Introduction to computers
INTRODUCTION TO COMPUTERS
Definition
A computer is a electronic device that processes data, converting it into information that is
useful to people
Monitor/ VDU
Mouse
The Parts a Computer
Keyboard
A personal computer can take on many guises. Modular units usually
consist of the following separate components:
The Computer
The Monitor
The Keyboard
The Mouse
The Floppy Diskette Drive
The CD-ROM Drive
Peripherals
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Introduction to computers
The computer
"Computer" is a collection of devices that function as a unit. The most basic collection
includes a Computer CPU, a Monitor, a Keyboard, and a Mouse. The Computer CPU is
normally a rectangular box that sits on your desktop (called a "Desktop Case") or next to
your knee under the desk (called a "Tower Case"). The computer's CPU is actually a small
electronic device inside the case but the term is often used to refer to the whole collection
of electronics inside the box
The Monitor
The monitor shows information on the screen when you type. The Computer Monitor is the
computer user's window into the workings of the computer. It consists of a television
picture tube that had been modified to accept the type of video signal created by the
computer's electronics.
The Keyboard
The keyboard is used to type information into the computer or input information. The
Keyboard is the primary input device used to communicate with the computer. A computer
keyboard closely resembles a conventional typewriter keyboard with the addition of
numerous keys that are used specifically for computing functions.
The Mouse
The mouse is another input device used to point at objects on the computer monitor and
select them. Using the mouse and keyboard in combination allows the computer user
substantial latitude in how to accomplish a wide variety of tasks.
The Floppy Diskette Drive
Floppy diskettes are normally used a temporary storage containers or transportation media
for data. A standard floppy diskette can hold 1.44 MB of computer data. Computer
diskettes are not as reliable or fast as the internal storage drives on the computer.
The CD-ROM Drive
The Compact Disk-Read Only Memory (CD-ROM) disk itself is a collection of concentric
circles containing millions of pits and plateaus which correspond to on/off bits of data. The
disk is read with an optical laser similar to the one used to scan your groceries at the
supermarket. Most disks of this kind are "Read Only" meaning that the computer can
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Introduction to computers
retrieve information from the disk, but cannot place information on it. New developments
have improved this technology to allow writing and rewriting data to the disk.
Computer Peripherals
Computer peripherals are any electronic devices that can be hooked up to a computer other
than the standard input-output devices (monitor, keyboard, and mouse). Peripheral
devices include speakers, microphones, printers, scanners, digital cameras, plotters,
and modems. Peripherals often require special software packages called "drivers". These
drivers are usually included with the peripheral at purchase time.
SWITCHING ON A COMPUTER
The act of switching on a computer is termed as booting. We boot a computer that is fully
connected (i.e. all its components are intact). There are two types of booting.
1. Cold booting
i.
Switch on the main switch (wall switch)
ii.
Switch the power button on the system unit
iii.
Then switch the power button on the monitor /screen.
iv.
Follow the commands form the computer.
2. Warm booting – This is the term used to mean restarting or resetting your computer.
And it is either using the reset button on the system –unit or by the use of a
combination of Ctrl+Alt+Del keys form the keyboard.
SWITCHING OFF A COMPUTER
i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
Start by closing down any open window/ program
Then click the start button
Click shut down
On the windows that appears, select shut down and click OK
Then wait until the computer tells you “its now safe to turn off your computer”
After that switch off the power button on the screen / monitor
Switch off the power button on the system unit.
Lastly switch off the main power button (wall switch)
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Introduction to computers
HARD WARE
The hardware are the parts of computer itself including the Central Processing Unit
(CPU), keyboards, monitors, case and drives (floppy, hard disk, CD, Other extra parts
called peripheral components or devices include mouse, printers, modems, scanners, digital
cameras and cards etc...Together they are often referred to as a personal computer or PC.
