What Is a Computer and What Does It Do?

Computer: programmable, electronic device that accepts data, performs operations, presents the results, and can store the data or results

Input—entering data into the computerProcessing—performing operations on the dataOutput—presenting the resultsStorage—saving data, programs, or output for

future use

What Is a Computer and What Does It Do? Cont’d

Data vs. Information

• Data = raw, unorganized facts– Can be in the form of text, graphics, audio, or

video

• Information = data that has been processed into a meaningful form

• Computers process data into information

The components of a computer

• 6 Primary components– Input devices– Processor– Memory– Output devices– Storage devices– Communication devices

• All the components are housed in a box called the system unit

Hardware

• The physical parts of a computer are collectively referred to as hardware

– Internal hardware: located inside the main box (system unit) of the computer

– External hardware: located outside the system unit and plug into connectors called ports located on the exterior of the system unit

Storage Devices

• Used to store instructions data and information when they are not being used for memory

• Disks

• Tape

• Mobile Storage

Communication Devices

• Hardware component that allows a computer to send and receive data, instructions and information to and from 1 or more computers

• Communications occur over transmission media

INPUT AND OUTPUT

• Hardware that allows you to enter data, programs or commands

• Keyboard• Mouse• Scanner• Microphone

• Hardware that makes the information that was processed available for use

• Printers• Display devices• Speakers

Software

• The programs or instructions used to tell the computer hardware what to do

• System software: allows a computer to operate

• Operating system: the main system software program– Boots the computer and launches programs etc. at

the user’s direction– Windows, Mac OS, Linux, etc.

Software

• Application software: performs specific tasks or applications– Creating letters, budgets, etc.– Managing inventory and customer databases– Scheduling appointments– Viewing Web pages– Sending and receiving e-mail– Designing homes– Playing games– And much, much more

Electrical Components

• Electrical components include:– Motherboard– Processor

• ALU• CPU

– Memory• Usually measured in kilobytes (1,000 bytes),

megabytes (1 million) or gigabytes (1 billion)• A byte is equal to one character

Computers to Fit Every Need

• Five basic categories

– Mobile devices

– Personal computers

– Midrange servers

– Mainframe computers

– Supercomputers

Mobile Devices

• Very small device with some type of built-in computing or Internet capability

• Typically based on cellular phones• Smart phones can be used to access

the Web and e-mail, take photos, play games, access calendars, and address books

• Smart watches can download information from the Internet, store data, play music files, etc.

Personal Computers

• Small computer system designed to be used by one person at a time; small enough to fit on a desktop, inside a briefcase

• Also called a microcomputer• PC-compatible: evolved from the original IBM PC;

typically runs the Windows operating system• Macintosh: type of personal computer manufactured

by Apple, uses the Mac OS operating system• Can be desktop, notebook, tablet, or handheld

computers

Desktop PCs

• Desktop PC: the complete computer system fits on or next to a desk; case styles include:

• Tower

• Desktop

• All-in-one

Midrange Servers

• Minicomputer or midrange computer: medium-sized computer used to host programs and data for a small network

• May consist of a collection of individual circuit boards called blades (blade servers)

Mainframe Computers

• Standard choice for large organizations, hospitals, universities, large businesses, banks, government offices

• Larger, more expensive, and more powerful than midrange servers; usually operate 24 hours a day

• Also called high-endservers or enterprise-class servers

Supercomputers

• Fastest, most expensive, most powerful type of computer

• Space exploration, missile guidance, satellites, weather forecast, oil exploration, scientific research, complex Web sites, decision support systems, 3D applications

• Commonly built by connecting hundreds of smaller computers, supercomputing cluster

Supercomputers, Cont’d

Computer Networks and the Internet

• Computer network: collection of hardware and other devices that are connected together so that users can share hardware, software, and data, as well as communicate with each other

• Network servers: manage resources on a network

• Clients: computers on a network that access resources through the network server

• Computer networks exist in many sizes and types

What Are the Internet and the World

Wide Web?• Internet: largest and most well-known computer

network in the world• Individuals connect to the Internet using an

Internet service provider (ISP)• Most common Internet activities: e-mail and

accessing the World Wide Web (WWW)• “Internet” refers to the physical structure of that

network, the World Wide Web is one resource (a vast collection of Web pages) available through the Internet

Accessing a Network or the Internet

• Need a modem or network adapter to physically connect your computer to the network

• Software (often built into the operating system) allows you to log on to the network and access resources

• Many networks and Internet connections require a user ID and password to log on to the network

Accessing a Network or the Internet, Cont’d

• Internet addresses are used to access resources on the Internet– IP address —numeric address that identifies

computers (207.46.138.20)– Domain name —text-based address that

idenfies computers (microsoft.com)– Uniform resource locator (URL) —identifies

Web pages (http://www.pbskids.org)– E-mail address —identifies people for e-mail

exchange (jsmith@thomson.com)