Computer Fundamental By BALJEET SINGHSINWAR/1 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 is ve very fa fast. (b) Computer is is ac accurate. (c) (c) They They can can pro proce cess ss mill millio ions ns of inst instru ruct ctio ions ns per per sec secon ond. d. (d) Computer is very versatile. (e) (e) Comp Comput uter er work works s at cons consta tant nt effi effici cien ency cy.. (f) (f) Perf Perfor orm m rep repet etit itiv ive e tas tasks ks very very well ell wit witho hout ut erro error. r. (g) (g) Comp Comput uter er can can sto store re info inform rmat ation ion for for futu future re ret retri riev eval al or or use. use. (h) (h) Comp Comput uter er can can comm commun unic icat ate e wit with h oth other er comp comput uter er sys syste tems ms..
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 Develo Developed ped by Gottf Gottfrie ried d Von Leibni Leibnitz, tz, a Germa German n Mathe Mathema matic tician ian who was was an improvement over Pascal's adding machine. All the above were based on mechanical precision and since mechanical precision was was not that accura accurate te during during those those days days the reliabili reliability ty of the machine machines s was was rather 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 Differ Differenc ence e Engine Engine the level level differ differenc ence e betwee between n the values values comput computed ed for a formu formula, la, remains the same. For example, Compute the Squares of first 6 natural numbers
Computer Fundamental By BALJEET SINGHSINWAR/2 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 3 6 - 2 5 = 11
2nd Difference 357911 -
1=2 3=2 5=2 7=2 9=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. Simila Similarly rly,, Lady Lady Ada Lovela Lovelace ce is famous famous as the First First Progra Programm mmer, er, for having having devised a suitable use of Binary Number system for programs and data to be fed into the Analytical Computer. GEORGE GEORGE BOOLE BOOLE developed developed the applicatio application n of logic in computers 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 statistician at the US US Census Bureau developed card punching and reading machines. He formed his own company later, "The Computing Tabul Tabulati ating ng Record Recording ing Compan Company" y" which which is better better known today today as one of the larges largestt manuf manufac actur turers ers of comput computers ers - IBM or Intern Internati ationa onall Busine Business ss Machi Machine ne Corpor Corporati ation on 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 Howard Aiken with IBM's IBM's support support built the first automatic automatic Electro-m Electro-mechan echanical ical 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 occupying several several rooms, was thoroughly thoroughly searched for the fault. After spen spendi ding ng cons consid ider erab able le time time and and effo effort rt it was was foun found d that that on one one of the the elec electr tric ical al 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 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. use. After After this this the progre progress ss in the Digita Digitall Comput Computers ers has been been simply simply stupen stupendou dous s (amazing). JOHN VAN NEUMANN Outlin Outlined ed the basic basic requir requireme ements nts for the design design of moder modern n digita digitall comput computers ers.. 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 (1975-up -up till till now) now) Use Use of VLS VLSIC IC (Ver (Very y Large Large Scale Scale Inte Integra grated ted Circui Circuit) t) and 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. Fift Fifth h Gene Genera rati tion on -: -:
(Dev (Devel elop opme ment nt con conti tinu nued ed... ...)) Will be use ULSIC (Ultra Large Scale Integrated Circuit) Use Artificial Intelligence Super Computer. Thi This s type type of comp comput uter er will will unde unders rsta tand nd natu natura rall lang langua uage ges s like 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 SINGHSINWAR/4 Classification of Computer Computer can be classified into four part :1. MicroComputer -: There are two types of Microcomputer (a) Hom Home Com Compute puterr : Use Use TV for for Outp utput Use Cassette/floppy as backing storage Low Cost (A few thousand of rupees) Use for Home education, Home games etc. (b) (b) Busi Busine ness ss Com Compute puterr :Use :Use a Sepa Separa rate te VDU VDU for for out outpu putt 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 Co Computer -: -:
Multi lti Us User, Multi Ta Tasking, Fa Faster th than Mic MicrroComputer, 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 Hardware is the consist of the mechanical, mechanical, electrical electrical and electronics part of the Computer. b) Software Softw Software are is the set of detail detailed ed step step by step step ins instru tructi ctions ons called program through which user instruct the computer to do something. c) Hear Heartw twar are e or Live Livewa ware re - Hear Heartw twar are e is the the peop people le who who sche schedu dule le the the operation of hardware hardware and write or modify modify the software. 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 abse absenc nce e of elec electr tric ical al powe power. r. Star Startu tup p rout routin ines es and and lowlow-le leve vell inpu input/ t/ou outp tput ut instructions are stored in firmware.
