Practicals Computer Science Important
1 Write down the steps to shutdown and restart
Windows
2 How would you launch the start Menu and Access
the Program Menu?
3 How would you create new folder on the desktop
and in windows?
4 Write down the steps to create ,rename and
delete the folder
5 Write down the steps
i) To search a file from computer.
ii) To view the properties of your computer.
6 How would you search files or folders on your
computer?
6 How would you get help in Window Operating
System?
7 How would you maximize, minimize, close and
restore the window?
8 How would you load Windows Explorer?
9 How would you Set Date/Time?
10 How would you arrange desktop icons
11 How would you view and empty the Recycle Bin?
Introduction to Computers
Computer
A Computer is an automatic electronic,
calculating device which can process a given input in a prescribed manner to
produce a desired output, at a very high speed with remarkable accuracy. It can
also perform all arithmetic and logical functions according to instructions
given in a systematic order to solve any problem and produce processed
information.
Advantages of Computers
Speed
Since Computer is an electronic machine and
electrical pulses travel at the rate of passage of electric current. This speed
enables the computer to perform millions of calculations per second.
Storage
A computer has too much storage capacity. Once
recorded, a piece of information can never be forgotten.
High Accuracy
A computer can be considered as 100% accurate.
Checking circuits are built directly into the computer, that computer errors
that undetected are extremely rare.
Versatility
Computer can perform any task, provided it can
be reduced to a series of logical steps.
Diligence
Computer never gets tired. It performs most
boring, repetitive and monotnous task.
Automatic Operation
Once a program is fed into computer the
individual instructions are processed on after the other. Thus computer works
automatically without manual intervention.
Obedience
The ability to take in and store a sequence of
instructions for the computer to obey. Such a sequence of instruction is called
a PROGRAM and it must be written in the Computer Language.
Decision Making Capability
Computer can take simple decisions, such as less
than, greater than or equal to. It also determines whether a statement is true
or false.
Hardware
the physical components and other attached input
and output devices of computers are called Hardware. All Hardware components
may be connected mechanically, electrically or electronically with each other.
Hardware includes input/output devices, CPU, backing storage devices and
electronic circuit.
Software
Computer required a number of instructions to do
any job. The set of these instructions forms programs. Numbers of programs are
combined for some purposes are called software.
They are designed by manufactures and
programmers.
Types of Software
1. System Software
2. Application Software
Ages of Computer
At the early age people used pebbles, stones,
sticks, scratches, symbols and finger tips to count, which were later replaced
by numbers.
The history of computing is divided into three
ages during which man invented and improved different types of calculating
machines. These ages are,
- Dark age - 300 BC to 1890
- Middle age - 1890 AD to 1944
- Modern age - since 1944 AD
Dark Age (3000 BC to 1890 AD
ABACUS
About 3000 years BC, Chinese developed the first
calculating machine named Abacus or Soroban.
Abacus consists of a rectangular wooden frame
having rods which carry round beads. Counting is done by shifting the beads
from one side to another.
OUGHTRED’S SLIDE RULES
In 1632 AD William Oughtred, an English
mathematician developed a slide rule. This device consists of two movable rules
placed side by side on which number were marked.
PASCAL’S CALCULATOR
Blasé Pascal (1623-1662), a French developed the
first mechanical calculating machine in 1642. This machine consists of gears,
wheels and dials. It was capable of adding and subtracting operations.
GOTTEFRIED WILHOLM LEIBNITZ
In 1671, a German, Gottfried Von Leibnitz
(1646-1716) improved Pascal’s calculator to make it capable of performing all
maths operations.
JACQUARD’S LOOM
In 1801, a French, Joseph Marie Jacquard
developed the first punch card machine.
BABBAGE DIFFERENCE ENGINE
Charles Babbage (1792-1871) an English
mathematician also called Father of modern computer. As he gave the true
concept of computer at Cambridge University, he developed Babbage Difference
Engine in 1823 and Babbage Analytical Engine in 1833.
Lady Ada Augusta an assistant of Babbage is
called the first programmer.
Middle Age (1890 AD TO 1944 AD)
DOCTOR HERMAN HOLLERITH
In 1880s Herman Hollerith an American developed
a machine which used punch card system. The machine could sense and punch
holes, recognize the number and make required calculations. This machine was
first used in 1890s by American Census Bureau.
HOWARD AIKEN- MARK-1 COMPUTER
In 1937, Professor Howard Aiken build the first
electro-mechanical computer Mark-1, by trying to combine Babbage’s theory and
Hollerith’s punching technologies. He completed his project in 1944 with the
help of IBM Engineers.
Mark 1 could multiply two, twenty digit numbers
in 5 seconds and made a lot of noise. It had a shape like a monster about 50
feet long, 8 feet high, having wiring of length equal to distance from Lahore
to Gilgit or Karachi to Bahawalpur (800km) and had thousand ends of
electro-magnetic relays.
ABC (ATANASOFF BERRY COMPUTER)
ABC a special purpose computer was developed in
1938 by Dr. John Vincent Atanasoff and Clifford Berry at Iowa State College,
USA.
Modern Ages (Since 1944 AD)
JOHN VON NEUMAN
In 1945, Dr. John Von Neuman suggested the
concept of Automatic Data Processing (ADP) according to the stored program and
data. ENIAC
(FIRST ELECTRONIC COMPUTER)
Electronic Numerical Integrator And Calculator
(ENIAC) was the first electronic computer made in 1946 by John Presper Eckert
and John Williams Mauchly, at the University of Pennsylvania, USA. This was
based on decimal number system and it has no memory.
It could perform 5000 additions or 350
multiplications in one second. It contained 18000 vacuum tubes, 70,000
resistors, 10,000 capacitors and 60,000 switches and occupied a two room car
garage. It consumed 150 kW of power. It weighed 27 tons.
EDSAC (FIRST STORED PROGRAM COMPUTER)
Electronic Delay Storage Automatic Computer
(EDSAC) was first computer based on stored program concept. It was completed by
Mourice Wilkes at Cambridge University in 1949.
EDVAC
Electronic Discrete Variable Automatic Computer
(EDVAC) was built by John Williams Mauchly, John Presper Eckert at Moore
School, Pennsylvania in 1951.
UNIVAC (FIRST COMMERCIAL COMPUTER)
UNIVersal Automatic Computer (UNIVAC) was the
first commercially used computer made by John Presper Eckert and John Williams
Mauchly in June 14, 1951.
Classification of Computers According to Purpose
1. General Purpose Computers
General purpose computers are designed to solve
a large variety of problems. The different programs can be used to solve many
problems. Most digital computers are general purpose computers and used in
business and commercial data processing.
2. Special Purpose Computers
A computer designed for machine control or
process control would be different than a general purpose computer. The special
purpose computers are designed to solve specific problems. The computer program
for solving a specific problem is built right into the computer. Most analog
computers are special purpose computers. These special purpose computers are
widely used in industrial robotics.
Types of Computers
1. Analog Computers
Analog computers are used to process continuous
data. Analog computers represent variables by physical quantities. Thus any
computer which solve problem by translating physical conditions such as flow,
temperature, pressure, angular position or voltage into related mechanical or
electrical related circuits as an analog for the physical phenomenon being investigated
in general it is a computer which uses an analog quantity and produces analog
values as output. Thus an analog computer measures continuously. Analog
computers are very much speedy. They produce their results very fast. But their
results are approximately correct. All the analog computers are special purpose
computers.
2. Digital Computers
Digital computer represents physical quantities
with the help of digits or numbers. These numbers are used to perform
Arithmetic calculations and also make logical decision to reach a conclusion,
depending on, the data they receive from the user.
3. Hybrid Computers
Various specifically designed computers are with
both digital and analog characteristics combining the advantages of analog and
digital computers when working as a system. Hybrid computers are being used
extensively in process control system where it is necessary to have a close
representation with the physical world.
The hybrid system provides the good precision
that can be attained with analog computers and the greater control that is
possible with digital computers, plus the ability to accept the input data in
either form.
Classification of Computers According to Size
1. Super Computers
Large scientific and research laboratories as
well as the government organizations have extra ordinary demand for processing
data which required tremendous processing speed, memory and other services
which may not be provided with any other category to meet their needs.
Therefore very large computers used are called Super Computers. These computers
are extremely expensive and the speed is measured in billions of instructions
per seconds.
2. Main Frame Computers
The most expensive, largest and the most
quickest or speedy computer are called mainframe computers. These computers are
used in large companies, factories, organizations etc. the mainframe computers
are the most expensive computers, they cost more than 20 million rupees. In
this computers 150 users are able to work on one C.P.U. The mainframes are able
to process 1 to 8 bits at a time. They have several hundreds of megabytes of
primary storage and operate at a speed measured in nano second.
3. Mini Computers
Mini computers are smaller than mainframes, both
in size and other facilities such as speed, storage capacity and other
services. They are versatile that they can be fitted where ever they are
needed. Their speeds are rated between one and fifty million instructions per
second (MIPS). They have primary storage in hundred to three hundred megabytes
range with direct access storage device.
4. Micro Computers
These are the smallest range of computers. They
were introduced in the early 70’s having less storing space and processing
speed. Micro computers of todays are equivalent to the mini computers of
yesterday in terms of performing and processing. They are also called “computer
of a chip” because its entire circuitry is contained in one tiny chip. The
micro computers have a wide range of applications including uses as portable
computer that can be plugged into any wall.
5. Laptop Computers
The smallest computer in size has been
developed. This type of small computers look like an office brief case and
called "LAPTOP" computer. The laptops are also termed as
"PORTABLE COMPUTERS." Due to the small size and light weight, they
become popular among the computer users. The businessmen found laptop very
useful, during traveling and when they are far away frm their desktop
computers. A typical laptop computer has all the facilities available in microcomputer.
The smallest laptops are called "PALMTOP".
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Generations of Computer
First Generation of Computer (1946-1959)
Main Features
- Major Innovation - Vacuum Tubes
- Main Memory - Punched Cards
- Input Output Devices - Punched cards and papers
- Languages - Low level machine language
- Operating System - No operating system, human operators
to set
switches
- Size - Main frame for example ENIAC, EDVAC, UNIVAC
The duration lasted from
1946-1959 was based on vacuum tubes. These vacuum tubes were about the size of
100 watt light bulb and used as the internal computer component. However
because thousands of such bulbs were used, the computers were very large and
generate a large amount of heat, causing many problems in temperature
regulation and climate control.
In this generation input and out put device
(punched card) that was used fro data storing purpose were very slow. The
computers were operating manually and the language used was a low level machine
language (symbolic language) with binary code that required a high programming
skill. ENIAC, EDVAC, UNIVAC and Mark-1 were some of the major inventions of
this generation.
Advantages of First Generation
1. Vacuum tubes were used as electronic
component.
2. Electronic digital computers were developed
for the first time.
3. These computers were the fastest calculating
devices of their time.
4. Computations were performed in millisecond.
Disadvantages of First Generation
1. Too large in size.
2. They were unreliable.
3. Induce a large amount of heat due to the
vacuum tubes.
5. Not portable.
6. Limited commercial use.
Second Generation of Computers (1959-1964)
Main Features
- Major Innovation - Transistors as main component.
- Main Memory - RAM and ROM.
- External Storage - Magnetic tapes and Magnetic Disk.
- Input Output Devices - Magnetic tapes and Magnetic
Disk.
- Languages - Assembly language, some high level
languages for Example BASIC, COBOL, FORTRAN.
- Operating System - Human handles punched card.
- Size - Main frame for example IBM-1401, NCR-300,
IBM-600 etc.
The period of this generation
is from 1959 to 1964. During this period transistor were used for internal
logic circuits of computers. These computers could execute 200000 instructions
per second. The input/output devices became much faster by the use of magnetic
table. During this period the low level programing language were used however
the high level programming languages such as FORTRAN and COBOL were also used.
The problem of heat maintenance was solved and size of computer reduced, while
speed and reliability were increased. Many companies manufactured second
generation computers and many of those for business applications. The most
popular second generation computer was IBM-1401, introduced in 1960, while the
following computers were used by many business organizations. IBM-1400 series,
IBM-1600 series, UNIVAC-III, NCR-300 etc.
Advantages of Second Generation
1. Smaller in size as compares to 1st
generation.
2. Much more reliable.
3. Less heat generated.
4. Computation was performing in micro second.
5. Less hardware and maintenance problem.
6. Could be used for commercial use.
Disadvantages of Second Generation
1. Very costly for commercial use.
2. It still required frequent maintenance.
3. Frequent cooling also required.
Third Generation of Computers (1965-1970)
Main Features
- Major Innovation - Integrated circuit (ICs) as basic
electronic component.
- Main Memory - PROM and DRAM.
- External Storage - Improve disk (Floppy Disk)
- Input and Output Devices - Keyboard for input, monitor
for output.
- Languages - More high level languages.
- Operating System - Complete operating systems were
introduced.
- Size - Mini, for example: IBM SYSTEM / 360, ICH-360,
HONEY WELL-316 etc.
In this generation the
integrated circuits (IC) were used. Integrated circuits contain many electronic
components on a single chip. The disk oriented systems wee made at the end of
this generation. The size of computer became very small with better performance
and reliability. High level programming languages were extensively used. In
1969 the first microprocessor chip INTEL 4004 was developed but it was used
only in calculators. The faster input/output devices made possible
multi-processing and multi programming. Where by a number of input terminals
could be run virtually at the same time on a single centrally located computer.
The famous computer were IBM-360, IBM-370, UNIVAC 9000 series etc.
Advantages of Third Generation
1. Smaller in size as compared to second generation.
2. More reliable.
3. Portable
4. Less electricity consumption.
5. Heat generation was rare.
6. General purpose computer.
Disadvantages of Third Generation
1. Air conditioning was required in many cases
due to ICs.
2. Very advance technology was required to make
the ICs.
Fourth Generation of Computers (1971-1981)
Main Features
- Major Innovation - LSIC and VLSIC (Micro Processor)
- Main Memory - EPROM and SRAM.
- External Storage - Floppy Disk and Hard Disk.
- Input and Output Devices - Monitor for output.
- Languages - Languages and application softwares.
- Operating System - MS-DOS and PC-DOS
- Size - Micro computer e.g. IBM-PC, Apple Macintosh etc.
The Integrated circuits were
more developed and called Small scale integration (SSI), after some time the
SSI were more developed and termed as Large scale integration (LSI). There was
a great versatility of input/output devices. In 1971, a powerful microprocessor
chip INTEL 8008 was introduced. The first microprocessor which is used in
personal computers (PC) was INTEL 8080. The 8 inch floppy disk was also
introduced in 1971, while hard disk was introduced in 1973. The 5.25 floppy disk was first time used in 1978. The optical disk
was developed in 1980. First portable computer "Osborne I" was
marketed in 1981. IBM-3033, IBM-370, IBM system 34, IBM system 36, Cray-I, CP/M
etc were introduced in this generation.
Advantages of Fourth Generation
1. Smaller in size and much reliable.
2. No cooling system required in many cases.
3. Much faster computation.
4. Portable and cheap.
5. The heat generated was negligible.
6. Totally general purpose computer.
Disadvantages of Fourth Generation
1. Very advanced technology was required to
fabricate to the ICs.
Fifth Generation (1981-Onward)
Main Features
- Major Innovations - ULSIC (Ultra large scale integrated
circuit)
- Main Memory - EEPROM, SIMM and DIMM.
- External Storage - Modified magnetic and Optical disks.
- Input/output Devices - Keyboard, Pointing Device,
Scanner as input and Monitor as main output.
- Languages - AI (Artificial Intelligence) Expert
systems.
- Operating System - GUI based e.g. Windows 95, Windows
NT.
- Size - Very small in size example: Laptop, Note book,
Digital Diary, Palm top and Pocket PC.
This generation is started from
1981 and still continued, new technologies are adopted to fabricate IC chips,
such as electron beam, X-rays or laser rays. The Very Large Scale Integration
(VLSI) was developed, so the computer became
much smaller than ever before. New memory storage device like bubble memory,
optical or memory are being designed. the new computer will be controlled by
using human voice and will work by giving command in our own language. Future
computer will in some way to be intelligent and capable of making decision.
Advantages of Fifth Generation
1. Very large storage capacity.
2. Long bit processor builds.
3. Artificial Intelligence Language developed.
Short Notes
1. Super Computer
These are the largest and fastest machines today
where numerical computations are carried out speeds of up to 50 millions
operation per second. Super computers are very sophisticated machines designed
to perform complex calculations at fastest speeds. Super computers are used to
model very large dynamic systems, such as weather patterns national or global
weather forecasting, satellite tracking, cold-testing of atomic and nuclear
weapon etc. Carry research and Intel are well known producers of Super
Computers.
