The document provides an introduction to computers by defining what a computer is, describing its basic components and functions. It explains that a computer accepts data as input, processes it, produces output and stores results. The main components are the processor, memory, storage devices, input devices like keyboards and mice, and output devices like monitors and printers. It also discusses computer software, networks, the internet and how computers are used for electronic commerce.

1. Introduction to
Computers
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2. What is a computer?
 Computer
 an electronic device, operating under the control of
instructions stored in its own memory unit
 this memory unit can
 accept data – input
 manipulate data – process
 produce information – output
 store results for future use - storage
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3. What does a computer do?
 Computers perform four general operations
 input, process, output, and storage
 Information processing cycle
 inputting, processing, outputting, and storing make-up this cycle
 Processing requires data
 data – collection of raw facts, figures, and symbols given to a
computer during the input operation
 Manipulate data to create information
 information – data that is organized, meaningful, and useful
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4. Why is a computer so powerful?
 Power is derived from the computer’s capability
to perform the information processing cycle with
speed, reliability, and accuracy
 The computer’s capacity to store huge amounts of
data and information
 The computer’s ability to communicate with other
computers
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5. How does a computer know
what to do?
 It must be given a detailed set of instructions
 These instructions are called a computer program
or software
 Executes one program instruction after another
until the job is complete
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6. What are the components
of a computer?
 Six primary components
 input devices
 the processor
 memory
 output devices
 storage devices
 communications devices
 the processor, memory, and storage device are
housed in a box-like case called the system unit
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7. Input Devices
 Input device – any hardware component the
allows you to enter data, programs, commands,
and user responses into a computer
 primary input devices
 keyboard
 mouse
 other input devices
 digital camera
 scanner
 microphone
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8. Input Devices con’t…
 The Keyboard
 desktop computer keyboard typically has 101 to 105 keys
 handheld computers use an onscreen keyboard and use a stylus to
select keys
 The Mouse
 a pointing device that fits under the palm of your hand
 control the movement of the pointer on the screen and make
selections from the screen
 one to five buttons
 bottom is flat and contains a mechanism or ball that detects
movement
 notebooks have a pointing device built into the keyboard
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9. Processor
 Processor or Central Processing Unit (CPU) –
interprets and carries out the basic instructions that
operate a computer
 made up of the control unit and arithmetic/logic unit
 control unit – interprets the instructions
 arithmetic/logic unit – performs the logical and arithmetic
processes
 42 million transistors and performs operations 10 million
times in a tenth of a second
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10. Memory
 Memory or Random Access Memory (RAM) –
electronic components that store instructions waiting to
be executed by the processor, data needed by those
instructions, and the results of processed data
 consists of one or more chips on the motherboard
 motherboard or system board – main circuit board to which
electronic components are attached
 memory is measured in kilobytes or megabytes
 1 kilobyte (K or KB) = 1,000 memory locations
 1 megabyte (M or MB) = 1,000,000 memory locations
 memory location or byte – stores one character 10