Computer Fundamental By BALJEET SINGHSINWAR/5 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 computer system system.. The contro controll unit retrieves retrieves comp computer uter instruct instructions ions in proper proper sequence, sequence, interprets interprets each instructio instruction n and then directs 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 tempor temporary ary memory memory used used for for storing storing data or instructio instructions ns during during processin processing. g. A Any ny storage storage location location can be directly directly accessed accessed using using its address. address. RAM RAM loses loses its contents contents when when the power power is turned off and hence is also known as Volatile Memory. 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 memory which contains basic information the CPU needs when you first turn on the computer as well as at other times times during the operation operation of the computer. computer. This informat information ion is written written onto the the chip chip durin during g manu manufa fact ctur ure. e. Info Inform rmat atio ion n can only only be read, 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. Backing Storage or Secondary Storage - These devices are used to store c) 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 isk Capacity ity from 20 MB to 40 GB and above * Zip drive * CD-ROM * Magnetic Tape * Cartridge Tape etc.
Computer Fundamental By BALJEET SINGHSINWAR/6 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 "Binar "Binary y Digits Digits". ". Progra Programs ms and ins instru tructi ctions ons is handle handle by comput computer er as string string of bits. 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, 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 form on a shee sheett of pape paperr such such as the the marks arks shee sheett of students of a class. We do so, because it is very convenient to read read the the marks arks writ writte ten n in tabu tabula larr form form.. In case 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 with othe otherr data data as per per the the inst instru ruct ctio ions ns.. In a manu manual al 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 marks.. In an electr electroni onic c data data proces processin sing g system system these 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. cycle. In the marks processi processing ng case, case, the marks of each each stude student nt in each each subjec subjectt are are transf transferr erred ed to printe printed d report report cards. Remarks like pass/fail are also recorded on this report along with the merit and the grades. A class teacher does this this job job in a manu manual al data data proc proces essi sing ng syst system em and and by a computer printer in an electronic data processing system.
Computer Fundamental By BALJEET SINGHSINWAR/7 SINGHSINWAR/7 TYPES OF SOFTWARE 1.
2.
SYSTEM SO 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 of ot other so software (b) Com Communic unicat atin ing g with ith per periphe iphera rall devi devic ces such uch as prin printe ters rs,, card readers, disk and tape devices etc. (c) (c) Deve Develo lopm pmen entt of othe otherr type types s of soft softwa ware re.. (d) (d) Moni Monito tori ring ng the the use use of vari variou ous s hard hardwa ware re res resou ourc rces es suc such h as memory, peripherals, CPU etc. System software thus makes the operation of the computer system more effective and efficient. APPLICATION SO S OFTWARE - 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. Tra Tradi diti tion onal ally ly,, appl applic icat atio ion n pack packag ages es are are limi limite ted d to the the general-pu general-purpose rpose functions functions of production production schedule, schedule, general general ledger and general accounting packages. Since there is a great demand of gene genera rall-pu purpo rpose se soft softwa ware re,, ther theref efor ore e ther there e is ever ever incr increa easi sing ng development of software. Special purpose packages have also been develo developed ped for for such such areas areas as bankin banking, g, hospit hospital al adminis administra tratio tion, n, insurance, desktop publishing, manufacturing etc.
