activities.

System Management Programs

Programs that manage the hardware, software, and data resources of the computer system during its execution of the various information processing jobs of users. They include:

• Operating Systems

• Network Management Programs

• Database Management Systems

• System Utilities

System Development Programs

• Programs that help users develop information system programs and prepare user programs for processing. Major development programs include:

• Programming Language Translators and Editors

• Programming Tools

• CASE (Computer-Aided Software Engineering) Packages

OPERATING SYSTEMS• The most important system software package for any

computer is its operating system. An operating system is an integrated system of programs that:

• Manages the operations of the CPU

• Controls the input/output and storage resources and activities of the computer system

• Provides various support services as the computer executes the application programs of users.

Primary purpose of the operating system is:

• Maximize the productivity of a computer system by operating it in the most efficient manner.

• Minimize the amount of human intervention required during processing.

• Helps your application programs perform common operations such as accessing a network, entering data, saving and retrieving files and printing or displaying output.

Operating System Functions

The User Interface

The user interface is the part of the operating system that allows the end user to communicate with the operating system so they can load programs, access files, and accomplishes other tasks. Three main types of user interfaces are:

• Command Driven

• Menu Driven

• Graphical User Interface (GUI)

Trend

Moving Away From: • The entry of brief end user commands, and choices

from menus of options

Moving Towards: • Easy-to-use graphical user interface (GUI), which

uses icons, bars, buttons, boxes, and other images relying on pointing devices, like the electronic mouse or trackball to make selections that help you get things done.

• What is a graphical user interface (GUI)?Allows you to Allows you to interact with interact with the software the software using graphics using graphics and iconsand icons

Controls how Controls how you enter data you enter data and how the and how the screen displays screen displays informationinformation

Resource Management

An operating system uses a variety of resource management programs to manage the hardware and networking resources of the computer system, including its:

• CPU• Memory• Secondary Storage Devices• Telecommunications processors• Input/Output Peripherals

Memory management programs:

• Keep track of where data and programs are stored.

• May also subdivide memory into a number of sections and swap parts of programs and data between main memory and magnetic disks or other secondary storage devices.

File Management

File management programs of an operating system:

• Control the creation, deletion, and access of files of data and programs.

• Keep track of the physical location of files on magnetic disks and other secondary storage devices, such that each application program is running independently at the same time.

Task Management

• Task management programs of an operating system:

• Manage the accomplishment of the computing tasks of end users.

• Allocate CPU time to tasks and interrupt tasks being executed to substitute other tasks.

• May involve a multitasking capability where tasks of several programs can process at the same time.

Popular Operating Systems

• MS-DOS• Windows 95/200/Vista/XP/7/8• Linux• Unix

APPLICATION SOFTWARE

Application Software• What is application software?

Programs that perform specific tasks for users

Types of Application SoftwareProprietary

– Designed to solve a unique and specific problemIn-house

– Development of application software using the company’s resources

Contract– Developed for a particular company

Off-the-shelf– An existing software program that can be used

without considerable changes expected

Application software

Off-the-shelf software

Standard package

Customized package

Contract

Proprietary software

In-house developed

In-house customized

Contract customization

Application Software• How is software distributed?

Packaged software

Custom software

Shareware, distributed free for trial period

Freeware, copyrighted software provided at no cost

Public-domain software, freeware with no copyright restrictions

Business Software Software that assists people in becoming more effective and efficient

Business Software

What is word processing software? Allows users to create and manipulate text and graphics

documents

What is voice recognition? The computer’s capability of distinguishing spoken words

What is spreadsheet software? A spreadsheet is an interactive computer application program

for organization, analysis and storage of data in tabular form.

What is database software? A Database is a software tool that allows multiple users to store,

access, and process data into useful information.

Business Software

What is presentation graphic software? Used to create visual aids for presentations. A presentation is sometimes called a slide show e.g. Ms Power

point.

What is note taking software? Enables users to enter typed text, handwritten comments,

drawings, or sketches anywhere on the page

What is PDA software? Allows PDA users to create documents, take notes, manage

budgets, view photographs, and more

Business Software

• What is a software suite?

A collection of individualapplications sold as

a single package

A collection of individualapplications sold as

a single package Two major advantages:Two major advantages:

lower cost ease of use

SOFTWARE SUITES

These are a combination of the most widely used application packages that come bundled together.

They include suites such as • Microsoft Office,• Lotus SmartSuite, • Corel WordPerfect Office, • Sun’s Star Office.

Advantages of software suites:

• These software tools can be used to increase your productivity, collaborate with your colleagues, and access intranets, extranets, and the Internet.

• Suites integrate software packages for web browsing, word processing, spreadsheets, presentation graphics, database management, personal information management, and more.

• Suites cost a lot less than the total cost of buying their individual packages separately.

• All programs use a similar graphical user interface which gives them the same look and feel, and make them easier to learn and use.

• Suites also share common tools, such as spell checkers and help wizards to increase their efficiency.

• Programs are designed to work together seamlessly and import each other’s files or transfer data between applications

• They are easy to install and deploy

• Software is available immediately

Disadvantages of software suites:

• Critics argue that most end users never use many software suite features.

• Suites take up a lot of disk space and may require significant amounts of memory.

• Suites may compromise on the speed, power, and flexibility of some of their functions to achieve integration.

• Integrated packages

• May not meet the requirements of the users

Business SoftwareWhat is project management software?

Allows you to plan, schedule, track, and analyze the events, resources, and costs of a project

What is accounting software?• Helps companies record and report their financial

transactions

Graphics and Multimedia Software

•What are some popular graphics and multimedia software products?

Graphics and Multimedia Software

• What is computer-aided design (CAD)? Software that allows you to create engineering, architectural, and scientific designs

Graphics and Multimedia Software

• What is desktop publishing software? Enables you to design and produce sophisticated

documents that contain text, graphics, and brilliant colors

Graphics and Multimedia Software

• What is paint/image editing software?

Used to create and modify graphical images

Sometimes called illustration software

Graphics and Multimedia Software

• What is video and audio editing software? Video editing software allows you to modify a segment of a video, called a clip

Audio editing software allows you to modify audio clips

Graphics and Multimedia Software

animation

graphicalimages

audio

videoorganize

managemaintain

Web pagesand/or

Web sites

Allows users of all skill levels to create Web pages Some application software programs include Web page authoring

programs

What is Web page authoring software?

Software for Home, Personal, and Educational Use

•What software products are available for home, personal,and educational use?

InstantInstantmessagingmessaging

NewsgroupsNewsgroupsFTPFTP

Application Software for Communications

• What software facilitates communication?

VideoVideoconferencingconferencingChat roomsChat rooms

WebWebbrowsersbrowsersE-mailE-mail

Self-directed, self-paced instruction on a topic on the Web Distance learning (DL) is

the delivery of education at one location while the learning takes place at other locations

Applications on the Web

• What is Web-based training (WBT)?