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© Math & Computer Department Foundation Program

Spring 2006

Essential Computing Concepts

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• People: the most important part

• Hardware: consists of the equipment: keyboard, monitor, etc…

• Software: refers to the programs and its purpose is to convert data into information

• Data: unprocessed facts, and once processed, it becomes information

• Procedures: guidelines for people to follow when using software, hardware, and data

Information SystemInformation System

An Information System has the following parts:

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A Computer Information A Computer Information SystemSystem

Guidelines/Protocol/

Procedures

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What is a Computer?What is a Computer?

Hardware Software

Equipment Programs

Hardware:Physical parts of the computer that you can touch or see

Software: A computer software is made up of instructions to perform one or more tasks e.g. Microsoft Word, Games, etc

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Any Computer System

Memory

Central processing unit(CPU)

Input

Hard Disk

Output

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Main Parts of a PC include:Main Parts of a PC include:

• The System Unit

• Input / Output Devices

• Secondary storage Devices

• Communication Devices (Sends and receives data and programs from

one computer to another )

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The System UnitThe System Unit

• The Motherboard, CPU, RAM, ROM, Hard Drive, Video Card and Power Supply are all inside the System Unit

• Ports are used to connect Input, Output, Secondary Storage and Communication devices to the System Unit

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The MotherboardThe Motherboard

• Everything inside the system unit is connected to the motherboard

• Cards are plugged into slots on the Motherboard

• Example: Graphics Card, Sound Card, Network Card

• Hard drive is connected by cables

• CPU is a silicon chip on the motherboard

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CPU(Central

Processing Unit)

RAMRandom Access Memory

(Main Memory)

Extension slots

ROM (Read Only Memory)

MotherboardMotherboard

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The CPUThe CPU

• Central Processing Unit (or Processor)

• The brain of the computer

• Does all the Calculation and Processing

• Contains:

– Control Unit: interprets instructions

– Arithmetic Logic Unit (ALU): performs logical & arithmetic operations

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The speed of the CPUThe speed of the CPU

• Measured in Hertz• 1 Hertz = 1 cycle per second• 1 cycle = 1 addition• Megahertz = 1,000,000 cycles/second• Gigahertz = 1,000,000,000 cycles/second• Typical speed of modern CPU is 3 GHz

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Random Access MemoryRandom Access Memory(RAM)(RAM)

• Electronic Components that temporarily store data (numbers, text, graphics, etc) being processed

• All programs and data are loaded into RAM

• Volatile – is deleted when the computer is switched off

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Read Only MemoryRead Only Memory(ROM)(ROM)

• A set of chips containing permanent (non-changeable) instructions to make the computer start working

• Can be read but cannot be written to

• ROM-BIOS – When the computer is switched on, these instructions check the computer and load the operating system into RAM

• Test is called POST– Power On System Test

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Input DevicesInput Devices

• Mouse• Keyboard • Scanner• video camera• light pen• Joystick etc…

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Output DevicesOutput Devices

• Monitor/Screen (VDU – Visual Display Unit)

• Printers– Laser printers

– Inkjet printers • Plotters• Speakers etc…

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Secondary Storage DevicesSecondary Storage Devices• Provide Permanent Storage• Common Storage Devices are:

– Hard (Fixed) Disk : Consists of 1 or more rigid metal platters coated with a metal oxide material for recording.

– Floppy disk : Consists of thin, circular, flexible plastic disk with magnetic coating.

– CD (Compact Disk) : Flat, round, portable, metal storage. Uses laser technology.

– DVD (Digital Versatile Disk)– Flash Memory: Uses a USB connector

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Formatting Floppy DiskFormatting Floppy DiskTracks and SectorsTracks and Sectors

Track

Sector

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CPU

RAM

HARD DISK

CD

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Ports and BusesPorts and Buses• Located on the system

unit• Used to connect

peripherals (any outside device you can attach to your computer)

• Types:– Serial Port– Parallel Port– Universal Serial Bus

(USB)

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Serial PortsSerial Ports

• Serial – data transferred bit by bit

• Normally two: COM1 and COM2

• Used to connect devices such as modems

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Parallel PortsParallel Ports

• Transfer more than one bit in one read/write

• Used to connect devices such as printers

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• Serial – one bit in one read/write

• Used for devices like scanners, digital cameras and flash drives

UniversalUniversal Serial Bus (USB) Serial Bus (USB)

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Supercomputer: The fastest and most expensive high-capacity computers used by very large organizations

Mainframe: Large computers, capable of great processing speeds and data storage

Minicomputer: midrange computers used by medium-sized companies

Microcomputer: Least powerful, small computers, but most widely used (desktop, Notebook or laptop, and Personal Digital Assistants)

Types of ComputersTypes of Computers

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SUPERCOMPUTER•Most Powerful computers

•Fastest, can perform morethan one trillion calculationsper second

MAINFRAME•Used in large organization

•Not as powerful as the Supercomputer

•Capable of very high processing Speeds and data storage

MINICOMPUTER•Midrange computers

•used by medium-sized organist ions

MICROCOMPUTER•Mostly for personal useE.g. Desktop PC, Laptop, PDA etc

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Computer = Hardware + Software

• Hardware : refers to the Equipment

• Software : refers to the Programs– A program is a set of instructions which

tells the computer how to do its work

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Types of SoftwareTypes of Software

• System Software : Programs to control the operation of the computer– E.g. Operating System (Windows, Unix, Linux etc), Utility Programs, Device Drivers

• Application Software : Programs for various applications– E.g. Programs for word processing, business,

scientific and other applications such as Microsoft Office which consists of MS Word, MS Excel etc.