DIFFERENCE BETWEEN SYSTEM AND APPLICATION SOFTWARE : System System softwa software re offers offers sever several al advant advantage ages s and conven convenien iences ces to applic applicati ation on 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 soft softwa ware re is a comp comple lex x task task that that requ requir ires es exte extens nsiv ive e know knowle ledg dge e and and cons consid ider erab able le specialized training in computer science. Syst System ems s prog progra ramm mmer ers, s, who who prep prepar are e syst system ems s soft softwa ware re,, are are high highly ly trai traine ned d comput computer er specia specialis lists ts and impor importan tantt membe members rs of the comput computer er archit architect ecture ure team. 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 who buys buys or leas leases es a comp comput uter er syst system em woul would d usua usually lly rece receiv ive, e, in addi additi tion on to the the hardware, some software needed for the effective operation of his computer. A computer withou withoutt some some kind kind of system systems s softw software are would would be very very ineffe ineffecti ctive ve and most most likely likely impossible to operate. OPERATING OPERATING SYSTEM SYSTEM SOFTWARE SOFTWARE - Operating System is a set of programs that is extrem extremely ely import important ant to activa activate te and Co-Ord Co-Ordina inate te the activi activitie ties s of variou various s hardwa hardware re 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 assig assigns ns a process processors ors to diff differe erent nt tasks tasks being being perfo performe rmed d by the comput computer er system. (b) (b) It allo llocate cates s the main memo emory and other her stora torag ge area reas to the the syst system em programs as well as user programs and data.
Computer Fundamental By BALJEET SINGHSINWAR/8 SINGHSINWAR/8 (c) (c)
(d) (d)
(e) (e) (f) (f) (g) (h) (i)
(j) (j) (k) (l) (l)
It carri carries es out the input/ input/ou outp tput ut manag managem emen entt and and coor coordi dina nate tes s and and assi assign gns s different input and output devices while one or more programs are being executed. It mana manage ges s file files s on vario various us stora storage ge devic devices es and the trans transfe ferr of these these files files from from one one stor storag age e devi device ce to anot anothe her. r. It also also allo allows ws all all file files s to be easi easily ly change changed d and modifie modified d throug through h the use of text text editor editors s or some some other other file file manipulation software packages. It esta establ blis ishe hes s and and enfo enforc rces es the the job job prio priori rity ty.. That That is, it dete determ rmin ines es and and maintains the order in which jobs are to be executed in the computer computer system. It autom utoma atica ticall lly y tran ransits sits fro from job job to job job as dire direct cted ed by spec pecial ial cont contro roll statements. It is is able able to inte interpr rpret et com comma mands nds and ins instru tructi ctions ons.. It co-ord co-ordinat inates es and and assigns assigns compi compilers, lers, assembler assemblers, s, utility utility progra programs, ms, and and other other software packages to various users working on the computer system. It estab establis lishes hes data data secu securit rity y and inte integri grity. ty. That That is, is, it keep keeps s differ different ent prog program rams s and and data data in such such a mann manner er that that they they do not not inte interf rfer ere e with with each each othe other. r. Moreover, it also protects data from being destroyed by and other user. It also also pro produ duce ces s trac traces es,, error error mess messag ages es,, and othe otherr debug debuggi ging ng and and error error detecting codes. It maint maintain ains s interna internall time time clock clock and and log of syst system em usage usage for for all all users. users. It faci facili lita tate tes s easy easy com communi munica cati tion on betw betwee een n the the com compute puterr syst system em and and the the computer operator (human).
STORAGE STORAGE AND RETRIEVAL RETRIEVAL SOFTWARE 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 anothe anotherr dis disk k unit. unit. This This result results s in a more more effici efficient ent utiliz utilizati ation on of the data data prepar preparati ation on 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-s off-the-shelf helf packages themselves, themselves, are designed designed to create create customiz customized ed solutions 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 very high high leve levell lang langua uage ges, s, for for use, use, and and thei theirr main ain obje object ctiv ive e is to cut cut down down on
Computer Fundamental By BALJEET SINGHSINWAR/9 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
Forth Generation Language May be used by non-programming ing professionals (i.e. .e. users) as well as professional programmers. Requires specification of how to perform a Requ Requir ires es spec specif ific icat atio ions ns of what what task task to task. perform (system determines how to perform the task). All alternatives must be specified. Default alternatives are built-in. User need not specify these alternatives. Requ Requir ires es larg large e num number ber of pro procedu cedura rall Requires far fewer instructions (less than one instructions. tenth in most cases). Code Code may may be diffic difficult ult to read, read, unders understan tand, d, Code is easy to understand and maintain. and maintain by the user. Difficult to debug. Errors are easier to locate because of shorter programs, more structured code, and use of defaults. Typically file oriented. Typically database oriented. Q.