2. Main Frames
A main frame originally meant the cabinet
containing the central processor unit of a very large computer. After mini
computer became available, the word main-frame comes to refers to the large
computer itself.
Mainframes, the biggest and the most productive
general purpose systems, that are made to model large dynamic computing need of
a big organizations that serve hundreds of terminals all at the same time. A
terminal consists of a monitor and keyboard that allow a person to enter
information and retrieve it from the computer. These computers are the ultimate
in sophistication, flexibility and speed.
3. Mini-Computer
Mini computer are increasingly powerful and do
almost any thing that large computers do, only more slowly and at much lower
cost than mainframes. This makes it ideal for small companies where capacity
and speed of operations in not highly critical. These computers are smaller
than mainframe and larger than micro computer in size. A mini computer is a
multiprocessing system having terminals attached to it and is capable of
supporting 4 to 200 users simultaneously. DEC VAX and IBM AS/400 are commonly
used mini-computers.
4. Micro-Computer
Micro-Computers are computers that are powered
by microprocessors. Sometimes they are referred as SINGLE CHIP PROCESSOR a
SYSTEM-ON-A-CHIP. Micro-computers or personal computers are the smallest
computers, designed to be used by individuals for writing, illustrating,
budgeting, playing games and communicating with other computers.
Programming Language
A programming language is a type of software. A
program is a set of step by step instruction that directs the computer to do
the tasks you want it to do and produce the result you want. A set of rules
that provides a way of telling a computer when operations to perform is called
a Programming Language.
Machine Language (Low Level Language)
Every creation of this universe has its own
language. Like wise, computer has a language that is called Machine Language
(machine level language) for instructing computer to perform specific task. It
is also called binary language because it is the language of 0s and 1s, means
every instruction in Machine language consists of a series of 0s and 1s (binary
code) that a computer can understand and execute directly. Each machine
language statement corresponds to one machine action. An operation that
requires one machine language instruction in one computer may require several
instructions in another computer. Each computer has its own unique machine
language.
Assembly Language
In assembly language, the statements are written
in symbolic codes (termed as mnemonics) that are easier for human to read and
write as compared to machine language. Each assembly language statement
corresponds to one machine language statement.
Advantages of Assembly Language
1. Operation codes of machine language are
mnemonics, which are easy to remember.
2. An Assembly language program may be written
easily as compared to machine language.
3. The memory addresses are used in machine
language which is replaced by the variable names in this language.
4. Revision of complete program is quite easy.
5. The insertion and deletion of the
instructions in the program are quite easy.
Disadvantages of Assembly Language
1. As compared to machine language assembly
language is less efficient.
2. An assembly language program cannot be
executed on small size computers.
High Level Language
High level languages are closer to human
languages than low-level language and include statement like GOTO and PRINT
which are regular words. Unlike the assembly language, the program of high
level languages do not have to be written for a particular computer, but it can
be execute on any machine that has a compiler for that language.
Internet
Internet is the largest network of the world
that connects computers located t different parts of the world. The Internet
has had a huge impact on society. The Internet provides information and
service, as well as the ability to communicate to people all around the world
in a variety of ways. These range from bulletin boards and chat rooms to voice
conversations and video conferencing.
The Internet creates new ways for citizens to
communicate, congregate and share information. It is obvious that the Internet
has and will continue to change the way we live.
All in all, the Internet is affecting so many
people's lives in most welcome, exciting and challenging ways.
Advantages of Internet
1. It gives information about every field of
life.
2. You may take advantages from encyclopedias
and dictionaries with the help of Internet.
3. You my get information according to your need
through Internet.
4. It gives a co-ordination with whole world and
its interests.
5. It helps to exchange views with the person of
same mental attitude.
6. Internet brings the world closer.
7. Current happening incident can be discovered
by the use of Internet.
8. Any kind of topic related with politics,
fashion, science etc can be discovered by use of Internet.
Disadvantages of Internet
1. The student waste their precious hours on
sitting on Internet without taking any positive and constructive benefit.
2. Most of the people using Internet to satisfy
their negative desires.
3. Adult material is easily available through
Internet which destroys the moral values of young boys and girls.
4. Computer hacking is very common by the use of
Internet some extreme minded people can digest the money through the use of
credit cards of others.
5. The students waste their time in useless
talking with each other.
6. Several hours on Internet without any purpose
produce wrong effects on a person.
Compiler
A compiler is complex system software that
automatically converts a program written in some high-level language into an
equivalent low-level machine language. The compiler or the language processor
converts the entire program into machine code before execution. A program
written by a programmer in a language other than machine language is called a Source
Program. The output from a compiler or an
assembler, which consists of machine language instructions, is called the Object
Program.
Interpreter
An interpreter is another type of translator
that converts each statement of a program written in a high level language into
machine code and executes it before translating the next statement of the
source program. It differs from a compiler that translates the entire source
program into object program without undergoing its execution.
Short Notes
BASIC - Beginner's All-Purpose Symbolic Instruction Code)
John Kemeny and Thomas Kurtz developed BASIC in
1964 for beginners. BASIC is a very simple language to use and understand. It
uses simple English words. Even a person with a little knowledge of computer
programming can learn it and utilize it for business and scientific purpose. It
is a powerful language that has grasped millions of users. The biggest problem
with it is that it has no standard version and different manufacturers modified
it into different versions.
PASCAL
A French mathematician Blaise Pascal introduced
a programming language by the name of PASCAL. It is a highly structured
programming language. It was developed in 1970's after the concept of
structured programming.
FORTRAN (Formula Translation)
It was developed in 1957 for IBM computers to
solve mathematical, scientific and engineering problems. It was one of the
first languages to introduce the concept of "Modular Programming". It
has been revised so many times.
Advantages and Disadvantages of Computers
Following are some advantages and disadvantages
of computer in our life.
Advantages
1. Computers make us more productive in many of
our jobs.
2. In education they can help us for better
understanding faster learning and broaden our thinking.
3. In hospitals we have better diagnosis, proper
treatment and better healthcare.
4. In business, they are used to record stocks
of raw materials as well as finished products, making customer's bill,
analyzing sales of various products etc.
5. In banks, they are used for day-to-day
processing of customer's accounts and payments.
6. In manufacturing, they provide ways to
develop a representation of the product and to test it in a variety of
simulated environments.
Disadvantages
1. Unemployment due to automation.
2. Wastage of time and energy in useless
computer activities.
3. Data security.
4. Privacy
5. Computer Crimes.
Read more: Introduction to Computers http://www.friendsmania.net/forum/9th-class-computer-notes/20349.htm#ixzz35Baey5an
Choose any one of the following correct answers:
1. __________ is a category of computer
hardware.
(Input, Output, Storage, Processing, all of the
above)
2. __________ is an important component of
microcomputer system.
(Kilobyte, Microprocessor, Megabyte, Byte, None
of the above)
3. __________ is not found in C.P.U.
(ALU, Control Unit, RAM, Processing Register)
4. __________ is a type of impact printers.
(Laser, Thermal, Dot-Matrix, Inkjet)
5. __________ program design technique shows
program logic.
(Flow chart, Logical Operation, Computer, None
of the above)
6. __________ is used as counter in BASIC
programs.
(A = A+1, A<1, A or 1, None of the above)
7. __________ characteristic is applied to the
third generation of computers.
(Integrated Circuit, Transistor, Vacuum Tubes,
All of the above)
8. The most important characteristic of ROM is
__________.
(It performs mathematical calculation, it is
volatile, it is non – volatile, None of the above)
9. __________ statement is used to transfer the
control of program conditionally.
(GOTO, ON GOTO, END, All of the above)
10. Disk operating system is abbreviated as
__________.
(DOS, DS, OS, None of above)
11. __________ is an example of integer data.
(HASAN, D-143, 143, all of the above)
12. High level languages were designed in
__________.
(Laboratory, Third generation, Computers, New
York)
13. __________ is a high level language.
(BASIC, BESIK, BACIK, BESIC)
14. Binary number system has __________.
(Ten digits (0,9), Three digits (-1,0,1), One
digit (1), Two digits (0,1))
15. LET statement is __________.
(Optional statement, Assigning statement, Used
for expression assignment, all of the above)
16. DATA statement is __________.
(Executable statement, Non-executable statement,
Optional statement, None of the above)
17. BASIC stands for __________.
(Basic All-purpose Symbolic Instructon Code,
Beginners Assembly Symbols Instruction Code, Basic All Standards In COBOL,
Beginners All-purpose Symbolic Instruction Code)
18. When using READ statement, it must to
provide __________.
(PRINT statement, RESTORE statement, INPUT
statement, None of above)
19. ANSI stands for __________.
(All New Small Integration, A National Small
Institute, American National Standard Institute, None of the above)
20. Sign of exclamation is __________.
(!, :, I, %)
21. The example of random access storage media
is __________.
(Floppy disk drive, Hard disk drive, Tape unit,
51/4’’ floppy disk)
22. The type of memory whose contents can not be
changed is __________.
(ROM, RAM, Cache, EAPROM)
23. The command to see the contents of a disk is
__________.
(DIR, CD, MD, TYPE)
24. DISKCOPY command can format the destination
disk __________.
(Before copying, after copying, can not format,
format while copying)
25. TYPE command is used to __________.
(To see the contents of a file, Chage the type
of a file, make a sub directory, Type a file in the computer)
26. Each statement of BASIC must have a
__________.
(Function, Statement number, Program name, File
name)
27. The command to create a sub-directory is
__________.
(DIR, CD, MD, APPEND)
28. TAB () function is used to __________.
(Print, Display, Print and Display, None of the
above)
__________________
Read more: Multiple Choice Questions "Computer" Class 9th http://www.friendsmania.net/forum/9th-class-computer-notes/86622.htm#ixzz35BlJHQCg
BASIC
Removal of Errors
Friendsmania.net
Remove the errors in the following BASIC
Statements, if any:
1. 5 REEM ** MARKS SHEET **
2. 5.5 INPUT TAB (90) “NAME” : N$
3. –65 PRINT “MY SCHOOL”
4. 100S$ = MID$(A$5)
5. 99 READ 4, 5, SIX: DATA A, B, C$
6. 25 GOSUB R
7. 10 IF A = 10 TO 50 THEN END
8. 15 LET X “=” A “*” B
9. 80 FOR I = 20 TO 10 STEP –2
10. 18 LOCATE (5, 10): PRINT “ME”
11. 10 LET Z = “PAKISTAN”
12. 06 PRINT RIGHT (8, A$)
13. 20 IF X $ = 6 THEN : GOTO 120
14. 41 DATA 18, CLASS, SCHOOL: READ N, P, C
15. 5.5 INPUT “YOU NAME” N
16. RAM TO CALCULATE NUMBERS
17. –8 ON GOTO CH 100, 200, 300
18. 66 A$ = 5 TO 1 STEP –1
19. PRINT “OK”: TAB (10)
20. 50.5 PRIT “MY SCHOOL”
21. 38 REED A: DATA 40
22. 141 RAM “PRACTICAL EXAM”
23. 80 FOR R = IT 0010: NEXTR
24. 100 PRINT TAB (10); PAKISTAN
25. –32C= 10 TO 20 STEP –2
26. 53 READ A$; B; C$ : DATA AEROPLANE ; 200;
CARD
27. 200 INPUT; “WHAT IS YOU NAME?”; A$
28. 10IF A = 100 THEN GOTO R
29. 20 REEM ABC
30. 10 LET A = “Karachi City”
31. 06 PRINT RIGHT (A$, 8)
32. 20 IF X$ = 6 THEN GOTO 120
33. 41 DATA. 18, page, Cat: READ N; P$; C$
34. 50.5 INPUT “What is your age?” A
35. 66 PRINT TAB (2): “ALL”; TAB (7); “The”; TAB
(12) “Best”
36. 32 SCREEN 86
37. 706 LINE (40, 80) (300, 150); 3
38. 25 LOCATE 12.30: PRINT “Friendship”
39. 14 PRINT MID$ (A$, 10, 3)
40. 10 For X = 1 TO 5 STEP –1
20 J=X = 10
30 IF J = 80 THEN 100
40 NEXT Y
50 END
41. 10 INPUT
20 B – C = D
30 B = A * 2
40 PRINT E
50 END
42. 10 CLS
20 FOR I = 1 TO 10
30 LET A = 1
40 ? A
60 ? “This is the end of program.”
70 END
43. 10 INPUT A.B
20 LET A = A * 5
30 LET B = B * 2
40 TAB 20, 30: PRINT A;B
50 FINISH
44. 10 LOCATE 75, 10
20 PRINTER “Am I wrong?”;
30 LET T = 25 X 4 + 60
40 PRINTER T
50 END
45. 10 LET A = “KARACHI CITY”
46. 06 PRINT RIGHT (A$, 8)
47. 20 IF X$ = 6 THEN GOTO 120
48. 41 DTA 18, PAGE, CAT: READ N; P$; C$
49. 50.5 INPUT “WHAT IS YOU AGE?” A
50. 66 PRINT TAB (2); “ALI”; TAB (7); “THE” ;
TAB (12); “BEST”
@import
"/extensions/GoogleAdSense/GoogleAdSense.css";
51. 32 SCREEN 86]
52. 70.6 LINE (40, 80) – (300 – 150) ;3
53. 25 LOCATE 12, 30 : PRINT “FRIENDSHIP”
54. 14 PRINT MID$ (A$, 10, 3)
55. 10 GOTO 60, 70
56. 20 FOR I=1 10 STEP 2
57. 14 S$ = PAKISTAN
58. 26 READ P$, X: DATA THRE, 3
59. 65 PRINT A = A, B, C
60. 121 IF X = 20: THEN GOTO 20
61. 70 LET X = LAE A + Y
62. 20 “INPUT ENTER YOU NAME”;N
63. 46.5 IF C$= COMPUTER THEN END
64. –25 C$ = A4 + B + C
65. 10 CLS, X = X + 1
66. 55 Z$ = CHR (29)
67. 129 READ 50, 100 ATA A, B
68. 30 FOR 50 = A TO B
69. 40 GOTO CLS
70. 66 IF X$ = 50THEN GOTO A$ ELSE GOTO 30
71. 55 REM REM
72. 100 LET P$ = X
73. 123 LOCATE 35, 90 : PRINT “PAKISTAN”
74. 999 PRINT TAB (90) STRING$ (120, “-“
75. 50 N$ = RIGHT$ (C$, 3)
76. 7 A = LET M +1
77. 10 LPRINT = A, B, CAT
78. AN INPUT “STUDENT ROLL NUMBER “;SRN
79. 8 SCREEN: COLOUR A, B
80. 41 C = 10 TO 20 STEP 2
81. 100 GOTO 4
82. 265 IF W$ = “YES” THEN STOP
83. 2C LINE (20, 50) – (300, 150) ,2
84. PRINT A$ , B$, C
85. 10 PRINT 5(2 + 7)
86. 20 PRINT 8x8
87. 20 PRINT X = 15
88. 20 PRINT NAME IS =; N$
89. 30 PRINT: PRINT
90. PRINT “PAKISTAN ZINDABAD”
91. 10 PRINT “TEMPERATURE =; T; C
92. 10 INPUT ‘CAPITAL IS =’ C$
93. 30 INPUT ENTER VALUES OF A, B AND C
94. 50 AND “PROGRAM IS FINISH”
True and False
Friendsmania.net
Write True or False for the following sentences:
1. The central processing Unit (C.P.U) is the
brain of computer system.
2. Logical errors are caused by faulty program
designs.
3. Diamond-shaped symbol in program flow chart
is used for decision points.
4. Dot Matix printers are non-impact printers.
5. Data stored in ROM can be changed.
6. Impact printers work by hitting an inked
ribbon against the paper,
7. High level language is used to convert the
source program into object program.
8. Mark-1 is the first Digital Computer.
9. ROM stores data or program permanently and
RAM stores data or program temporarily.
10. A set of bits considered as a unit, normally
consisting of 8 bits is known as Byte.
11. Abacus is an early Electro-Mechanical device
for counting.
12. Software comprehends computers programming
languages; translates application programs and operating systems programs.
13. Mark-I is the first digital computer.
14. First microprocessor chip INTEL 4004 was
developed in 1990.
