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Introduction to Computers

Introduction to Computers
Furqan Shahzad
Department of Information Technology
Types of Devices
Digital versus Analog
A digital device uses discrete data.
Discrete data is distinct or separate.
Ex: Numbers or digits.
Most computers today are digital. Their circuits have only two
possible states, such as “Off” and “On” or “0” and “1”.
An analog device operates on continuously varying data.
Continuously varying data has an infinite number of possible
A digital thermometer will give a specific numerical reading when
used to measure someone’s body temperature.
An old fashioned mercury thermometer’s reading of someone’s
body temperature could be interpreted differently by different users.
Definition of Computer
 A device that computes, especially a programmable electronic
machine that performs high-speed mathematical or logical
operations or that assembles, stores and processes information.
 “A computer is an electronic device, operating under the control of
instructions stored in its own memory unit, that can accept data
(input), process data arithmetically and logically, produce output
from the processing, and store the results for future use.”
 An Electronic device which can accept data (Raw Material) as
input, Process it and delivers the Results as Output (Information or
Process data)
Packaging the Computer
 The many physical forms of the
Fast Expensive Complex Large
general purpose computer:
All follow general
 Primary memory
Input units
 Output units
 Central Processing
Grouped according to
speed, cost, size, and
Super Computers
Mainframe Computers
Palmtop Computer
Slow Cheap Simple Small
Basic Concepts of Computer Hardware
Primary Memory
(Central Processing Unit)
 This model of the typical digital computer is often called the
von Neumann computer.
Basic Concepts of Computer Hardware
Programs and data are stored in the same memory:
primary memory.
 The computer can only perform one instruction at a
Input/Output (I/O): Refers to the process of getting
information into and out of the computer.
 Input: Those parts of the computer receiving
information to programs.
 Output: Those parts of the computer that provide
results of computation to the person using the
Primary Memory
 Primary storage or memory: Is where the data and program
that are currently in operation or being accessed are stored
during use.
Consists of electronic circuits: Extremely fast and
Two types:
RAM (non-permanent)
 Programs and data can be stored here for the computer’s
 Volatile: All information will be lost once the computer shuts
ROM (permanent)
 Contents do not change.
The Central Processing Unit
 The Central Processing Unit ( CPU)
Often referred to as the “brain” of the computer.
Responsible for controlling all activities of the computer
The three major components of the CPU are:
1. Arithmetic Unit (Computations performed)
Accumulator (Results of computations kept here)
2. Control Unit (Has two locations where numbers are kept)
Instruction Register (Instruction placed here for analysis)
Program Counter (Which instruction will be performed next?)
3. Instruction Decoding Unit (Decodes the instruction)
Motherboard: The place where most of the electronics
including the CPU are mounted.
Moving Information within the Computer
 How do binary numerals move into, out of, and within
the computer?
Information is moved about in bytes, or multiple bytes
called words.
 Words are the fundamental units of information.
 The number of bits per word may vary per computer.
 A word length for most large IBM computers is 32 bits:
Moving Information
Within the Computer
 Bits that compose a word
are passed in parallel from
place to place.
Ribbon cables:
Consist of several
wires, molded
One wire for each bit
of the word or byte.
Additional wires
coordinate the activity
of moving information.
Each wire sends
information in the form
of a voltage pulse.
Examples of Computer Hardware
Computers Have Two Main Parts
1. Computer Hardware
Computer Hardware is the physical part of the
computer system, the machinery and equipment.
Parts of the computer “you can see and touch”
Types of Computers,
Central Processing,
Keyboard, Mouse
2. Computer Software
Set of programs used to run Computer system
Application S/w & System S/w
Word Document
Operating System
Sources of Data for the Computer
 Two types of data stored within a computer:
 Original data or information: Data being
introduced to a computing system for the first time.
Computers can deal directly with printed text,
pictures, sound, and other common types of
Previously stored data or information: Data that
has already been processed by a computer and is
being stored for later use.
 These are forms of binary data useful only to
the computer.