Expla plain the dif differen erenc ce betw betwee een n assembly bly langua guage and machine language. Ans. A comput computer er understa understands nds inform informatio ation n compose composed d of only zeros and ones. A program 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 written in alphanume alphanumeric ric symbols symbols instead of "0s" and "1s". "1s". Meaningfu Meaningfull symbols 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 comput computer er will will not unders understan tand d this. this. Theref Therefore ore,, a progra program m writte written n in other other languages must be translated into machine language before it is executed. The task of translation is done by software. A prog progra ram, m, whic which h tran transl slat ates es an asse assemb mbly ly lang langua uage ge prog progra ram m into into a machine language program, is called an Assembler. Q. Differe Differenti ntiate ate a highhigh-leve levell lang languag uage e from from an assem assembly bly langua language. ge. Ans.. A languag Ans language e in which which each stat stateme ement nt or an instru instructi ction on is direct directly ly transl translate ated d 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 processo processorr cannot cannot be used used for another another proces processor sor.. In other other words 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 precis precise e knowle knowledge dge of the architec architectur ture e of a proces processor sor,, which which is to be used. used. A
Computer Fundamental By BALJEET SINGHSINWAR/10 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 Give the the diff differe erenc nce e betwe between en comp compil ilers ers and and inter interpre prete ters. rs. Ans. An Int Interpreter is a pr program, whi which tra translates sta statements of a hi high-level language program into machine codes i.e. in the form of 1 and 0. It translates one stat statem emen entt of the the prog progra ram m at a time time.. It read reads s one one stat statem emen entt of a high high-le -leve vell 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 inst instru ruct ctio ion n is used used the the next next time time,, it must must be inte interp rpre rete ted d once once agai again n and 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. Differ Differen entiat tiate e betwe between en syst system em softwa software re and and applic applicati ation on pack package ages? s? Ans. System System softwar software e is norma normally lly develo developed ped and and distrib distribute uted d by the the compu computer ter manuf manufactu actures. res. The 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 system software software works as a mediator mediator of Compute Computer's r's hardware hardware and Liveware Liveware.. It accepts accepts instructions from user and controls the hardware of the computer accordingly. accordingly. Good system software allows application packages to be run on the computer with less effort. effort. Without Without system system software software,, applicat application ion package packages s cannot cannot be run on the computer 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. Writ Write e short short notes notes on on Multi Multipro progr gram ammi ming ng and and Time-s Time-sha hari ring. ng. Ans. Multiprogramming In multiprog multiprogramm ramming ing a computer computer processes processes several several programs programs simultane simultaneously ously.. 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 programs concurrently concurrently.. This is achieved by overlapping overlapping CPU and I/O operations operations when several programs are running simultaneously. Timesharing Users enter data at very slow rate, and computer processes data at very fast rate. Maki Making ng use use of this this fact fact a comp comput uter er serv serves es seve severa rall user users s simu simult ltan aneo eous usly ly 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 among all the users on a schedu scheduled led basis. basis. Each Each user user can utilize utilize the common common resources such as high-speed printer, computer's memory etc. Q. What What is ASCI ASCIII cod code? e? Ex Expl plai ain n its its use? use? Ans. ASCII is a binary binary code for data that that is used extensively extensively in communic communication ations, s, 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. Explai Explain n the the term term - Hardw Hardware are,, Soft Softwar ware, e, Firmwa Firmware re and and Livewar Liveware. e. 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 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 elec electr tric ical al powe power. r. Star Startt-up up rout routin ines es (boo (boots tstra traps ps prog progra rams ms)) and and lowlow-le leve vell input/ input/out output put ins instru tructi ctions ons are stored stored in firmw firmware are.. It falls falls betwee between n softwa software re and hardware in ease of modifications. Liveware : Livew Liveware are is the human human beings beings employ employed ed to handle handle hardwa hardware re and software. It is a slang for computer trained people. Q. what is is Ca Cache Me Memory? Ans. An s. Cach Cache e memo memory ry,, a smal smalll buff buffer er stor storag age, e, smalle smallerr and and fast faster er than main main stor storag age e (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 time is cons consid ider erab ably ly fast faster er than than if the the prog progra ram m must must wait wait for for the the disk disk-d -driv rive e mechanism to fetch the information from disk. Q. What is is Mn Mnemonic? Ans.. Any kind Ans kind of ment mental al trick trick we use use to help help us remem remember ber.. For exam example ple,, a compute computerr 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 Give the reason reason for using using binar binary y digits digits to code code data data stored stored in in a comp compute uter. r. Ans. An s. A bit is a single single digit digit in a binary binary numbe numberr (1 or 0). With Within in the the compu compute ter, r, 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. Writ Write e sho short rt note notes s on on TSR TSR Prog Progra rams ms.. Ans. An s. TSR TSR (Ter (Termi mina nate te and Stay Stay Reside Resident nt)) prog progra rams ms are RAM resi reside dent nt progra programs ms that 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 each one one figh fighti ting ng for for the the righ rightt to exis existt withi ithin n the the com compute puter, r, and and vari variou ous s combinati combinations ons of programs will not work together. together. Windows Windows environments environments for DOS such as Windows 3.11 or Windows 98 etc. provide the ability to switch back and forth quickly between multiple applications.
