What is a Computer? A computer is an electronic device operating under the control of instructions stored in its own memory unit, that can accept data.

What is a Computer?

A computer is an electronic device operating under the control of instructions stored in its own memory unit, that can accept data (input) process the data and generate results (output) and store the results for future use.

Hardware & Peripheral devices

• The electric, electronic, and mechanical equipment that makes up a personal computer is called hardware.

• Devices that surround the system unit (i.e., the keyboard, mouse, speakers, monitor, and so on) sometimes are known as peripheral devices.

• other devices (such as a scanner) that could be part of a computer system.

Information Processing Cycle

• Four general operations of computer

• Input

• Process

• Output

• Storage

Data Vs Information

• Data is a collection of raw facts, figures, and symbols, such as numbers, words, images, video and sounds

• Data is given to computer during the input operation

• Computers manipulate the data and produce organized, meaningful and useful information

Processing speed

• Today’s supercomputer can perform 1.8 trillion operations per second.

• If a person did one arithmetic operation a second without stopping, it would take more than 31,000 years to perform the number of operations a supercomputer can do in one second.

Computer users, end users or just users

• People who use the computer directly or use the information it generates are called computer users, end users, or sometimes, just users.

Why is a computer so Powerful?

• The power of a computer comes from its ability to perform the information processing cycle quickly, reliably (low failure rate), and accurately.

• capacity to store large amounts of information

• ability to communicate with other computers

Computer Program or Software

• A detailed set of instructions that tells computer exactly what to do to perform an operations are called a computer program or software.

What is the difference between hardware and software?

Hardware Vs Software

• A 3.5 inch floppy disk is a hardware but the program that is stored in a floppy disk is a software

• Computer programs are written using programming languages (such as BASIC, COBOL, C, Pascal, and so on) each of which has specific rules, or syntax, governing its use.

Components of a computer

• Six primary components of the computer are– Input devices– Processor (control unit and arithmetic/logic unit)– Memory– Output devices– Storage devices– Communication devices

The processor, memory, and storage devices are inside the system unit.

Input Devices

• An input device is an hardware component that allows you to enter data, programs, commands and so on in to a computer

• Different types of input devices are designed to transmit different types of data or to transmit data in different ways.

• The two primary input devices used are the keyboard and the mouse

Keyboard

• Keyboard contains keys you press to enter data into the computer

• A desktop computer keyboard typically has 101 to 105 keys

Mouse

• The mouse is called a pointing device because it controls the movement of a pointer, or mouse pointer, on the computer screen and make selections from the screen.

• The mouse either use optical sensor or ball that detects the movement of the mouse

Processor

• Also called Central Processing Unit

• It has two units: Control Unit and Arithmetic logic unit.

• The control unit interprets the instructions

• The arithmetic logic unit (ALU) performs logical and arithmetic operations.

• Example: Celeron, Athlon XP, Pentium processors

Memory

• Also known as RAM (Random Access Memory)

• It stores– Instructions– Data– Results (information)

• Amount of memory in computers typically is measured in kilobytes or megabytes

Output Devices

• Display the processed information

• Example: Printer, Display device

• Two types of printer– Impact– Nonimpact

Impact and non impact printer

• Impact printer prints by striking an inked ribbon against the paper– Dot matrix printer

• Non impact printers form characters by means other than striking a ribbon against paper– Laser printers– Ink-jet printers

Advantages of Non impact printers

• It can print higher quality text and graphics than an impact printer

• It also do better job printing different fonts

Display Devices

• A monitor is a display device that display the processed output.

• Two basic types of monitor– CRT (cathode ray tube)– LCD (liquid crystal display)

• CRT is the most common display device used with desktop computers

• LCD also called flat panel monitor uses a liquid display crystal, similar to digital watch, to produce images on the screen

• Monitor is composed of individual picture elements called pixels

Byte or Memory location

• 1 byte = 8 bits

• 1KB = about 1,000 bytes, (1024 or 2^10)

• 1MB = about 1,000,000 (one million) bytes, (1,048,576 or 2^20)

• 1GB= about 1,000,000,000 (one billion) bytes (1,073,741,824 or 2^30)

Storage Devices

• Storage devices are used to store instructions, data, and information when they are not being used in memory

• Six common types of storage devices are– floppy disks– zip disks– hard disk– optical discs– tape– Miniature storage media

Floppy Disks

• Floppy disk is a portable storage medium• It consists of a thin, circular, flexible plastic disk

with a magnetic coating enclosed in a square-shaped plastic shell

• A floppy disk drive is a device that can read from and write to a floppy disk

• Formatting is the process of preparing a disk for reading and writing by organizing the disk into storage locations called track and sectors

Zip Disks

• Portable magnetic media

• Hold about 500 times more than a standard floppy disk

• Used to back up important data and information

Hard Disk

• A hard disk consists of one or more rigid metal platters coated with a metal oxide material that allows data to be recorded magnetically

• personal computer hard disks usually are fixed (i.e., not removable),

• some portable computers have removable hard disk drives

Optical disc

• Uses laser technology for recording

• Two types of optical discs are CD (compact disc) and DVD (digital video disc)

• CDs are available in a variety of formats– CD-ROM– CD-R– CD-RW

Optical disc

• DVDs are available in the following formats– DVD-ROM– DVD-RW

TAPE

• Capable of storing large amounts of data and information at a low cost

• Primarily used for long-term storage and backup

Miniature Storage Media

• Rewritable media usually in the form of a flash memory card

• It is the primary storage media used with digital cameras, music players, PDAs and so on

Communication Devices

• Helps a computer to send and receive data, instructions, and information to and from one or more computers

• Communication occur over transmission media, such as cables, telephone lines, satellites

Computer software

• Can be categorized in to two types– System software– Application software

• System software is a program that controls the operations of computer equipment

• Operating system is a part of system software• Application software consists of program that tell

a computer how to produce information– Example: Word Processing, Spredsheet, database,

presentation graphics

Networks

• A network is a collection of computers and devices connected through the communication media such as cables, telephone lines, modems or other means– Local area network– Wide area network

Internet & Intranets

• Worlds largest network• Links millions of computers by means of cables,

telephone lines and other communication devices

• Users connect to the Internet either through an internet service provider or through an online service provider

• Intranet is a special type of web that is available only to the users of a particular type of computer network, such as a network used within a company or organization for internal communication.

World Wide Web

• Contains billions of document called web pages• Web site is a collection of web pages• Web browser helps to access and view web

pages• Each web page has a unique address called

URL (Uniform Resource Locator)• URL consists of a protocol, domain name, and

sometimes the path to a specific web page.• Web server is a computer that delivers

requested web pages

World Wide Web

• The first web page in the web site is called the home page

• A hyperlink is colored or underlined text or a graphic that, when clicked, connects to another web page

• Microsoft Internet Explorer is a widely used browser

Electronic Commerce

• Conducting business activities online

• Three types of e- commerce– Business to Consumer (B2C) Business selling

goods/products to the general public– Consumer to Consumer (C2C) Consumer

selling directly to another consumer– Business to Business (B2B) Business

provides goods and services to other businesses