BBA First Semester Computer Notes

COMPUTER NOTES

INTRODUCTION ,FUNCTIONS,CHARACTERISTICS AND GENERATION OF COMPUTERS

What is a (Digital) Computer?

A computer is an electronic device system that accepts raw data as inputs, processes and manipulates them in digital form to give outputs (results) and store them for future use.

Functionality of a computer:

·         Inputs from Input devices. 

·         Store or hold the input data. 

·         Process by CPU (Central Processing Unit). 

·         Output from Output devices. 

·         Store in memory.

Characteristics of Computer

·         Speed

·         Accuracy

·         Diligence

·         Versatility

·         Storage and memorizing

·         Automatic

·         Processing

·         Non-intelligent

Speed: 

·         A computer can do numbers of tasks with in a fraction of time for which a human takes a longer period of time even days or month.

·         Capable of processing a very large amount of data.

·         Speed in terms of microsecond, nanosecond and pico-second.

Accuracy:

·         The result produced by a computer can be of higher precision and accuracy.

·         Its accuracy can be increased higher as requirements.

·         Provide outputs based on inputs.

Diligence (Carefulness):

·         It is hard-working and keeps working until it is stopped.

·         It keeps on working according to the program and do not feel tiredness or being lazy.

Versatility:

·         Flexibility, changeability.

·         Same computer can be used for different jobs or work.

·         More usefulness.

·         Same computer for different task.

Storage and Memorizing:

·         A computer can store large amount of data.

·         Once stored, it can be used any time as needed and don’t forget the data.

·         Can store different types of data (Image, Text, audio etc).

Automatic:

·         Once programmed, it automatically keeps doing the task.

Processing:

·         Large amount of data and commands are processed in the computer.

·         As requirement data are processed and gives an output.

·         Every task need to be processed.

Non-intelligent:

·         Absence of intellectualism.

·         It can not decide what to do.

·         It keeps working how it has been programmed to do.

·         No logical thinking if not programmed.

Applications of Computer

·         Education, Library and Design

·         Industries and Manufacturing

·         Research, Survey and Simulation

·         Hospital and Health

·         Data Processing

·         Science and Engineering

·         Offices and Hotel Management

·         Advertisement and Marketing.

·         Entertainment and Communication.

·         Weather Forecasting

·         Airlines and Navigation

Advantages of Computer

·         Computers are much more accurate and reliable than any other devices and human beings.

·         They are very much useful for repeated jobs which are difficult and tedious for humans to do.

·         Computers are much faster than humans.

·         With the help of computer, complicated things are easy to simulate and show.

·         It is versatile and can perform various types of works.

·         It can be used in multiple fields so it is called general purpose machine.

·         Because of the availability of storage, data can be store for future use and programs can be modified to add features for different purpose.

·         No repeated jobs so save time, labor and physical wastage (Draft) material. 

·         Communications technologies have advanced a lot with the use of computers.

Disadvantages Of Computer:

·         It is expensive and is beyond the reach of poor people. This limitation is being overcome because its cost is drastically decreasing day by day. 

·         It is an electronic machine, so there is much danger of electric shock and other physical damage. 

·         Since people are getting more relied upon computer, sometimes the failure in devices and programs can produce unreliable information and cause loss of data in a great extent. 

·         It increases dependency on machine. Even for every simple calculation people need them. 

·         Although it helps in faster and cheaper communication, there is much danger for security leakage. 

·         It increases piracy of intellectual properties (movies, publications etc) in big volume. 

·         Since computers are used in sensitive areas like national defense, civil aviation, banking, even a simple fault can cause loss of life and property. 

Generations of Computers

·         First Generation (Vacuum tube based).

·         Second Generation (Transistor based.)

·         Third Generation (Integrated Circuit based.)

·         Fourth Generation (VLSI microprocessor based.)

·         Fifth Generation(Bio-Chips & Artificial Intelligence)

First Generation:

·         The period of first generation was 1942-1954.

·         Vacuum tubes (Valves) as basic components for memory and circuitry for CPU.

·         Very large in size occupying entire room.

·         Consume large amount of power (electricity) and produce large amount of heat.

·         Punch cards and Paper tapes were used as Input and Outputs were limited on printouts.

·         Use of machine level language.

·         Storage capacity was limited to 1KB-4KB.

·         Slow operating speeds and slowest than all of the other generations’ computers..

fig:First generation computer

·         Example: UNIVAC and ENIAC.