 Examples: Floppy disks, DVD disks, and music
Monitor: T.V. like screen used to show pictures and words
Central Processing Unit this is where most of the computer’s
calculations take place. In terms of computing power,
the CPU is the most important element of a computing system.
Keyboard: This device is used to type information into the computer and
contains the different no of keys combinations.
Mouse: a small device, which you move across the top of the desk
to move the pointer or cursor on the screen.
Printer: used to make a paper copy of the information into the computer.
Image Scanner: an electronic device that generates a digital
representation of an image for data input to a computer
Main Computer - Front
Main Computer - Back
Main Computer - Inside
 Instructions and associated data, stored in electronic
format, that direct the computer to accomplish a
 System software helps the computer carry out its
basic operating tasks.
Operating systems
System Software
 An Operating System (OS) is the master
controller within a computer.
EX: Windows, MacOS, DOS, UNIX, Linux
 An operating system interacts with:
All hardware installed in or connected to a
computer system.
All software installed or running from a
storage device on a computer system.
System Software
 Microsoft Windows
Most popular operating system.
Supports a vast array of application software
and peripheral devices.
 MacOS
For Macintosh computers.
Proprietary system.
Does not have same functionality and
support for software and peripheral devices.
System Software
 Network operating system (NOS)
 Manages network resources.
 Maintains security.
 Tracks user accounts.
 Handles communication between workstations and
 Popular network operating systems
Windows NT, Novell Netware, UNIX
System Software
 Utilities augment functionality of operating systems.
Utilities includes device drivers and Troubleshooting
 Utilities provide file management capabilities such
as copying, moving or renaming a file.
 Norton Utilities includes an undelete function that
can recover deleted files.
 Symantec and McAfee Virus checkers add
protection for all system and data files.
Application Software
 Accomplishes specific tasks for users.
 Enables a computer to become a multi-purpose
 Produce worksheets
and reports.
 Create flow charts and
graphic organizers.
 Automate record
keeping like
attendance and
 Communicate
Application Software
 Productivity Software
 Spreadsheets
 Databases
 Presentation Software
 Document Preparation
 Word Processing
 Desktop Publishing
 Project Management Software
Application Software
 Graphics Creation and Manipulation
 Animation and 3D Graphics
 Video Editing
 Internet Connectivity
 Website Creation and Management
 Groupware
 Financial Management
 Educational Games and Tutorials
Programming Languages
 Basic building blocks of any software.
 Programming languages allow a programmer to write
instructions that a computer can understand.
 Programming languages have some resemblance to the
English language.
Basic Desktop
Start Menu
Quick access
to saved files
Detail of the
Answer to
List of
Log Off
Turn off
Help Section
Word Document
Turn Off Computer
Restart the
Turn off the
Back out
General Understanding of how your computer works!
To understand anything it helps to break it down into it's basic
components. Then you need to know how each component works.
Finally you look at how all the components work together to achieve
the desired end product or result.
So we can break the Computer System into Different components.
 Motherboard
 Memory
 Storage
 Input Devices
 Output Devices
 Software
General Understanding of how your computer works!
 Motherboard
It is the main circuit board inside the CPU case. It holds the
microprocessor, memory and other crucial circuits and components that
control the operation of the Personal Computer. Every device inside or
connected to a Personal Computer finds it's way to this board.
 Memory
The mother board takes the input you give it like mouse clicks, and
produces output for you like displaying or printing a file. It can't do this
without memory. The PC operating system used by the PC is copied from
storage to memory at power up. The OS copy in memory then runs the
PC. Memory is volatile which means that when your PC is turned off the
contents of memory are lost. It is completely blank and must reloaded
each time the PC is powered up.
 Storage
Storage is non-volatile which means it retains information even when it is
powered off. It stores programs which run the PC as well as data, which
is a digital form of everything you use like documents, music, pictures,
 Input Devices
The keyboard and mouse are the main input devices you use to control
your PC.
General Understanding of how your computer works!
Output Devices
When you send inputs into the PC, it processes them and produces
useful output for you. The primary output devices are the video display,
printer and speakers.
