introduction of computer
DESCRIPTION
basic info about ComputerTRANSCRIPT
A machine that can be programmed to acceptdata (input), process it into usefulinformation (output), and store it away (insecondary storage devices) for safekeepingor later reuse
Process is directed by software but performedby the hardware
What is a Computer?
Who are the Users?
Any individual who
operates a computer to
accomplish a task either
at:
Home
Office
Business
etc
Users Examples
Data Entry Operator (DEO) – type data into a machine-
readable format
Computer Operator – monitor the computer
Computer Programmer – write, test, implement, and
maintain programs
Systems Analyst – plan and design computer systems
Network Administrator – oversees the network
Chief Information Officer (CIO) – department manager
who makes strategic decisions relating to the flow of
information in the organization
Q 1
Software
Set of instructions and commands
that directs the hardware to do a
required task and produce the desired
results also known as Program
Classifications of Computers
Use the computer that fits your needs
Based upon
Size
Speed
Cost
Portability
Number of simultaneous users supported
Available software
Typical use
Types of Computers
Super Computers
Mainframe Computer
Mini Computer
PC/ Desktop/ Micro Computer
Laptop Computer
Notebook Computer
etc
Computers Applications
Graphics
Education
Energy
Law Enforcement
Transportation
Money
Agriculture
Government
The Home
Health and Medicine
Robotics
Training and Paperwork
Computer System
Processor (CPU)
Memory
Peripheral equipment
Connected to the computer by a
cable
Input Devices
Output Devices
Storage Devices
Other
Input Devices
Keyboard
Mouse
Trackball
Touchpad
Pointing stick
Digital Cameras
Optical-mark readers
Bar-code readers
Scanners
etc
Pixel and Resolution
Pixels (or picture element) - tiny dots that
compose a picture
Resolution - the number of pixels displayed
on the screen (the higher the resolution, the
closer together the dots)
Size - 14 / 17 / 19 / 21 inches etc.
Graphics Standards
SVGA (Super VGA)
Resolution – 800 x 600, 1024 x 768, 1280 x 1024, 1600 x 1200 pixels
16 million colors
XGA (Extended Graphics Array)
High resolution
Supports more colors
Printer
Produces information on paper
Orientation
Portrait
Landscape
Methods of printing
Impact
Non-impact
Line printer prints One line at a time
Line printer prints One line at a time
Line printer prints One line at a time
Dot-matrix printer: One character at a time
Dot-matrix printer: One character at a time
Dot-matrix printer: One character at a time
Example
Transfers images to paper
Prints one page at a time
600-1200 dpi – High quality
Speed
Personal laser printers: 8-10 ppm
Network laser printers: 35-50 ppm
High-volume laser printers: up to 1000 ppm
Black and white / color
Laser Printer
Ink-jet Printer
Spray ink at paper
Black and white / color
Excellent graphics
Good quality
Slower than laser
CD-ROM
CPU
Expansion slots
Floppy drive
Hard disk
Memory chip
Motherboard
Power supply
Inside the Computer
Back of the Computer
Cooling Fan
Power Supply
Keyboard Connector
Mouse Connector
Parallel Printer Port
Video Connector
Motherboard
Microprocessor chip
Memory chips
Connections to other parts of
the hardware
Additional chips may be
added – math coprocessor
The CPU stands for Central Processing Unit
When circuits are built into a single silicon chip,the chip is referred to as a microprocessor.
The CPU
The CPU Function
CPU processes information and performs all the
necessary arithmetic calculations.
• The CPU is like the “brain” of the computer
Information comes in many forms
Computers store information in digital form
i.e. 0 and 1
Text
12 3Numbers SoundsPictures
Information
A bit (binary digit)
is the smallest unit of information
can have two values: 1 or 0
can represent numbers, codes,
or instructionsOn
Bit Basics
Bit, Nibble, Byte
BIT
Binary DigIT
On/off circuit
1 or 0
Nibble
4 bits
BYTE
8 bits
Store one alphanumeric character
Measuring Storage Capacity
Byte
Kilobyte (KB)
Megabytes (MB)
Gigabytes (GB)
Terabytes (TB)
= 8 bits
= 1 Thousand Bytes
= 1 Million Bytes
= 1 Billion Bytes
= 1 Trillion Bytes
Terms used to describe file size or memory size:
RAM (Random Access Memory):
is used to store program instructions and
data temporarily
unique addresses and data can be stored in
any location
will not remain if power goes off (volatile)
RAM
ROM (Read-Only Memory):
information is stored permanently on a chip.
contains startup instructions and other
permanent data.
Cannot be changed by the user
Nonvolatile
ROM
Secondary Storage Devices
Magnetic Disk
Hard disk (40, 60, 80 GB etc)
Zip Disks (250 MB)
Floppy Diskette (1.44 MB)
Optical Disks
CD-ROM (700 MB = 450 standard Floppy Disks)
CD-R (WORM: Write Once, Read More)
CD-RW (Read-Write More)
DVD-ROM (4.7 GB to 17 GB)
Compressed storage
Diskette – about 500 printed pages
Optical disk – about 500 books
Economy
Savings in physical storage costs
Savings in the speed and convenience of
storing and retrieving data
Secondary Storage Benefits
Data Compression
Why use? Squeeze big files onto small disks
Speed up data transfer of files
Techniques Remove all extra space characters
Substitutes a smaller data string for afrequently occurring set of characters
Software uses formula to determine how tocompress
Must be decompressed
Network
Definition A system that uses communications equipment to
connect computers and share their resources.
Types
Local area network (LAN) – connects computers in
close proximity
Metropolitan area network (MAN) – connect
computers between buildings in the same geographic
area
Wide area network (WAN) – connects computers over
great distances
Modem
Modulate
Convert from digital to analog
Demodulate
Convert from analog to digital
Speeds up to 56,000 bps (56K)
Types of Modems
Direct-connect
External
Internal
PCMCIA
Personal Computer Memory Card International Association
Used in Notebook and Laptop computers
Network Topology
Physical layout
Star
Ring
Bus
Node – any device connected to the network, e.g.
Server
Computer
Printer
Other peripheral
Q 2
Star
Central hub
All messages routed through hub
Hub prevents collisions
Node failure – no effect on overall network
Hub failure – network fails
Ring
Travel around circular connection in one direction
Node looks at data as it passes
Addressed to me?
If not my address, Pass it on
No danger from collisions
Node failure – network fails
Bus
Single pathway
All nodes attached to single line
Collisions result in re-send
Node failure – no effect on overall network