Second Generation:

·         The period of second generation was 1952-1964. 

·         Transistors were used instead of vacuum tubes. 

·         Smaller in size as compared to First generation computers. 

·         Consumed less power and generate less heat compare to First generation computers. 

·         Faster and reliable than First generation computers. 

·         Assembly language and high level programming like FORTAN, COBOL were used. 

·         Use of magnetic core technology in place of magnetic drum. 

·         Magnetic core memories for internal storage, and magnetic disk and tapes for auxiliary memory. 

fig:Second generation computer

·         Example: ATLAS , Mark III, IBM 7000

Note: A transistor is a small electronic device made up of semiconductor material like germanium and silicon. It is much smaller in size as compared to vacuum tubes and consumes less power. In 1947, Bell Laboratory introduces the first transistor and was used in computer in 1958.

Third Generation:

·         The period of third generation was 1964-1972.

·         Integrated Circuits (ICs) were used in place of transistors.

·         Smaller in size than second generation as many transistors can be integrated in an IC.

·         Low power consumption than previous generation.

·         High level language like FORTAN-II, ALGOL-68 were used.

·         More reliable and efficient than previous generation computers.

·         Keyboard and monitor as input and output device.

·         Real-time and multi-programming Operating system were used.

·          

fig:Third generation computer

·         Example: IBM-360 series, IBM-370/168

Fourth Generation:

·         The period of Fourth Generation was 1972-present.

·         Use of Very Large Scale Integration (VLSI) technology and microprocessor.

·         Since thousands of transistors and other circuits were integrated in a single chip, size of computer drastically decreased.

·         Cheaper in price and lower power consumption.

·         Major achievement in computer technology took place in this era including hardware and software.

·         Still using the computer from this generation.

·         Highly accurate, reliable & operation speed.

·         Massive use of magnetic and optical storage device.

·         Multiprocessing, Multiprogramming, multimedia and distributed computing possible.

·         Concept of internet was introduced.

·         Introduction of PC’s for general people.

fig:Fourth generation computer

·         Example : IBM PC, Pentium PC

Fifth Generation:

·         The period of Fifth generation is present –future. 

·         Based on artificial intelligence and still in development. 

·         Some applications such as voice recognition are introduced. 

·         The use of parallel processing and superconductors. 

·         More user friendly interface with multimedia features. 

·         Quantum computation, molecular and nanotechnology uses that will change the face of computer. 

·         Development of devices to respond to natural language input. 

·         Self learning and organization capability.

COMPUTER SOFTWARE ,OPERATING SYSTEM

Software: Types (System and Application software), Functions of operating system

Computer Software:

• Also known as set of programs. 
• Collections of instruction for a computer. 
• Solve user problem and control different operation. 
• Computers requires program to function, typically executing the program’s instruction in CPU. 

A software is a set of programs designed to perform certain task or operation. Software is any set of machine readable instructions that directs a computer's processor to perform specific operations. The term is used to contrast with computer hardware, the physical objects (processor and related devices) that carry out the instructions. computer hardware and software require each other and neither can be realistically used without the other.

Software may be categorized along functional lines: -

1. System software 
2. Application software. 

Application Software:

• It is a computer software designed to perform a specific function directly for the user or in some case for another application program. 
• Also called software applications, applications or apps. 
• Examples: Productive software, Presentation software, graphics software, CAD, specialized scientific application, industry specific software. 

Application software is a program needed to perform various applications on the computer by the user. It helps a computer user to solve specific problem like prepare letters and documents, to create pictures and advertisements, to perform large calculations etc. The application software runs on the top of the operating system software.


System Software:

• Operating system and utility programs. 
• Manage computer resources at a low level. 
• Allows the parts of a computer to work together. 
• It insulate the applications programmer/user as much as possible from detail of the particular computer complex being used. 

A collection of programs designed to manage, control and operate the processing capabilities of the computer. System software is a set of programs to implement certain functions in a computer system. It controls the overall operations and components of a computer system. It is the base on which application programs are executed. It is an interface between user and computer.
— Divided basically:

1. Operating System 
2. Utility Software 
3. Language Processor (Compiler, Interpreter, Assembler).
4. Device Drivers

Operating system (OS):

• Interface between hardware and user. 
• Responsible for the management and coordination of activities. 
• Sharing of the resources of the computer that acts as a host for computing application run on the machine. 
• Application program makes the use of OS by making request for services. 
• Examples: Linux, Windows, OS/400 ETC. 