Some people want to use the power of their computer to create works of
art, others want to create music, or play games, surf the web, or play the
stock market. Whatever you want to do with your computer, software is
the key to doing it.
What happens when your PC is powered on?
With a simple push of a button, your computer comes to life.
Basic Computer Terms and Definitions
Basic Computer Terms and Definitions
CPU: This computer component has several names: Central Processing Unit,
microprocessor or processor. This unit is the brain of the
computer processes and executes instructions in a software program.
The CPU’s primary functions include retrieving instructions from the
computer’s memory, including random access memory,
comprehending and executing instructions, and directing the input and
output activity of the computer.
Desktop: The first screen that you see when any Windows operating system
screen is up and running. One of the main purposes of the Desktop
is to make it easier to access different application programs, files
and documents.
File: Unit for storing information that may include a word-processing document,
a spreadsheet, a picture, a graphic, musical piece, or even part of an
application program. Examples of "files" include text files which could
be a letter or report and graphic files which could be a picture. Each file
has a name because the data or information created in a software
program is saved with a file name.
Basic Computer Terms and Definitions
Folder: Method for organizing files that is related by topic, by purpose, by type,
by program, or even by a project that you are working on. NOTE:
When an application program is loaded onto your computer, it will
group similar applications in a folder. As you add or create files, you
can organize them however you want.
Hyperlink: Allows you to move from one web page document to another. It can
be text which is usually underlined or a graphic. When you move your
mouse over a hyperlink, the mouse cursor usually becomes a hand
which indicates a hyperlink is present. Once you click on the link, you
move to another web page document or to another place on the same
web page.
Icon: A small picture that represents processing options such as programs,
documents, and shortcuts. When you click on the icon, the file or
program will open. The most easily recognized icon is the Recycle Bin
which is the graphic below.
Input: Commonly known as data and refers to numbers, letters, words, images,
video, music and even sounds. Other computer input includes
commands and user response. A command directs the computer to
execute tasks or perform certain activities. One example of a
command is a command buttons OK, Cancel and Help seen on the
Shut Down Windows dialog box.
Basic Computer Terms and Definitions
Internet: A world wide network that connects millions of computers to share
and exchange data, news, opinions, and research results. The
Internet is not the same as the World Wide Web (WWW). The World
Wide Web is a service that is provided on the Internet.
Keyboard: The keyboard is an input device that allows you to enter letters,
numbers and symbols into your computer. The keyboard keys
include the alphanumeric keys (letters and numbers), numeric
keypad, special function keys, mouse cursor moving keys, and status
Files and Folders: Think of a computer folder as being similar to a filing
cabinet folder, whereas a computer file is similar to the pieces of
paper that are placed in the folders.
Graphic User Interface (GUI): Combines text and graphics to make software
easier to use. Graphical User Interface features include icons,
windows, menus, and buttons.
Hard Copy: Usually refers to a printout on paper.
Basic Computer Terms and Definitions
Hard Drive: The purpose of the hard drive is to store information. This device
that allows the computer to permanently retain and store data like the
operating system, programs and information data. The hard drive holds
more data than a diskette and accesses information faster than on
diskettes. Storage refers to the capability of storing things, and as for the
computer, it is information.
Hardware: Refers to any component of the computer system that you can like
the monitor, keyboard, mouse, printer, computer unit, scanner,
speakers and even the components inside of the computer unit if you
opened the box up.
Menu: List of options that may be commands or other options from which you
can choose from. The following illustration is the File Menu Bar command
menu list.
Mouse: Besides a keyboard, a mouse is the most common input device for a
computer. The mouse is a small, palm-sized input device that you move
across a flat surface, such as a desktop, to control the movement of the
pointer on the screen. Technically, there are many operations that are
much easier to perform with a mouse than a keyboard because you can
just point and click to select an item on a screen or choose an item from a
list of options.
Basic Computer Terms and Definitions
Mouse Commands: Before examining the various commands, you must
understand how to execute each mouse command. The mouse commands
include move, point, click, deselect, double-click, drag, and right-click.