15. The heavy computers are called “Laptops’.
16. A digital computer can work at high speed.
17. Registers are the part of ROM.
18. RAM stands for Read Access Memory.
19. Convention memory and extended memory almost
work at the same speed.
20. EPROM is a special type of RAM.
21. The main memory of CPU is the place where
the computer programs and data is stored permanently.
22. RAM is a volatile memory for temporary
storage of data or programs.
23. Data processing is the manipulation of data
into more useful form.
24. EDP stands for Expanded Data Processing
Cycle.
25. An input device receives data from computer.
26. Mouse is an input device.
27. It is possible to display several colors on
a monochrome monitor.
28. A printer does not provide a soft copy of
output.
29. Impact printers can produce carbon copies.
30. LASER does not stands for Low Amplification
by Stimulated Emission of Rays.
31. Keyboard is a backing storage device.
32. Magnetic tape is the fastest media for data
storage.
33. There are several tracks on a floppy disk,
which are further divided into sectors.
34. 2KB = 2024 bytes.
35. Impact printer work by hitting an inked
ribbon against the paper.
36. Backing storage devices are the permanent
storage outside the main memory.
37. A mouse is called pointing device.
38. Micro floppy disks were developed before
mini floppy disks.
39. 90 IF X$ = “DATA” THEN PRINT “SOFT” is a
valid statement.
40. The FOR statement must not be used with
NEXT.
41. There is no difference between A1 and A(1)
as variable names.
42. 50 PRINT TAB (30); S$; TAB (10); Y$ prints
S$ and Y$ on same line.
43. DATA statement is used with INPUT statement.
44. The purpose of GOTO statement is to transfer
control.
45. 20 IF A$ = 1234 THEN 50 ELSE 80 is a valid
line.
46. When the command AUTO1, 10 is given, then
the first line number will be 10.
47. INPUT statement is often useful when no
interaction between computer and user is required.
48. It makes a sense to use the condition A =
“B” in a IF… Then statement.
49. Formula can be written as T = K/U*(P + A).
50. DATA statement is optional with READ
statement.
51. BASIC is a difficult language.
52. User defined functions do not act like
library function.
53. There is nothing wrong in NO ERROR GOTO 100
statement.
54. CLS statement can be used to clear half of
the screen.
55. The ¸ symbol is used for division in BASIC
programs.
56. A subroutine may also be called from with in
another subroutine.
57. Software comprehends computer-programming
languages, translates application program and operating system programs.
58. Application software is prepared by computer
manufacture.
59. Low level language is nearest to machine
language.
60. COBOL stands for Commercial Business
Oriented language.
61. FORTRAN is an interpreter language.
62. Assembler translates the high level language
into machine language.
63. The interpreter is a program that serves the
same purpose as des the compiler.
64. Compiler translates the high level language
into low level language.
65. RPG stands for Report Program Generator.
66. FORTRAN was basically developed for
scientific and engineering data processing purpose.
67. Statement number are must in BASIC program.
Since they are required to establish a sequence in which the instructions are
to be executed.
68. BASIC uses statement number as address for
the conditional and unconditional branching instruction.
69. REM statement cannot be accessed via
branching instructions.
70. REM statement should be the first statement
in a program.
71. CLS statement cleans the disk.
72. PRINT statement assigns value before
printing.
73. PRINT statement prints only values of the
variables.
74. LOAD command load a program from the disk.
75. DELETE command delete a line from the disk
76. SAVE command is used to store a program in a
computer memory.
77. List command displays the contents of the
disk on a screen.
78. GOTO statement unconditionally transfers the
program control to the new location.
79. Branching if IF – THEN takes place only if
the condition specified in IF is false.
80. In nested loops, the computer reaches the
outer most loop before reaching the inner most loop. Therefore, the outer loop
is executed completely before taking up the execution of the next inner loop.
81. Line number after ON-GOTO must only be in
ascending order other wise error conditions result.
82. One can have more than one NEXT statement
for every FOR. However at least one NEXT for every FOR is mandatory.
83. A subroutine contains repetitively used
statements. It can be accessed via a GOTO or a GOSUB statement.
84. The computed GOSUB statement is similar to
compute GOTO. However, it calls to four subroutine at the maximum.
85. There can be many RETURN statements in a
subroutine and they can be placed anywhere, even at the first line of the
subroutine.
86. A subroutine may contain any number of
RETURN statements. However the last statement must be a RETURN statement.
87. The first statement of the subroutine must
be a REM statement.
88. DIM statement can be used to reserve memory
space even below 10 spaces reserved implicitly.
89. Array can store only numeric values.
90. DIM statement, like RAM, is a non-executable
instruction.
91. DIM statement should be placed before the
array is called in the program.
92. Negative sign is allowed in a subscript.
93. A file is a collection of record.
94. A random file record can be read
sequentially.
95. CLOSE statement only close the sequential
file.
96. FIELD is a key word of BASIC language.
97. READ statement is used to read the record
from a file.
Read more: True and False http://www.friendsmania.net/forum/9th-class-computer-notes/20357.htm#ixzz35Bld92d5
Output of BASIC Programs
Friendsmania.net
Write down the output of the following BASIC
Programs:
1. 10 READ J, K, L
20 FOR I = J TO K STEP L
30 PRINT I
40 NEXT I
50 DATA 2, 10, 3
60 END
2. 10 CLS
20 FOR I = 1 TO 10
30 PRINT I, “MY NAME”
40 NEXT I
50 END
3. 10 READ A, B, C
20 FOR I = A TO B STEP C
30 PRINT I
40 NEXT I
50 DATA 2, 10, 2
60 END
4. 10 CLS
20 INPUT U, V
30 LET W = U + V
40 LET Y = W * V
50 LET Z = Y/U
60 PRINT U, V
70 PRINT W, Y, Z
80 END
5. 10 CLS
20 LET R = -2
30 FOR T = 2 TO 15
40 LET R = R + 1
50 PRINT R
60 NEXT T
70 END
6. 10 A = 5: B = 13: C = 931
20 C = 5 * A Ù B + B Ù 2/2
30 PRINT C
40 END
7. 10 FOR I = 1 TO 100 STEP 10
20 PRINT I
30 IF I = 10 THEN I = 100
40 NEXT I
50 END
8. 10 CLS
20 N$ = “ABDUS-SAMAD”
30 N1$ = LEFT$ (N$, 1)
40 N2$ = MID$ (N$, 5, 1)
50 N3$ = MID$ (N$, 8, 1)
60 N4$ = RIGHT$ (N$, 1)
70 NN$ = N1$ + N2$ + N3$ + N4$
80 PRINT NN$
90 END
9. 10 X$ = “DATA – SOFT”
20 FOR I = 1 TO 9
30 Y$ = LEFT$ (X$, I)
40 PRINT Y$
50 NEXT I
60 END
10. 10 LET A = 11
20 WHILE A < 99
30 LET A = A + 11
40 PRINT A
50 WEND
60 END
11. 10 LET A = 0
20 LET B = 1
30 LET C = A + B
40 PRINT C
50 LET A = B
60 LET B = C
70 IF C < 21 THEN GOTO 30
80 END
12. 10 CLS
20 FOR I = 1 TO 10
30 FOR J = 1 TO I
40 PRINT I;
50 NEXT J
60 PRINT
70 NEXT I
80 END
13. 10 FOR A = 10 TO 0 STEP –2.5
20 PRINT A
30 LET S = S + A
40 NEXT A
50 ? S
60 END
14. 10 CLS
20 LET K = -1
30 FOR L = 1 TO 20
40 LET K = K + 2
50 PRINT K;
60 NEXT L
70 END
15. 10 ? “This is first line”
20 ? “It is second row”
30 ? “What is it?”
40 ? “Remember where it should be!”
16. 10 CLS
20 FOR I = 1 TO 8
30 PRINT X
40 PRINT I
50 NEXT I
60 END
17. 10 CLS
20 A = A + 1
30 B = A Ù 2
40 C = A Ù 3
50 D = A Ù 4
60 PRINT A, B, C, D
70 IF A = 6 THEN END ELSE GOTO 20
18. 10 LET K = -1
20 FOR I = 1 TO 20
30 LET K = K + I
40 PRINT K
50 NEXT I
19. 10 FOR I = 1 TO 10
20 PRINT I, “PAKISTAN ZINDABAD”
30 NEXT I
40 END
20. 10 FOR X = 0 TO 20 STEP 2
20 SUM = SUM + X
30 PRINT X, SUM
40 NEXT X
21. 10 FOR X = 6 TO 18 STEP 2
20 LET A = X- 4
30 IF A = 10 THEN 60
40 PRINT A, X
50 GOTO 70
60 PRINT “X=”;X
70 NEXT X
80 END
Read more: Output of BASIC Programs http://www.friendsmania.net/forum/9th-class-computer-notes/20355.htm#ixzz35Bm1X0th
Conversion Decimal to Binary
Friendsmania.net
Convert the following decimal numbers into their
binary equivalents:
1. 211
2. 222
3. 333
4. 444
5. 0014
6. 1024
7. 100
8. 786
9. 909
10. 898
11. 386
12. 221
13. 116
14. 8
15. 19
16. 0418
17. 29
18. 333
19. 936
20. 0410
21. 312
22. 217
23. 111
24. 826
25. 999
26. 995
27. 894
28. 402
29. 25
30. 408
31. 1024
32. 001122
33. 801
34. 312
35. 235
36. 211
37. 765
38. 111
39. 0100
40. 26
41. 0
42. 55555
43. 6666
44. 3368
45. 765
46. 1750
47. 826
48. 12
49. 100
50. 1023
51. 4587
52. 69523
53. 8776
54. 328
55. 496
56. 507
Read more: Conversion Decimal to Binary http://www.friendsmania.net/forum/9th-class-computer-notes/20354.htm#ixzz35BmJl2M2
Conversion Binary to Decimal
Friendsmania.net
Convert the following binary numbers into their
decimal equivalents:
1. 10111
2. 111
3. 101001
4. 100101
5. 101011
6. 0011
7. 1100
8. 1001
9. 1111
10. 10101
11. 010101
12. 000011
13. 1111111
14. 100011
15. 100
16. 10
17. 11101011
18. 000001
19. 101110
20. 0001000
21. 111101
22. 0101011
23. 11111
24. 10101101
25. 1100110
26. 1010101
27. 101
28. 0011101
29. 1100001
30. 110011
31. 111111
32. 101100110
33. 1111010010
34. 1110001
35. 11011
36. 10011
37. 1100110
38. 111101
39. 00011
40. 010111
41. 1110011
42. 10001001
43. 0100111001
44. 0101011
45. 0000
46. 11100111
47. 100011
48. 1001110
49. 101101
50. 10000000000
51. 10100
Read more: Conversion Binary to Decimal http://www.friendsmania.net/forum/9th-class-computer-notes/20353.htm#ixzz35BmVSJdR
Multiple Choice Questions
Friendsmania.net
Choose any one of the following correct answers:
1. __________ is a category of computer
hardware.
(Input, Output, Storage, Processing, all of the
above)
2. __________ is an important component of
microcomputer system.
(Kilobyte, Microprocessor, Megabyte, Byte, None
of the above)
3. __________ is not found in C.P.U.
(ALU, Control Unit, RAM, Processing Register)
4. __________ is a type of impact printers.
(Laser, Thermal, Dot-Matrix, Inkjet)
5. __________ program design technique shows
program logic.
(Flow chart, Logical Operation, Computer, None
of the above)
6. __________ is used as counter in BASIC
programs.
(A = A+1, A<1, A or 1, None of the above)
7. __________ characteristic is applied to the
third generation of computers.
(Integrated Circuit, Transistor, Vacuum Tubes,
All of the above)
8. The most important characteristic of ROM is
__________.
(It performs mathematical calculation, it is
volatile, it is non – volatile, None of the above)
9. __________ statement is used to transfer the
control of program conditionally.
(GOTO, ON GOTO, END, All of the above)
10. Disk operating system is abbreviated as
__________.
(DOS, DS, OS, None of above)
11. __________ is an example of integer data.
(HASAN, D-143, 143, all of the above)
12. High level languages were designed in
__________.
(Laboratory, Third generation, Computers, New
York)
13. __________ is a high level language.
(BASIC, BESIK, BACIK, BESIC)
14. Binary number system has __________.
(Ten digits (0,9), Three digits (-1,0,1), One
digit (1), Two digits (0,1))
15. LET statement is __________.
(Optional statement, Assigning statement, Used
for expression assignment, all of the above)
16. DATA statement is __________.
(Executable statement, Non-executable statement,
Optional statement, None of the above)
17. BASIC stands for __________.
(Basic All-purpose Symbolic Instructon Code,
Beginners Assembly Symbols Instruction Code, Basic All Standards In COBOL, Beginners
All-purpose Symbolic Instruction Code)
18. When using READ statement, it must to
provide __________.
(PRINT statement, RESTORE statement, INPUT
statement, None of above)
19. ANSI stands for __________.
(All New Small Integration, A National Small
Institute, American National Standard Institute, None of the above)
20. Sign of exclamation is __________.
(!, :, I, %)
21. The example of random access storage media
is __________.
(Floppy disk drive, Hard disk drive, Tape unit,
51/4’’ floppy disk)
22. The type of memory whose contents can not be
changed is __________.
(ROM, RAM, Cache, EAPROM)
23. The command to see the contents of a disk is
__________.
(DIR, CD, MD, TYPE)
24. DISKCOPY command can format the destination
disk __________.
(Before copying, after copying, can not format,
format while copying)
25. TYPE command is used to __________.
(To see the contents of a file, Chage the type
of a file, make a sub directory, Type a file in the computer)
26. Each statement of BASIC must have a __________.
(Function, Statement number, Program name, File
name)
27. The command to create a sub-directory is
__________.
(DIR, CD, MD, APPEND)
28. TAB () function is used to __________.
(Print, Display, Print and Display, None of the
above)
Fill
in the Blanks
Friendsmania.net
Fill in the Blanks of Computer Science
1. The processing unit responsible for
mathematical computation is called __________.
2. A kilobyte is equal to __________ bytes.
3. The electronic technology used in second
generation computer system was __________.
4. A __________ translates program language
instructions one at a time.
5. Output on the screen is called __________
whereas output by the printer on paper is called __________.
6. IBM stands for __________.
7. In BASIC, function key F4 is used for
__________.
8. Machine language is a __________ level
language.
9. GOTO statement is known as __________
statement.
10. __________ is a set of well-defined
instructions.
11. The diagrammatic representation of logic is
called __________.
12. A computer output taken on paper is called
the __________ copy.
13. Monitors and printers are __________
devices.
14. Mathematical calculation is carried out by
__________ of C.P.U.
15. The use of _________ was a marked feature of
the generation of computers.
16. __________ command branches unconditionally
to a specified line number.
17. Vacuum tubes were used in the __________
generation of computers.
18. Charles Babbage invented __________.
19. __________ statement in DOS is used to
delete a file from the disk.
20. The volatile part of internal memory is
called __________.
21. __________ is the set of instructions that
tells the computers what to do.
22. A kilobyte is equal to __________ bytes.
23. Each statement or command is preceded by a
line number in the __________ mode.
24. The keyboard and the mouse are __________
devices.
25. A diagram to plan a program is called
__________.
26. Data processing consists of three basic
steps __________, __________ and __________.
27. __________ memory is that type of memory
which does not lose the information stored when the power is turned off.
28. Every BASIC statement consists of a
__________, keyword and the parameter.
29. __________ statement is used to transmit
numeric or string output data from the computer and displays it on the screen.
30. We use __________ to convert the digital
data into analog data.
31. The introduction of __________ brought the
computer age into the third generation.
32. In computer terms 64k means __________ bytes
or characters.
33. A software developed for specific purpose is
called an __________ software.
34. Data processing devices are __________,
__________, and __________.
35. In first generation __________ symbolic
languages were used.
36. Disk oriented computers were introduced in
__________ generation.
37. A micro second is equivalent to
1/__________.
38. PC stands for __________.
39. The term VLSI is used for __________.
40. Humanware is an alternative word for
__________.
41. A firmware is necessary to __________ the
computer.
42. __________ computers have both analog and
digital methods of processing information.
43. The introduction of __________ brought the
computer age into fourth generation.
44. The physical units making up a computer
system are known as computer __________.
45. Charless Babbage is called the father of
__________.
46. EDP stands for __________.
47. A __________ data processing system consists
of various input and output devices connected with an electronic computer.
48. A microprocessor chip consists of three
basic parts __________, __________ and __________.