Operating system is software to control overall operations and components of a computer system.

Utility software:

• Also known as service routine, tools or utility routine. 
• Designed to help manage and tune the computer hardware, OS or application software by performing a single task or small range of tasks. 
• Some utilities are integrated into major operating system. 
• Defragmenter, anti-virus, data compression, disk scanner, file viewer etc. 
• Utility programs is used to solve a particular problem of software or hardware.

Device Drivers:
Device Drivers is software that permits a computer system to communicate with a device. We install device and its driver before using a device. Eg. Modem driver, printer driver etc.


Language Processors:
Language processors is software that converts a source program into object program. For example C-compiler converts a program written in C language into object program (machine code).


Operating System:

• It is an interface between hardware and user.
• It is responsible for the management and coordination of activities.
• Sharing of resources of computer.
• It creates links between user and computer as well as controls the execution of application programs. 
• It minimizes the amount of human intervention required during processing.
• Makes a computer more convenient to use.
• —The end users are not particularly concerned with the computer’s architecture, and they view the computer system in terms of application.
• —Provides some basic utilities to assist user in creating programs, the management of files, and the control of I/O devices.
• Eg: Linux, Windows, VMS, OS1400, UNIX

A- User/Application
B- Virtual Machine Interface
C- Operating System
D- Physical Machine Interface
E- Hardware (Physical Machine)
— An O/S is a virtual machine (emulated hardware) that aims to provide a simpler programming environment than the raw machine. An operating system is a set of programs that interface between hardware, software and user creating a simpler user friendly environment. Management and operation of hardware and software are all done by operating system.
An operating system is a collection of programs that together controls the operations of computer system. It activates and recognizes the hardware devices and provides operating environment for other application software. It is an interpreter which is responsible for bridging the gap between hardware and application needs.

Functions of Operating System

• Job Management: Functions of monitoring and tracking the time and resources used by various operations, task or users.
• Processor Management: Assigning the processor to a process and deallocate processor when not required.
• Coordination between software and users: Coordination and assignment of compilers, interpreters, assemblers and other software to the various user of the computer systems.
• Protection and Security: Prevention from unauthorized access to programs and data. Use of password, user login etc.
• Device and file Management: Allocates and deallocates the resources and decides what will get the resources. It controls which process gets the device or file for what duration.
• Memory Management: Decision of providing the duration and part of memory for a process or program.
• Error-detection and recovery: Error detection, alert, messages, debugging or recovery from error.
• Virtual Storage Management: Virtual memory is a feature of an operating system (OS) that allows a computer to compensate for shortages of physical memory by temporarily transferring pages of data from random access memory (RAM) to disk storage (hard disk). The OS will also retrieve the data that was moved to temporarily to disk storage to RAM. This process is known as swapping or paging which helps to solve the problem of shortage of RAM location.
• User Interface:— Makes a computer more convenient to use.—The end users are not particularly concerned with the computer’s architecture, and they view the computer system in terms of application.

Utility software:
It is also known as service program, service routine, tools or utility routine. It is computer software designed to help manage and tune computer hardware, operating system or application software by performing a single task or small range of tasks. Integrated in major OS.
Examples:
Disk storage Utilities (Disk Defragmenters, Disk Checkers, Disk Cleaner, Disk Space Analyzer, Disk Partition, file managers).
System Profiler.
Anti-virus software. etc.

Disk Cleanup: It can find files that are unnecessary to computer operation or take up considerable amount of space. Disk cleanup helps the user to decide what to delete when their hard disk is full. Disk clean up targets:

• Compression of old files.
• Temporary internet files.
• Downloaded program files.
• Recycle Bin
• Setup log files. etc.

Disk defragmenter: It is a computer program inbuilt in MS - Window, designed to increase access speed by rearranging files stored in disk to occupy contiguous storage location, a technique commonly known as defragmenting. The purpose is to optimize the time it takes to read and write files to/from the disk by minimizing head travel time and maximizing transfer rate.

Antivirus software: A virus is a unwanted program that bring unwanted modification or operation in a computer. Antivirus is a computer software designed and used to prevent, detect and remove virus software. Examples of Antivirus are Avira, Avast, Norton etc.