INPUT DEVICES
An Input device is any piece of computer hardware equipment used to provide data and
control signals to an information processing system (such as a computer). Input and output
devices make up the hardware interface between a computer and the user or external
world.
Typical examples of input devices include keyboards and mouse. In general, any sensor
which monitors, scans for and accepts information from the external world can be
considered an input device, whether or not the information is under the direct control of a
user
OUTPUT DEVICES
An output device is any piece of computer hardware equipment used to communicate the
results of data processing carried out by an information processing ...
Output devices are things we use to get information OUT of a computer.
Here are some examples of output devices.
Monitor - A monitor is the screen on which words, numbers, and graphics can be seem.
The monitor is the most common output device.
Compact Disk - Some compact disks can be used to put information on. This is called
burning information to a CD.
NOTE: A CD can also be an input device.
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Printer - A printer prints whatever is on the monitor onto paper. Printers can print words,
numbers, or pictures.
Speaker - A speaker gives you sound output from your computer. Some speakers are built
into the computer and some are separate.
Disk Drives - A disk drive is used to record information from the computer onto a floppy
disk or CD.
Floppy Disk - A floppy disk is used to record information on. The information is stored on
the floppy disk and can be used later or used on another computer.
Headphones - Headphones give sound output from the computer. They are similar to
speakers, except they are worn on the ears so only one person can hear the output at a
time.
SOFTWARE
Computer software is a general term used to describe a collection of computer programs,
procedures and documentation that perform some tasks on a computer system.
The term includes
Application software such as word processors which perform productive tasks for users,
System software such as operating systems, which interface with hardware to provide the
necessary services for application software, and
Middleware which controls and co-ordinates distributed systems.
STORAGE
Memory stores input for and output from the CPU as well as the instructions that are
followed by the CPU

The amount stored is measured in bits, bytes, Kbytes (K, Kb, 103 bytes), Megabytes
(Mb, 106 bytes), Gigabytes (Gb, 109), Terabytes (Tb, 1012)
There are two kinds of memory:

Main memory (or internal or primary memory) is essential for the operation of the
computer, all data and instructions must be in main memory first before it can be
processed by the computer
Characteristics of the main memory
o
o
o
Most costly memory
In the form of microchips integrated with the computer's central processor
Fastest access - any byte can be accessed equally rapidly (random access,
hence it is called RAM)
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Temporary - since data and instructions are stored in main memory as
electrical voltages, power failures cause the loss of all data in main memory
o Ranges from several hundred Kbytes for typical PC to many Megabytes for
mainframes
Secondary memory (or auxiliary memory or secondary storage) is used for large,
permanent or semi-permanent files
o GIS programs and data generally require very large amounts of storage
o Data storage is covered after this overview of the components of computers
o

Computer Terminology
CD-ROM: This one stands for Compact Disk-Read Only Memory. CD-ROM disks are
becoming the standard for delivering programs from the software developer to the
computer user. CD-ROM's come in a variety of flavors based on the language they are
written in (PC,
CPU: The brain of the computer. This is located on a circuit board inside the desktop or
tower computer case. This component has terms associated with it such as "486",
"Pentium" and "Celeron". Most of the CPU's are manufactured by a company called
Intel. They are the Microsoft of the hardware world.
Data: Computer food. Data can be numbers, letters, symbols, mathematical expressions,
mouse clicks, or button presses. The CPU translates all this activity to series of zeroes and
ones and then performs magic.
Drivers: Drivers are software packages that are needed to run certain peripheral devices.
Printers, monitors, scanners, and network cards all require software drivers so that the
computer knows how to communicate and control the device.
.
