Fundamental Of Computer

Computer Fundamental By BALJEET SINGHSINWAR/1 What is Computer? Computer is an electronic device. It accepts raw data from us, process it and gives meaningful information as required by user as per given instruction. Characteristics of a Computer (a) Computer is very fast. (b) Computer is accurate. (c) They can process millions of instructions per second. (d) Computer is very versatile. (e) Computer works at constant efficiency. (f) Perform repetitive tasks very well without error. (g) Computer can store information for future retrieval or use. (h) Computer can communicate with other computer systems. History of Computers 450 BC - ABACUS The Egyptians developed it and Improvements made by Chinese & Japanese. 1614 AD - Napier's Bones Developed by John Napier Scottish Mathematician. A set of 11 rods further divided into 9 diagonal numbered parts, based on logarithms. Improved in 1917 AD. 1620 AD - Slide Rule William Oughtred developed it, which is an analog device. 1642 AD - Pascal's Adding Machine Blaise Pascal, a French Philosopher consisted o mechanical gears. It is forerunner of all mechanical machines. 1694 AD - Gottfried Calculating Machine Developed by Gottfried Von Leibnitz, a German Mathematician who was an improvement over Pascal's adding machine. All the above were based on mechanical precision and since mechanical precision was not that accurate during those days the reliability of the machines was rather questionable. 1880 AD - Jacquard Punched Cards Machine Joseph Jacquard, French textile manufacturer, developed a machine, which used punched cards to make intricate patterns on woven cloth. Absence of hole Presence of hole

= =

Leading to warp thread raised Leading to warp thread not raised

This basic principle of one or other of the two states is the fundamental basis of the binary coding system used in computers. 1623 AD - Binary Codes The first use of binary codes for numerical representation by Francis Bacon. 1822 AD - Difference Engine & Analytical Engine Charles Babbage, English Professor of Mathematics developed both of them. In Difference Engine the level difference between the values computed for a formula, remains the same. For example, Compute the Squares of first 6 natural numbers

Computer Fundamental By BALJEET SINGHSINWAR/2 Number 1 2 3 4 5 6

Square 1 4 9 16 25 36

We compute the level of differences 2 times since we have squared the numbers and find that the level difference at the 2nd instances are equal as below :Squares 1 4 9 16 25 36

1st Difference 1 4-1=3 9-4=5 16 - 9 = 7 25 - 16 = 9 36 - 25 = 11

2nd Difference 3 5 7 9 11

-

1 3 5 7 9

= = = = =

2 2 2 2 2

Similarly, if we work out the cubes, the third level difference will be equal. Based on this principle Charles Babbage developed ANALYTICAL ENGINE which could calculate up to 20 decimals at about 60 additions per minute. However, financial constraints and inadequate technological advancements (electricity was discovered only in 1840's), his devices remained unfinished. But for his pioneering work he is called the FATHER OF COMPUTER. Similarly, Lady Ada Lovelace is famous as the First Programmer, for having devised a suitable use of Binary Number system for programs and data to be fed into the Analytical Computer. GEORGE BOOLE developed the application of logic in computers, which when applied to mathematical operation came to be known as Boolean Algebra. 1889 AD - Card Punching & Reading Machine Herman Hollerith, a census statistician at the US Census Bureau developed card punching and reading machines. He formed his own company later, "The Computing Tabulating Recording Company" which is better known today as one of the largest manufacturers of computers - IBM or International Business Machine Corporation Headquartered in the USA. 1906 AD - Thermionic Valves Lee De Forest, in 1906, made a breakthrough in developing the technology of "Thermionic Valves". 1937-1944 AD - MARK I Computer Howard Aiken with IBM's support built the first automatic Electro-mechanical computer using relays and switches. The BUGS There is a well known fable about Mark I which indication to the adoption of the word "BUG" for use in computers. Once Mark I developed a certain fault and no amount of effort was spared to locate the same. Every portion of the huge Mark I, computers of those days used to be monstrously big machines occupying several rooms, was thoroughly searched for the fault. After spending considerable time and effort it was found that on one of the electrical connections of the "Back-Plane Panel" of the machine a "MOTH" had got struck bringing the machine to a grinding halt. The moth was removed when Mark-I started functioning. It was then stated that "Mark I was 'Debugged'."

Computer Fundamental By BALJEET SINGHSINWAR/3 Bug was incorporated into the computer vocabulary to mean all kinds of errors and like-wise debugging meant removing those errors. These two words are commonly used words now in relation to both the hardware and software of computer. 1946 AD - ENIAC Electronic Numerical Integrator and Calculator were developed for World War II use. After this the progress in the Digital Computers has been simply stupendous (amazing). JOHN VAN NEUMANN Outlined the basic requirements for the design of modern digital computers. These relate to the binary coding scheme for data representation, storage of data and program within the computer, the manipulation of programs by other programs, choice of alternative procedures and use of input- output devices for feeding data and retrieving information. Generation of computers First Generation -: (1946 - 1954)

Use Vacuum Tubes Use Assemble language for programming large in size slow processing Example : IBM 704, IBM 709, EDVAC, UNIVAC etc.

Second Generation -: (1955-1964) Use of transistors instead of vacuum tube Increased Operating speeds & improved Storage devices High speed card readers Used high-level languages such as FORTRAN (1956), COBOL (1960), Line printers and magnetic tape transport units. Reduction in size, improved reliability, reduction in operating cost. Example : IBM 1400, IBM 7040, CDC 3600, GE635, B300 Third Generation -: (1965-1974)

Use of IC (Integrated Circuit) Starting use of Semiconductor Memory (RAM or ROM) More miniaturization Reliability and Accuracy Example : IBM 370, Honeywell 200, B2000

Fourth Generation -: (1975-up till now) Use of VLSIC (Very Large Scale Integrated Circuit) and Magnetic Oxide Semiconductor Operating system speed in nano & pico sec. Refinement of I/O units. Reduction in size. Refinement of HLL and software packages for DBMS Reduced operating cost, recording of errors. Fifth Generation -:

(Development continued...) Will be use ULSIC (Ultra Large Scale Integrated Circuit) Use Artificial Intelligence Super Computer. This type of computer will understand natural languages like English, Hindi etc. and programmer have to instruct only what to do, not how to do. These computers will have full ability to understand sounds and visions & it will reduce the burden of programming.