11. Output Devices
 Output devices – make information from
processing available for use
 can be presented in many forms
 printed report or displayed on a screen
 printers and display devices are common output
devices for word processing, spreadsheets, and
database management
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12. Output Devices con’t…
 Printers
 two kinds of printers
 impact printers – strikes an inked ribbon against the paper
(dot matrix printer)
 Nonimpact printers – form characters by means other than
striking a ribbon against paper (ink-jet printers or laser
printers)
 advantage – print higher-quality text and graphics, better job
printing different fonts, quieter, can print in color
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13. Output Devices con’t…
 Display devices – an output device that visually conveys text,
graphics, and video information
 monitor – plastic or metal case that houses a display device
 three types of monitors – CRT, LCD and LED
 cathode ray tube (CRT) – television- like, most common
 LCD or flat panel monitor – uses a liquid display crystal, similar to a digital
watch.
 LED-Light Emitting Diode
 surface of screen is composed of individual picture elements called
pixels
 resolution of 800 x 600 = 480,000 pixels
 each pixel can be illuminated to form parts of a character or graphic shape on
the screen
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14. Storage Devices
 Storage devices – used to store instructions, data,
and information not being used in memory.
 six types of storage devices
 floppy disks
 zip disks
 optical discs
 tape
 miniature storage media
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15. Storage Devices con’t…
 Floppy disks or Diskette
 portable, inexpensive storage medium that consists of a thin,
circular, flexible plastic disk with a magnetic coating enclosed in a
square-shaped plastic shell
 typically can store up to 1.44 megabytes of data or 1,474,560
characters
 a portable storage medium
 portable means you can remove the medium from one computer and
carry it to another computer
 floppy disk drive – device that can read from and write to a floppy
disk
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16. Storage Devices con’t…
 Floppy disks con’t…
 a type of magnetic disk, which uses magnetic patterns to store items
on its surface
 read/write storage media
 can access (read) data from and place (write) data on a magnetic disk
 must be formatted
 formatting – process of preparing a disk for reading and writing by
organizing the disk into storage locations called tracks and sectors
 track – a narrow recording band that forms a full circle on the surface of the
disk
 sector – capable of holding 512 bytes of data
 80 track per side and 18 sectors per track
 access time – time required to access and retrieve data
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17. Storage Devices con’t…
 Zip Disk – portable magnetic media
 can store up to 750 MB
 can be built-in or external
 make it easier to transport many files or large items
 graphics, audio, or video files
 back up important data and information
 backup – a duplicate of a file, program, or disk that you can
use in case the original is lost, damaged, or destroyed
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18. Storage Devices con’t…
 Hard Disks – consists of one or more rigid metal
platters coated with a metal oxide material that allows
data to be recorded magnetically
 data is recorded on a series of tracks
 spin 5,400 to 7,200 revolutions/minute
 number of platters vary
 storage capacity one billion characters to more than 200
billion characters
 1 billion bytes = 1 gigabyte (GB)
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19. Storage Devices con’t…
 Optical Discs – storage medium that consists of a
flat, round, portable, metal storage medium
 4.75 inches in diameter
 less than 1/20 of an inch thick
 Two types of optical discs
 CD
 DVD
 Variety of formats
 CD-ROM, CD-R, CD-RW, DVD-ROM, DVD+RW
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20. Storage Devices con’t…
 CD-ROMs or Compact Disc Read-only Memory- type of
optical disc that uses laser technology for recording
 can contain audio, text, graphics, and video
 can only read, cannot erase or modify the content
 holds 650 MB – 1 GB of data
 CD-R or Compact Disc-recordable – multisession optical
disc that you can record your own items on
 can read from many times
 can write on each part only one time
 cannot erase
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21. Storage Devices con’t…
 CD-RW or Compact Disc-rewritable – an erasable disc
you can write on multiple times
 write and rewrite data, instructions, and information multiple
times
 DVDs – technology that can be used to store large
amounts of text and even cinema-like videos
 DVD-ROM or digital video disc-ROM – high capacity optical
disc
 store 4.7 GB to 17 GB
 read-only
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22. Storage Devices con’t…
 DVD+RW or DVD-Rewriteable – can erase and
record multiple times
 major use
 edit videos from a video camera or VCR, stored and edited on
your computer, and then written to a DVD+RW disc
 Tape – magnetically coated ribbon of plastic housed
in a tape cartridge capable of storing large amounts of
data and information at a low cost
 primarily used for long-term storage and backup
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23. Storage Devices con’t…
 Miniature Storage Media – rewritable media in
the form of a flash memory card
 solid-state device that consists entirely of electronics
and contain no moving parts
 used with PDAs, digital cameras, music players, and
smart phones
 used to store digital images, music, and documents
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24. Communications Devices
 Communications Device – hardware component
that enables a computer to send (transmit) and
receive data, instructions, and information to and
from one or more computers
 widely used communication device is the modem
 communications occur over transmission media
 cables, telephone lines, cellular radio networks, and satellites
 some are wireless
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25. Computer Software
 two types of software
 System Software
 Application Software
 System Software – programs to control the operations of
computer equipment
 Operating System – set of programs that tell the computer how to
perform the functions of loading, storing, and executing an
application program and how to transfer data
 booting – when a computer is turned on, the operating system is
loaded into the computer’s memory from auxiliary storage
 Graphical User Interface (GUI) – visual cues or icon symbols
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26. Computer Software con’t…
 Application Software – programs that tell a
computer how to produce information
 Examples – personal information manager, accounting,
computer-aided design, desktop publishing, picture and
video editing, and educational
 Commonly Used Applications – word processing,
electronic spreadsheet, and presentation graphics
 Software Package – Microsoft Office
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27. Computer Software con’t…
 Word processing software – used to create, edit,
format, and print documents
 advantage – users can easily make changes to the
document
 Electronic spreadsheet software – user can add,
subtract, and perform user-defined calculations on
rows and columns of numbers
 eliminates tedious recalculations, easily converted into a
graphic form 27

28. Computer Software con’t…
 Database Software – user can enter, retrieve, and
update data in an organized and efficient manner
 Can access data in different ways and create custom
reports
 Presentation Graphics Software – allows users
to create documents called slides to be used in
presentations
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29. Networks and the Internet
 Network – collection of computers and devices connected
via communications media and devices such as cables,
telephone lines, modems
 users can share resources, such as hardware devices, software
programs, data, and information
 saves time and money
 LAN or Local Area Network – network that connects computers in a
limited geographic area
 computer lab, offices, groups of buildings
 WAN or Wide Area Network – network that covers a large
geographical area
 districts offices of a national corporation
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30. Networks and the Internet con’t…
 The Internet – worldwide collection of networks
that links together millions of computers by means
of modems, telephone lines, cables, and other
communications devices and media
 world largest network
 use the Internet for a variety of reasons
 Sending messages (e-mail), accessing information, shopping,
meeting and conversing with people, and accessing sources of
entertainment and leisure
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31. Networks and the
Internet con’t…
 Connect to the Internet in one of two ways
 through an Internet service provider
 through an online service provider
 Internet service provider (ISP) – organization that
supplies connections to the Internet for a monthly fee
 Online service provider (OSP) – provides access to the
Internet, but it also provides a variety of other specialized
content and services
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32. Networks and the Internet con’t…
 The World Wide Web or the Web – contains
billions of documents called Web pages
 most popular segment of the Internet
 Web page – document that contains text, graphics,
sound, and/or video and has built-in connections, or
hyper-links, to other Web documents
 Web site – related collection of Web pages
 Web browser – software program used to access and
view Web pages 32

33. Networks and the Internet con’t…
 Uniform Resource Locator or URL – unique
Web page address
 consists of a protocol, domain name, and sometimes the
path to a specific Web page or location in a Web page
 URLs begin with http://
 http stands for Hypertext Transfer Protocol
 domain name – identifies the Web site, which is stored on a Web server
 Web server – computer that delivers (serves) requested Web pages
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34. Networks and the Internet con’t…
 Electronic Commerce or e-commerce –
conducting business activities online
 Three types of e-commerce
 Business to consumer (B2C) – sale of goods to the
general public
 Consumer to consumer (C2C) – one consumer selling
directly to another
 Business to business (B2B) – goods and services to
other businesses
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