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What What is is Com Compu puter ter? ? Wha Whatt are are the the adva advant ntage ages s and and disa disadva dvant ntage ages s of computer? Com Comput puter is an ele elect ctro roni nic c dev devic ice. e. It accep ccepts ts raw raw dat data a as as we well as ins instruct ructio ions ns from the user, process it and gives meaningful information as required by user as per given instruction. Advantages: Advantages: -
Computer Fundamental By BALJEET SINGHSINWAR/12 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: 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.
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Explain Expla in the the dif differ feren entt comp compon onen entt of a comp compute uter r syste system? m? Disc Discus uss s the 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. Comp Comput uter er Syst System em con consi sist st of 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 i nstruct the computer to do something. c) Heartwa Heartware re or Livewa Liveware re - 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 the abse absenc nce e of elec electr tric ical al powe power. r. Star Startu tup p rout routin ines es and and lowlow-le leve vell 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 proper sequence, sequence, interprets interprets each instruction instruction and then directs the other other parts of the computer system for the execution. A.L.U. (Arith (Arithmeti metic c & Logic Logic Unit) Unit) - The b) A.L.U. The ALU ALU actu actual ally ly carr carries ies out out Arithmetic Arithmetic operations operations like addition, addition, subtracti subtraction on etc. and Logic operations operations like comparison of values etc. Main Memory Memory - Memo c) Main Memory ry is the the mind mind of the the com compute puter. r. It may 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 Volati Volatile le Memory Memory.. While While the comput computer er is on, inform informat ation ion 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 comput computer er as well well as at other other times times during during the operatio operation n of the comp comput uter er.. This This info inform rmat atio ion n is writ writte ten n onto onto the the chip chip duri during ng manufacture. Information can only be read, and no new information
Computer Fundamental By BALJEET SINGHSINWAR/13 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 instru ins tructi ctions ons,, a comput computer er is not not becom become e able able to perfor perform m any action 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 Processed data is delivered delivered as Output Output through through Output Output device. 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, ix, Ink-Jet, Laser etc.) * Plotter (U (Used in Engineering pu purpose) * Scre Screen en (VDU (VDU-V -Vis isua uall Dis Displ play ay Unit Unit,, Liq Liqui uid d Cry Cryst stal al Disp Displa lay) y) etc. 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 fr from 20 20 MB MB to to 12 120 GB GB an and ab above * Zip drive * CD-ROM * Magnetic Tape * Cartridge Tape etc. Q. Ans.