Computer Fundamental By BALJEET SINGHSINWAR/4 Classification of Computer Computer can be classified into four part :1. MicroComputer -: There are two types of Microcomputer (a) Home Computer : Use TV for Output Use Cassette/floppy as backing storage Low Cost (A few thousand of rupees) Use for Home education, Home games etc. (b) Business Computer :Use a Separate VDU for output Floppy or Hard disk for backing storage Used by Small business and company department More powerful Micros have Mini like Capacities called Super Computer Types of Business Computer :PC PC - AT PC - XT PC - AT 286 PC - AT 386 PC - AT 486 Pentium I/II/III/IV 2.

Mini Computer -:

Multi User, Multi Tasking, Faster than MicroComputer, Larger memory capacity, Larger C.P.U./A.L.U. Cost a few lacks of rupees Need site preparation and air conditioned environment Need UPS (Uninterrupted Power Supply)

3.

Main Frame -:

Faster than Mini computer Cost a few ten lacks of rupees Used by Big companies, banks and government

4.

Super Computer -:

Have greater processing power Used as whether forecasting Used in Oil exploration, Energy conservation, Nuclear Reactor, Safety Analysis etc.

Application of Computer Today computer is going to be an essential part of our life. In many part of life, we can think life without computer. It is useful at so many places among someone are:(a) Education (b) Library (c) Medical Science (d) Engineering (e) Agriculture (f) Industry (g) Scientific Research (h) Traffic Control (i) Design (j) Checking of Examination Paper (k) Media (l) Airways & Railways Ticket Reservations Computer System Computer System consists of :a) Hardware Hardware is the consist of the mechanical, electrical and electronics part of the Computer. b) Software Software is the set of detailed step by step instructions called program through which user instruct the computer to do something. c) Heartware or Liveware - Heartware is the people who schedule the operation of hardware and write or modify the software. d) Firmware Firmware are the routines or programs that are stored in read-only memory (ROM). Unlike RAM, ROM retains programs intact even in the absence of electrical power. Startup routines and low-level input/output instructions are stored in firmware.

Computer Fundamental By BALJEET SINGHSINWAR/5

HARDWARE Hardware may be classified as :1. CPU (Central Processing Unit) 2. Peripherals 1.)

CPU - CPU may also be classified as :a) CU (Control Unit) - The CU controls and directs the operations of the entire computer system. The control unit retrieves computer instructions in proper sequence, interprets each instruction and then directs the other parts of the computer system for the execution. b) A.L.U. (Arithmetic & Logic Unit) - The ALU actually carries out Arithmetic operations like addition, subtraction etc. and Logic operations like comparison of values etc. c) Main Memory - Memory is the mind of the computer. It may be classified as:i) RAM (Random Access Memory) - It is a temporary memory used for storing data or instructions during processing. Any storage location can be directly accessed using its address. RAM loses its contents when the power is turned off and hence is also known as Volatile Memory. While the computer is on, information can be written onto the RAM chips and read from them. ii) ROM (Read Only Memory) - It is a permanent memory which contains basic information the CPU needs when you first turn on the computer as well as at other times during the operation of the computer. This information is written onto the chip during manufacture. Information can only be read, and no new information can be written onto the ROM. There is also some kind of ROM:a) PROM b) EPROM c) EEPROM 2. PERIPHERALS :- It can be classified as :a) Input - Data is accepted as Input through the standard Input device. A number of storage devices are using now a days as * Keyboard * Joystick * Mouse * OCR * MICR * Punch card Reader etc. b) Output - Processed data is delivered as Output through input/output device. A number of output devices are also available as * Printer * Plotter * Screen (Monitor) etc. c) Backing Storage or Secondary Storage - These devices are used to store the data for a long time permanently. A number of backing storage devices is also available as * Floppy 31/2" (Capacity - 1.44 MB) 5-1/4" (Capacity - 1.2 MB) * Harddisk Capacity from 20 MB to 40 GB and above * Zip drive * CD-ROM * Magnetic Tape * Cartridge Tape etc.

Computer Fundamental By BALJEET SINGHSINWAR/6 REPRESENTATION OF INFORMATION : Modern computers are based on Binary system. Binary devices works only on two stages - "ON" and "OFF". The stages are represented as "0" and "1" which is known as "Binary Digits". Programs and instructions is handle by computer as string of bits. Microcomputer and some other computer as well handle 8 bits at a time. A set of 8 bits is known as a "Byte". 4 bits or a half of a byte is known as "Nibble". So, 8 Bit 1024 Byte 1024 KB 1024 MB

= = = =

1 1 1 1

Byte KB (Kilobyte) MB (Megabyte), i.e. 10,48,576 Bytes. GB (Gigabyte), i.e. 1,07,37,41,824 Bytes.

DATA PROCESSING CONCEPTS : Manipulation of facts to the advantage of the users is called data processing. It may be done using manual or electronic methods. The main purpose of electronic data processing (EDP) is to do complex jobs at incredible speed and accuracy.

Different cycle in which data is processed electronically is given below : Input Cycle : In this phase, data is prepared in some convenient form and on a medium most suitable entry into a processing machine. In manual system, we may prefer to write data in a tabular form on a sheet of paper such as the marks sheet of students of a class. We do so, because it is very convenient to read the marks written in tabular form. In case of electronic data processing machines, we may record data on a magnetic tape or floppy disk. Processing Cycle : In this cycle, we manipulate or combine the inputted data with other data as per the instructions. In a manual processing cycle, a class teacher adds the marks secured by each student in different subjects. He divides this aggregate by the maximum marks and calculates the percentage of marks. He can also award a grade, based on the percentage of marks. In an electronic data processing system these actions are performed automatically in accordance with a series of instructions called a program, which is stored in the computer. The computer will do exactly the same job as is told to it by the set of instructions or program. Output Cycle : Once data are processed, the results need to be brought out in a form most suitable for the user. This is called the output cycle. In the marks processing case, the marks of each student in each subject are transferred to printed report cards. Remarks like pass/fail are also recorded on this report along with the merit and the grades. A class teacher does this job in a manual data processing system and by a computer printer in an electronic data processing system.

