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Basics of information technology

Unit objectives Define “information technology” (IT),

distinguish between hardware and software, and identify types of computers

Identify the parts of a computer and the factors that influence computer performance

Differentiate between application and operating system software, and describe the software development process

Differentiate between LANs and WANs, and describe the Internet and intranets

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Topic A

Topic A: Overview of information technology

Topic B: Hardware and storage devices

Topic C: Software Topic D: Networks

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Hardware devices

The physical devices that make up a computer system

Examples of hardware: – Monitor – Mouse – Keyboard – Central processing unit (CPU)

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Software

The instructions that make a computer work

Can be stored on a computer’s hard disk or on an external storage device such as a floppy disk or CD-ROM

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Computer types

Mainframes Minicomputers Personal computers Portable computers Networked computers

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Mainframes

First computers, introduced in 1950s Used by large businesses Support 100 to 500 users Very expensive Used for very large processing tasks

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Minicomputers

Support 10 to 100 users Smaller and less expensive than

mainframes

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Personal computers (PCs)

Small, self-contained computers with their own CPUs

Used by home and business users

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Portable computers

Useful for people on the move Smaller and more lightweight than

PCs

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Networked computers

Connected to other computers Two common terminal types:

– Intelligent: Has its own OS– Dumb: Runs off the server’s OS

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Topic B

Topic A: Overview of information technology

Topic B: Hardware and storage devices

Topic C: Software Topic D: Networks

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The CPU

Controls computer processes Within the system unit Speed measured in gigahertz (GHz)

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Features of a CPU

Control unit:– Executes instructions in sequence– Controls movement of data in the PC– Is like a traffic light at a busy intersection

Arithmetic and logic unit (ALU):– Performs math and logic– Is like a small, powerful calculator

Memory access:– Provides access to memory for storage

of results for later use

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Input devices

Enter information into a computer Examples:

– Mouse – Keyboard – Trackball – Touchpad – Light pen – Joystick – Digital camera– Microphone– Bar code reader– Scanner

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Output devices

Send information out from a PC Examples:

– Speakers – Monitors – Printers

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Memory types

Random access memory (RAM) Read-only memory (ROM)

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RAM

Temporary storage for programs and other data while you work on them

Most PCs have at least 128 MB

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ROM

Small startup instructions placed in a permanent memory chip by the manufacturer

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Storage devices

Capacity measured in megabytes (MB)

Types:– Floppy disks– CD-ROMs– Hard disks– Zip disks– Tape drives

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Floppy disks

Store up to 1.44 MB of data Usually 3.5" square disks Removable

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Hard disks

Fixed permanently in a hard disk drive inside a system unit

Used to store the operating system, applications, and data

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CD-ROMs

Read-only memory devices (but CD-R and CD-RW discs are recordable)

Store up to 650 MB of data Portable and can be used on any

computer that has a CD-ROM drive

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Zip disks

Store up to 250 MB of data Used for backing up files or

transporting large files

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Tape drives

Work like a tape recorder Vary in capacity and access speed Relatively expensive Generally used to back up data

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Memory units

Smallest unit is a binary digit (bit):– Represented by 0 or 1

8 bits = 1 byte 1000 bytes = one kilobyte (KB) One million bytes = 1 megabyte (MB) One billion bytes = 1 gigabyte (GB) One trillion bytes = 1 terabyte (TB)

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Performance factors

CPU speed Amount of RAM Hard disk speed Hard disk capacity

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CPU speed

Governed by a clock Measured in millions of cycles per

second, or megahertz (MHz)– 700 MHz means 700 million operations

per second

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RAM

Measured in megabytes (MB) Most computers have at least 128 MB

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Hard disk speed and capacity

Speed is judged by how fast the disk can access files

Capacity is measured in gigabytes (GB)

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Topic C

Topic A: Overview of information technology

Topic B: Hardware and storage devices

Topic C: Software Topic D: Networks

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Operating system

Loads automatically when you switch on a computer

Main roles:– Controls hardware and software – Permits you to manage files – Acts as intermediary between user and

applications

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Application software

Performs specific tasks:

– Word processing

– Calculations

– Information storage and retrieval

– Accounting Cannot function without the OS

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Software development process

1. Research

2. Analysis

3. Programming

4. Testing

5. Release

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Topic D

Topic A: Overview of information technology

Topic B: Hardware and storage devices

Topic C: Software Topic D: Networks

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Local area network (LAN)

A network connecting computers at a single site

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Wide area network (WAN)

Network over many sites:– Across a country, such as a bank’s

network of automatic teller machines– Across the globe, such as a multinational

company’s communications network

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Public Switched Telephone Network (PSTN)

Regular telephone system Analog system (transmits in continuous waves) Uses a modem to convert between digital and

analog signals

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Integrated Services Digital Network (ISDN)

Digital Greater capacity than analog lines Allows simultaneous transmission of

voice, data, fax, and video

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The Internet

A vast network of computers throughout the world (a network of networks)

Requirements to connect:– ISP – Computer – Modem

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Intranets

Networks of computers used within a company or an organization

Benefits:– Sharing information among employees– Sharing resources and hardware

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Unit summary

Learned about information technology (IT), hardware, and software, and learned how to identify types of computers

Learned about computer hardware and the factors that influence computer performance

Learned the difference between application and operating system software, and learned about the software development process

Learned about the difference between LANs and WANs, and learned how to describe the Internet and intranets