What What are are the the fiv five e basi basic c opera operatio tions ns per perfor forme med d by any any com comput puter er sys system tem? ? All comput computer er systems systems perfor perform m the follow following ing five basic operation operations: s: 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 - Inpu Inputt tted ed data data firs firstt stor stored ed in the the comp comput uter er's 's memo memory ry beca becaus use e capacity of the CPU register is not so much that it can receive and process all the the data data at a time time.. CPU CPU rece receiv ives es data data and and inst instru ruct ctio ions ns one one by one. one. The The intermediate results should also be remaining in the computer's memory for
Computer Fundamental By BALJEET SINGHSINWAR/14 SINGHSINWAR/14
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next operation. After all, if we not completed or completed the today's task then then also also it may may requ requir ire e in futu future re.. So, So, stor storin ing g of data data and and inst instru ruct ctio ion n 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 How man many type types s of memor memory y a comp comput uter er has? has? Just Justiify the the need need for eac each type? or The ROM contains the essential information and the hard disk contains all relevant programs. What purpose does the RAM serve? A compute computerr system system has mainly mainly two two types types of of memor memory: y: 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 comp comput uter er or atta attach ch a new new devi device ce to comp comput uter er.. Due Due to this this firm firmwa ware re 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 system's 's kernel kernel,, applic applicati ation on system system's 's data data etc. etc. Howeve Howeverr it is volati volatile le 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. Secondary Memory/Backing Storage - It is generally Non-volatile in nature, 2. 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 syste system m unit unit has has follo followin wing g compon component ents: s: 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, Mothe Motherr board, board, hard hard dis disk, k, floppy floppy drive, drive, CD-ROM CD-ROM etc. are fitted fitted by comput computer er 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, keyboa keyboard, rd, monit monitor or etc. etc. In front front it exists exists power power switc switch h and reset reset button button to start/restart computer. CD-ROM/Floppy drive can only be accessed from front side. 2. VDU - Visu Visual al Disp Displa lay y Unit Unit is also also know known n as stan standa dard rd outp output ut devi device ce.. This 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 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 different functions functions in different different languages languages and packages. packages. Generally 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 sectio section n are known known as Cursor Cursor movem movement ent keys. keys. These These keys keys contro controls ls 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 pressed on the keyboard, keyboard, actually completes completes some circuits exis exists ts bene beneat ath h the the keys keys.. Thes These e circ circui uits ts send send some some bina binary ry valu values es to comput computer' er's s input input modul module. e. From From the input input modul module, e, contro controll unit unit receiv receives es 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 Blue). black black ink and anothe anotherr conta contains ins three three colour colours s (Red, Green, reen, 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 electric supply to all computer computer componen components. ts. 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 is a binary binary code for for data that that is used used extensivel extensively y in communi communicatio cations, ns, in most 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 ors occur in computer due to human rather than tec technolo ological weaknesses. Discuss. or Explain "Garbage in Garbage Out". A ma machine ca can wo work on only as as pe per th their mechanism ism cr created by by hu human be being. Computer has inherited the same thing. We know that computer is consist of so many many hard hardwa ware re part parts s who who work works s as per per give given n inst instru ruct ctio ion n thro throug ugh h prog progra ram m 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 develo developin ping g progra program. m. For examp example le a comput computer er progra programm mmer er have have if no more 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 last we can can say say that that comp comput uter er have have no any any thei theirr own own capa capaci city ty of thin thinki king ng.. It thin thinks ks only only its its prog progra ramm mmer er thin thinks ks.. So, So, it can' can'tt work work beyo beyond nd its its programmer mind and may be unusable for some users. What is the dif differenc ence betwee tween n a graph raphiical printer and a plotter ter? Compare in terms of speed, accuracy or quality of output. A g gra raph phic ical al prin printe terr is is a prin rinter, ter, which hich is used used to prin rint any any type type of gra graph phic ics s or or photographs through it. It may be any Dot Matrix, Inkjet or Laser printer. It may be color color or mono. Generally this type of printer prints forward forward direction only, i.e. the paper skips forward continuously and the printer's head moves left and right to prin printt the the requ requir ired ed text text or grap graphi hics cs.. So, So, it is comp compul ulso sory ry for for CPU CPU to feed feed the 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 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.