Disk compression: It is the utility software which increase the amount of data that can be stored on a hard disk of given size. Whenever the operating system attempts to save a file on disk, the utility intercepts it and compress. Similarly, when operating system attempts to open a file, the disk compression utility intercepts the file, decompress it and then passes it to the operating system. To be specific, it differs with file compression software. In file compression, only specific files are compressed and requires the user designate files to be compressed. Example of Disk compression are NTFS compression, WIMBoot compression, Diskdoubler. Example of file compressor are winzip, winrar, stuffit etc.

Disk partition software: Disk partition is the act of dividing a hard disk into multiple logical storage units and each unit treat as one physical disk drive. So the utility software which is used for disk partition is known as disk partition software. Examples Bootpart, Diskpart, Partition Wizard etc.

Number System

Number system (Decimal, Binary, Octal, Hexadecimal)

Number System:
A number system is a system in which different notations are used for representing numbers of given set. Depending upon the number of distinct notations used, there are are Decimal (base 10), Binary (base 2), Octal (base 8) and Hexadecimal (base 16) number system.

Decimal (base 10): let start with the familiar number system "Decimal". It is a base 10 number system in which we use 10 distinct notations starting with 0. The notations used in Decimal are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. If more notations required then we increase the number of digits with carryover. For 1 more than 9 is represented by 10 which means 2 digits are used; 1 is carry and 0 is starting of the count.
1+1=2, 8+1=9, 9+1=10, 10+1=11, 19+1= 20.
Counting Sequence:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21................

Binary (base 2): Two distinct notions (0, 1) are used. So, if these two notation are used and need to represent more, we make a carry. For 1 more than 1 is represent by 10 which means 2 digits are used; 1 is carry and 0 is starting of the count on first digit.
0+1=1, 1+1=10, 10+1=11, 11+1=100, 100+1=101
Counting Sequence:
0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 111............
Only two notations (0, 1) need to be used to represent number.

Octal (base 8) : Octal is a base 8 number system in which we use 8 distinct notations. The notations used in Octal are 0, 1, 2, 3, 4, 5, 6 and 7. If 1 is added to 7 then the representation of number is 10 where first number 1 is carry and 0 is initial start of count on first digit.
1+1= 2, 5+1=6, 6+1=7, 7+1=10, 11+1=12, 16+1=17, 17+1=20
All the above numbers are base 8 number.
Counting Sequence:
0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 20.....
Only 8 notations (0, 1, 2, 3, 4, 5, 6, 7) need to be used to represent number.

Hexadecimal: Hexadecimal is a base 16 number system in which we use 16 distinct notations. The notations in Hexadecimal are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F. In the notation A= decimal 10, B = decimal 11 C=12, D=13, E=14 and F= decimal 15. After F, the next number is 10 because all the unique notations have been used so make carry and 0 is initial start of count on first digit.
1+1=2 6+1=7, 9+1=A, C+1=D.
Counting Sequence:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A. B. C. D. E. F. 10. 11. 12. ......18, 19, 1A, 1B, 1C, 1D, 1E, 1F, 20, 21.....

Decimal                Binary                   Octal                      Hexadecimal

0                              0                              0                              0

1                              1                              1                              1

2                              10                           2                              2

3                              11                           3                              3

4                              100                         4                              4

5                              101                         5                              5

6                              110                         6                              6

7                              111                         7                              7

8                              1000                       10                           8

9                              1001                       11                           9

10                           1010                       12                           A

11                           1011                       13                           B

12                           1100                       14                           C

13                           1101                       15                           D

14                           1110                       16                           E

15                           1111                       17                           F

16                           10000                    20                           10

Base Conversion:
Number from one number system can be converted to other number base system.

Binary to Decimal:
For example:

(1101101)₂ to (?)₁₀

=1x2⁶+1x2⁵+0x2⁴+1x2³+1x2²+0x2¹+1x2⁰

=1x64+1x32+0x16+1x8+1x4+0x2+1x1

=64+32+8+4+1=109 decimal Answer

Octal to Decimal

(2507143)₈ to (?)₁₀

=2x8⁶+5x8⁵+0x8⁴+7x8³+1x8²+4x8¹+3x8⁰

=2x262144+5x32768+0x4096+7x512+1x64+4x8+3x1

=691811 decimal Answer

Hexadecimal to Decimal

(AE4B)₁₆ to (?)₁₀

=A x 16³+E x 16²+4 x 16¹+B x 16⁰

=10 x 4096+14 x 256+4 x 16+11 x 1

= 44619 decimal Answer

Programming Language

Programming Language:

A programming language is a formal constructed language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs to control the behavior of a machine or to express algorithms.