My Computer: An icon that opens into a folder of icons for all of the resources on
the computer like the hard drive and printer.
Operating System: Software that acts as an interface between you, the
application software (like word processing or accessing the Internet), and the
computer components. This includes interpreting and carrying out basic
instructions that operate a computer like recognizing information from the
keyboard and mouse, sending information to the monitor, printer, or speakers
and scanners, storing information to the hard drive and removable drives.
Common operating systems include Windows XP, Windows 2000, Windows
ME, and MAC OS.
RAM: This is an acronym for Random Access Memory. This memory is a work
area or a temporary storage space where the computer places program
information so that it can execute the program instructions and
information. When the program or file is closed, the data or programs are
removed from RAM. The amount of RAM you have on your computer is
crucial in determining how many programs can be opened (running) and how
much data is available for each program. RAM is available in MB or
megabytes. An example is 256MB of RAM.
Input Devices
Input Devices
 Input is all information put into a computer. Input
can be supplied from a variety of sources:
A person
A storage device on computer
Another computer
A peripheral device
Another piece of equipment, such as a musical
instrument or thermometer
Input Devices
 Two categories of input hardware:
Those that deal with original data.
 Those that handle previously stored data.
 Input hardware: Those that deal with original data.
 Keyboard
 Mouse
 Voice recognition hardware
 Scanner
 Digital camera
 Digitizing: The process of taking a visual image, or audio
recording and converting it to a binary form for the computer.
 Used as data for programs to display, play or manipulate the
digitized data.
Input Devices
 Connecting Hardware to the computer:
Hardware needs access through some general
input/output connection.
 Port: The pathway for data to go into and out of the
computer from external devices such as keyboards.
 There are many standard ports as well as custom electronic
ports designed for special purposes.
 Ports follow standards that define their use.
 SCSI, USB: Multiple peripheral devices (chain).
 RS-232, IDE: Individual peripheral devices.
Peripheral device: A piece of hardware like a
printer or disk drive, that is outside the main
Input Devices
 Connecting Hardware to the computer: (continued)
 Hardware needs software on the computer that can
service the device.
Device driver: Software addition to the operating
system that will allow the computer to communicate
with a particular device.
 Common Basic Technologies for Storing Binary Information:
Input Devices
 Electronic Circuits
 Most expensive of the three forms for storing binary
 A flip-flop circuit has either one electronic status or the
other. It is said to flip-flop from one to the other.
 Electronic circuits come in two forms:
 Permanent
 Non-permanent
Input Devices
 Magnetic Technology
 Two parts to most of the magnetic forms of information
The medium that stores the magnetic
 Example: Floppy disk. Tiny spots on the disk are
magnetized to represent 0s and 1s.
The device that can “read” that information from
the medium.
 The drive spins the disk.
 It has a magnetic sensing arm that moves over the disk.
 Performs nondestructive reading.
Input Devices
 Optical
Uses lasers to “read” the binary information from the medium,
usually a disc.
Millions of tiny holes are “burned” into the surface of the disc.
The holes are interpreted as 1s. The absence of holes are
interpreted as 0s.
 Secondary Memory Input Devices
These input devices are used by a computer to store information
and then to retrieve that information as needed.
External to the computer.
Commonly consists of floppy disks, hard disk drives, or CDROMs.
Secondary memory uses binary.
The usual measurement is the byte.
 A byte consists of 8 binary digits (bits). The byte is a standard unit.
Input Devices
 The four most important characteristics of storage devices:
Speed and access time
 Cost / Removable versus non-removable
 Capacity
 Type of access
 Speed (Access time) - How fast information can be taken from or
stored onto the computer memory device’s medium.
 Electronic circuits: Fastest to access.
40 billionths of a second.
Floppy disks: Very slow in comparison.
Takes up to 1/2 second to reach full speed before access is even
Input Devices
 Cost
1024 Bytes.
A Million Bytes.
A billion Bytes.
A Trillion Bytes.