49. A blinking point on the CRT, whose position
can be controlled by the operator of the computer, is known as __________.
50. The very small bulbs on the keyboard or CPU
are called __________.
51. In BASIC function key F2 is used to
__________.
52. ASCII stands for __________.
53. A __________ is used to play games.
54. __________ and __________ are the latest
input devices.
55. CRT stands for __________.
56. SVGA stands for __________.
57. __________ and __________ are impact
printers.
58. __________ and __________ are non-impact
printers.
59. A small spot of light displayed on the
screen is called __________.
60. The devices through which we enter data into
the computer are known as __________ devices.
61. A blinking cell on the display screen is
known as __________.
62. __________ and __________ are the only
figures used in binary number system.
63. DOS is an acronym for __________.
64. __________ data represents only numbers.
65. There are three types of languages
translators: __________, __________ and __________.
66. A keyboard has a number of keys, but usually
it has __________ keys.
67. Types of data are __________, __________ and
__________.
68. Types of numeric data are __________ and
__________.
69. Types of numerical real data are __________
and __________.
70. Machine language programs are usually
written in __________ number system.
71. A program translated by the compiler is
called __________.
72. Destructive programs are classified as
__________, __________ and __________.
73. BASIC is an acronym for __________.
74. __________ is the lowest limit of line
number allowed in BASIC program.
75. In BASIC each statement must begin with a
__________.
76. __________ statement clears VDU.
77. The __________ statement accepts data in
execution mode.
78. Before a value is assigned to a numeric
variable, its value is assumed to be __________.
79. __________ command produces the source
statements of current program, available in memory, on CRT.
80. __________ and __________ statements may be
used to define the beginning and the end of a loop.
81. __________ allows to write more than one
statement on a line.
82. BASIC was developed at __________ by
__________ and __________.
83. __________ command automatically generates
line numbers.
84. BASIC program is a collection of __________.
85. The purpose of __________ command is to
re-sequence the line numbers of the program.
86. In the year __________ the __________
standardized an essential subset of BASIC, in order to promote uniformity from
one version to another.
87. The maximum line number in BASIC is
__________.
88. The data can be distributed over __________
statements within a program.
89. There can be up to __________ characters in
a single program line.
90. Numeric data can be expressed in two ways:
__________ and __________.
91. The use of __________ can alter the normal
hierarchy of calculation operations.
92. BASIC statements are __________ and
__________.
93. REM is used to __________.
94. __________ is used to reuse the data given
in __________ statement (s).
95. Semicolon is used to suppress __________ in
__________ statement.
96. When a variable name appears in a __________
statement, the contents of location are displayed.
97. __________ is used to access an individual
element from an array.
98. The __________ statement is used to assign a
numerical or string value to a variable.
99. __________ command prints the source
statement of current program available in the memory, on the printer.
100. A __________ is a quantity that may change
during the execution of program.
101. __________ and __________ statements are
used to execute a series of statements in a loop as long as given condition is
true.
102. __________ statement is required to create
arrays.
103. The purpose of __________ is to part from
usual execution in the order given by the line number.
104. __________ notation is used to represent
very very small or very very large numbers.
105. Remarks statements are only shown up when
you __________ a program.
106. RABs must be in ascending order in a
__________ statement.
107. A set of values arranged in regular order
is called __________.
108. The __________ statement in BASIC program
has the highest statement number (logically).
109. The symbols <, > and = if used in a
program are called __________ operators.
110. A pictorial representation of the sequence
of steps of computation for solving a problem is called __________.
111. __________ command returns control to
operating system.
112. __________ statement is used to transmit
numeric or string output data from the computer and display it on the screen.
113. The LINE statement is used to draw a
straight line in __________ screen mode.
114. __________ is simply paper work and
documentation involved with the operation of computer.
115. __________ software is supplied by the
computer manufacture.
116. __________ software is the set of
instructions that are developed by the computer user.
117. A computer __________ is a set of
instructions sequenced in a logical manner to achieve a definite task.
118. The set of information that are fed to the
computer is called __________.
119. __________ is the person who designs and
writes the computer program.
120. __________ level language is nearest to the
human language.
121. Assembly language is __________ level
language.
122. Two classes of High level language
are__________ language and __________ language.
123. A __________ is a way of communicating with
the computer.
124. Internal Command is a part of __________.
125. CLS is an __________ command.
126. FORMAT is an __________ command.
127. The information stored in computer is in
__________ state.
128. The bi-stable state ON is known as the
state of __________.
129. The bi-stable state OFF is known as the
state of __________.
130. A __________ represent a meaningful
information like a number, an alphabet or any special character.
131. The computer stores an extra bit, called
__________ bit.
132. The traditional five stages in development
of source program are __________, __________, __________, __________ and
__________.
133. An algorithm gives the __________ of
solution of a problem.
134. A flow chart depicts the __________ of
solution of a given program.
135. Types of flowchart are __________ and
__________.
136. The __________ statement is used to reserve
storage for an array.
137. DIM is usually placed at the __________ of
the program.
138. A$(5) will reserve __________ spaces in
memory.
139. Table is a __________ array.
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Data
Processing
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Data Processing
Data processing often referred as D.P is a
process of collecting the data together and converting the data into
information. The method used for collecting the data may be manual, mechanical
or electronic.
Data processing is a term mostly associated with
business and commercial work. Since computers are being used in the processing
of data the term “electronic data processing” may also be used.
Electronic Data Processing
Data processing means transformation of data
into more meaningful results for carrying out scientific, business activities.
The result of data processing is called “information”. The transformation of
data consist of a sequence of operations. The sequence is called “procedure”.
Input -> Processing -> Output
Data processing is a system which takes data as
an input, carries out the required processing on the data and produces the
information. The system is called “MANUAL” when processing is performed by
human beings and “AUTOMATIC” when machines are used. When computers are used
for data processing the system is called “Electronic Data Processing”.
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Elements of EDP
There are five basic elements in a processing
system which uses a computer for processing data. These are hardware, software,
user program, procedure and personnels.
1. HARDWARE
All the physical parts which makes up a computer
system called hardware i.e. all the devices or peripherals which performs the
data processing operations.
2. SOFTWARE
Software consists of programs and routines whose
purpose is to make the computer useable for the user. These software normally
supplied by computer manufacturers or software manufacturers.
3. USER PROGRAM
A program consist of a related instructions to
perform operations. A data processing job may require a number of programs.
4. PROCEDURE
The operations of data processing system
requires procedure for use, in preparing data, for operating the computer and
distributing the output after processing.
5. PERSONNELS
E.D.P basically needs three kinds of skilled
personnels.
a) System Analyst
b) Progammer
c) Operator
a) SYSTEM ANALYST
System Analyst studies information needs and
data processing requirements, design a data processing system and prepare
specification.
b) PROGRAMMER
A Programmer writes a programmer on
specification by System Analyst.
c) OPERATOR
An Operator is a person who operates the
computer system.
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Input
and Output Devices
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PRINTER
A computer peripheral that puts text or a
computer generated image on paper or on another medium, such as a transparency.
Printer can be categorized in several ways the most common distinction is
IMPACT and NON-IMPACT.
IMPACT PRINTING
Is the method used by the conventional type
writers. In some type of impact printing a metal “hammer” embossed with a
character strikes a print ribbon, which presses the characters image into
paper. In other types the hammer strikes the paper and presses it into the
ribbon characters created through impact printing can be formed by either a
solid font or dot matrix printing mechanism.
NON – IMPACT PRINTING
Does not depend on the impact of metal on paper.
In fact no physical contact at all occurs between the printing mechanism and
the paper. The most popular non-impact methods today utilize thermal transfer,
ink-jet.
TYPES OF PRINTERS
DOT MATRIX PRINTER
Any printer that produces character made up of
dots using a wire pin printed head. The quality of output from a dot matrix
printer depends largely on the number of dots in the matrix, which might be low
enough to show individual dots or might be high enough to approach the look of
fully formed characters. Dot matrix printers are often categorized by the
number of pins in the printer head typically, 9 or 24.
LINE PRINTERS
Any printer that prints one line at one time, as
opposed to one character at a time or one page at a time. Line printer
typically produce the 11 by 17 inch “computer” printout. They are high speed
devices and are often used with mainframes, minicomputers, or networked
machines rather than with single user system. Types of line printers include
chain printers and band printer.
LASER PRINTERS
An electrophotographic printer that is based on
the technology used by photocopiers. A focussed laser beam and a rotating
mirror are used to draw an image of the desired page on a photosensitive drum.
This image is converted on the drum into an electrostatic charge, which
attracts and holds toner. A piece of electrostatically charged paper is rolled
against the drum, which pulls the toner away from the drum and onto the paper.
Heat is then applied to fuse the toner to the paper. Finally, the electrified
charge is removed from the drum and the excess toner is collected. By omitting
the final step and repeating only the toner application and paper handling
steps, the printer can make multiple copies.
DAISY WHEEL PRINTER
Daisy wheel printer are some times called letter
quality printer because they are often used to produce attractive correspondence.
The D.W.P is a flat circular device made of metal with character embossed on
it. As this wheel spins at a very high speed the hammer hits the specific
character against the ribbon which presses against the paper.
THERMAL TRANSFER PRINTER
It is a kind of non-impact printer. In
electrothermal printing, characters are burned on to a special paper by heated
rods on a print heat. They transfer ink from a wax-based ribbon onto plain
paper. These printer can support high quality graphic.
INK – JET PRINTER
It is a kind of non-impact spray small dots of
electrically charged ink onto a paper to form images. Ink jet printer are
flexible enough to be used as plotters.
SECONDARY STORAGE DEVICES
Secondary storage devices are also called backup
storage because it is used to store data. Volume of data on permanent basis
which can be partially transferred to the primary storage, when required for
data processing. Afterwards these devices are comparatively cheap and provide
greater space to store the data /instructions are stored on secondary storage
devices in the same binary codes as in primary storage.
NEEDS OF SECONDARY STORAGE DEVICE
The storage capacity of the primary storage of
today’s computer is not sufficient. To store a large volume of data as a result
additional memory called secondary storage is needed with most of the computer
system.
These devices also provides the fast
communication than I/O devices. The internal memory of a computer is a volatile
memory. Therefore, we cannot save the data permanently. In that case we require
secondary storage device which provide the facility to store the data for
future use.
RANDOM ACCESS DEVICES
Random Access Devices are those devices on which
we can directly access the data. These devices are comparatively provide the
fast communication.
For example, hard disk, floppy disk, optical
disk.
FLOPPY DISK
A floppy disk, also called simply a diskette or
disk, is a small flexible Mylar disk coated with iron oxide on which data are
stored. The floppy disk has been around since early 1970s, today it is
available in three 3½ inch, 5¼ inch and 8 inch sizes. The 5¼ and 8 inch
diskettes are covered by stiff protective jacket with different holes. The
central big hole called hub ring which is used to hold by disk drive during
rotation. The elongated read write window is used to read and write data
through read/write head. The small hole next to the hub ring is called index
hole which is used to locating data through computer. The cut out on the side
of the floppy disk is called write protect notch. If we cover this opening with
a piece of paper then we can’t write data on to disk.
In small diskette a hard plastic cover and
protective metal is used to protect disk. Before using a disk we have to format
a disk in which disk is divided into tracks and sectors for storing the data.
Diskettes may be double sided and single sided while the storage capacity
become less or more.
Floppy diskettes are more convenient to use with
microcomputers. A floppy disk which is a random access device can access data
fast than magnetic tape.
SEQUENTIAL ACCESS DEVICES
Sequential Access Devices are those in which we
can access the data one by one in a sequence. These devices provide slow
communication as compared to Random Access Device.
MAGNETIC TAPE
Magnetic tape is a sequential access device
about one half or one fourth inch in size and made of Mylar (a plastic
material) coated with a thin layer of iron oxide. Data can be read and write
through a device which is called tape drive. The read/write head of tape drive
which is an electromagnetic component read, write and erase data from magnetic
tape. Magnetic tape is divided into nine separate strips or tracks in which
eight tracks are used to store data and ninth track is used for error checking
bit.
Magnetic tape can store large quantities of data
therefore they are erasable, usable and durable secondary storage device. But
it can use with large computers.
INPUT DEVICES
Input devices are used to provide data or
information to the computer. The computer follows the instructions given to it
by and input device. A variety of input devices are used with the computer
depending on the type and purpose of input information. For example, a keyboard
is commonly used to transfer data or information from human readable form to
machine readable form. Other examples of input devices are: mouse, joystick,
trackball, light pens, digitizers, scanners, optical character reader (OCR),
touch window, etc.
MOUSE
The mouse is an input device that usually
contains one or two buttons. As a user moves the mouse on a flat surface, the
mouse controls the cursor movement on the screen. When the user presses one of
the buttons, the mouse either marks a place on the screen or makes selection
from data or menu on the screen. A mouse has a sphere on its underside. This
rotates as the mouse is moved along a flat surface.
The mouse translate the direction and speed of
rotation into a digital signals that identifies the position or control, the
cursor on the computer.
A mouse can be used for many application,
ranging from games to drawing and designing products with computer graphics. It
provides an alternative for people who are uncomfortable with a keyboard but it
also can be used in combination with a keyboard to input data.
TRACKBALL
A Trackball is a pointing device almost like a
mouse turned upside down. The user controls the cursor on the screen by rolling
a plastic ball with a fingertip or wrist. To execute commands with a Trackball,
one or more buttons are pressed, much in the same way as is done with a mouse.
The cursor can be moved around on the screen by rolling the ball with a thumb
or finger.
Trackball is popular among users of laptop
computers when space is limited and may be mounted on either side of the
keyboard. For handicapped people who may have difficulty pressing keys on a
standard keyboard or using a mouse, the trackball may be the answer since it
edoes not require to moves the entire arm to use it.
SCANNER
Scanner is an input device. It is also called
Optical Reader or Digital Scanner. It scans or reads text and picture printed
on a paper and enters them directly into the computer memory.
The advantage of a scanner is that the user
needs not type the input data in. This is a lust and accurate method for
entering data into the computer. The scanner takes electronic images, of text
or pictures from the paper it breaks each image into light and dark dots and
stores them into the computer memory in machine codes. Scanned text can be
edited by OCR software. Optical Character Recognition (OCR) software translates
the scanned document into text that can be edited.
The image scanner is useful because it
translates printed images into an electronic format than can be stored in
computer's memory. The stored image can be transferred into a paint program or
directly into a word processor. You can use software to organize and manipulate
the electronic image.
KEYBOARD
A keyboard is the most commonly used input
device which helps us in simply keying in required information in a computer.
This information is subsequently stored in the computer’s memory. A keyboard
can be used effectively to communicate with the computer but considered to be
relatively slow as compared to other input devices. The keyboard is divided
into following divisions:
ALPHABETIC KEYPAD
These keys are similar to a standard typewriter
and is used to type general information.
NUMBERIC KEYPAD
These keys are used to input numeric data only.
These are very useful in case of large numeric data input because all numeric
keys can be accessed by one hand only. These keys can also be used as an
alternative to the screen navigation and editing keys.
FUNCTION KEYS
These are keys marked as F1 - F12, located
normally at the top of the keyboard. These are special keys provided to a
programmer which allow him to attach special functions to each key. Each of
these function keys are also given some special function in different packages.
SCREEN NAVIGATION AND EDITING KEYS
These keys are provided to move around in the
screen. May programs use these keys to let the user move around the screen
display. In some keyboards these keys are also provided inside the numeric
keypad as alternate keys.
The description of commands assigned to function
keys under the BASIC mode.
F1 - LIST Function - Used to display the lines
of your program on the screen.
F2 - RUN Function - Used to execute a program
from its beginning.
F3 - LOAD Function - Used to read a program from
a storage device and store it in main memory.
F4 - SAVE Function - Used to store a program on
a storage device from Memory.
F5 - COUNT Function - Used to restart a program
after it has temporarily interrupted by a stop or CTRL + BREAK.
F6 - LPT1 Function - Used to transfer data from
the video screen to the line printer.
F7- TRON Function - Refers to "trace
on". This function causes the line number of program line to be displayed
as these lines are executed.
F8 - TROFF Function - Refers to "trace
off". This function cancels TRON function.
F9 - KEY Function - Use to change the function
of the other function keys.
F10 - SCREEN Function - Used to return program
to the character mode from the graphic mode and a;so to turn off the colour.