Computer Fundamental By BALJEET SINGHSINWAR/7

TYPES OF SOFTWARE 1.

2.

SYSTEM SOFTWARE - System Software or System Packages are sets of one or more programs that are basically designed to control the operation of a computer system. They are general programs written to assist users in the use of the computer system by performing tasks, such as controlling all of the operations, moving data into and out of a computer and all the other steps in executing the application program. In general, system packages support the following : (a) Running of other software (b) Communicating with peripheral devices such as printers, card readers, disk and tape devices etc. (c) Development of other types of software. (d) Monitoring the use of various hardware resources such as memory, peripherals, CPU etc. System software thus makes the operation of the computer system more effective and efficient. APPLICATION SOFTWARE - Application software, or Application packages are sets of one or more programs designed to carry out operations for a specified application. For example, every month a payroll package produces the payslips for the workers of a company. Similarly an inventory package may produce the list of different parts/equipment available in an organization. Traditionally, application packages are limited to the general-purpose functions of production schedule, general ledger and general accounting packages. Since there is a great demand of general-purpose software, therefore there is ever increasing development of software. Special purpose packages have also been developed for such areas as banking, hospital administration, insurance, desktop publishing, manufacturing etc.

DIFFERENCE BETWEEN SYSTEM AND APPLICATION SOFTWARE : System software offers several advantages and conveniences to application programmers and computer users. Good systems software allows application packages to run on the computer with lesser time and effort. Without system software, application packages cannot be run on the computer system. However, the production of systems software is a complex task that requires extensive knowledge and considerable specialized training in computer science. Systems programmers, who prepare systems software, are highly trained computer specialists and important members of the computer architecture team. Because of its technical complexity, systems software is rarely developed in-house. They are normally developed and distributed by the computer manufacturers. The customer who buys or leases a computer system would usually receive, in addition to the hardware, some software needed for the effective operation of his computer. A computer without some kind of systems software would be very ineffective and most likely impossible to operate. OPERATING SYSTEM SOFTWARE - Operating System is a set of programs that is extremely important to activate and Co-Ordinate the activities of various hardware resources like the processor and input/output devices. In other words, Operating System controls the movement of information on in the Computer. OS is the first program loaded into the computer's memory after the computer is switched on. The operating system is an important component of the computer system, because it sets the standards for application programs that run in it. All programs must be written to "talk to" Operating System. The main functions of a OS are :(a) It assigns a processors to different tasks being performed by the computer system. (b) It allocates the main memory and other storage areas to the system programs as well as user programs and data.

Computer Fundamental By BALJEET SINGHSINWAR/8 (c) (d)

(e) (f) (g) (h) (i) (j) (k) (l)

It carries out the input/output management and coordinates and assigns different input and output devices while one or more programs are being executed. It manages files on various storage devices and the transfer of these files from one storage device to another. It also allows all files to be easily changed and modified through the use of text editors or some other file manipulation software packages. It establishes and enforces the job priority. That is, it determines and maintains the order in which jobs are to be executed in the computer system. It automatically transits from job to job as directed by special control statements. It is able to interpret commands and instructions. It co-ordinates and assigns compilers, assemblers, utility programs, and other software packages to various users working on the computer system. It establishes data security and integrity. That is, it keeps different programs and data in such a manner that they do not interfere with each other. Moreover, it also protects data from being destroyed by and other user. It also produces traces, error messages, and other debugging and error detecting codes. It maintains internal time clock and log of system usage for all users. It facilitates easy communication between the computer system and the computer operator (human).

STORAGE AND RETRIEVAL SOFTWARE - These utility programs facilitate transfer of data from one I/O device to another. They make possible the copying of data from one unit, for instance, magnetic tape to another unit, for instance, magnetic disk. It is also possible to copy data from one tape unit to another tape unit or from one disk unit to another disk unit. This results in a more efficient utilization of the data preparation equipment. CUSTOM MADE SOFTWARE - Custom made software is the package that is designed and programmed for a particular customer, in contrast with software packages that are available off-the-shelf for a particular industry, such as insurance or banking. Software packages, such as spreadsheets and database management systems, although canned, off-the-shelf packages themselves, are designed to create customized solutions to a user's problem as well. GENERATION OF LANGUAGES The term "Generation" of computer language is used to categories the generic enhancements in the various computer languages that have evolved over the last 50 years. Each generation indicates significant progress in making computers easier to use. In the early days of computing, it was assumed that only a few elite technical specialists would learn to use computers, but now their use by a larger proportion of population is taken for granted. Computer languages by generation are classified as follows : (a) First Generation (Late 1940s) Machine Code. (b) Second Generation (early 1950s) Assembly language (c) Third Generation (Late 1950s to 1970s) High Level Language (d) Forth Generation (Late 1970s onwards) including a whole range of structured query languages and other tools. FORTH GENERATION LANGUAGE (4GL) - Forth generation language is non procedural - that is, the programmer specifies what has to be done, but not how the task is to be performed. Some 4GLs are aimed at the end user, and ease of use is then a prime consideration. Professional computer experts design others, which could be described as very high level languages, for use, and their main objective is to cut down on

Computer Fundamental By BALJEET SINGHSINWAR/9 development and maintenance time. Some, such as ORACLE, offer a number of tools (SQL*CALC, SQL*FORMS, SQL*REPORT) suitable for an end user. Comparison of Third and Fourth Generation Languages Third Generation Language Meant for use by professional programmers Requires specification of how to perform a task. All alternatives must be specified. Requires large number of procedural instructions. Code may be difficult to read, understand, and maintain by the user. Difficult to debug. Typically file oriented.

Forth Generation Language May be used by non-programming professionals (i.e. users) as well as professional programmers. Requires specifications of what task to perform (system determines how to perform the task). Default alternatives are built-in. User need not specify these alternatives. Requires far fewer instructions (less than one tenth in most cases). Code is easy to understand and maintain. Errors are easier to locate because of shorter programs, more structured code, and use of defaults. Typically database oriented.

Q.