 Capacity - The amount of information that can be stored on the medium.
1 bit
1 nibble
1 byte
1 kilobyte
1 megabyte
1 gigabyte
1 terabyte
1 binary digit
4 bits
8 bits
1,024 bytes
1,048,576 bytes
1 million bytes
1,073,741,824 bytes
1 billion bytes
1 trillion bytes
Approximate Size
1 character
1/2 page, double spaced
500,000 pages
5 million pages
5 billion pages
Input Devices
 Type of Access
 Sequential - Obtained by proceeding through the
storage medium from the beginning until the
designated area is reached (as in magnetic tape).
 Random Access - Direct access (as in floppy and
hard disks).
Input Devices
 Input devices gather and translate data into a
form the computer understands.
 Primary input device:
Keyboard - Most common input device;
used to type in commands and data.
Mouse or trackball enhances user’s ability
to input commands, manipulate text, images.
Joystick useful in education as an adaptive
or assistive input device.
Input Devices
 Scanners are peripheral input devices which
allow users to import:
 Specialized software aids in translating
information into a format the computer can
understand and manipulate.
The most commonly used input device is the keyboard on which data is
entered by manually keying in or typing certain keys. A keyboard typically
has 101 or 105 keys.
3 Finger
 The keyboard allows the computer user to enter words, numbers,
punctuation, symbols, and special function commands into the
computer’s memory.
The Mouse
Is a pointing device which is used to control the movement
of a mouse pointer on the screen to make selections from
the screen. A mouse has one to five buttons. The bottom of
the mouse is flat and contains a mechanism that detects
movement of the mouse.
Types of Mice
 Wheel mouse – Contains a rotating wheel used to scroll vertically
within a text document; connects to PS/2 port or USB port
 Cordless mouse – Uses infrared signals to connect to the
computer’s IrDA port; it must be within sight of the receiving port
Using the Mouse
 Mouse buttons enable the user to initiate actions.
Clicking (left-, right-, or double-clicking) allows the
user to select an item on the screen or open a
program or dialog box
Click and drag – Holding down the left mouse button
and moving the mouse enables the user to move
objects on the screen
The Mouse
Pointing devices - direct
 Touch screens
Touch screens
 Often used for applications with occasional use, for
 Bank ATMs etc.
 No extra hardware - used for input and for output
 Can be precise to 1 pixel
 Good for menu choice - not so good for other
 Tiring if at wrong angle (needs to be 30-45% from
 Get greasy, jammy
 Finger can obscure screen
 Alternative - use stylus to touch screen, or lightpen
Indirect Pointing Devices
 Need more cognitive processing than direct methods,
but can be more efficient
 mouse
 tracker ball
 track point
 touchpad…
Indirect pointing devices - other
 Tracker ball, trackpad,
 Less space on desktop
 Good in moving environments,
e.g. car, train
 Joystick
 The main use of a joystick is to play
computer games by controlling the way that
something moves on the screen.
Digital camera
 Digital Cameras are peripheral input devices that allow
users to create pictures and/or movies in a digital format.
Some require specialized software to import images
into the computer.
Some record digital images directly to a disk that can be
read by the computer.
A digital camera can store many more pictures than an
ordinary camera. Pictures taken using a digital camera are
stored inside its memory and can be transferred to a
computer by connecting the camera to it. A digital camera
takes pictures by converting the light passing through the
lens at the front into a digital image.
Microphones - Speech Recognition
•Use a microphone to talk to your
•Add a sound card to your computer
•Sound card digitizes audio input into 0/1s
•A speech recognition program can process the input and convert it
into machine-recognized commands or input
 Speech recognition is a type of input in which the computer
recognizes words spoken into a microphone.
 Special software and a microphone are required.
 Latest technology uses continuous speech recognition where the
user does not have to pause between words.
Microphones - Speech Recognition
A scanner can be used to input pictures and text into a
computer. There are two main types of scanner; Handheld and Flat-bed.
Light pen
A light pen is a small ‘pen-shaped’ wand, which contains
light sensors.