Hard Disk Drive (HDD): This is the internal magnetic storage device housed inside the
computer case. These come in a variety of sizes, measured in how many bits of information
they can contain. The magnetic material stores information as sequences of the digits "0"
and "1" (hence the name digital storage). Since it takes many bytes to store such things as
letters, words, and sentences, the amount of information that a Hard Drive can store is
measured in multiples of 1000-bytes, 1,000,000 bytes, or 1,000,000,000 bytes. Terms
such as kilobyte (1000 bytes or 1KB), megabyte (1,000,000 bytes or 1MB), and gigabyte
(1,000,000,000 bytes or 1GB) have evolved to represent these storage capacities. When
you purchase a computer, get as large a Hard Drive as you can afford. The standard in
1998 was between 4GB and 8GB. The Hard Disk Drive is often referred to as the "C:" drive.
Floppy Diskette: The floppy diskette is a removable storage device that is used by the
Floppy Diskette Drive (also known as the A: drive or FDD). This storage device is capable
of holding 1,440,000 bytes (1.44MB) of data. The Floppy Diskette is inserted and removed
from a slotted opening on the front of the computer case.
Keyboard: The main tool to get information into the computer and the most common way
to tell the computer what you want it to do Computer keyboards have additional keys that
perform computer-specific functions.
Modem: A telecommunications peripheral device that allows computer to communicate
with one another via conventional telephone lines. Modems are required for home
computers to access the Internet or to send and receive facsimile transmissions (FAX).
Modems are rated by their speed in moving data from the computer to the telephone line.
This speed is measured in bits per second (bps). Standard modern modems are rated at
28,800 bps, 33,600 bps and 56,400 bps.
Monitor: The "Television" screen that allows you to see what the computer is doing.
Many newcomers to computing mistakenly think of the monitor as the computer itself.
Computers can operate without a monitor, but computer users cannot.
Motherboard: The circuit board on which most of the major electronic components are
situated. Most manufacturers integrate cable attachment ports on the back-end of the
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motherboard. They also include slots so that owners can add their own cable attachment
ports. The slots are designed to accept cards. These are normally found near the back of
the computer case.
Mouse: A common input device used to tell a computer what it needs to do. With the
invention of the Macintosh and Windows operating systems, computer users needed a
device to point at objects on the screen and select them.
MS-DOS: An older operating system that powered personal computers through their
beginning years. Prior to the development of the graphics-oriented Macintosh and Windows
operating systems, this system relied on typing commands one line at a time to tell the
computer what you wanted it to do. This system is still in use in the Windows family of
software and still has many practical uses. Windows 3.1 relies on MS-DOS to operate. MSDOS stands for Microsoft-Disk Operating System.
Network Card: A card that can be installed in one of the motherboard slots to give the
computer the ability to talk to other computers with similar cards. A collection of similarly
equipped computers connected by specially designed cables is known as a network. The
mechanism (including languages and protocols) used to communicate on a network are
varied, but the most common networking designs in use are Ethernet and Token Ring.
Operating System Software (OS): The instructions that allow the computer to start
working and permit it to run other programs. The major OS software types include MSDOS, Windows 3.1, Windows 95, Windows NT, Macintosh, UNIX, and LINUX. The most
popular OS in use at present is Windows 95. Most computers come with one of these preinstalled.
Pentium - Pentium II: Faster, larger CPU devices that are designed to allow more
computing instructions to occur per second. Most computers manufactured in the past 3 to
4 years contain this device.
Peripheral Device: Any device that is connected to the computer in addition to the basic
CPU-Monitor-Keyboard-Mouse configuration. External speakers, microphones, joysticks,
printers, and scanners are examples of peripherals.
Printer: A peripheral device that allows the computer user to produce paper copies of the
information processed by the computer.
Program: A complex set of instructions that allow the computer user to process data.
Common programs include word-processing, spreadsheets, databases, drawing and
painting, Internet tools, and games. Programs are necessary for computers to be useful to
humans.
RAM: This acronym stands for Random Access Memory. RAM is commonly called
"memory". Memory is measured in megabytes (MB) and usually comes in multiples of 2 or
4. The more RAM that a computer has, the better it can carry out instructions. It is
recommended that a new computer have 32 MB, 64MB, or 128MB of RAM.
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