Explain the difference between assembly language and machine language. Ans. A computer understands information composed of only zeros and ones. A program written in terms of "0s" and "1s" is called a machine language program. Computer instructions are written binary codes. A machine language uses only binary codes. To write a program in a machine language is a very difficult, tiresome and very boring job. Moreover, it is errorprone. To overcome this difficulty a program can be written in alphanumeric symbols instead of "0s" and "1s". Meaningful symbols called mnemonics are used for this purpose. For example ADD is used for addition, SUB for subtraction, CMP for comparison etc. A language, which uses mnemonics, is called an assembly language program. When a program is written in a language other than machine language, the computer will not understand this. Therefore, a program written in other languages must be translated into machine language before it is executed. The task of translation is done by software. A program, which translates an assembly language program into a machine language program, is called an Assembler. Q. Differentiate a high-level language from an assembly language. Ans. A language in which each statement or an instruction is directly translated into a single machine code is known as a low-level language. Each mnemonic of an assembly language has a unique machine code. An assembly language is a lowlevel language. An assembly language depends on the internal architecture of a processor. Each processor has its own assembly language. Assembly language of one processor cannot be used for another processor. In other words it is not portable. To write an assembly language program, a programmer must have the detailed knowledge of the instruction set of the particular processor, it's internal architecture, registers, and connection of peripherals to ports etc. It is not very fast and easy programming language. To overcome the difficulties associated with assembly language, high level or procedure-oriented languages have been developed. In a high-level language an instruction is called statement rather than mnemonic. Statements more closely resemble English and Mathematics than mnemonics. High-level languages permit programmers to describe tasks in the forms, which are problem oriented rather than computer oriented. Programming in a high-level language does not require precise knowledge of the architecture of a processor, which is to be used. A

Computer Fundamental By BALJEET SINGHSINWAR/10 program written in a high-level language will run on any computer, which has a compiler for that language. In other words a high-level language is portable. Q. Give the difference between compilers and interpreters. Ans. An Interpreter is a program, which translates statements of a high-level language program into machine codes i.e. in the form of 1 and 0. It translates one statement of the program at a time. It reads one statement of a high-level language program translates it into machine code and executes it. Then it reads the next statement of the program, again translates and executes it. In this way it proceeds further till all the statements of the program are translated and executed. On the other hand, a compiler goes through the entire high-level language program once or twice and then translates the entire program into machine codes. A compiler is 5 to 25 times faster than an interpreter is. An interpreter is a small program as compared to a compiler. It occupies less memory space, so it can be used in a smaller system, which has limited memory space. The object program produced by the compiler is permanently saved for future reference. On the other hand, the object code of the statement produced by an interpreter is not saved. If an instruction is used the next time, it must be interpreted once again and translated into machine code. For example, during the repetitive processing of the steps in a loop, each instruction in the loop must be reinterpreted as the loop is executed. Q. Ans.

Differentiate between system software and application packages? System software is normally developed and distributed by the computer manufactures. The customer who buys or leases a computer system would usually receive, in addition to the hardware, some software needed for the effective operation of his computer. Actually a system software works as a mediator of Computer's hardware and Liveware. It accepts instructions from user and controls the hardware of the computer accordingly. Good system software allows application packages to be run on the computer with less effort. Without system software, application packages cannot be run on the computer system. Application software are those software who may be developed to perform any specific task, desired by user, such as for accounting purpose, word processing purpose etc.

Q. Write short notes on Multiprogramming and Time-sharing. Ans. Multiprogramming In multiprogramming a computer processes several programs simultaneously. Usually a CPU is much faster as compared to I/O devices. While I/O devices are performing certain tasks the CPU may not be doing any task, i.e. it may be lying idle. To keep CPU busy for most of the time, it is desirable to process a number of programs concurrently. This is achieved by overlapping CPU and I/O operations when several programs are running simultaneously. Timesharing Users enter data at very slow rate, and computer processes data at very fast rate. Making use of this fact a computer serves several users simultaneously by attending them in turn. It usually gives 20-millisecond time to each user. Each user feels that he is using the computer exclusively because the computer processes his data as fast as he enters it. Thus, a timesharing system has many terminals linked up to the same computer at the same time. In timesharing, the CPU time is divided among all the users on a scheduled basis. Each user can utilize the common resources such as high-speed printer, computer's memory etc. Q. What is ASCII code? Explain its use? Ans. ASCII is a binary code for data that is used extensively in communications, in most minicomputers and in all PCs. It stands for American Standard Code for Information Interchange. ASCII that was originally a 7-bit code allowing 128 possible character combinations, the first 32 of which is used for communications and printing control purposes. Since today's common unit of storage is an 8-bit byte and ASCII is only 7 bits, the extra bit has been as a parity bit or for a variety of different symbols. For example, the IBM PC uses the additional 128 characters, called extended ASCII for lines, borders, foreign languages and special graphics symbols. Q. Explain the term - Hardware, Software, Firmware and Liveware. Ans. Hardware : All the mechanical, electrical and electronics parts of the computer system is known as the Hardware of the computers.