•It is used to choose objects or commands on the screen
either by pressing it against the surface of the screen or
by pressing a small switch on its side.
•A signal is sent to the computer, which then works out the
light pen’s exact location on the screen.
•The advantage of a light pen is that it doesn’t need a
special screen or screen coating.
Bar codes
•A bar code is a set of lines of different thicknesses that
represent a number
•Bar Code Readers are used to input data from bar codes.
Most products in shops have bar codes on them
•Bar code readers work by shining a beam of light on the
lines that make up the bar code and detecting the amount of
light that is reflected back
Summary Input Devices
Touch Pad
Output Devices
Output Devices: Engaging our Senses
 Output devices are peripheral devices that enable us to view or
hear the computer’s processed data.
Visual output – Text, graphics, and video
Audio output – Sounds, music, and synthesized
Output from the Computer
 Reports
 Graphics
 Audio
 Video
 Multimedia
 Virtual Reality
Output Devices
 Monitors
 Flat Panel Displays
 Projectors
 Plotters
 Microfilm
 Voice
 Speakers
 Impact Printers
 Dot
 Daisy Wheel
 Band and Chain
 Non Impact Printers
 Ink-Jet
 Laser/Page
 Thermal
Output Devices
 Output units store and display information (calculated
results and other messages) for us to see and use.
Floppy disk drives and Hard disk drives.
Display monitors: Hi-resolution monitors come in two
 Cathode ray tube (CRT) - Streams of electrons
make phosphors glow on a large vacuum tube.
Liquid crystal display (LCD) - A flat panel
display that uses crystals to let varying amounts
of different colored light to pass through it.
 Developed primarily for portable computers.
Output Devices
Monitors are the most commonly used output device.
Most monitors use a bitmap display.
 Allows user to resize the display.
 Divides the screen into a matrix of tiny square “dots” called
 The more “dots” a screen can display, the higher the
resolution of the monitor.
 Monitors are connected to a computer system via a
port integrated on the video adapter or graphics
 Graphics cards convert digital data output from
software to analog data for display on monitors.
Typically have additional memory chips on card, 4MB to
 A monitor is a peripheral device which displays computer output on
a screen.
 Screen output is referred to as soft copy.
 Types of monitors:
Cathode-ray tube (CRT)
Liquid Crystal Display (LCD or flat-panel)
 cathode ray tube
 electron gun shoots a stream of electrons at a specially
phosphor-coated screen
 on impact, the phosphor flares up for a fraction of a second
 electron gun sweeps across the screen many times a second
 liquid crystal display
 one of several types of “flat-panel” displays
 forms output by solidifying crystals and “backlighting” the image
with a light source
TV sets are CRTs and many desktop monitors use this technology
LCD is primarily used for laptops and other portable devices
A liquid crystal display (commonly abbreviated LCD) is a thin, flat
display device made up of any number of color or monochrome pixels
arrayed in front of a light source or reflector. It is prized by engineers
because it uses very small amounts of electric power, and is therefore
TFT-LCD (Thin Film Transistor-Liquid Crystal Display) is a variant of
Liquid Crystal Display (LCD) which uses Thin-Film Transistor (TFT)
technology to improve image quality. TFT LCD is one type of active
matrix LCD, though it is usually synonymous with LCD. It is used in
both flat panel displays and projectors. In computing, TFT monitors are
rapidly displacing competing CRT technology, and are commonly
available in sizes from 12 to 30 inches. As of 2006, they have also
made inroads on the television market
Video Display Terminology
 Pixel
picture element (smallest unit of an
image, basically a single dot on the
 Resolution
 number of pixels in the image
 Common resolution size is 1024x768
 Refresh rate
how often a CRT’s electron gun
LCD displays do not use an electron
gun, so do not perform refreshing
The CRT electron gun
“shoots” 3 electrons at
the screen representing
the amount of red,
green and blue for the
 A printer is a peripheral device that produces a
physical copy or hard copy of the computer’s output.
 Dot matrix
 Seldom used in a classroom.