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Hardware

System

Application

S / W Back-end

Front-end

E.g. Operating system such as Windows XP

E.g. End-user programs such as MS Word

Types of Software

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ConnectivityConnectivity• Connectivity is the capability of your

microcomputer to share information with other computers

• Central to the concept of connectivity: Network

• Network– A communications system connecting two or

more computers– The largest network in the world is Internet

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Data StorageData Storage

• A Bit (short for Binary digit) is the smallest unit of storage in the computer. It represents a pulse of electricity: Off = 0, On = 1

• All numbers in the computer must be represented by Bits (0 or 1). We cannot do this with decimal numbers, so instead we use binary numbers

• Storage capacity: The amount of information that can be stored in a secondary storage device or in memory

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Data StorageData Storage• All the information are stored in the computer

storage devices (such as hard disk) in Binary format

• Binary Number System is made up of only two value or numbers: 0 or 1. Hence it is known as Base 2 number system.

• A bit is a binary digit having a value 0 or 1.

Example:012 2 bit

0102 3 bits

10102 4 bits

• A group of 8 bits = 1 byte 010100102 = 1 byte

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How your PC sees dataHow your PC sees dataData representation is the process of changing the data into a form that computers can understand and process.

Most computers are digital devices, devices that work with separate, discrete data, such as the digits 1 and 0.

Some are analog devices, devices that work with a continuous range of data.

A light switch is digital.

The light is either on, represented by a 1, represented by 1010. These 1s and 0s are binary digits. Binary digits are also called bits.

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Now, if you type letter “A” in your computer, how do we know thenumber of bits and the bit order of letter “A”?

ASCII EXTENSION CODEThis is a code that represents the characters and their binary code as shown below:

Binary Symbol

01000001  A

01000010 B

01000011 C

01000100 D

01000101 E

01000110 F

01000111 G

01001000 H

01100001  a

01100010 b

01100011 c

01100100 d

01100101 e

01100110 f

01100111 g

01101000 h

Using the extended ASCII table if you write the following in your PC: “Baba” What will be the binary format in which this data is going to saved by the computer?

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Binary Storage Capacity

Unit Value

KB (Kilobyte) 210 Bytes = 1024 Bytes(approx 1,000 bytes)

MB (Megabyte)

220 Bytes = 1024 KB(approx 1,000,000 bytes)

GB (Gigabyte) 230 Bytes = 1024 MB

TB (Terabyte) 240 Bytes = 1024 GB

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Storage Capacity Storage Capacity

Temporary Storage • Random Access Memory (RAM) 256MB – 1GB

Permanent Storage• Floppy Disk 1.44 MB • CD (Compact Disk) about 700 MB • DVD (Digital Versatile Disk) 4 - 8.5 GB • Hard Disk 40 – 120 GB

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Binary Numbering SystemBinary Numbering System

• Base 2 • Consists of only two digits: 0 and 1• Converting a binary number to decimal

(Example): 1101 (binary) = 1*23 + 1*22 + 0*21 + 1*20

= 1*8 + 1*4 + 0*2 + 1*1 = 8 + 4 + 0 + 1 = 13 (decimal) 

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Storage Capacity Storage Capacity

Temporary Storage • Random Access Memory (RAM) 256MB –

1GB

Permanent Storage• Floppy Disk 1.44 MB • Hard Disk 40 – 120 GB • CD (Compact Disk) about 700 MB • DVD (Digital Versatile Disk) 8.5 GB • DAT tapes 4 GB

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Occupational Health & SafetyUsing the computer for long periods of time, may pose risk to health.

Ergonomics:• Position of the monitor – Frame above screen should be level with eyes, so that you look slightly down. Distance should be less than an arm’s length. Avoid screen reflection and flickering.• Posture of the user – Chair back upright, lower back supported, feet flat on floor, Forearms should be horizontal, wrists straight and task materials within comfortable reach of both hands.

Preventive exercises should be done before commencing work, during work and after lunch breaks.• Eye exercises: Take frequent short rests: Look away from screen towards objects 20-30 ft away, or look outside the window far out, or close your eyes.• Muscle exercises: Do neck exercises. After every hour walk around, stretch all muscles and perform whatever relieves the feeling of muscle fatigue/strain

Suggested reading: www.healthycomputing.com/office