lecture of computer
TRANSCRIPT
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What Is A Computer?
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y A computer is an electronic device, operating under the
control of instructions (software) stored in its own memory
unit, that can accept data (input), manipulate data (process),
and produce information (output) from the processing.
Generally, the term is used to describe a collection of devices
that function together as a system.
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What Is A Computer?
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y A computer is a programmable machine that receives
input, stores and manipulates data, and provides output in a
useful format.
y
takes input.. processes it according to storedinstructions produces results as output.
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Devices that comprise a computer system
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Printer
(output)
Monitor
(output)Speaker
(output)
Scanner
(input)
Mouse
(input)
Keyboard
(input)
System unit
(processor, memory)
Storage devices
(CD-RW, Floppy, Hard
disk, zip,)
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What Does A Computer Do?
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y Computers can perform four general operations,
Input
Process
Output Storage
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What Are The Primary Components Of
A Computer ?
y Input devices.
y Central Processing Unit.
y Memory.
y Output devices.
y Storage devices.
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Binary Numbers
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THE LANGUAGE OF COMPUTERS
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Binary Numbers
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Binary language consists of combinations of 1's and 0's that represent
characters of other languages (in our case the English language).
For example: 101 is a byte that represents an integer 5; each 1 or 0 is a bit.)
Units: 1 bit
8 bits = 1 byte
1kbyte = 210 = 1024 bytes
1Mbyte = 220= 1048576 bytes
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Hardware
The physical (electronic and mechanical) parts of
a computer.
Software The programs that control the operation of the
Computer
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Uses for a PC
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y Word Processing
y Database Management
y Spreadsheets
y Communication
y Finance
y Education
y Entertainment
y News and Information
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Input Devices
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yKeyboard.
yMouse.
yTouch ScreensyPens
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The Central processing Unit
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y The central processing unit (CPU) contains electronic circuits that
cause processing to occur. The CPU interprets instructions to the
computer, performs the logical and arithmetic processing
operations, and causes the input and output operations to occur. It
is considered the brain of the computer.
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The Central processing Unit
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y Its speed is measured in Megahertz (MHZ) (Millions of
cycles per second) or Gigahertz (GHZ) Billions of cycles per
second.
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Memory
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y Memory also called Random Access Memory or RAM
(temporary memory/ Non-volatile) is the main memory of the
computer. It consists of electronic components that store data
including numbers, letters of the alphabet, graphics and sound.
Any information stored in RAM is lost when the computer isturned off.
y Read Only Memory or ROM (Volatile memory) is memory that is
etched on a chip that has start-up directions for your computer. Itis permanent memory.
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Output Devices
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y Output devices make the information resulting from the
processing available for use. The two output devices more
commonly used are the printer and the computer screen.
y The printer produces a hard copy of your output, and the
computer screen produces a soft copy of your output.
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Storage Devices
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y secondary storage devices are used to store data when they are not
being used in memory. The most common types of auxiliary
storage used on personal computers are floppy disks, hard
disks and CD-ROM drives.
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Operating System Software
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y Operating system software tells the computer how to perform the
functions of loading, storing and executing an application and how
to transfer data.
y Operating System is the software that manages the overall
operation of the computer system.
y Main purpose is to support application programs..
y Hide details of devices from application programs..
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Application Software
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y Application Software consists of programs that tell a computer
how to produce information. Some of the more commonly used
packages are:
Word processing
Electronic spreadsheet
Database
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Classification of Computers
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Classification of Computers
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ySupercomputersy The largest, most powerful, and most expensive
y Used by universities, research institutions, large corporations,
and the military
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yMainframe Computersy Less powerful and less expensive than supercomputers
y Used by businesses with large amounts of data that need to be
stored in a central computer
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Classification of Computers
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yMinicomputer
yOften used as the host computer in a network
of smaller computers
yPriced in the tens of thousands to a few
hundred thousand dollars
yManufacturers:Compaq (VAX), IBM
(AS/400), and Hewlett-Packard
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Classification of Computers
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yServers
ydesigned to support a computer network that
allows you to share files, application software,
hardware, such as printers and other network
resources.
yExample: file server, printer server, database
server,
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Classification of Computers
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Server computers usually have following characteristics:
Designed to be connected to one or more networks
The most powerful CPUs available
Multiple CPUs to share the processing tasks
Large memory and disk storage
High-speed communications capabilities
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Classification of Computers
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yPersonal Computers / Clients The most common for home users , computers that can fit
on a desktop or in one's briefcase.
Can perform all of its input, processing, output and storageactivities by itself.
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Importance of Standards
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yCompatibility
y Software and peripheral devices from one computer can be
used with another computer.
y In a networked environment, computers need to communicate
to share databases and other computing resources.
y In addition to power and cost, compatibility is an extremely
important factor in purchasing decisions.