OUTPUT DEVICES
An output device is used to display the data or
information that we receive from the computer. An output device can be used to
display or print the intermediate or final results performed by computer. A
variety of output devices are used with computer. The use of these devices
depends on the type and purpose of output. Some examples of output devices are:
Monitors, Printer, Plotters, Visual display unit (VDU), liquid crystal display
(LCD), etc.
MONITOR
To display result or output from computer, a T.V
like device is used which is called monitor. The monitors are also referred as
C.R.T (Cathode Ray Tube), V.D.U (Visual Display Unit). The monitor assist
during input from the keyboard, this display is called a soft copy. The monitor
can be of various kinds, depending on the type of application. Monitors are
categorized into two groups:
* Monochrome monitors
* Colour monitors
MONOCHROME MONITORS
Monochrome monitors are used specially for text
editing purpose. These monitors can display only one colour. Normally amber,
green or paper white.
COLOUR MONITORS
Colour monitors serves a wide range of selection
according to the application. Such as red, green, blue, Enhance Graphic Array
(EGA), Colour Graphic Array (CGA), Video Graphics Array (VGA), Super Video
Graphics Array (SVGA).
There are two types of colour monitors:
1. CRT Monitor
2. LCD Monitor
CRT MONITOR
The CRT monitors are a lot like television set,
using the same CRT or Cathorde Ray Tube technology. The CRT monitor has two
major parts; the screen and the cathode ray tube (CRT). The screen is the front
of the monitor and CRT is fitted inside the monitor.
LCD OR FLAT PANEL MONITOR
Another monitor type is LCD or Liquid Crystal
Display. LCD monitors are a lot like CRT monitors without the bulkiness but
they do not have CRT. LCD monitors use a flat lightweight surface filled with
millions of tiny glass bubbles, each having a phosphoric covering. These
phosphoric coverings glow to create an image. LCD screens provide clarity and
flicker-free viewing.
PLOTTER
Plotter is a special output device, which is
used to produce high quality, perfectly proportional hard copy output. Plotters
are designed to produce large drawings or images such as construction plans for
buildings or blue prints for mechanical devices. Plotters have been used in automotive
and aircraft design, topological surveys, architectural layouts and other
similar complex drafting jobs.
A plotter is composed of a pen, a move-able
carriage, a drum and a holder for chart paper. Both the pen and the paper can
move up and down and back and forth. This permits very detailed drawings. Some
plotter having coloured pens can make coloured drawings also.
There are two types of plotters, which are as
follows:
1. Drum Plotter
2. Flatbed Plotter
DRUM PLOTTER
On the drum plotter, the pens, and the drum move
concurrently in different axes to produce the image. Drum plotters are used to
produce continuous output, such as plotting earthquake activity, or for long
graphic output, such as structural view of a skyscraper.
FLATBED PLOTTER
On some flatbed plotters, the pen moves in both
axes while the paper remains stationary. However, on most desktop plotters,
both paper and pen move concurrently in much the same way as on drum plotters.
HARD DISK
Hard disk is a thin circular metal plate coated
both side with a magnetic material. A hard disk pack consist of a number of
disk mounted on central shaft which rotate at a speed of 2400 rpm or more. In a
hard disk information is stored on both the surfaces of each disk plate except
the upper and the lower surfaces of the bottom plate which are not used.
Information is recorded on the track of the disk surfaces in the form of
invisible tiny magnetic spot. The presence of a magnetic spot represent 1 bit
and its absence represents 0 bit.
Hard disk are potentially very high capacity
storage devices typically in the range of 20 megabyte to 1 gigabyte. Data are
recorded on the tracks of a spinning disk surface and read from the surface by
one or more read/write heads. There are two basic types of disk system.
1. Moving head
2. Fixed head
MOVING HEAD
The moving head consist of one read/write head
for each disk surface mounted on an axis and which can be moved in and out. In
this system each read/write head moves horizontally across the surface of the
disk. So that it is able to access each track individually. Information stored
on the tracks which constitute a cylindrical shape through the disk pack are
therefore accessed simultaneously.
FIXED HEAD
In the fixed head system the axis are
non-movable. A large number of read/write heads are distributed over the disk
surfaces. One head for each track as a result no head movement is required and
therefore information is accessed more quickly.
VOICE RECOGNITION
A voice recognition system compares a person's
live speech to their stored voice pattern. Larger organizations sometimes use
voice verification systems as time attendance devices. Many companies also use
this technology for access to sensitive files and networks. Some financial
services use voice verification systems to secure telephone banking
transactions. These systems use speaker dependent voice recognition software.
This type of software requires the computer to make a profile of your voice,
that is, you train the computer to recognize your inflection patterns.
SHORT NOTES
DISK DRIVE
Disk drive is a peripheral device that reads or
write the disks (hard disks, floppy disks, etc) that store information. Disk
drives are called "Storage Device" because they store information or
portabel or permanent disks. The drive contains a motor to rotate the disk at a
constant rate and one or more read/write heads, which are positioned over the
desired track.
CD-WRITER
A CD writer is a device connected to your
computer which can write on CD-WR and CD-R discs. CD-WR discs may be written,
erased and rewritten, while CD-R discs may be written only once. CD writer
performances is measured in X unit, where IX =150 kilobytes/sec. This allows
user to master a CD-ROM or audio CD for publishing CD-R devices can also read
CD-ROMs and play audio CDs. The CD writer is also called a CD-R drive (short
for Compact Disc - Recordable Drive)
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Programming
and Basics
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LOOP
While writing a program it is necessary to
repeat a part of a program for a number of times. The best solution for this is
to use a loop it is a method which executes a part of the program repeatedly as
specified by the programmer.
TYPES OF LOOPS
a) Pre-Test Loop
b) Post-Test Loop
a) PRE – TEST LOOP
As its name indicates, checks the looping
condition at the start of the loop if the condition is true the loop execution
starts otherwise stops. This loop is used in a situation when part of program
is to be repeated for a fixed number of time.
e.g., FOR …… NEXT.
b) POST – TEST LOOP
This loop checks the looping condition at the
end of loop and decides whether or not to continue the execution. This loop is
used when a part of the program needs to be repeated until a specified
condition is met.
e.g., WHILE …… WEND.
FLOW CHART
Flow chart is a symbolic representation of flow
of programme. It can graphically represent data processing procedure Flow chart
serves two purposes, i.e., the planning of the program structure as an aid in
writing the computer program. Secondly the documentation of the program logic
and work flow for the purpose of the communication with other person and to
recall a program at a later time. If the program needs to be changed. The
second purpose is very important because it is very difficult to check the
logic of the program.
SYMBOLS OF FLOW CHART
TERMINAL
The terminal symbol is used to indicate the
beginning, ending of the program logic flow. It is the first and last symbol of
the flow chart.
INPUT / OUTPUT BOX
The input/output box is used to denote any
function of an input and output in the program. If there is a program
instruction to input or output the data from any I/O device that step will be
indicated on this symbol.
PROCESS BOX
A processing symbol is used in a flow chart to
represent arithmetical and data movement instructions.
FLOW LINES
Flow lines are used to indicate the flow of
operations. The exact sequence in which the instructions are to be executed.
The flow of flow chart is normally from top to bottom and left to right.
DECISION BOX
The decision box is used in a flow chart to
indicate a point at which a decision has to be made and to branch to one or
more alternative points that is possible during execution. The appropriate path
followed, depends on the result of the decision.
CONNECTOR
A flow chart becomes complex, when the number
and direction of flow lines is confusing or it spread over more than one page.
It is useful to utilize the connector symbol as a substitute for flow lines.
SYSTEM FLOW CHART
System Flow Chart is used to describe complete
data processing cycle including the hardware devices and media used. A System
Flow Chart shows flow of data in a system where and in what form it is received
by the system, how it is input to the computer and what storage media are used
to hold it. The symbol used in system flow chart indicates the peripherals to
be used in data processing procedure, where output will be produced. System
flow chart do not explain the logic of the programs.
ERRORS
Errors are the mistakes made by the programmer
during program writing. A program relays run perfectly for the first time and
each program needs to be tested to ensure that it is correct and contains no
errors. There are three types of errors generally encountered.
a) Syntax Error
b) Logical Error
c) Run Time Error
SYNTAX ERROR
The syntax of a programming language is the set
of rules to be followed when writing a program in that language. These rules
are similar to the grammar rules of Urdu or English language. When a program
violates these rules, computer generates a syntax error. Syntax must be correct
before program execution.
LOGICAL ERROR
These errors are the most difficult ones to
find, if a programmer enters a sign of multiply instead of addition at the time
of making the program, the answer will not be correct because interpreter will
not be able the detect these types of errors. A logical error will not stop the
execution of the program but the result will not be accurate.
RUN TIME ERROR
These types of errors stop the execution of the
program. It may be due to entering the invalid data at the time of executing a
program. For example, if a program is expecting the user to enter the numeric
data and the user enters a string data, computer will display an error message.
BITS & BYTES
The smallest piece of data that can be
recognized and used by a computer, is the bit, a binary digit. A bit is a
single binary value, either a 1 or 0. A group of eight bits is called a byte.
The byte is the basic unit for measure of the size of the memory, with today’s
computer memory sizes. It is more common to hear the term kilobyte (KB) or
megabyte (MB).
COMPUTER WORD
A computer word is the number of adjacent bits
that can be stored and manipulated as a unit. Just an English vocabulary words
are of varying lengths so are computer words. Many microcomputers have the
ability to manipulate a 32 bit word, while some models have words length of 8
and 16 bits.
LIBRARY FUNCTIONS
GW-BASIC provides many built in functions which
are called binary functions. Each function is composed of a format or a short
program, that requires at least one parameter to be passed. A parameter is a
value which is in that formula or program and this formula or program returns a
result. This result can be stored in any appropriate variable or directly
displayed on monitor. A library function which has “$” sign is called string
library function while others are called numeric library function. A string
function returns string value while a numeric function returns numeric value.
Following are some library functions.
ABS, MID$, LEN, LEFT$, ASC, CHR$, TAB
EXPRESSIONS
An expression is a combination of constants and
variables linked by arithmetic operators like (+, -, *, /, \). Expressions are
used to perform different operations. The expressions are evaluated from left
to right but some operators have priority over the others. Parenthesis are
evaluated first then multiplication and division have the same priority from
left to right. Similarly the addition and subtraction are evaluated with equal
priorities. If all the operators are used in an expression have the same
priority then the expression be executed from left to right.
The expressions can be of three types.
* Arithmetic expressions
* Logical expressions
* Relational expressions.
ARITHMETICAL EXPRESSIONS
In an arithmetic expression the following
operators are used in conjunction with the operands.
SymbolMeaning
+ Addition
- Subtraction
* Multiplication
/ Division
^ Exponentiation
( Left parenthesis
) Right parenthesis
RELATIONAL EXPRESSION
A Relational expression is composed of operands
linked by the relational operators. The relational operators used in the
relational expression are given.
SymbolMeaning
= equal to
> greater than
< less than
<> not equal to
>= greater than or equal to
<= less than or equal to
Example
A > B
B <> C
LOGICAL EXPRESSIONS
When a selections is based upon one or more
condition being true. It is possible to combine the condition together using
logical operators and the resulting condition would either be true or false the
most commonly used logical operators are AND, OR and NOT.
COMPUTER LANGUAGE
Language is a system for representation and
communication of information or data. Like human beings, a language or signal
is required to communicate between two persons. Similarly, we cannot obtain any
result by computer without langtage. Computer does not understand directly what
we are communicating with computer as English or Arabic, it understands only
machine language (binary codes 0-1). Computer translates English language into
machine codes through interpreter then process instructions and give us the
results.
The computer languages can be divided into two
main levels.
* Machine language (0-1)
* Symbolic language (A-Z)
Symbolic languages are further divide into two
main levels
* High-level language
* Low-level language
MACHINE LANGUAGE
Although computers can be programmed to
understand many different computer language. There is only one language
understood by the computer without using a translation program. This language
is called the machine language or the machine codes. Machine codes are the
fundamental language of the computer and is normally written as strings of
binary 0-1.
ADVANTAGES AND LIMITATIONS OF MACHINE LANGUAGE
Programs written in machine language can be
executed very fast by the computer. This is mainly because machine instructions
are directly understood by the CPU and no translation of program is required.
However, writing a program in machine language
has several disadvantage.
MACHINE DEPENDENT
Because the internal design of every type of
computer is different from every other type of computer and needs different
electrical signals to operate. The machine language also is different from
computer to computer.
DIFFICULT TO PROGRAM
Although easily used by the computer, machine
language is difficult to program. It is necessary for the programmer either to
memorize the dozens of code number for the commands in the machine’s
instruction set or to constantly refer to a reference card.
DIFFICULT TO MODIFY
It is difficult to correct or modify machine
language programs. Checking machine instructions to locate errors is difficult as
writing them initially.
In short, writing a program in machine language
is so difficult and time consuming.
SYMBOLIC LANGUAGES
In symbolic languages, alphabets are used (a-z).
symbolic languages are further divide into two main levels.
* High level languages
* Low level languages
LOW LEVEL LANGUAGE
A language which is one step higher than machine
language in human readability is called Assembly Language or a low-level
language. In an assembly language binary numbers are replaced by human readable
symbols called mnemonics. Thus a low-level language is better in understanding
than a machine language for humans and almost has the same efficiency as
machine language for computer operation. An assembly language is a combination
of mnemonic, operation codes and symbolic codes for addresses. Each computer
uses and has a mnemonic code for each instruction, which may vary from computer
to computer. Some of the commonly used codes are given in the following table.
COMMAND NAMEMNEMONIC
Add - ADD
Subtract - SUB
Multiply - MUL
Compare Registry - CR
Compare - COMP
Branch Condition -BC
Code Register -LR
Move Characters -MVE
Store Characters -STC
Store Accumulator - STA
An assembly language is very efficient but it is
difficult to work with and it requires good skills for programming. A program
written in an assembly language is translated into a machine language before
execution. A computer program which translates any assembly language into its
equivalent machine code is known as an assembler.
HIGH – LEVEL LANGUAGE
A language is one step higher than low-level
languages in human readability is called high-level language. High – level
languages are easy to understand. They are also called English oriented
languages in which instruction are given using words. Such as add, subtract,
input, print, etc. high level language are very easy for programming,
programmer prefer them for software designing that’s why these languages are
also called user’s friendly languages. Every high level language must be converted
into machine language before execution, therefore every high level language has
its own separate translating program called compiler or interpreter. That’s why
some time these languages are called compiler langauges. COBOL, BASIC, PASCAL,
RPG, FORTRAN are some high level languages.
INTERPRETER
An interpreter is a set of programs which
translates the high-level language into machine acceptable form. The
interpreters are slow in speed as compared to compilers. The interpreter takes
a single line of the source code, translates that line into object code and
carries it out immediately. The process is repeated line by line until the
whole program has been translated and run. If the program loops back to earlier
statements, they will be translated afresh each time round. This means that
both the source program and the interpreter must remain in the main memory
together which may limit the space available for data. Perhaps the biggest
drawback of an interpreter is the time it takes to translate and run a program
including all the repetition which can be involved.
PROGRAM DEVELOPMENT PROCESS
In order to develop a computer program, a
programmer has to go through the following stages:
1. DEFINING AND ANALYSING THE PROBLEM
In this step a programmer studies the problem
and decides how the problem will be best solved. Studying a problem is
necessary because it helps a programmer to decide about:
* The facts and figures to be collected.
* The way in which the program will be designed.
* The language in which the program will be most
suitable.
* What is the desired output and in which form
it is needed, etc.
2. DESIGNING THE ALGORITHM
An algorithm is a set of instructions or
sequence of steps that must be carried out before a programmer starts preparing
his program. The programmer designs an algorithm to help visualize possible
alternatives in a program.
3. FLOWCHARTING
A flow chart is a graphical representation of a
program which helps a programmer to decide on various data processing
procedures with the help of labeled geometrical diagrams. A flow chart is
mainly used to describe the complete data processing system including the
hardware devices and media used. It is very necessary for a programmer to know
about the available devices before developing a program.
4. CODING OR WRITING THE PROGRAM
The next job after analysing the problem is to
write the program in a high-level language, usually called coding. This is
achieved by translating the flow chart in an appropriate high-level language,
of course according to the syntax rules of the language.
5. TEST EXECUTION
The process of execution of any program to find
out for errors or bugs (mistakes) is called test execution. This is very
important because it helps a programmer to check the logic of the program and
to ensure that the program is error-free and workable.
