What is a
computer?
The
word 'Computer' has been derived from the Latin word ' Compute' which means to count. In former time, computer was used to
manipulate data like words and numbers. So, it was called as a 'Computing
machine'. Presently, a computer has become an electrically powered device
through different evolutions of technology. According to the definition made by
the Microsoft technologists- “A Computer is an electrically powered device or
set of devices which works under the control of a stored program automatically
accepting and processing data with minimum human intervention to produce
results. Hence, a computer is automatic, re-programmable and a data processor
to store information'. That is to say, the following concepts may be accepted
apropos the definition of computer.
·
Literally, the
term computer means equipment that can compute.
·
The computer is a
combination of electronic devices used to process data.
·
In the computer
all types of data is converted to numbers. The computer can only work with
numbers, not letters, sounds or pictures. All forms of data are converted to
numbers for processing.
·
Computers can
receive, analyze, store information and produce reports.
·
Computers are
useful for accurate and fast processing of accounts.
·
A computer is an
electrically powered device.
·
It works under
the control of a stored program.
·
It accepts data,
analyzes data, preserves data and displays them in the form of result.
·
It completes work
related to accounts very speedily and correctly
·
It works out complex mathematical problems
·
It analyzes data
and displays results by the representation of charts and graphs.
Brief History of Computer:
·
On about 3000 BC
‘Abacus’ was invented in China
which was the earliest calculator. It was used for addition, subtraction,
multiplication and division.
·
On the 17th
century a number of instruments were invented which could be used as
calculator.
·
On the 18th
century a French scientist named Jacquard, invented an automated loom that
could receive designs from punched cards.
·
At a certain step
of perpetual research, came Charles Babbage with unique ideas. He is often
called the father of modern computers. He invented ‘Differential Engine’ on
1812.
·
He performed fast
calculations with this machine. On 1833 he planned to make a ‘Analytical
Engine’. This research did not go far due to hindrance of promised fund by the
Royal Society of England.
·
Later Lady Ada
Augusta invented a number of techniques, which utilized the concept of the
Analytical Engine. She was the daughter of the English poet Lord Byron and a
close friend of Babbage. She invented the techniques required to solve
mathematical problems, step by step. This is why she is considered as the first
computer programmer in the world.
·
On 1944, A
machine called ‘Mark-1’ was built
under the supervision Professor Howard Eken of Harvard University of USA. This
machine was 51 feet wide, 8 feet high. It had 5000 miles of electric cable and
combination 7.5 lakh electronic parts. Though a dinosaur among today’s neat compact
computers, this was the first computer of the first computer-age (1944-50).
·
The ENIAC
(Electronic Numerical Integrator and Calculator) was built in the University of Pennsylvania on 1946; it consisted of
almost eighteen thousand valves. It was made for the Ministry of Defense. In
1948 transistors were introduced, which ultimately replaced the valves.
Transistors are miniature electronic switches that functions the same as the
electronic valves and then some. 1958 saw the introduction of Integrated Circuits,
popularly known as IC, which made the huge availability of computers today
possible.
·
Then came Gordon
Moore on 1971 with his revolutionary invention of microprocessors.
·
After the
microprocessors, the progress was fast. IBM of USA introduced Microcomputers,
which is now popularly known as PC or Personal Computer.
·
The speed of data
processing depends on how powerful the processor is. Currently a processor with
speed above 500 MHz is available in the market.
·
The latest magic
in the computer world today is the Internet; virtually the whole world can be
reached through this little box with an Internet connection.
·
We conclude, on
the note that the computer has become an inseparable part of the modern
civilization.
Structure of a data processing system: Input ® Process ® Output
We
send information and instructions with the help of Input device (e.g. Keyboard
and Mouse) which are displayed in the Monitor and then reported to the CPU
where the data are processed, controlled and stored in the respective memory location
and then in the form of output we acquire result in the Printer.
Input:
Keyboard,
mouse , floppy disk, hard disk, mike etc.
Processing
Unit: CPU: CU, ALU, Memory.
Output device:
Printer.
Most
important component is output
Different
parts of a PC
Monitor:
The
monitor displays input data and the computer puts out after processing. Data or
information is in the form of word and pictures.
CPU:
It stands for Central Processing Unit
It
consists of two major components inside (a) Processor or active unit, which
does the computational or processing jobs on data and information.
Memory:
both long term ( in the form what are called hard disk, floppy disk ) and short
term memory ( for intermediate
processing called Ram or Random Access memory and Read only memory or ROM i.e.