Computer Fundamental By BALJEET SINGHSINWAR/11 Software : Software is the program who instructs the hardware to perform any specific tasks in a certain way. Firmware : Firmware is the programs stored in read-only memory (ROM). Unlike random access memory (RAM), read-only memory stays intact even in the absence of electrical power. Start-up routines (bootstraps programs) and low-level input/output instructions are stored in firmware. It falls between software and hardware in ease of modifications. Liveware : Liveware is the human beings employed to handle hardware and software. It is a slang for computer trained people. Q. what is Cache Memory? Ans. Cache memory, a small buffer storage, smaller and faster than main storage (often made of Static RAM), that is used to hold a copy of instructions and data in main storage that are likely to be needed next by the processor and that have been obtained automatically from main storage such as hard disk. Cache memory is used to increase the speed of processing by making current programs and data available to the CPU at a rapid rate. A cache is useful when RAM accesses are slow compared with the microprocessor speed because cache memory is always faster than main RAM memory. A disk cache is a portion of a computer's RAM set aside for temporally holding information read from disk. A disk cache does not hold entire files, as does a RAM disk. Instead, a disk cache is used to hold information that either has recently been requested from disk or has previously been written to disk. For example, a program might need to read in repeatedly from disk either a portion of itself or the same portions of a data file. If the required information remains in a disk cache, access time is considerably faster than if the program must wait for the disk-drive mechanism to fetch the information from disk. Q. What is Mnemonic? Ans. Any kind of mental trick we use to help us remember. For example, a computer may be designed to interpret the machine code of 1111 (binary) as the subtract operation, but it is easier for a human being to remember it is SUB. The SUB is known as mnemonic code for subtraction. Q. Give the reason for using binary digits to code data stored in a computer. Ans. A bit is a single digit in a binary number (1 or 0). Within the computer, a bit is physically a memory cell, a magnetic spot on disk or tape or a pulse of high or low voltage travelling through a circuit. Computers, which are in use today, are digital computers. They manipulate numbers. They operate on binary digits 0 and 1. The main reason for operating on binary digits is that it is much easier for the computer to distinguish 1 or 0 because either the voltage is present or not present. Thus a digital computer operating on the binary digit is more accurate as it can distinguish between the presence and the absence of a voltage. Q. Write short notes on TSR Programs. Ans. TSR (Terminate and Stay Resident) programs are RAM resident programs that remain in memory at all times whenever a computer is switched on so that they can be instantly activated. In IBM compatible PCs running under DOS, desktop accessory TSR programs have become popular in order to have instant access to a calculator or calendar. However, these TSR programs often conflict with each other, each one fighting for the right to exist within the computer, and various combinations of programs will not work together. Windows environments for DOS such as Windows 3.11 or Windows 98 etc. provide the ability to switch back and forth quickly between multiple applications. Q. Ans.

What is Computer? What are the advantages and disadvantages of computer? Computer is an electronic device. It accepts raw data as well as instructions from the user, process it and gives meaningful information as required by user as per given instruction. Advantages: -

Computer Fundamental By BALJEET SINGHSINWAR/12 (a) Computer works very fast. (b) Computer gives accurate result. (c) It can process millions of instructions per second. (d) Computer is very versatile. (e) Computer works at constant efficiency. (f) Perform repetitive tasks very well without error. (g) Computer can store information for future retrieval or use. (h) Computer can communicate with other computer systems. Disadvantages: (a) If wrong programmed then it produces wrong answers. (b) If it gets down then so many working hours wasted. (c) It brings unemployment because one computer can handle work of many people. (d) Stealing of information through computer is become too much easy. (e) Computer on Internet is not safe due to Virus or other attacks. Q.

Ans.

Explain the different component of a computer system? Discuss the respective roles played by the different components of CPU? What is the role of Input and Output devices in a computer system? Name few of them. Computer System consist of :a) Hardware Hardware is consist of the mechanical, electrical and electronics part of the Computer. b) Software Software is the set of detailed step by step instructions called program through which user instruct the computer to do something. c) Heartware or Liveware - Heartware is the people who schedule the operation of hardware and write or modify the software. d) Firmware Firmware are the routines or programs that are stored in read-only memory (ROM). Unlike RAM, ROM retains programs intact even in the absence of electrical power. Startup routines and low-level input/output instructions are stored in firmware. HARDWARE Hardware may be classified as :1. CPU (Central Processing Unit) 2. Peripherals 1.)

CPU - CPU may also be classified as :a) CU (Control Unit) - The CU controls and directs the operations of the entire computer system. The control unit retrieves computer instructions in proper sequence, interprets each instruction and then directs the other parts of the computer system for the execution. b) A.L.U. (Arithmetic & Logic Unit) - The ALU actually carries out Arithmetic operations like addition, subtraction etc. and Logic operations like comparison of values etc. c) Main Memory - Memory is the mind of the computer. It may be classified as:i) RAM (Random Access Memory) - It is a temporary memory used for storing data or instructions during processing. Any storage location can be directly accessed using its address. RAM loses its contents when the power is turned off and hence is also known as Volatile Memory. While the computer is on, information can be written onto the RAM chips and read from them. ii) ROM (Read Only Memory) - It is a permanent memory which contains basic information the CPU needs when you first turn on the computer as well as at other times during the operation of the computer. This information is written onto the chip during manufacture. Information can only be read, and no new information

Computer Fundamental By BALJEET SINGHSINWAR/13 can be written onto the ROM. There are also some kind of ROM:a) PROM b) EPROM c) EEPROM 2. PERIPHERALS :- It can be classified as :a) Input - Data is accepted as Input through the Input device. Keyboard is known as Standard Input Device. Input device makes availability of data to CPU to process it or store it for future retrieval. Without inputting data or instructions, a computer is not become able to perform any action or processing. So minimum one input device is must for every computer. It may be like keyboard through which any thing can be fetched or it may be like Optical devices like Scanner, OCR, OMR etc., which can directly capture data for computer. Pointing devices like mouse, joystick, tracking ball etc. can be used to fetch only instructions to the computer system. A number of storage devices are using now a days are * Keyboard * Joystick * Tracking Ball * Mouse * OCR (Optical Character Reader) * OMR (Optical Mark Reader) * OBR (Optical Barcode Reader) * MICR (Magnetic Ink Character Reader) * Punch card Reader * Mike etc. b) Output - Processed data is delivered as Output through Output device. After processing it is compulsory to get result either in form of soft copy (i.e. on screen) or in form of hard copy (i.e. through printer). These outputs may be distributed between required persons and authority for their information purpose. Later these outputs may use as input for any other processing job. A number of output devices are also available as * Printer (Dot Matrix, Ink-Jet, Laser etc.) * Plotter (Used in Engineering purpose) * Screen (VDU-Visual Display Unit, Liquid Crystal Display) etc. c) Backing Storage or Secondary Storage - These devices are used to store the data for a long time permanently. A number of Backing storage devices are also available as * Floppy 31/2" (Capacity - 1.44 MB) 5-1/4" (Capacity - 1.2 MB) * Harddisk - Capacity from 20 MB to 120 GB and above * Zip drive * CD-ROM * Magnetic Tape * Cartridge Tape etc. Q. Ans.