6. DEBUGGING
It is a term which is used extensively in
programming. Debugging is the process of detecting, locating and correcting the
bugs by running the programs again and again.
7. FINAL DOCUMENTATION
It is written information about any computer
software. Final document guides the user about how to use the program in the
most efficient way.
MODES OF OPERATION
There are two modes of operation for BASIC. The
mode that you are in determines what BASIC will do with the instruction you
give it. When you start BASIC you receive the OK prompt. You then have two
modes available to you immediately.
DIRECT MODE
In the direct mode BASIC acts like a calculator.
No line numbers are required. Direct mode is not of course the main purpose of
BASIC, but it is useful at times particularly when you are debugging program or
short problems in which you want to perform quick calculation e.g., PRINT 3+4.
INDIRECT MODE
In this mode you first put a line number on each
statement. Once you have a program you can run it and get your results. The
indirect mode saves your instructions in the computer along with their line
number, you can execute the program as many times as you wish simply by typing
RUN.
STEPS OF PROGRAMMING
There are five steps in preparing a computer
programme which are also called ABCDE of Programming.
ANALYSIS
In this step the system analyst tries to become
familiar with the problem. He has to study the problem and prepare some notes
upon that problem. He also notes that what is given, what is required and what
will computer can do.
BLOCKING
In this step the programmer converts the analyst
report to a series of steps through which the computer will give the required
result. The steps are commonly known as Algorithm. There are different ways to
write those detailed sequential steps. The most common method used is flow
charting. A flow chart is symbolic representation of flow of a programme.
CODING
In this step the programmer writes the programme
in any computer language. This step is known as coding. After this programme is
fed into the computer and is compiled with the help of a given compiler.
DEBUGGING
Debugging is a step in which a programmer
corrects a syntax error which may come after the compilation.
TESTING
Testing is a step where the programmer is
finally testing the programme for execution (there may be any logical mistake
which compiler cannot trace).
EXECUTION
In this step we send the programme for execution
where company’s data will be fed and process.
VARIABLES AND CONSTANTS
VARIABLES
Variables are names used to represent values
used in BASIC programme. The values of a variable may be assigned by the
programmer or it may be assigned as the result of calculation in the programme.
Before a variable is assigned a value is assumed to be zero (or null for string
variable).
VARIABLES NAMES & DECLARATION CHARACTERS
Variable names may be of any length up 40
characters are significant. Variable name can contain letters, numbers and
decimal point. However, the first character must be a letter. A variable should
not be a reserve word.
Variable may represent either a numeric value or
a string.
NUMERIC VARIABLE
Numeric variable names may be declared as
integer, single precision, double precision values. The type of declaration
characters for these variable names are as follows.
STRING VARIABLE
In programming we often use to handle
alphanumeric or string variables. String variables consist of names, addresses
or in general any string or series of letters, number or special characters.
Without the use of string variable whenever any
differentiation needs to be made e.g., from employee to employee or from
application no. to application no., a number has to be assign to each employee
or each application.
A string variable name starts with an alphabet
and terminate with a dollar sign ($). In a string the value must be in
quotation marks. No arithmetic operations except addition and in addition the
values do not add they are just written together. The maximum number of
character allowed in a string varies from system to system but a typical value
is 256.
CONSTANTS
Constants are those that do not change while
executing the programme. BASIC deals with two types of constant.
1. Numeric constant
2. String constant
NUMERIC CONSTANT
All numbers belong to this category because
their values remain constant during execution.
They may take any of the following forms:
1. Commas are not allowed in a numeric constant.
2. The use of the positive sign is optional but
negative sign should be used if the number is negative.
STRING CONSTANT
A string constant is any set of valid basic
characters enclosed in quotation marks. The quotation marks do not form part of
string. Strings are used to represent non-numeric information such:
1. Name of persons and places
2. Addresses
3. Days, Months, Years.
INTRODUCTION TO BASIC
BASIC is a high level language used for purpose
of writing a program on a computer. It stands for Beginners All-purpose
Symbolic Instruction Code. BASIC is an easy to use “friendly” language where
instruction resembles elementary, algebraic formulas and certain English
keywords such Let, Read, Print, Goto etc.
HISTORY OF BASIC
The language was developed at Dartmouth College
in 1967, under the direction of John Kemeny and Thomas Kurtz. It was quickly
discovered and adopted. All the major computer manufacturers offered their own
version of BASIC for their particular computers.
In 1978, the American National Standard
Institute standardized an essential subset of BASIC in order to promote
uniformity from one version of BASIC into another.
In recent years some new version of BASIC have
been developed which included a variety of features that are not included in
more traditional versions.
STRUCTURE OF BASIC PROGRAM
Each instruction in a BASIC program is written
as a separate statement. Thus a program will be composed of a sequence of
statements.
The following rules apply to all BASIC
statements:
1. Every statement must appear on a separate
line number.
2. Each statement number must be followed by a
BASIC keyword which indicates the type of instruction.
3. On one single line number we cannot write two
statements, if we need we must use “colon”.
4. We can write 255 characters on one line.
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Computer
Components
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Central Processing Unit - CPU
The central processing unit (CPU), also called
the microprocessor, the processor or central processor is the brains of the
computer. The CPU is housed on a tiny silicon chip. This chip contains millions
of switches and pathways that help your computer make important decisions. The
switches control the flow of the electricity as it travels across the miles of
pathways. The CPU knows which switches to turn on and which to turn off because
it receives its instructions from computer programs. Programs are a set of
special instructions written by programmers that control the activities of the
computer. Programs are also known as software.
The CPU has two primary sections:
* Control Unit
* Arithmetic/Logic Unit
Arithmetic/Logic Unit
Because all computer data is stored as numbers,
a lot of the processing that takes place involves comparing numbers or carrying
out mathematical operations. In addition to establishing ordered sequences and
changing those sequences the computer can perform only two types of operations:
arithmetic operations and logical operations. Arithmetic operations include
addition, subtraction, multiplication and divisions. Logical operations include
comparisons, such as determining whether one number is equal to, greater than
or less than another number. Also, every logical operation has an opposite. For
example, in addition to "equal to" there is "not equal to."
Many instructions carried out by the control
unit involve simply moving data from one place to another - from memory to
storage, from memory to the printer and so forth. However, when the control
unit encounters an instruction that involves arithmetic or logic, it passes
that instruction to the second component of the CPU, the arithmetic or logic
unit, or ALU. The ALU includes a group of registers - high-speed memory
locations built directly into the CPU that are used to hold the data currently
being processed. For example, the control unit might load two numbers from
memory into the registers in the ALU. Then, it might tell the ALU to divide the
two numbers (an arithmetic operation) or to see whether the numbers are equal
(a logical operation).
Secondary Storage
Secondary storage or secondary memory also
referred as backing storage is used to supplement the capacity of main storage;
the memory stores a bulk of information. It is also called auxiliary storage or
mass storage. The information stored in this memory is used by the CPU by first
bringing it to main memory.
Examples of Secondary Storage Devices
Some Examples of secondary storage devices are
as follows:
1. Magnetic Disks
2. Magnetic Tape
3. Mass Cartridge Systems
Types of Secondary Storage/Backing Storage
Access Methods
There are two types of secondary storage/backing
storage access methods:
Sequential Access Storage
Access through sequential access storage is
non-addressable that is why an operator cannot refer directly to the contents
of a particular storage location such as used with magnetic tape. This involves
examining sequentially all beginning of the tape and continuing to search
through all record until the desired information area is found.
Direct Access Storage
Direct Access Storage is addressable that is a
given item can be selected from anywhere in storage by simply specifying the
address where it is located direct access devices such as magnetic disks
provide immediate access to individual records and do not require reading from
the beginning of a file to find a particular record.
Computer Bus
In computer the term bus refers that paths
between the components, actually bus, is a group of a wire. The bus is the
common path way through which the processors send/receive data and commands
to/from primary and secondary storage and all can transport 8 bits at a time
whereas a bus with 16 lines can transport 16 bits at a time.
Types of Computer Bus
There are two main buses in a computer:
1. Data Bus
2. Address Bus
Data Bus
The data bus is an electrical path that connects
the central processing unit (CPU) memory, and the other hardware devices on the
motherboard. Actually, the bus is a group of parallel wires. The number of wires
in the bus affects, the speed at which data can travel between components, just
as the number of lanes on a highway effects how long it takes people to get to
their destinations. Because each wire can transfer one bit at a time, an
eight-wire bus can move eight bits at a time. A 16-bit bus can transfer two
bytes and a 32-bit bus can transfer four bytes at a time.
Address Bus
The second bus that is found in every micro
computer is the address bus. The address bus is a set of wires similar to the
data bus, but is connects only the CPU and memory and all it carries are memory
addresses. The reason that the address bus is important is that the number of
lines in it determines the maximum number of memory address. For example, one
byte of data is enough to represent 2 = 256 different values, if the address
bus could carry only eight bits at a time, the CPU could address only 256 bytes
of memory. Most of the early PCs had 20-bit addres bus, so the CPU could
address only 2(20) bytes or 1 MB of data.
Computer Ports
A system board with its processor and memory
unit can work only when linked to input/output storage and communication
devices to receive data and communicate results of processing. Peripheral
devices such as a keyboard, mouse, monitor and a printer come with a cable and
a multiple connector. To link a device to the PC, you plug its connector into a
receptacle called a port in much the same way you plug a lamp cord into
electrical outlet. A port is one of the entry lines coming into the computer. A
port provides a direct link to the microcomputer's common electrical bus.
Types of Computer Ports
There are two types of ports used in computer:
1. Serial Ports
2. Parallel Ports
Serial Ports
A serial port provides a connection for
transmitting data one bit at a time. A serial port connects your computer to a
device such as modem, which requires two-way data transmission, or to a device
such as a mouse, which requires only one-way data transmission. IBM-compatible
computers use either 9-pin or 25-pin connectors for their serial ports COM1,
COM2 etc.
Parallel Ports
A parallel port provides a connection for
transmitting data eight bits at a time over a cable with eight separate dta
lines. Parallel transmission is fast because eight bits travel simultaneously.
Parallel transmission is typically used to send data to the printer. The cable
that connects two parallel ports contains 25 wires, eight wires carry data and
the remaining wires carry control signals that help to maintain orderly
transmission and reception. IBM-compatible computes generally allow you to use
up to three ports which are designated as LPT1, LPT2 etc.
Memory Unit
Memory unit is the place where the computer
program and data are stored during processing. It is the area, through which all
the data which is input into or output of the CPU must pass. It is monitored by
OU which keeps track of every thing in the storage. It is a random access
device, which consists of thousands upon thousands of storage locations, each
of which can be directly reached by the CU. Each storage location is
distinguished by the address.
Types of Memory Unit
It is divided into two parts:
1. Read Only Memory (ROM)
2. Random Access Memory (RAM)
Read Only Memory (ROM)
This part of memory contains permanently stored
information. When the power is switched off. ROM does not wash away. This
information is available to a computer to read and process but not to be
changed is kept on ROM. This information is stored on small pieces of memory
chips, before the computer is assembled.
Random Access Memory (RAM)
This part of memory consists of blank chips and
hence the computer can use it to store and retrieve (write and read)
information during its processing. The information stored in RAM is volatile,
that is, when the computer is shut down the stored information is lost
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Storage Devices
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Primary Storage Devices
The names of some computer's primary storage
devices are as follows:
1. Random Access Memory (RAM)
* DRAM
* SRAM
2. Read Only Memory (ROM)
* EPROM
* PROM
3. Memory
4. Cache Memory
Secondary Storage Devices
1. Hard Disk
2. Floppy Disk
3. CD-ROM (Compact Disc Read only Memory)
RAM
RAM is that part of main memory in which data
and instructions are held temporarily. RAM provides a working area to the user
to enter and process data. In RAM each data element has its own address
(location). Any data element can be read easily and quickly by using that
address. It is also called as Read-And-Write Memory (RAM) since the computer
can store or write data at any selected location (address) and can retrieve or
read data when needed. It is a temporary memory of a computer used to store
data and an instruction when the computer is on; everything that is stored in
RAM is lost when the computer is turned off. For this reason it is also called
volatile memory. Large RAM sizes provide larger data that computer can hold and
process. Additional RAM chips can be installed in a computer simply by plugging
them on motherboard. This increases the storage capacity of RAM of computer.
RAM is a semiconductor memory with no moving
part. Data can be accessed from RAM at very high speed very close to the speed
of light. A memory chip less than one-fourth size of a postage stamp can store
more than 500,000 bytes equivalent to the printed matter on a popular daily
newspaper.
ROM
ROM stands for Read Only Memory. The
instructions written in ROM can only be read but cannot be changed or deleted.
The ROM is, there fore, also called non-volatile memory. It is not possible to
write new information or instructions into the ROM. This is the reason why it
is called Read Only Memory.
ROM stores data and instructions permanently.
When the power is turned off, the instructions stored in ROM are not lost. The
instructions are written into the ROM chips at the time of its manufacturing.
When the computer is switched on, the instructions in the ROM are automatically
loaded into the memory of the computer. These instructions prepare the computer
system for use and display the initial operating system screen.
A variation of ROM is programmable read only
memory (PROM). PROM is a ROM into which you can load read only programs and
data. Some microcomputer software packages, such as electronic spreadsheets are
available as PROM units as well as on interchangeable disks. ROM and PROM are
used in variety of capabilities within a computer system.
Difference Between RAM and ROM
Everything that is stored in RAM is lost when
the computer is turned off. For this reason it is also called volatile memory.
In contrast the Read Only Memory (ROM) is
non-volatile memory. Instructions can only be read from ROM. Instructions once
written on ROM chip cannot be changed. It is a permanent memory of a computer,
i.e. the contents of this type of memory are not lost when the computer is
turned off. As soon as the computer is turned on, a program that resides on ROM
automatically makes the computer ready for use. ROM is a semiconductor memory
generally programmed by the manufacturer.
Difference Between SIMMs and DIMMs
The capacity of RAM in a computer affects
computer's power. More RAM can make computer run faster. The computer does not
necessarily have to load a complete program into its main memory to run it.
However greater is the part of a program it can fit into memory, the faster the
program will run.
Many RAM chips are installed on a small
circuit board. These RAM chips are wired together to form a single module of
large memory called Single In-Line Memory Modules (SIMMs). SIMM has contact
terminals on it one side. It can easily be plugged into the motherboard. SIMMs
had different capacities such as 1 Mbyte, 4Mbytes, and 16Mbytes with varying
speed.
SIMMs were popular by PC users in 1980s but
has now been replaced by DIMMs. Like SIMMs, Dual In-Line Memory Modules (DIMMs)
have been developed installing many RAM chips. DIMMs provide larger capcity as
compared to SIMMs. DIMMs have wider data bus and thus have higher rate of data
transfer. DIMMs are available in several configurations having different
capacities and speeds. You can expand RAM capacity of your computer by simply
plugging in more DIMMs.
Short Notes
Floppy Diskette
It is a small removable, portable storage device
that is made of polyester film coated with a metal oxide compound. It looks
like a 45 rpm phonograph record except that it is enclosed in a jacket square
in shape. It is readable by a computer with a floppy disk drive. The physical
size of disks has shrunk from the early 8 inch to 5.25 inch square and about 1
millimeter thick (mini-floppy) to 3.5 inch square and about 2 millimeters thick
(microfloppy) while the data capacity has risen.
Hard Disk
A hard drive is a a magnetic disk on which you
can store computer data. The term hard is used to distinguish it from a soft,
or floppy disk. Hard disk holds more data and is faster than floppy disks. In
general, hard disks are less portable than floppies, although it is possible to
buy removable hard disks. Today's computers typically come with a hrd disk that
contains several billion bytes (giga bytes) of storage.
CD-ROM
CD-ROM (Compact Disc, Read Only Memory) is an
adaption of the CD that is designed to store computer data in the form of text
and graphics, as well as hi-fi stereo sound. It is a non-volatile optical data
storage medium that is physically the same as an audio CD and is capable of
storing large amounts of data up to 1 GB, althrough the most common size is 650
MB about 12 million bytes per pound weight. All CD-ROMs confirm to a standard
size and format, so you can load any type of CD-ROM into any CD-ROM player. In
addition CD-ROM players are also capable of playing audio CDs. A standard CD is
120mm (4.75 inches) in diameter and 1.2 mm (0.05 inches) thick.