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Need and Advantages of Networking To share Co Computer Fi Files To share Computer Eq Equipment To enab enable le unli unlike ke com compute puterr Equ Equip ipm ment ent to comm commun unic icat ate e To Im Improv rove Co Communic unica atio tion sp speed eed an and acc accu uracy racy Low Cost of Transfer of Data Inst nstantan ntaneo eou us Avail vaila abili bility ty of Info nforma rmation ion 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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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 communications Improved standardization Better control Controlled Security Data sharing • • • • •
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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 WANs are are typi typica call lly y crea create ted d usin using g spec specia iall lly y cond condit itio ione ned d telep telepho hone ne line lines, s, microwaves, or satellite data transmission. NETWORK TOPOLOGY Topol Topology ogy is the way way netwo networks rks are physic physicall ally y connec connected ted toget together her.. Topolo Topology gy determ determine ines s the comple complexit xity y and theref therefore ore the cost cost of networ network k cables cables ins instal tallat lation ion.. Topology Topology also determin determines es the strategy strategy for physically physically expanding expanding the network. 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 serv server er,, usin using g its its own own dedi dedica cate ted d segm segmen entt of cabl cable. e. This This topo topolo logy gy has has the 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 CIRCUL CIRCULAR AR TOPOLOG TOPOLOGY Y - In this this layo layout ut,, each each node node is phys physic ical ally ly 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 beca becaus use e each each port portio ion n of the the cabl cablin ing g syst system em is hand handli ling ng only only the the data data flow 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 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 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. COMPUTE COM PUTER R VIRUS VIRU S
Q. Ans. An s.
What is is Co Computer Vi Virus? A Compu Compute terr virus virus is a smal smalll bloc block k of code coded d inst instru ruct ctio ion n that that obtai obtains ns contr control ol of a PC's CPU and directs it to perform unusual and often destructive actions. Virus knows knows how to copy copy itself itself and attaches attaches itself itself to other other progra programs ms,, which which furthe furtherr 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.
(b)
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.
(c)
Melissa and SKA virus - Melissa virus attacks MS-WORD or MS-EXCEL files and sprea spread d very very fast fast.. This This viru virus s chan change ges s the the Norm Normal al.D .Doc oc,, disa disabl blin ing g the the macr macro o protection message and inflects all the Word files opened or created subsequently. Some Someti time mes s Melis Melissa sa viru virus s spre spread ad arou around nd the the worl world d rapi rapidl dly y infe infect ctin ing g many 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 SINGHSINWAR/19 places places,, name name them them and eventu eventuall ally y remove remove them. them. The capabi capabilit lity y to detect 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 The Intern Internet et is a loose loose connec connectio tion n of thousa thousands nds and thousa thousands nds of comput computer er 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 The Inte Intern rnet et star starte ted d as a US gove govern rnme ment nt proj projec ectt in the the 19 1960 60s s call called ed the 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 made up of hype hypert rtex extt docu docume ment nts s stor stored ed on serv server ers s arou around nd the the worl world. d. Hype Hypert rtex extt 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 dials to ISP with any one of these these local local teleph telephone one numbers numbers and then after after asking 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 that compan company. y. For For examp example le in http:/ http://ww /www.m w.micr icroso osoft. ft.com com,, http http (Hyper (HyperTex Textt Transf Transfer er 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 Throu Through gh the Intern Internet et and sui suitab table le softwa software re if someo someone ne talks talks with with any other other CHATTING. Generally chatting has been done person, then this talking is known as CHATTING. 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 shows that that person person's 's name name throug through h blinki blinking ng or throug through h any sound sound etc. etc. Throug Through h this 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 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 :Back Displays a pa page in in tth he li list of of p prreviously vi 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 hide ides) the Search Explorer Bar Bar in left pane pane,, whic which h prov provid ides es acce access ss to Inte Intern rnet et Sear Search ch Engines.(Default through MSN search). Favorites Displays (or hides) the Favorites Explorer Bar in left pane pane Which Which provid provides es access access to our favor favorite ite sites. 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 eithe eitherr we have have to choo choose se Ad Add d to Favo Favorit rites es from from Favo Favori rite te menu enu or clic click k Ad Add d to Favo Favori rite tes s on the the Favorites Explorer Bar at left pane. In the coming dialog box, Type the name of the page against the Name Name and then select select the location location of the favorite 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, orga organi nize ze and and retu return rn to favo favorit rite e page page as much much as similar to Windows Explorer. History (Toggle) Dis Display plays s (or (or hides hides)) the the His History tory Exp Explore lorerr Bar Bar at lef left pane that provides access to sites we have visited recently. Full Screen (Tgl)(Tgl)Swit Switch ches es to to (or (or from from)) full full scr scree een n view view,, whic which h prov provid ides es maxi maximu mum m view viewin ing g spac space e for for Inte Intern rnet et Expl Explor orer er's '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.