What are the five basic operations performed by any computer system? All computer systems perform the following five basic operations: 1. Inputting - Fetching data as well as instructions in the computer's memory so that it can be process by the CPU. It may be fetching character one by one through keyboard or it may be capturing data through any optical device like scanner, OCR etc. 2. Storing - Inputted data first stored in the computer's memory because capacity of the CPU register is not so much that it can receive and process all the data at a time. CPU receives data and instructions one by one. The intermediate results should also be remaining in the computer's memory for

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next operation. After all, if we not completed or completed the today's task then also it may require in future. So, storing of data and instruction temporarily or permanently is must. 3. Processing - It is the most vital task of computer system. It can compute the data as per given instructions in form of programs or software and then gives meaningful information. As soon as we change the instruction, the output may differ. 4. Outputting - After processing user demands for a result, which is given by computer in form of output through printer, or on screen. 5. Controlling - A computer system have so many additional devices attached with them to perform various tasks. One major task of a computer system is controlling its devices and minimizes the collision between them. How many types of memory a computer has? Justify the need for each type? or The ROM contains the essential information and the hard disk contains all relevant programs. What purpose does the RAM serve? A computer system has mainly two types of memory: 1. Main Memory/Primary memory - This type of memory have very few storage capacity and it contains generally small amount of essential data. This have also two major type, i.e. a) ROM - Read only memory contains firmware given by the manufacturer of the relevant device. This firmware is very useful whenever we start the computer or attach a new device to computer. Due to this firmware computer can easily identify the attached device. It is Non-Volatile Memory. b) RAM - Random Access Memory is a volatile memory. Initially it has no any data when computer system boots up. Sequentially it stores operating system's kernel, application system's data etc. However it is volatile in nature, but CPU can access any information from here very quick. Its speed is too much greater than hard disk. During processing, CPU also uses it as intermediate device to keep intermediate results of any process. Without RAM there is no any difference between a computer and calculator. When a user work on any file then it first saves in computer's memory and then after receiving Save command it transfer the data to hard disk. 2. Secondary Memory/Backing Storage - It is generally Non-volatile in nature, which is used to store data permanently for future uses. It has a large size, so it actually stores all the programs like Operating system, application software etc. During processing if the computer needs more RAM than available, then it works as virtual RAM, known as Virtual memory. To share information from one to another computer we also need some backing storage device. What are the main components of a PC system unit? Explain each component? A PC system unit has following components: 1. CPU Cabinet - It stands for Central Processing Unit cabinet. Actually it is a container in which different components like Processor, RAM chip, Sound card, Mother board, hard disk, floppy drive, CD-ROM etc. are fitted by computer assembler. This box is the most important because it contains most expensive and useful parts of computer. It has so many output and input ports mostly at back side of it through which we can connect several devices like - printer, keyboard, monitor etc. In front it exists power switch and reset button to start/restart computer. CD-ROM/Floppy drive can only be accessed from front side. 2. VDU - Visual Display Unit is also known as standard output device. This produces soft copy of entered data and processed results. A user can interact through VDU mostly. Major component of VDU is CRT (Cathode Rays Tube). Another type of VDU used LCD (Liquid Crystal Display) which consumes too less power and generally used with Mobile computer like Laptop, Palmtop etc. What type of keys, other than alphabetic and digits, are available

Computer Fundamental By BALJEET SINGHSINWAR/15 on a keyboard and for what purpose? How is a key pressed on the keyboard interpreted by the computer? 3. Keyboard - This is also known as standard Input device. It contains about 104105 keys in case of a standard keyboard. It has rich set of keys which can be classified into five major category: a) Alphanumeric keys - This section contains characters from a to z and 0 to 9 including standard keys available at normal typewriter keyboard. b) Numeric Key pad - This section exists at right side of keyboard, which is useful, if someone wants to feed only numerical data. This section contains numbers along with major mathematical operators. c) Function Keys - These keys are labeled from "F1" to "F12" and perform different functions in different languages and packages. Generally these keys contain shortcut commands. d) Cursor Movement Keys - Eight keys including four arrow keys and Home, End, Page Up, and Page Down, exist between alphanumeric and numeric section are known as Cursor movement keys. These keys controls the movement of cursor (A dash like sign who indicates that where we are performing writing or deleting operation). e) Special Keys - Esc, backspace, Return, Control, and Alert etc. is known as special keys. These keys are used to supply some instructions to computer system either alone or with combination of any other alphanumeric keys. The functions of these keys are vary from application to application. Any key pressed on the keyboard, actually completes some circuits exists beneath the keys. These circuits send some binary values to computer's input module. From the input module, control unit receives these binary values, check and decide whether it has to show on screen (in case of alphanumeric keys) or has to perform some operation (in case of function or special keys). After decision it prints the character or saves it or process in any other manner. Printer - This peripheral device is used to take hard copy of the report. If we want to keep copy for future use then we must take print out through printer. There are mainly three types of printer: a) Dot Matrix Printer - An Impact printer who uses 9 or 24 pin to hammer on a ribbon so that the character or picture appears at another side of ribbon on paper. b) Inkjet Printer - This printer uses one or two ink cartridge, first one contains black ink and another contains three colours (Red, Green, and Blue). Combination of these colours produces millions of colours. This is a NonImpact printer, which generally prints one line at a time. c) Laser Printer - This Non-Impact printer uses Toner to print on paper. It uses Laser light to print. Printing quality of laser printer is Superior than other printers. Its main uses are at Printing press and offices where required fine and heavy printing. 5. UPS/CVT - Uninterrupted Power Supply/ Constant Voltage Transformer is used to supply required level of electric supply to all computer components. The computer components are very sensitive in term of electric supply, so it needs constant voltage. Some operating system or application software also need to close it in proper way (Shut Down), so, we must keep UPS in case of such an OS or Application Software. Write short notes on ASCII? ASCII is a binary code for data that is used extensively in communications, in most minicomputers and in all PCs. It stands for American Standard Code for Information Interchange. ASCII that was originally a 7-bit code allowing 128 possible character combinations, the first 32 of which is used for communications and printing control purposes. Since today's common unit of storage is an 8-bit byte and ASCII is only 7 bits, the extra bit has been as a parity bit or for a variety of different symbols. For example, the IBM PC uses the additional 128 characters, called extended ASCII for 4.