 Still frequently used in business.
 Ink Jet Printer
 least expensive, color, slower with a higher per page
cost than laser printers
 Laser Printer
 More expensive, faster, lower per page cost than ink jet,
Types of Printers
 Inkjet printer, also called a
bubble-jet, makes characters by
inserting dots of ink onto paper
 Letter-quality printouts
 Cost of printer is inexpensive
but ink is costly
 Laser printer works like a
 Quality determined by dots per
inch (dpi) produced
 Color printers available
 Expensive initial costs but
cheaper to operate per page
 A plotter is a printer that uses a pen that moves over a
large revolving sheet of paper.
 It is used in engineering, drafting, map making, and
Output Devices
Projection systems or classroom TVs can display
information from a computer system on a larger screen
for whole-class instruction.
Output Devices
 Audio Output Devices
 Windows machines need special audio card for audio
 Audio output is useful for:
 CD player is a computer.
 Most personal computers have CD players that can access
both music CDs and CD-ROMs.
Voice synthesis (becoming more human
Specialized tasks (i.e.: Announcements)
Output Devices
 Optical Disks: CD-ROM and DVD
 CD-ROM (Compact Disk - Read Only Memory)
By its definition, CD-ROM is Read Only.
Special CD drives “burn” information into blank
 Burn: A laser is used to “burn” craters into the surface to
represent a binary 1.
 Two main types of CDs:
 CD-R (Compact Disk - Recordable)
 CD-WR (Compact Disk - ReWritable)
It takes longer to write to a CD-R than a hard
Special software is needed to record.
Output Devices
 DVD (Digital Versatile Disk)
 Allows up to 17 gigabytes of storage (from 4.7 GB to
17 GB).
 Compatible with older CD-ROM technology.
 The four versions of the DVD:
Output Devices
 Storage Requirements: How much storage
capacity is needed for…
One keystroke on a keyboard.
One page single-spaced document.
Nineteen pages formatted text.
Complete word processing program.
1 byte (8 bits)
4.0 K
75 K
8.4 MB
 Storage Capacity: How much data can be stored
One inch of 1/2 in. wide magnetic tape.
One 3 1/2” floppy disk, high density.
One Compact Disk.
1.4 MB
650 MB
Storage Devices
Secondary Storage
 Magnetic Disks
 Diskettes/Floppy disks
 Hard Disks
 Magnetic Tape
 PC Card
 Access speed measured in ms
 Capacity measured in KB, MB, & GB
Storage - Examples
Hard Drives (IDE and SCSI)
 Prepares a diskette so it can store data by defining the
tracks, cylinders, and sectors on the surfaces of the
 Track- a narrow recording band forming a full circle
around the diskette
 Cylinder- all tracks of the same number regardless of
side. Ie. Track 2 side 1 & 2.
 Sector- a pie shaped section of the diskette which
holds 512 bytes
 Cluster- comprised of 2 to 8 track sectors depending
on operating system
Memory (RAM)
RAM or Random Access Memory
“Waiting room” for computer’s CPU.
Holds instructions for processing data, processed data, and
raw data.
Ram is measured by:
 Capacity (in Megabytes or Gigabytes)
 Speed (in Nanoseconds)
Amount of RAM installed will determine.
 Which software applications will run
 How many software applications can be open
simultaneously (multitasking ability)?
RAM upgrades are cost-effective and easy to install.
Check your computer manual for RAM type (DIMM, SDRAM)
and speed (100, 90ns).
Memory (RAM)
 All software applications will have RAM
specifications listed on their packaging.
 Many applications list both a minimum and a
recommended amount of RAM necessary to run
the software.
 Be cautious about buying software for a system
based on minimum requirement.
Storage Technology
 Electronic devices that store, retrieve, and save
instructions and data.
Today’s microcomputers or PCs include several types of
storage devices.
Capacity and speed are important considerations when
selecting a new storage device for a PC.
Magnetic storage devices store data by magnetizing
particles on a disk or tape. They have a limited life-span of
1 to 5 years, depending on the device.