Permanent Memory )
The CPU also contains other components like
communication devices, speaker etc.; One such communication device called
modem. Modems can be outside a CPU. They allow the computer to communicate with
another computer via a telephone line.
Computer Software:
Computer
Software is a set of instructions that controls the computer and its peripheral
devices. The non-physical property of a computer system is called Software.
Types of software:
There
are three types of Software: a. Operating
Software, e.g. DOS (Disk Operating System), Windows' 95 b. Application Software, e.g. Microsoft
Word, Microsoft Excel, Microsoft PowerPoint etc., c. Programming Software e.g. C ++, Java, Q-Basic, PASCAL,
Oracle etc.,
Operating the Personal computer: ON/ Off
For On: Wall socket, Voltage Stabilizer, UPS, Monitor and
CPU.
For off: Just the reverse but before switching off the
Computer, you must apply Shut Down
Process as follows: Click Start
Button, Click Shut down, Click yes
to confirm Shut down and then O.K. to display the message " It is now safe to turn off your Computer
"
Classification of Computer:
Computer may be classified into two ways: a. According
to Memory location and b. According to Technology. According to Memory size:
Business Micro, e.g. PC (Personal Computer).We are commonly conversant with PC,
Main frame Computer, Mini and Super Computer. According to Technology: Digital
Computer, Analogue Computer and Hybrid Computer.
Hardware
·
The term hardware
refers to the part of the computer that you can touch namely the various types
of equipment and peripherals are the hardware of a computer. For example: CPU,
monitor, keyboard, mouse etc.
·
Each type of
hardware of the computer has a specific or several functions. For example:
keyboard and mouse are used to input data into the computer. The monitor is
used to display the output. The block diagram below lists the most common
hardware of the computer.
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Summary
Device: All
hardware peripherals of a computer are called devices.
Input device: A device through which data is fed into the
computer. For example: keyboard, mouse, and scanner.
Process Unit:
After the data is entered into the computer it is processed to produce outputs.
Processing is done by the microprocessor.
Output Device:
The devices through which we can receive the processed information are the
output devices. For example: printer and monitor.
Memory
Memory
is the computer’s electronic scratch pad.
Programs are loaded into and run from memory. Data used by program is also
loaded into memory for fast access.
RAM (Random Access Memory): The most common type of memory is RAM. It is volatile
memory, as it needs constant supply of power. When you turn off a computer,
everything in RAM disappears.
ROM (Read Only Memory): This is nonvolatile memory. Data and instructions are
permanently programmed in this type of memory.
Storage Unit
It
is possible from a computer to function with just processing, memory, input and
output devices. To be really useful, however, it also needs a place to keep
program files and related data when it is not using them. The purpose of
storage is to hold data.
The
device that holds a disk is called a disk drive. Some disks are built into the
drive and are not meant to be removed. For example: Hard disk. Other kinds of
drives let you to remove and replace disks, such as a floppy disk drive.
Introduction
to some common computer hardware
Processing
Unit: The brain of the computer. This
is where data and instructions in are processed to produce meaning full
information.
Hard
Disk: Fixed, built-in storage unit of the computer.
Floppy
Disk Removable: storage unit of the computer. This device has
much less storage capacity than hard disks.
CD-ROM: Also
a removable storage unit. This device has larger storage capacity than the
floppy disks. It is a rounded thin plastic disk. A CD-ROM drive is required to
read from CD-ROMs.
Monitor: This
output device is like a television screen that displays output such as a text
that you are typing.
Keyboard: An input device. It is an electronic version of the typewriter machine. There are special function keys, alphabets, numbers assembled on the keyboard. There can be 101 to 105 numbers of keys on a keyboard.
Mouse: An input device. You can click, double click and drag with a mouse. Click is when you press a button on the
mouse. Double click is clicking twice
in rapid succession. Drag is to press
a mouse button and ‘drag’ the mouse physically as the button remains pressed.
Printer Output device that produces hardcopy
outputs. It prints out the output such as processed data, reports on paper.
There are different types of printers available at different price ranges. Most
commonly used nowadays are dot-matrix printer and Laser printer.
Floppy Disk
Drive: Used to read from and write to
floppy disks. It is like an audio cassette player. You must insert the floppy
disk into the floppy disk drive. It can read from and write to the floppy disk.
CD ROM Drive : Used to read from CD ROMs. It cannot write to a CD
ROM.
CD ROM
Writer Used to read from and write to
CD ROMs.