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lines, borders, foreign languages and special graphics symbols. Errors occur in computer due to human rather than technological weaknesses. Discuss. or Explain "Garbage in Garbage Out". A machine can work only as per their mechanism created by human being. Computer has inherited the same thing. We know that computer is consist of so many hardware parts who works as per given instruction through program developed by a programmer. But it is possible that there may be lack of any option in a circuit to process any specific type of signal. If a programmer wants to process such signals it may produce error, but it is not of computer's, it is human being weakness. It is also possible that a programmer have limited knowledge about the developing program. For example a computer programmer have if no more knowledge of Civil or other engineering requirements then he can't develop any CAD/CAM software for that engineers. If he develop something then it is possible that it have not more options or those engineers may reject it. But in this case, again computer is not responsible for that error. Here programmer is responsible. At last we can say that computer have no any their own capacity of thinking. It thinks only its programmer thinks. So, it can't work beyond its programmer mind and may be unusable for some users. What is the difference between a graphical printer and a plotter? Compare in terms of speed, accuracy or quality of output. A graphical printer is a printer, which is used to print any type of graphics or photographs through it. It may be any Dot Matrix, Inkjet or Laser printer. It may be color or mono. Generally this type of printer prints forward direction only, i.e. the paper skips forward continuously and the printer's head moves left and right to print the required text or graphics. So, it is compulsory for CPU to feed the instructions in the manner that printer need not roll back the paper. To do so, it is important that the printing matter should be converted into any image finally at computer system and then the printing should starts. But in case of plotter, it may be one or more pens who are free to move left to right as well as top to bottom and vice versa. So, the CPU need not create the image in advance before printing. In the case of Plotter the CPU may fetch bottom side's instruction first and then instructions for topside. It is useful in designing dress materials, map for buildings etc.

Computer Fundamental By BALJEET SINGHSINWAR/17 NETWORKING CONCEPTS Networking is a form of computer communications generally used for the transfer of data and information within an organization. Networking in this context refers to the confines of an office, a group of offices, a building or a closely spaced group of two or more PCs connected together by some type communication media (wire or cable) to form a data path between the computers. Once the PCs are physically connected, software designed specifically for network. This software also allows any user to access shared data storage and output devices connected to the network. Examples of shared devices are printers, plotters, imaging devices, hard disks and tape drives. a. b. c. d. e. f. g.

Need and Advantages of Networking To share Computer Files To share Computer Equipment To enable unlike computer Equipment to communicate To Improve Communication speed and accuracy Low Cost of Transfer of Data Instantaneous Availability of Information Multimedia Transfer

LAN (Local Area Network) Local Area networking is a form of computer communications generally used for the internal transfer of data and information within an organization. "Internal" in this context refers to the confines of an office, a group of offices, a building or a closely spaced group of two or more PCs connected together by some type of communications media to form a data path between the computers. Advantages

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Disadvantages Economic Shared peripherals such as printers • Less computer memory available Technological flexibility • High Cost Incremental growth • Greater complexity • Less user control • Prone to Security loss Organizational Improved communications Improved standardization Better control Controlled Security Data sharing WAN (Wide Area Network)

Wide Area Network is a network that spans large geographical distances. WANs usually operate at lower speed than LANs. Wide area network (WAN) is a network that spans large geographical distances. WANs usually operate at lower speed than LANs. WANs are typically created using specially conditioned telephone lines, microwaves, or satellite data transmission. NETWORK TOPOLOGY Topology is the way networks are physically connected together. Topology determines the complexity and therefore the cost of network cables installation. Topology also determines the strategy for physically expanding the network. There is several type of topology but mainly three type are :1. STAR TOPOLOGY - Each node is connected to a single, centrally located file server, using its own dedicated segment of cable. This topology has the advantage of minimum data traffic along the cables (node to server only), thus providing optimum performance. But because a single machine must co-ordinate

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all the data communications, this requires an extremely powerful and expensive file server. RING OR CIRCULAR TOPOLOGY - In this layout, each node is physically connected to only two others. Each node passes information along to the next, until it arrives at its intended destination. Performance is faster on this system because each portion of the cabling system is handling only the data flow between two machines. LINEAR BUS TOPOLOGY - In this layout, a single main cable connects each node, in what amounts to a single line of computers accessing it from end to end. Each node is connected to two others except the machines at either end of the cable, which are connected only to one other node. The network operating system keeps track of a unique electronic address for each node and manages the flow of data based on this addressing scheme. TREE TOPOLOGY - This is a network topology containing zero or more nodes that are linked together in a hierarchical fashion. The topmost node is called the root. The root may have zero or more child nodes, connected by edges (links); the root is the parent node to its children. Each node can in turn have zero or more children of its own. Nodes sharing the same parents are called siblings. Every node is a tree has exactly one parent node (except for the root, which has none) and all nodes in the tree are descendants of the node. These relationships ensure that there is always one and only one path from one node to any other node in the tree. GRAPH TOPOLOGY - In this method of connection, zero or more nodes are linked together in an arbitrary fashion. Any two nodes in a graph may (or may not) be connected by a link. Not all the nodes in a graph need to be connected, but if a path can be traced between any two nodes, the graph is a connected one. COMPUTER VIRUS

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What is Computer Virus? A Computer virus is a small block of coded instruction that obtains control of a PC's CPU and directs it to perform unusual and often destructive actions. Virus knows how to copy itself and attaches itself to other programs, which further spread the infection. Anti-Virus is the method to get rid of perverse software or the viruses. There are following types of viruses :-

(a)

TROJANS HORSE - A Trojans Horse is a program that invades a computer system by secretly attaching itself to a valid program downloaded into the computer. It may be used to locate password information or it may alter an existing program to make it easier to gain access to it.

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Time and Logic Bombs - A time and logic bomb is a program that destroys data; for example it may reformat the Harddisk or randomly insert garbage into data files. A time bomb formats the Harddisk on a given date or slows down computer every Friday.

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Melissa and SKA virus - Melissa virus attacks MS-WORD or MS-EXCEL files and spread very fast. This virus changes the Normal.Doc, disabling the macro protection message and inflects all the Word files opened or created subsequently. Sometimes Melissa virus spread around the world rapidly infecting many computers and bringing down networks. SKA increases the size of the file and change the extension of the files to .SKA. These virus delete the Microsoft Document files or change their contents.

