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.
Devices that comprise a computer system
(CD-RW, Floppy, Hard disk, zip,…)
Computers can perform four general operations, which
comprise the information processing cycle.
All computer processing requires data, which is a collection
of raw facts, figures and symbols, such as numbers, words, images, video and
sound, given to the computer during the input phase.Computers
manipulate data to create information. Information
is data that is organized, meaningful, and useful.During the output Phase, the information that has been
created is put into some form, such as a printed report.The information can also be put in computer storage for
future use.
Why Is A Computer So Powerful?
The ability to perform the information processing cycle with
amazing speed.Reliability (low failure
rate).Accuracy.Ability to store huge amounts of data and information.Ability to communicate with other
computers.
How Does a Computer Know what to do?
It must be given a detailed list of instructions, called a
compute program or software, that tells it exactly what to do.Before processing a specific job, the computer program corresponding
to that job must be stored in
memory.Once the program is stored in memory the compute can start
the operation by executing the
program instructions one after the other.
What Are The Primary Components Of A Computer ?
Central Processing Unit (containing the control unit and the
arithmetic/logic unit).
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.
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.
The Central processing Unit
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.
Memory also called Random Access Memory or RAM (temporary
memory) 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 is turned
off.Read Only Memory or ROM is memory that is etched on a chip that
has start-up directions for your computer. It is permanent memory.
Amount Of RAM In Computers
The amount of memory in computers is typically measured in
kilobytes or megabytes. One kilobyte (K or
KB) equals approximately 1,000
memory locations and one megabyte (M or MB) equals approximately one million
locations A memory location, or byte, usually stores one character.Therefore, a computer with 8 MB of memory can store
approximately 8 million characters. One megabyte can hold approximately 500
pages of text information.
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.The printer produces a hard copy of your
output, and the
computer screen produces a soft copy of your output.
Auxiliary 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.
A floppy disk is a portable, inexpensive storage medium that
consists of a thin, circular, flexible plastic disk with a magnetic coating
enclosed in a square-shaped plastic shell.
Structure Of Floppy Disks
Initially Floppy disks were 8-inches wide, they then shrank
to 5.25 inches, and today the most widely used folly disks are 3.5 inches wide
and can typically store 1.44 megabytes of data.A folly disk is a magnetic disk, which means that it used
magnetic patterns to store data.Data in floppy disks can be read from and written to.Formatting is the process of preparing a disk for reading
and writing.A track is a narrow recording band that forms a full circle
on the surface of the disk.The disk’s storage locations are divided into pie-shaped
sections called sectors.A sectors is capable of holding 512 bytes of data.A typical floppy stores data on both sides and has 80 tracks
on each side with 18 sectors per track.
Another form of auxiliary storage is a hard disk. A hard
disk consists of one or more rigid metal plates coated with a metal oxide
material that allows data to be magnetically recorded on the surface of the
platters.
The hard disk platters spin at a high rate of speed,
typically 5400 to 7200 revolutions per minute (RPM).
Storage capacites of hard disks for personal computers range
from 10 GB to 120 GB (one billion bytes are called a gigabyte).
A compact disk (CD), also called an optical disc, is a flat
round, portable storage medium that is usually 4.75 inch in diameter.A CD-ROM (read only memory), is a compact disc that used the
same laser technology as audio CDs for recording music. In addition it can
contain other types of data such as text, graphics, and video.The capacity of a CD-ROM is 650 MB of data.
Computer software is the key to productive use of computers.
Software can be categorized into two types:
1. Operating system
software 2. Application software.
Operating System Software
Operating system software tells the computer how to perform
the functions of loading, storing and executing an application and how to
transfer data.Today, many computers use an operating system that has a
graphical user interface (GUI) that provides visual clues such as icon symbols
to help the user. Microsoft Windows 98 is a widely used graphical operating
system. DOS (Disk Operating System) is an older but still widely used operating
system that is text-based.
Application Software consists of programs that tell a
computer how to produce information. Some of the more commonly used packages
are:
Electronic
spreadsheet, Database, Presentation graphics.Word Processing software is used to create and print
documents. A key advantage of word processing software is that users easily can
make changes in documents.
Electronic Spreadsheets
Electronic spreadsheet software allows the user to add,
subtract, and perform user-defined calculations on rows and columns of numbers.
These numbers can be changed and the spreadsheet quickly recalculates the new
results.
Allows the user to enter, retrieve, and update data in an
organized and efficient manner, with flexible inquiry and reporting
capabilities.
Presentation Graphics
Presentation graphic software allows the user to create
documents called slides to be used in making the presentations. Using special
projection devices, the slides display as they appear on the computer
By
Tawfique Imam Khan
(anikkhanbd@gmail.com)
+8801942821249