Magnetic Tape
A magnetic tape is also a storage device from
which you can access data serially like an audio cassette from which you can
hear the songs in the order in which they are stored. Serial access is slower
than the direct access provided by media such as diskettes. When you want to
access some particular data from the tape, the device has to scan through all
the data you do not need but that data is stored before the required one. The
access speed can be quite slow when the tape is long and what you want is not
near the start. So the best use of the magnetic tape is for the data that you
do not use very often.
Magnetic Disk
A magnetic disk is a metal or plastic disk
coated with magnetic material. Data is recorded into the magnetic material in
machine code. Disks have became popular due to their random access. These disk
spin in the disk drives Read/Write heads moving on the disk along its radius
can read data at any location under the heads.
Different types of disk drives and magnetic
disks are in use. The most popular types of magnetic disks are interchangeable
disks called the floppy disks and fixed disks called the hard disks.
Generally PCs are configured with at least one
hard disk drive and on floppy disk drive. Hard Disk provided a very big storage
capacity and are very fast but these are not inter changeable. Floppy disks are
smaller than the hard disk, because they always consists only one platter.
Floppies are available in size of 3.5" and 5.25" inches. Both of them
are available in double density and high-density storage capacities. The
storage capacities of these diskettes used for IBM compatible computer.
Floppy Disk, although slower than a hard disk,
are inexpensive and can easily moved from computer to computer. They are
comparatively fragile and must be handled with care.
Difference in the Capacity Between Hard Disk
and Floppy Disk
A hard disk contains several disk platters
stacked on a single rotating spindle. Data are stored on all recording
surfaces. For a disk with four platters, there are eight recording surfaces on
which data can be stored. A floppy disk has only one platter on which data is
written, that is why the storage capacity of a hard disk is more as compared to
the floppy disk. Hard disks or fixed disks are also called Winchester disk are
permanently installed or fixed with in the system unit.
Data Representation - Computer Studies
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Data
The word data is derived from Latin language. It
is plural of Datum (But Data is usually used as a singular term.) Datum
(singular) - Data (plural). Data is any collection of facts of figures. The
data is the raw material to be processed by a computer.
Example
Names of students, marks obtained in the
examination, designation of employees, addresses, quantity, rate, sales figures
or anything that is input to the computer is data. Even pictures, photographs,
drawings, charts and maps can be treated as data. Computer processes the data
and produces the output or result.
Types of Data
Mainly Data is divided into two types:
1. Numeric Data
2. Character Data
Numeric Data
The data which is represented in the form of
numbers is known as Numeric Data. This includes 0-9 digits, a decimal point
(.), +, /, - sign and the letters "E" or "D". The numeric data
is further divided into two groups:
1. Integer Data
2. Real Data
Integer Data
Integer Data is in the form of whole numbers. It
does not contain a decimal point, however it may be a positive or a negative
number.
Example
Population of Pakistan, numbers of passengers
traveling in an airplane, number of students in a class, number of computer in
a lab etc.
2543, 7, -60, 5555, 0, + 72 etc
Real Data
Real data is in the form of fractional numbers.
It contains a decimal point. It can also be positive or negative number.
Real Data is further divided into two types.
a. Fixed Point Data
b. Floating Point Data
(a) Fixed Point Data
Fixed point data may include digits (0--9), a
decimal point, + / - sign.
Example
Percentage of marks, weight, quantity
temperature etc.
-23.0007, 0.0002, + 9243.9, 17013 etc
(b) Floating Point Data
Floating point data may include digits (0-9),
decimal point, + / - sign and letters "D", "d",
"E", or "e". The data, which is in the exponential form,
can be represented in the floating point notation.
Example
Speed of light, mass of atomic particles,
distance between stars and etc.
1.602 x 10(-19) (Charge of electron in coulomb)
- Here -19 = power
The value can be feed into the computer as 1.602
E-19.
Character Data
Character data falls into two groups.
1. String Data
2. Graphical Data
String Data
String data consists of the sequence of
characters. Characters may be English alphabets, numbers or space. The space,
which separates two words, is also a character. The string data is further
divided into two types.
1. Alphabetic Data
2. Alphanumeric Data
(a) Alphabetic Data
The data, which is composed of English
alphabets, is called alphabetic data. Names of people, names of places, and
names of items are considered alphabetic data.
For example : Ahmed, Hyderabad, Chair etc
(b) Alphanumeric Data
The data that consists of alphabets as well as
numerals and some special characters is called alphanumeric data. Address,
employee's code, etc are alphanumeric data.
For example: 10/B, Block No 2, E103 etc.
Graphical Data
It is possible that pictures, charts and maps
can be treated as data. The scanner is normally used to enter this type of
data. The common use of this data is found in the National Identity Card. The
photographs and thumb impression are scanned and stored into the computer to
identify a person.
@import
"/extensions/GoogleAdSense/GoogleAdSense.css";
Number System
The number system is the system of counting and
calculation. Number system is based on some characters called digits. Each
number is made up of these characters. The number of digits a sysem uses is
called its base or radix. For example the number system we use in our daily
life is called Decimal System. Its base is 10 (As the name 'Deci' implies which
mean that it uses 10 digits (i.e. 0-9)
Codes
When numbers, letters or words are represented
by a special group of symbols, we say they are being encoded and the group of
system is called "Code".
Types of Codes
The codes include Binary code,
Binary-coded-decimal code (BCD), and alpha numeric codes. Alphanumeric codes
include ASCII and EBCDIC.
ASCII Code
ASCII stands for American Standard Code for
Information Interchange. It is a 7-bit code used to handle alphanumeric data.
This code allows manufacturers to standardize input/output devices such as
keyboard, printers, visual display units etc. An extension of ASCII code uses
8-bits called as ASCII-8 code with an extra 8th-bit as a parity bit to make the
total number of 1's either odd or even.
EBCDIC Code
EBCDIC (Extended Binary Coded Decimal
Interchange Code) is an extended form of BCD (Binary Coded Decimal), which can
represent only 16 characters because it is a 4-bit code. EBCDIC is an 8-bit
code, so it can represent 256 different characters. It was developed by IBM and
is used in most IBM models and many other computers.
Boolean Algebra
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The Boolean algebra was developed by the English
mathematician George Boole; it deals with statements in mathematical logic, and
puts them in the form of algebraic equations. The Boolean algebra was further
developed by the modern American mathematician Claude Shannon, in order to
apply it to computers. The basic techniques described by Shannon were adopted
almost universally for the design and analysis of switching circuits. Because
of the analogous relationship between the actions of relays, and of modern
electronic circuits, the same techniques which were developed for the design of
relay circuits are still being used in the design of modern high speed
computers. Thus the Boolean algebra founds its applications in modern computers
after almost one hundred years of its discovery.
Boolean algebra provides an economical and
straightforward approach to the design of relay and other types of switching
circuits. Just as an ordinary algebraic expression may be simplified by means
of the basic theorems, the expression describing a given switching circuit
network may also be reduced or simplified using Boolean algebra.
Boolean algebra is used in designing of logic
circuits inside the computer. These circuits perform different types of logical
operations. Thus, Boolean algebra is also known as logical algebra or switching
algebra. The mathematical expressions of the Boolean algebra are called Boolean
expressions. Boolean algebra describes the Boolean expressions used in the
logic circuits. The Boolean expressions are simplified by means of basic
theorems. The expressions that describe the logic circuits are also simplified
by using Boolean theorems.
Boolean algebra is now being used extensively in
designing the circuitry used in computers. In short, knowledge of
Boolean-algebra is must in the computing field.
Definitions
Constants
Boolean algebra uses binary values 0 and 1 as
Boolean constants.
Variable
The variables used in the Boolean algebra are
represented by letters such as A, B, C, x, y, z etc, with each variable having
one of two and only two distinct possible values 0 and 1.
Truth Table
It is defined as systematic listing of the
values for the dependent variable in terms of all the possible values of
independent variable. It can also be defined as a table representing the
condition of input and output circuit involving two or more variables. In a
binary system, there is 2(n) number of combinations, where n is he number of
variables being used for e.g. each combination of the value of x and y, there
is value of z specified by the definition. These definitions may listed in
compact form using "Truth Tables". Therefore a truth table is able of
all possible combinations of the variables.
AND Operation
In Boolean algebra AND operator is represented
by a dot or by the absence of any symbol between the two variables and is used
for logical multiplication. For example A.B = X or AB = X.
Thus X is 1 if both A and B are equal to 1
otherwise X will be 0 if either or both A and B are 0 i.e.
1.1 = 1
1.0 = 0
0.1 = 0
0.0 = 0
OR Operation
OR operation is represented by a plus sign
between two variables. In Boolean algebra OR is used for logical addition. For
example A+B = X.
The resulting variable X assumes the value 0
only when both A nd B are 0, otherwise X will be 1 if either or both of A and B
are 1 i.e.
1+1 = 1
1+0 = 1
0+1 = 1
0+0 = 0
Laws of Boolean Algebra
As in other areas of mathematics, there are
certain well-defined rules and laws that must be followed in order to properly
apply Boolean algebra. There are three basic laws of Boolean algebra; these are
the same as ordinary algebra.
1. Commutative Law
2. Associative Law
3. Distributive Law
Commutative Law
It is defined as the law of addition for two
variables and it is written as:
A + B = B + A
This law states that the order in which the
variables are added makes no difference. Remember that in Boolean algebra
addition and OR operation are same. It is also defined as the law of
multiplication for two variables and it is written as:
A.B = B.A
Associative Law
The associative law of addition is written as
follows for three variables:
A + (B + C) = (A + B) + C
This law states that when ORing more than two
variables, the result is the same regardless of the grouping of the variables.
The associative law of multiplication is written
as follows for three variables.
A(BC) = (AB)C
This law states that it makes no difference in
what order the variables are grouped when ANDing more than two variables.
Distributive Laws
The distributive law is written for three
variables is as follows:
A(B+C) = AB + AC
This law states that ORing two or more variables
and then ANDin the result with a single variable is equivalent to ANDing the
single variable with each of the two or more variables and then ORing the
products. The distributive law also expresses the process of factoring in which
the common variable A is factored out of the product terms. For example:
AB + AC = A (B + C)
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Computer
Software
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Machine Language
Machine language is the only language that a
compute understands directly without any translation, it is the binary
language. It is the language of 0's and 1's . It consists of strings of binary
numbers.
The binary codes are very difficult to memorize
for human beings that is why a machine language is cumbersome for a user.
Difference Between a High-Level Language and
Low-Level Language
High-Level Languages
High-Level language are more suitable for human
use than machine languages and enable the programmer to write instructions
easily using English words and familiar mathematical symbols. These symbolic
languages are called High-Level languages. These high-level languages consist
of simple English sentences, which are very easy to understand and memorize for
human being.
Low-Level Languages
Both the machine and assembly languages are
called Low-Level Languages. An assembly language is one step higher than the
machine language in human readability. A machine language consists of totally
of numbers and is almost impossible for humans to read. In an assembly
language, some of these numbers are replaced by human readable symbols called
language for humans and almost of the same efficiency as machine language for
computer operations. An assembly language is a combination of mnemonic
operation codes and symbolic codes for address.
Assembly language is very difficult but it
requires good skills for programming. A program written in an assembly language
is translated into a machine language before computer can understand and
execute it. A computer program, which translates an assembly language program
into its equivalent machine language, is called assembler.
A program can be written in much shorter time
and much precisely when a high level language is used. A program written in a
high level language can be executed in any computer system, which has a
compiler for that programming language.
Operating System
Operating system provides link between the user
and the computer. It enables the user to have complete control over the
computer system by commands through the keyboard or any other input device. The
supervisor part of an operating system resides all the times in the memory
(RAM) of the computer after the computer is turned on. An operating system
performs the following tasks:
1. Controls basic Input and Output devices.
2. Allocates system resources.
3. Manages storage space
4. Supports application software
5. Maintains security
6. Detects equipment failure
This enables the user to achieve high
efficiencies of which the processing systems are capable. Operating systems can
be classified as:
1. Single User Operating System
2. Multi-User Operating System
Single User Operating System
Single user operating systems are used on
individual systems or Personal Computers. These operating systems reside on
disks and re called Disk Operating Systems (DOS). Some of the most widely used
single user operating systems are :
1. MS-DOS
2. PCDOS
3. OS/2
4. Windows 95
Multi-User Operating System
Multi-User Operating Systems are used for data
processing on lrge computer systems. They enhance the potential of computer
systems with multiprogramming, multiprocessing and timesharing facilities
making them suitable for large organizations. Some of the multi-user operating
systems are:
1. UNIX / XENIX
2. MACOSX
3. Windows NT
4. Windows 2000 Server
DOS
DOS stands for "Disk Operating
System". It is a program, which acts as an interface between the user and
the computer hardware. DOS allows manipulation of files and programs by
interpreting and processing the commands typed by the user.
The DOS software is automatically copied from a
floppy disk or the hard drive into the computer's memory whenever the computer
is turned on or booted(made a computer ready to be used by putting in its
instructions). DOS is not an application package that you start and then exit
when done. This is an operating system runs from the moment you turn the
computer on until you turn the machine off. The major tasks the DOS must carry
out are:
1. To control input and output devices.
2. To enable user to load and execute program.
3. To maintain an orderly system of data in the
disk.
Types of DOS Commands
There are two types of DOS Commands:
1. Internal Commands
2. External Commands
Internal Commands
Internal commands are a part of the DOS program
COMMAND.COM and are loaded into memory when you boot your computer. These
commands are needed to be used most often, although they are not seen when we
display the disk directory of filenames on our screen. Some internal DOS
commands are:
CLS
This command is used to clear the screen of a
monitor.
Syntax: CLS
DIR
This command is used to display a list of
current directly files and subdirectories.
Syntax: DIR[drive:][path][filename][/p][1w]
CHDIR (CD)
This command is used to display the current
directory or changes in the current (default) directory.
Syntax: CD[drive:][path]
DEL
This command is used to deletes one or more
specified files from the disk.
Syntax: DEL[drive][path]file name[/p]
e.g. DEL Aslam.Doc
External Commands
External Commands are programs, which exist on
the DOS disk or the hard disk. They are run when you type their name on the
command line. For example, typing FORMAT at the DOS prompt results in a program
called FORMAT.COM being executed.
External Commands are not frequently used and
DOS saves valuable memory space by loading them only when required. Some the
external commands are:
CHKDSK
This command is used to checks the validity of a
disk and reports the total space, used and free space on the selected disk.
Syntax: CHKDSK [drive][path][/f][/v]
SYS
This command is used to create a bootable drive
and installs the main DOS files.
Syntax: SYS[drive:][path]drive2:
e.g. SYS A:
TREE
This command is used to display directory
structure.
Syntax: TREE[drive:][path][/f][/a]
XCOPY
This commands is used to copy files (except
hidden and system files) and directories, including sub directories.
Syntax: XCOPY source
[destination][/a|/m][/d:date][/p][/s][/e][/v][/w]
e.g. XCOPY *.*A:
DELTREE
This command is used to delete all files and sub
directories in a directory.
Syntax: DELTREE[/Y][pathname]
Booting the System
The term boot or bootstrap, when used with
computers, means start or startup. When we boot our computers, we are turning
it on and loading the Disk Operating System (DOS) into our computer's memory.
The sequence of events that occur between the time you turn on your computer
and the time it is ready for you to issue commands is referred to as the boot
process. At the completion of the boot up process the system gives a DOS Prompt
as soon as it is ready for operations
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Introduction
to Windows Operating System
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Windows Desktop
Windows "Desktop" is like a working
surface of a desk. Desktop is where your applications, folders and shortcuts
are located. Desktop contains the following items.
1. Icons
2. Taskbar
3. Start Button
The function of these desktop items is given
below:
Icon
An icon is a small colourful graphical picture
that represents an object like a file, folder, program or any hardware
components of the computer. Every icon has a lable, which identifies it. The
labels can be changed.
Windows operating system uses different icons to
represent files, folders and applications. Icons found on the desktop are
normally left aligned. Icons of the Desktop. The icons provided by windows are:
1. My Documents
2. My Computer
3. My Network Places
4. Recycle Bin
5. Internet Explorer
Task Bar
The task bar is at the bottom of the desktop but
you can move it to the top or either side of the screen by clicking and
dragging it to the new location. Buttons representing programs currently
running on your computer appears on the task bar. At the very left of the task
bar is the start button. At the right side is an area called the system tray?
Here you will find graphical representation of various background operations.
It also shows the system clock.
Start Button
Start button is found at the lower left corner
of the screen. Click once on the start button to open a menu of choices.