Optical storage devices store data as light and dark
spots on the disk surface. They have an unlimited lifespan.
Storage Devices
Hard Disk Drives
Capacity is measured in gigabytes (GB or billions of bytes).
Typically permanently installed.
Used to store operating system, application software, utilities and
Magnetic storage device.
Floppy Disk Drives
Capacity is 1.44 to 2.0 megabytes (MB or millions of bytes).
Storage device with the smallest capacity
Most portable storage media
Magnetic storage device.
Storage Devices
CD-ROM Drives
Typically installed on all new computer systems. (Were add-on
device until the mid 1990’s).
Capacity is 600 to 750 megabytes
(MB or millions of bytes).
Most mass-produced commercial software is packaged on a
Used more often now for backup storage as CD-RW
(read/write) technology has become less expensive.
Data is read from CD by a laser.
Optical storage device.
Storage Devices
Other Types of Drives
 Zip Drives – Several different capacities are
 Tape Drives – Generally used for system backups,
becoming less common.
 DVD drives – Can also read CDs, now more
common as a standard device on new computer
Other Devices
Power Supply
 Power supply needed to
supply electrical power to
computer’s component parts
 Power supply measured in
 Power supply needs enough
watts to power computer’s
current needs and later
 Power supply must fit case
 Your motherboard determines your computer’s specifications
 Motherboard determines:
What type of processor
What type of RAM
What type of external ports and how many
What type of expansion ports
What type of hard drive
What type of case form factor
What type of power supply
 When you choose your motherboard you are choosing what
type of computer you will have
Typical full size ATX motherboard
 Everything in your
computer is hooked
together by the
 This determines
your computer’s
The back panel connectors of previous motherboard
 Everything in your
computer is
hooked together
by the
 This determines
your computer’s
Motherboard BUS system
 The motherboard BUS system
moves zeros and ones around
the computer
 You can see the wires
embedded in the motherboard’s
 BUS is not short for anything
What if I am missing a port I need on my
computer, or a new type of port is invented that I
need to add to my computer?
 Then hopefully you have expansion slots
Desktop Expansion Slots
 A connector on a
motherboard into which
an expansion card,
such as a sound card,
video card, USB card,
modem card, etc fits.
Expansion slots are a
means of adding or
enhancing the
computer's features
and capabilities.
Desktop Expansion Cards
 An expansion card,
such as a sound card
(above right), video
card, USB card,
modem card, etc, fits
into an expansion slot
on the motherboard
(below right).
Expansion slots are a
means of adding or
enhancing the
computer's features
and capabilities.
Desktop Expansion Slot Openings
 Expansion slot openings
are located on the back of
the computer. They look
like the ones shown in the
picture to the right. They
provide access to the
expansion slots on the
motherboard and the
cards in those slots
 For more information on
expansion slots see the
PowerPoint called: On
Your Own Computer Parts
 A collection of computers and other devices that
communicate to share data, hardware, and software.
 A stand-alone computer is called a workstation on
a network.
 A workstation provides access to:
Your computer’s local resources
Network resources
Network nodes include
workstations, printers,
and servers.
 A server is a computer connected to a network that
distributes and stores resources for other network
 With proper licensing, many network users can use
the same applications and data files simultaneously
and share other resources, such as storage space
or a printer.
Local Area Network (LAN) –
a network located in a limited area.
 LANs are found in most businesses.
 Many campuses use LANs.
A network interface card (NIC) –
a key hardware component.
 Connects a workstation to the network.
 A circuit board that sends data between the workstation
and the network.
Wide Area Network (WAN) –
a network that covers a large geographical area. TENET is a
classic example.
All types of networks require special networking hardware and
networking software to allow different computers to
communicate with each other.
 The Internet –Network of Networks, Largest of all
 Communication standards called protocols allow for
global exchange of information.
Transmission Control Protocol (TCP)
Internet Protocol (IP)
 Intranets are LANs or WANs that use these
communication standards or TCP/IP.
 Special hardware (modem) and software (browser)
are required.