Scanner
Input device used to scan image or text and put a
digitized version into the computer’s storage unit.
Speaker
Output device for sound or acoustic
data. Same as a speaker in the audio
cassette player.
Modem This is a communication device used to access the Internet or other
computers through phone line.
Introduction
to power appliances normally used with computers
Stabilizer
We are all familiar with the voltage up-downs in our
electric supply. Both High and low voltage can be harmful to the complex
electronic circuits and devices inside the computer. A stabilizer is used to
produce a static supply of power in the face of disturbance in the actual
supply. So using a stabilizer with your expensive computer is very much
recommended.
UPS It means uninterrupted
Power Supply. This appliance is useful in face of regular power failures. It
generates power when the main power supply fails and gives a user some time to
shut down the computer properly.
Hardware and Software
Let us discuss these two
commonly used terms in the computer literature by comparing them with a common
example, the audio cassette player. What do we do when we want to listen to our
favorite songs? We first insert an audiocassette into the player and switch the
player on. Then press the ‘Play’ button, and consequently the music starts. But
notice that we listen to the song, but we cannot ‘touch’ the song. In the
computer literature the player and audiocassette are HARDWARE and the song itself is the SOFTWARE. The difference between the song and software is that
while, song has no control over running of the cassette player, software is the
main controlling force of the computer’s hardware. Without the software the
computer hardware is just a dead machine.
Another relative point to
mention here is that computer cannot automatically perform a task. It can only
do jobs that have been programmed into its memory and programmers do all the
programming. Programmers are the people who write codes or instructions for the
computer to understand and work accordingly. The information and instructions
that have been fed into the computer’s memory to perform a specific task is
collectively known as software. The computer can be programmed to do almost
anything with the right set of instructions and codes; i.e. there can be
numerous types of software, one or more for each type of task imaginable. For
example software can be specially written to draft letters, memos or documents.
Another type of software can be developed to do your daily accounts, i.e.
addition, subtraction, multiply and division. Special types of software are
written just to keep the computer running. They create environments to enable
other software to run.
We can define software as
follows:
·
Software is sets
of data and instructions to control the computer hardware, and to perform
various tasks such as producing complex mathematical and logical results.
Categories of Software
Most software
falls into two major categories: system
software and application software.
One major type of system software, called operating
system software, tells the computer how to use its own components.
Application
software tells a computer how to accomplish specific tasks for the
user such as word processing (MS Word), drawing (MS Paint), spreadsheet (MS
Excel), presentation (MS PowerPoint) etc.
BIOS
When you turn on a computer, it
goes through several steps to prepare itself for use. The first step is a
self-test. The computer identifies the devices that are attached to it, counts
the amount of memory available and does a quick check see whether the memory is
functioning properly. This
routine is called the BIOS (Basic Input Output System) and is located in
read-only memory (ROM).
Operating
System
Next the computer looks in the
floppy disk drive and then the hard disk drive for a special program called
Operating System. The operating system tells the computer how to interact with
the user and how to use devices such as the disk drives, keyboard and monitor.
Application
Software
A computer that is
running only on operating system is not very useful because the operating
system exists mostly for the benefit of the computer. Other programs are
required to make the computer useful for people. Application software help
users accomplish specific tasks. Application software has been written to do
almost every task imaginable., from word processing to selecting a college to
attend.
Windows Explorer
Windows
Explorer in its simplest definition, is the table of contents of a computer.
We can see at a glance, all the drives,
folders and files that are contained in the computer, through using the Windows
Explorer. A user can organize his/her files and decide which files should go
into which folder, create new folders,
cut or coy and paste files and folders etc. Also, a file can be copied to
or from the floppy disk from or to the hard disk.
How to open Windows Explorer:
Method:
Windows Explorer Environment:
Folder
Folders
are like file cabinets. You can organize your files in different folders as you
choose. You can create folders within a drive; sub-folders can be created
within a folder.
Creating Folders
Open
Windows Explorer. Click on File menu. Click New. Click Folder. This is illustrated
in the figure below. The newly created folder is given the name ‘New Folder’ by
default. You can rename it with a more relevant name and press Enter.
Delete a Folder or File
As mentioned before, to delete a
file or folder is the easiest thing to do in a computer, so be extra careful of
what you are deleting.