Types of Programming Languages

There are two types of programming languages, which can be categorized into the following ways:

1) Low level language

a) Machine language (1GL)

b) Assembly language (2GL)

2. High level language

a) Procedural-Oriented language (3GL)

b) Problem-Oriented language (4GL)

c) Natural language (5GL)

1. Low level language:

This language is the most understandable language used by computer to perform its operations. It can be further categorized into:

a) Machine Language (1GL):

Machine language consists of strings of binary numbers (i.e. 0s and 1s) and it is the only one language, the processor directly understands. Machine language has an Merits of very fast execution speed and efficient use of primary memory.

Merits:

• It is directly understood by the processor so has faster execution time since the programs written in this language need not to be tanslated.
• It doesn’t need larger memory.

Demerits:

•  It is very difficult to program using 1GL since all the instructions are to be represented by 0s and 1s.
•  Use of this language makes programming time consuming.
•  It is difficult to find error and to debug.
• ¨It can be used by experts only.

b) Assembly Language:

Assembly language is also known as low-level language because to design a program programmer requires detailed knowledge of hardware specification. This language uses mnemonics code (symbolic operation code like ‘ADD’ for addition) in place of 0s and 1s. The program is converted into machine code by assembler. The resulting program is reffered to as an object code.

Merits:

• It is makes programming easier than 1GL since it uses mnemonics code for programming. Eg: ADD for addition, SUB for subtraction, DIV for division, etc.
•  It makes programming process faster.
•  Error can be identified much easily compared to 1GL.
• ¨It is easier to debug than machine language.

Demerits:

• Programs written in this language is not directly understandable by computer so translaters should be used.
•  It is hardware dependent language so programmers are forced to think in terms of computer’s architecture rather than to the problem being solved.
• Being machine dependent language, programs written in this language are very less or not protable.
•  Programmers must know its mnemonics codes to perform any task.

2. High level language:

Instructions of this language closely resembles to human language or English like words. It uses mathematical notations to perform the task. The high level language is easier to learn. It requires less time to write and is easier to maintain the errors. The high level language is converted into machine language by one of the two different languages translator programs;interpreter or compiler.

High level language can be further categorized as:

a) Procedural-Oriented language (3GL):

Procedural Programming is a methodology for modeling the problem being solved, by determining the steps and the order of those steps that must be followed in order to reach a desired outcome or specific program state. These languages are designed to express the logic and the procedure of a problem to be solved. It includes languages such as Pascal, COBOL, C, FORTAN, etc.

Merits:

• Because of their flexibility, procedural languages are able to solve a variety of problems.
•  Programmer does not need to think in term of computer architecture which makes them focused on the problem.
•  Programs written in this language are portable.

Demerits:

•  It is easier but needs higher processor and larger memory.
•  It needs to be translated therefore its execution time is more.

b) Problem-Oriented language (4GL):

It allows the users to specify what the output should be, without describing all the details of how the data should be manupulated to produce the result. This is one step ahead from 3GL. These are result oriented and include database query language.

Eg: Visual Basic, C#, PHP, etc.

The objectives of 4GL are to:

• Increase the speed of developing programs.
•  Minimize user’s effort to botain information from computer.
•  Reduce errors while writing programs.

Merits:

•  Programmer need not to think about the procedure of the program. So, programming is much easier.

Demerits:

• It is easier but needs higher processor and larger memory.
•  It needs to be translated therefore its execution time is more.

c) Natural language (5GL)

Natural language are stil in developing stage where we could write statrments that would look like normal sentences.

Merits:

•  Easy to program.
• Since, the program uses normal sentences, they are easy to understand.
• The programs designed using 5GL will have artificial intelligence (AI).
• The programs would be much more interactive and interesting.

Demerits:

• It is slower than previous generation language as it should be completely translated into binary code which is a tedious task.
• Highly advanced and expensive electronic devices are required to run programs developed in 5GL. Therefore, it is an expensive approach.

                           These are the different types of programming languages with their merits and demerits.

Flowchart examples

SOME EXAMPLES OF FLOWCHART

1)Input any three numbers then find the greater no among them.

ANS)

2)Find the factorial of the given number.

ANS)

3)Input any number and find whether the no. is even or odd.

ANS)

4)Draw a flowchart to find a quadratic equation.

ANS)