Through this button we can open the programs, installed on your computer and
access all the utilities available in the windows environment.
We can shutdown, restart and/or standby the
computer by using the start button.
Start menu displays a menu of choices:
1. Programs
2. Favorites
3. Documents
4. Settings
5. Find
6. Help
7. Run
8. Shutdown
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Short Notes
Recycle Bin
Recycle bin makes it easy to delete and undelete
files and folders. When a file or folder is deleted from any location, Windows
stores it in the recycle bin. If a file is deleted accidentally, you can move
it back from the recycle bin. We can also empty recycle bin to save disk space.
Steps to move back the file or folder from the
recycle bin.
1. Open Recycle bin by double clicking on its
icon.
2. Select the file or folder you want to move
back.
3. Click the right mouse.
4. A menu will appear, choose restore from it.
5. Windows will move the file or folder back to
the location from where it was deleted.
My Computer
My computer lets you browse the contents of your
computer. The common tasks that we can perform through my computer are:
1. Access information stored as different
storage devices connected with the computer, such as hard disk, floppy disk or
CD ROM.
2. Create, move, copy, delete or rename files,
folders and programs from one disk to another disk.
3. Execute or run programs from the disks.
4. Configure devices of the computer.
5. Add or remove a printer.
My Documents
It is a desktop folder that provides a
convenient place to store documents, graphics or other files that you want to
access quickly. On the desktop it is represented by a folder with a sheet of
paper in it. When you save a file in a program such as word pad or paint, the
file is by default saved in my documents unless you choose a different
location.
The following steps may be followed to open a
document from its window.
1. Move the mouse pointer to My Documents icon.
2. Double click on it to open its windows.
3. Double click on any of its item to open it.
Windows
It is a rectangular area of Screen that displays
different information. In windows every folder or application has a window.
Following are the properties of a window:
1. Every window has a title bar which displays
the name of the window.
2. A window can be resized, minimized and
maximized by pressing the buttons at the top right corner, of the title bar.
3. A window can be closed by pressing the x
button at the right of the title bar.
4. A window can be moved at any location of the
screen.
Items of Start Menu
Start menu displays a menu of choices:
1. Programs
2. Favorites
3. Documents
4. Settings
5. Find
6. Help
7. Run
8. Shutdown
Programs
Place the mouse pointer to the programs entry
and a sub menu will open, showing all programs or applications currently
installed. To open a program, which has been installed on your computer, click
on it and the program will open.
Favorites
Favorites menu present a list of the Internet
addresses that you have added to your Internet Explorer Favorite List.
Documents
The Documents menu lists the files you have
recently worked on. You can open the most recently used document directly from
here. To open a document from this list, simply click on it and the document
will open.
Settings
This menu provides the facility to change or
configure the hardware or software settings of the computer. This menu leads to
several choices.
The individual icons in the Control Panel refer
to a variety of tools to control the way of your computer, its components
presents information, as well as the tools to control the behaviour and
appearance of the Windows interface.
The Find/Search
This option of the start menu helps in locating
files or folders stored on the hard disk or network. This command is very
helpful in case we forget the exact location of a file or folder that we want
to access. The search option present different ways for finding a file or
folder. These options include search based on name, type, size, and date and
storage location of the file or folder. It opens a dialog box, where the user
can type a name of the file or folder to search for. The procedure of using
this command is given below:
1. Click on Find option of the start menu, the
Find dialog box will appear.
2. Enter the name of the file or folder in the
Named text box.
3. From the Look in drop down list box choose
the location where you imagine that your desired file or folder may be present.
4. Click on the Find now button to start search.
5. If find dialog box successfully searches the
location of the desired file or folder, it will display it in the window below
this dialog box.
Help
To access the Help system of windows, you can
select Help from the start menu. Help option helps us how to use the commands
and menus and in case of problems how to trouble shoot the windows operating
system.
Run
This command is used to execute a command or
program directly instead of using the icon or program menu. Press the
"Browse" button to locate the program you want to open through Run
command.
Shut Down
Shutdown is a process in which computer closes
all programs currently running and disconnects the devices connected with it
and turns it self off. Following step are followed to shutdown the computer.
1. Click on the start button to open the Start
Menu.
2. Click on the Shut Down.
3. Shut down dialog box will appear.
4. Choose the shut down option from the list nd
click the "OK" button.
Item of the Control Panel
Control Panel contains a number of icons used to
perform different settings of the computer. The frequently used icons are:
Accessibility Options
The accessibility options make it easier for
people with disabilities to operate a computer without installing special
software. Accessibility options such as Sticky Keys, Show Sounds and Mouse Keys
are designed to help users with specific disabilities take full advantage of
the computer.
Add New Hardware
It is used to install a new hardware to the
computer. Every new hardware comes with a device driver program that connects
it to the computer. For example we can connect a digital camera and installs
its driver with this icon.
Add/Remove Programs
This option helps us in installing new software
or removes software that we no longer want to keep in the computer. It lists
all the applications or programs currently installed on the computer. Programs
should be un-installed or removed through this icon instead of deleting them
one by one.
Date/Time
This option allows us to change or set the Date
and Time of the computer system. The date and time are displayed on the system
tray on Task bar. We can also bring the date and time settings dialog box by
double clicking time from the system tray.
Display
It is used to change the display setting of the
monitor. It has a number of tabs that changes or sets the display properties of
the monitor screen. We can also bring the display properties dialog box right
from the desktop by clicking the right mouse button on any blank space and
selecting properties from the menu.
Fonts
This option can be used to add new fonts in the
systems font's folder can also copy or remove fonts from this icon.
Internet Options
It changes settings from the web browser
software. Web Browser software is used in the Internet to open web pages.
Modems
Modem is a hardware device that enables the
computers to make a dialup networking. We can connect to the Internet by
modems. By using this option we can add modern driver and change its dialing
settings.
Mouse
By using this option we change the mouse pointer
styles and button setting of the mouse.
Printers
This option allows us to add or remove a driver
of the printer that is connected to the computer or on a network. Settings of
the printer can also change through this option.
System
This option provided us system information about
all the devices connected to the computer.
Users
This option is helpful in managing different
users of the same computer.
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Computer Virus
In the pas few years, a new processing crimes
has gained the attention of compute users all over the world. Some people have
found a way to create programs that silently replicate themselves on storage
media without the computer users realizing it. These programmers are referred
to as computer viruses. A computer virus is a program that literally infects
other programs and databases upon contact. When the program is loaded into the
computer, the virus attaches itself to other programs that are residing in the
system. When some one inserts an infected disk into a computer, the files in
computer's memory become infected. The reverse is also true, that is a disk
used in an infected computer becomes infected. Computer can be infected when a
hacker creates a virus and sends it over the phone lines to a network. Since
network is connected to thousands of computer, the infection is carried to all
the connected computers. Running a program or accessing the network or infected
disk activities the virus without the user's knowledge.
There are many types of viruses. Some act
quickly by erasing user programs and files on disk. Other grow like a cancer,
destroying small parts of a file each day. Some acts like a time bomb. They lay
dormant for days or months and all of a sudden becomes active, attacking on any
software on the system at a particular time. When the virus at a computer, it
performs the activities assigned to it for which it was created.
Virus Activities
Some of the activities that a virus has been
programmed to do are:
1. Copy themselves to other programs.
2. Display information on the screen.
3. Destroy data files
4. Erase an entire hard disk
5. Lie dormant for a specified time or until a
given condition is met.
Like the viruses that cause cold and diseases in
humans, computer viruses do not occur naturally. A virus program may be
harmless, simply producing an obcene or silly unexpectedly on the computer
screen. But it may also be a very destructive and harmful. It may wipe out huge
amount of data or corrupt files on the user's hard disk. Whatever is the motive
behind it anger, revenge or intellectual challenge, it is clear that people
creating virus do not have respect for other people's hard work.
Anti-Virus
Computer users need to protect their computers
from viruses until they are eradicated from the source and until they no longer
exist. Fortunately there are solutions to safe guard your system against
viruses. The first thing that you need to know is the ways in which your system
may be infected. The most common ways that may infect your system are:
1. A floppy or a removable hard disk from
another user may be a carrier of virus.
2. Virus may be transmitted to other computers
via Network. That is your system may be infected when you link your system with
another user, an online service, or the Internet.
3. Program purchased from unauthorized dealers
may be the potential carrier of viruses.
A number of programs have been designed to
protect software from viruses. These are called anti-virus programs. However no
anti-virus programs guarantees protection against all viruses. If you suspect
that a program is a carrier of virus, you can analyze the program using
anti-virus program to see if it contains any know viruses. Most anti-virus
programs can be used to eliminate to a virus found in a disk. Many computer
users have installed these anti-virus programs on their computers. A good
anti-virus program checks for infected files automatically every time you
insert any kind of disk or use your modem to retrieve a file, several
anti-virus programs rae available and some are even free. Some common
anti-virus programs are:
1. McAfee Virus Scan
2. Norton Antivirus
3. Virex
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Glossary of Computer Studies Class IX
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Algorithm
A series of instructions or procedural steps for
the solution of a specific problem.
Algorithm Code
A system of coding data by the use of
combination of letters to represent item of information.
Alphanumeric Code
Pertaining to character set or field of data in
which the coded characters may represent numerals or letters of the alphabets.
Analog Computers
Analog computers are machines designed to
perform arithmetical functions upon numbers where the numbers are represented
by some physical quantity.
Antivirus Utility
A program that scans disks and memory for virus,
detects and remove them.
Application Program
A program forming part of a user's job and
written by the user. As distinct from program forming part of the general
purpose software used to manage the operation of the total computer system.
ASCII Code
Acronym for American Standard Code for
Information Interchange.
Assembler
A computer program that converts the assembly
language program into machine on a language.
Assembly Language
Any symbolic language used for programming which
must go through an assembler in order to be converted into the machine code
required for operation on a computer.
BASIC
An acronym for Beginner's All-purpose Symbolic
Instruction Code. It is a high level programming language. Because of its
simplicity and comparative power, the language is much used on personal
computers.
BIT
An acronym for Binary digit, one of the two
digits (0 and 1) used in binary notation.
BUG
Any mistake or malfunction of a computer program
or system.
BYTE
A set of bits considered as a unit, normally
consist of 8 bits and corresponds to a single character of information.
Character
One of a set of symbols in a data processing
system used to denote, for example the numerals 0-9, the letters of the
alphabet, punctuation marks, etc.
COBOL
COBOL is an acronym for Common Business Oriented
Language. It is an internationally accepted programming language developed for
general commercial use.
Code
The representation of data or instruction in
symbolic form.
Coding
The written instruction for a computer coding is
the part of activity of programming.
Compilation
The process of using a compiler to create an
object program from a source language.
Compile
To create an object program by means of a
compiler.
Compiler
A complex program which converts computer
instructions written in a source language into machine code.
Computer
Any machine which can accept data in a
prescribed form process the data and supply the results of the processing in a
specific format as information or as signals to control automatically some
further machine or process.
Computer Program
A program written in a computer language.
Computer Simulation, Representing a system or a process by a computer model
constructed from a computer program.
Computer Word
A fixed sequence of bits, bytes, or characters
treated as a unit and capable of being stored in one storage location.
Constants
In a program constants are items of data which
remain unchanged for each run.
Cursor
A special character, usually a flashing square
block or underline, which indicates the position on a screen at which the next
information character will displayed.
Data
A general expression used to describe any group
of operands or factors consisting of numbers, alphabetic characters or symbols
which denote any conditions, value or state.
Data processing
The operations performed on data, usually by
automatic electronic equipment, in order to derive information or to achieve
order among files.
Debugging
Debugging is the technique of detecting,
diagnosing and correcting errors or bugs which may occur in programs or system.
Decision Symbol
A flow charting symbol used to indicate a choice
or branching in the information processing path. A diamond shape figure is used
to represent this symbol.
Difference
The result obtained in the arithmetic operation
of subtraction.
Digit
A component of an item of data.
Digital Computer
A digital computer is a machine capable of
performing operations on data represented in digital or number form, Disk: A
revolving plate upon which data and programs are stored.
DOS
An acronym for Disk Operating System.
Document
Any form or voucher containing detail of some
factors.
Documentation
It is the process of collecting, organizing and
storing all the information related to a specific program like flowchart,
algorithm, coding sheets, manuals etc, on papers.
EBCDIC
EBCDIC a data communication code in which 8
information bits are used to form 256 unique character codes. The term is an
abbreviation of Extended Binary Coded Decimal Interchange Code.
EOF BASIC
EOF BASIC reserved word which is an abbreviation
of End Of File.
Equivalence
A logical relationship in which two statement
are said to be equivalent.
Error
Any condition in which the unexpected results of
an compiled object code is obtained.
Expression
The symbolic representation of a mathematical or
logical statement.
Field
A sub division of a record containing a unit of
information.
File
An organized collection of records.
Floating Point Number
A form of number representation in which quantities
are represented by a number called the mantissa multiplied by a power of the
number base called exponent.
Flow Chart
The diagrammatic representation of a sequence of
events, usually drawn with conventional symbol representing different types of
events and their interconnection.
Format
The predetermined arrangement of data.
Function
That part of a computer instruction which
specifies the operation to be performed.
Giga
A prefix denoting one thousand million.
Graphics
The use of images generated by software for
output to a graphic display.
Hard Disk
A magnetic disk which is rigid.
High Level Language
A computer language which is nearest to human
language. A language in which each instruction or statement corresponds to
several machine code instructions.
Hybrid Computer
Any mixed computer system in which analog and
digital computing devices are combined.
Hz
Abbreviation of Hertz.
Information
These are the result which is derived from the
processing of data.
Input
The process of transferring data, or program
instructions, into memory from sone peripheral unit.
Instruction
That part of a computer program which tells the
computer what function to perform at that stage.
Interprpeter
Software that translates each statement of
source program into a sequence of machine instructions and executes these
machine instructions one by one before translating the next source language
statement.
Jump
Synonymous with branch.
Keyboard
An input device to feed alphabetic and numeric
data.
Kilobyte
1024 bytes.
Label
It is a DOS command which is used to assign a
lable to the disk.
Load
This is BASIC command which is used to load a
BASIC program from a secondary storage device to computer's memory.
Locate
This is BASIC command which is used to show the
location of cursor on the screen.
Loop
A series of instructions which are performed
repeatedly until some specified condition is satisfied.
Machine Language
The coding system adopted in the design of a
computer to represent the instruction of the computer.
Magnetic Disk
A storage device consisting of a number of flat
circular plates each coated on both surface with some magnetable material.
Main Storage
The store from which instructions are executed.
Megabyte
A million bytes.
Memory
This term is usually reserved for describing the
internal store of a computer.
Microcomputer
A computer based on microprocessor.
Modem
A device which transmits over distances without
error.
Nested Loop
Programs fling technique in which a loop of
instructions contains another loop, which may in turn contain another, and so
on.
Numeral
One of a set of digits that may be used in a
particular system of number system.
Numerical Data
Any field of characters which contains numeric
digits only.
Object Program
A program in which language produced by
translating the program written in source language through the use of a
compiler.
Operating System
A set of programs which manages resources of
computer include hardware, programs, data and operators.
Output
Result produced by a computer.
Output Device
The device which produces the results from the
computer in human readable form.
Printer
An output device which produce results in
printed form.
Procedure
The sequence of steps required in order to solve
a problem.
Program
A set of instructions composed for solving a
given problem by computer.
Programming Language
A language used for writing computer programs.
Prompt
Any message given to an operator by an operating
system.
RAM
Abbreviation of Random Access Memory. Memory
into which data can be written and from which data can be read.
Reserved Word
In a programming language, a data name not
available to the user because it has some specific significance to the
computer.
Resolution
The number of individually addressable and
variable picture elements available in a graphic display.
ROM
Acronym for Read only Memory. Memory containing
information which is permanent and which cannot be written to, but can be read
by program functions.
RUN
The performance of one program or routine.
Soft Copy
Output from a computer process which is
displayed on a visual display unit.
Software
The term is applied to all those programs which
in some way can assist all users of a particular type of computer to make the
best use of their machine.
Source Program
A program written in a source language.
Statement
A source language instruction.
Structured Programming
A methodology for programming which involves
systematic described in increasing detail until the final stage of coding is
required.
Subroutine
Part of a program which performs a logical
section of the overall function of the program and which is available whenever
the particular set of instructions is required.
Subscripted Variable
Whose numeric value can change? It is denoted by
an array name followed by a subscript; e.g. A(5) or AB$(22)
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