·
Open Windows
Explorer
·
Click the file or
folder you wish to delete
·
Press the Delete
key of the keyboard
Restoring a deleted file or folder
Deleted files and folders are actually moved to
another part of computer har disk, they are not completely erased from hard
disk. Deleted files and folders are kept in this separate portion of hard disk,
which is called a Recycle Bin. You can restore a deleted file by clicking
Restore in the Recycle Bin File menu. If you, however, Empty the Recycle Bin,
deleted files and folders will be lost forever.
Restoring Deleted File or Folder from
Recycle Bin
·
Double Click on
the Recycle Bin Icon of your Desktop.
·
Recycle Bin
window appears
·
Click the file or
folder you deleted and want to restore
·
Click File Menu
·
Click Restore
The figure below might make the steps clearer:
Cut, copy and paste
Preface: In our country,
especially in Dhaka city, we are all too
familiar with posturing on the walls. For this, the posters are prepared in the
press, then pasted using glue, to the walls. After pasting a poster to a
particular place we might change our mind and take it off to paste it somewhere
else, or we can make more copies and paste them to other walls. The posturing
aspect has amazing similarity to the cut, copy and paste options of a computer
application.
For
example: if you are preparing a document in the computer using a word
processing software, you may come across a need to use the same word or phrase
in a number of places. In which case, you can copy this word or phrase and
paste it to various places of the document, instead of typing it so many times.
You can paste a text as many times as you want after making a ‘copy’. Copy and
paste also applies in case of files and folders in Windows Explorer. You can
copy a file or folder and make as many copies of the same file in other folders
or sub-folders, as you want.
If
you want to remove a file or folder from a particular drive or folder and put
it in a different folder or drive, just ‘cut’ it and ‘paste’ it to the place
you want to put it. Similarly in our example of the document, you can ‘cut’ a
word or phrase and paste it to other place(s) which will remove the word or
phrase from the first place and move it to the second.
When
you cut or copy a file, folder, text or image, it is temporarily saved in a
place in the memory called the clipboard. When you click the paste option, the
file, folder or text from the clipboard is pasted. This is why you can make
exact copies of the same text, files, folders as many times as you wish.
Definitions,
Terminology and Method of Cut, Copy and Paste
‘Select’
is the key word in the process of cut, copy and paste. To select is to mark a
text, file, folder that must be copied or cut. You can click and drag the moue
to select a text or click a file or folder to select. The selected text, file
or folder will take on a different color (commonly black) to indicate a
selection.
‘Cut’
as mentioned before, is the process of moving the selected text, file or folder
from one place to another. In the Windows Explorer select a file; click on Edit
menu or the toolbar and then click the Cut or copy option. In a word processor,
follow the same steps.
‘Copy’
is the process of making replicas of a file, folder or text. The selected file,
folder or texts remain in its own places and an exact replica is created on the
clipboard. Clicking on ‘Paste’ toolbar or Edit-menu option moves this replica
from the clipboard to the clicked place.
‘Clipboard’
is the place where the cut or copied information is temporarily stored.
To copy a file to Floppy Disk
·
Open Windows
Explorer
·
Insert a floppy
disk into the Floppy Drive
·
Select the file
you want to copy
·
Click the Copy
Button on the toolbar
·
Click the A:\
drive
·
Click Paste toolbar
button
File Management
To find important files quickly, you should organize
your files in easily detectable folders. For example: supposing there is number
of files for the employees of an office, which contains the employee’s personal
information, salary, previous experience etc. You can keep these files in a
folder named ‘Employee’. Create sub-folders such as Personal, Salary,
Experience etc and keep relevant files in those sub-folders. You should take a
little time and thought to organize your files and folders, same as keeping
organized records and files in an office.
Find a file or Folder
Sometimes it is easy to lose a file among a hundred
other similar files. You can use the Find option in the Windows Explorer in
such situation. But the catch here is that you must remember something about
the file, such as its first 4 letters or last 4 letters or the date it was
created or the folder it was created in or its size or some of the text
contained in the file.
·
Open Windows
Explorer
·
Click Tools menu
·
Click Find
·
Click on File or
Folder option
·
A Find dialogue
box appears
·
Type the info you
remember about the file or folder
·
Click Find Now
Button
How to give electrical connection to Computers
To
protect your computer from power surges, frequent power failures and other
electric disturbances you should use stabilizers. Instead of directly
connecting your precious appliances to the main power line, connect the
computer to the stabilizer and the stabilizer to the wall socket. UPS are used
as a temporary power source for the computer in case of power failure. The
figure below shows the flow of electric connection among a computer, UPS and
stabilizer.
How do Computers work?