Virus Scanner and Remover - Virus scanners are products designed to help identify viruses within files, boot sectors, master boot sector, memory and other hiding

Computer Fundamental By BALJEET SINGHSINWAR/19 places, name them and eventually remove them. The capability to detect and identify a virus is probably the most important feature of a scanner. In most cases scanner comes with remover. Remover detects the quality of virus and removes it. Vaccine Program is a program that watches for typical things that viruses do, halts them and warns the computer operator about the computer security being threatened. INTERNET INTRODUCTION The Internet is a loose connection of thousands and thousands of computer networks scattered all over the globe. The only thing all the networks have in common is the use of the same transmission language, known as TCP/IP. However, you need not know anything about TCP/IP to use the Internet. The Internet started as a US government project in the 1960s called the ARPANET (Advanced Research Projects Agency Network) which was initially Network of Security Department of US. At its initial period scientists and engineers used it only. After more government and educational institutions got involved, it grew into an internetwork. Since 1993, the internet has been a hot topic - with more and more people getting to use it at a current rate of about a million new connections a month all over the month. WORLD WIDE WEB The World Wide Web is one of the most popular parts of the Internet. The Web is made up of hypertext documents stored on servers around the world. Hypertext documents contain links you can click on to move to another section of the page, to different documents, or to another type of Internet resource, such as electronic mail (email) or newsgroups. Web pages include text, graphics, animation, sound and sometimes movies also. The rich content, along with the ability to jump from one page to other page using links, has contributed to the explosive growth of the Web. BROWSER These are a software who organizes the information of the Internet and then systematically produce it to you. Netscape Navigator was the first popular browser but now-a-days Internet Explorer has been using widely. INTERNET SERVICE PROVIDER (ISP) ISPs means a company who provides Internet Services. This type of company takes some charges from user and then provides services for some time. ISP gives a username and password to users with some local telephone numbers. First of all user dials to ISP with any one of these local telephone numbers and then after asking username and password, company connects the user with Internet. UNIVERSAL (UNIFORM) RESOURCE LOCATER (URL) Many companies keep their data and information on World Wide Web. So, address of these companies should be unique. URL is the unique name of that company. It has two parts - First one indicates about the protocol and second one denotes IP address of that company. For example in http://www.microsoft.com, http (HyperText Transfer Protocol) is the protocol and microsoft.com is the IP address. HOMEPAGE Homepage is the main page of any Web Site. Generally a Homepage have all possible links of that Web Site. It may be understood as Contents of that Web Site. SURFING Surfing means without any planning wandering on different Web-sites to either search any type of information or answer of any question.

Computer Fundamental By BALJEET SINGHSINWAR/20 SEARCH ENGINE This is an utility provided by different portal to search any information on World Wide Web. After giving some word in search dialog box and requesting for search, the search engine searches and returns a list and links of similar Web Sites containing given words. After it user can search his information on that sites. INSTANT MESSANGER Through the Internet and suitable software if someone talks with any other person, then this talking is known as CHATTING. Generally chatting has been done through Host site, where user select desired room and then desired person for chatting. But in this system there is a problem that a user has to choose any person from a long list of known or unknown persons. But through the Instant Messenger a user creates list of those persons from whom he wants to chat. After it when any person among that list become online, indicator shows that person's name through blinking or through any sound etc. Through this Instant Messenger a user can talk to their limited persons. DOWNLOAD & UPLOAD To copy any information from World Wide Web or any other computer located far away, is known as Downloading. For this purpose either File Transfer Protocol (FTP) or Hypertext Transfer Protocol (http). Uploading is just reverse of Downloading. In Uploading a file may be copy to Server from the current computer. E-MAIL Full form of e-mail is Electronic Mail. In this system a user has a unique name. This name can be hire from any ISP or some Portal provides free facility to create an email address through that portal. After gaining an e-mail address user can send any letter in electronic form to someone other or can receive any mail, which was sent by any other person to him. ATTACHMENT Additional data, which will be send through e-mail, is known as Attachment. This attachment may be any text, audio, video or photo file. DOMAIN NAMES Most organizations use domain names that are easy to remember. Each domain name ends with an identifier that tells what type of web site it is. Following is the commonly used identifiers : Current Domain Identifiers .com Commercial business .edu Educational institutions .gov Government entities .net Internet Service Providers .mil Military Sites .org Organizations that do not fit any other category Proposed Domain Identifiers .arts Cultural and entertainment-related organizations .firm Business .info Information services .nom Web sites of individuals .rec Recreation-related organizations .store Stores and shops .web World Wide Web-related organizations. INTERNET EXPLORER Internet Explorer is a browser developed by Microsoft Corporation and a freeware. When we open it then following items come on the screen :-

Computer Fundamental By BALJEET SINGHSINWAR/21 Title Bar - On the left the title bar displays the name of the web page currently open and on the right side the maximize/minimize, restore and close button. Menu Bar - It is located just below the title bar, same as other application. Toolbars - It is located just below the Menu bar and generally it has following buttons :BackDisplays a page in the list of previously viewed pages. Forward Displays a page in the list next to viewed pages. Stop Stops downloading the current page. Refresh Downloads the current page again, ensuring that the latest version of the web page is displayed. Home Displays the home page. Search (Toggle) Displays (or hides) the Search Explorer Bar in left pane, which provides access to Internet Search Engines.(Default through MSN search). Favorites Displays (or hides) the Favorites Explorer Bar in left pane Which provides access to our favorite sites. Using Favorites commands, we can create a list of favorite pages and organize them into folders. Then to go to a favorite page we simply select the page we want from the Favorites menu. To add the Web pages to our Favorites list either we have to choose Add to Favorites from Favorite menu or click Add to Favorites on the Favorites Explorer Bar at left pane. In the coming dialog box, Type the name of the page against the Name and then select the location of the favorite page through Create In box. We can also use drag or drop feature to add any pages to Favorites. If we choose Organize Favorites option from Favorites menu then we can easily view, organize and return to favorite page as much as similar to Windows Explorer. History (Toggle) Displays (or hides) the History Explorer Bar at left pane that provides access to sites we have visited recently. Full Screen (Tgl)Switches to (or from) full screen view, which provides maximum viewing space for Internet Explorer's document area. Mail Launches your mail or newsreader program (by default - Outlook Express) and lets you send links and pages to others via e-mail. Print Prints the current page, if the printer is online.