To
illustrate how a computer processes data we can use an analogy between
computers and the human brain. The five human sense receivers are the input
devices of the human brain. The eyes, ears, skin, tongue and nose receives
different types of sensations and sends them to the brain for processing.
Similarly the keyboard, mouse, scanner and other input peripherals of the
computer collects different types of data and sends them to the processor to be
processed.
The human output devices such
as talking through mouth or physical gestures can be compared to the monitor or
printer of the computer, which shows or prints the processed result from the
processor.
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Users and Phobia
Now
that you have an idea on how to electrically connect the computer the next step
is to work with it. Unfortunately, like all other new technologies, the
computer has its own set of phobias for its users. Realistically, as we have pointed out before, to run a computer can be
as easy as switching on the television. You can only do physical harm to a
computer by breaking it or one of its components. The software that you will be
using, can be itself a trainer/instructor for a beginner like you. This is
because most computer software are developed in a user-friendly manner and has
in-built help-option to assist or guide you through your ordeal. So don’t be
abashed or apprehensive, switch on the ‘magic-box’ and get started.
Switch on the computer
See if the electric
connections are as it should be and press the power button of the CPU. The
computer screen will show various start up info and messages and will stop
after a reaching a state and wait for your intervention.
Shutdown and switch off the computer
There is a specific set of
steps that a user must follow to shut down the computer. Otherwise there maybe
problems like the software or hardware can get corrupted. Always follow the
steps outlined below.
When you click on the YES
button a message will appear “Its Now Safe to Turn of Your Computer”. After
seeing this message press the power button to switch off the computer.
Now switch off the UPS and
stabilizer and last but not least, switch off the wall socket i.e. the main
power supply.
· Where to find information you need
Help is the primary source
of information about windows. You can find common tasks in the contents and
more in the Index, and search for text by using the Find Tab. To find Help ,
Click the Start button, and then click Help.
· Help on a specific item
If
a window contains a question mark button, You can see a description of any item
in the window. Just click the button and then click the item.
· A new look and feel
The
look and feel of windows has been improved to make it easier and faster for you to get your work done.
¨
Start button and
task bar, My Computer, Windows Explorer,
Network Neighborhood, Long file name,
The desktop, Properties, Folders,
Shortcut Menus, Close, Minimize,
and Maximize And What is this ?
· Start button and task-bar:
At
the bottom of your screen is the task bar. It contains the start button, which
you can use quickly – start a program or to find a file. It is also the fastest
way to get help, when you open a program, document, or window, a button appears
on the task bar. You can use this button to quickly switch between the windows
you have opened.
· My Computer
You
can use My Computer to quickly and easily see everything on your computer. Double Click the My Computer icon on
the desktop to browse through your files and folders.
· Windows Explorer
In
windows explorer, you can see both the hierarchy of folders on the computer and
all the files and folders in each selected folders. This is especially useful
for copying and moving files. You can open the folder and contains the file you
can move or copy, and then drag it to the folder you want to put it in.
To
find windows explorer, Click the start button, and then point to the programs.
· Network neighborhood
If
you are using a net work, the network neighborhood icon appears in your
desktop.
Double
click it to browse through the computers in your work group and the computers on your entire
network.
· Long filenames :
You can now give any name
to a file; you are not limited to eight characters with a three-character
extension. You can even use spaces. The file name may be extended up to 255
characters with space.
· The desktop
When
you start windows, the large area you see is called the desktop. You can
customize the desktop by adding shortcuts to your favorite programs, documents,
and the printers, and by changing it look to fit your mood and personality.
To
adjust settings such as desktop color and background, use your right mouse
button to click anywhere on the desktop, and click properties.
· Properties
When
you want to view or change information about any item, such as a document,
program, folder, disk drive, or printer, you can look at its properties.
Use
the right mouse button to click the item, and then click properties on the
menu.
For
Ms Dos based programs, you no longer need to create and modify PIF files, you
just modify the properties for the program.
·
Folders :
Your
documents and programs are stored in folders, which you can see in
My Computer. In previous versions of windows,
folders were called directories.
·
Shortcut menus :
You
can use your right mouse button to click any item and see a shortcut menu. This
menu contains common commands that you can use on the item you clicked. For
example, by clicking a file with your right mouse button, you can choose to
open, copy, or delete it.
·
Close, Minimize, and
Maximize buttons :
Every window has X (close button) in the upper right corner that
you can click to close the window and quit the program.
The
minimize and Maximize buve a new look.
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