COS 101 Notes on Introduction to Computer Sciences

**CIT /CSC 101** 1. ###. WHAT ISCOMPUTER? - **The word "computer" is comes from the word "TO COMPUTE" meansto calculate.** - **A computer is normally considered to be a calculation device which canperform the arithmetic operations veryspeedily.** - **A computer may be defined as a device which operates upon thedata.** - **Data can be in the form of numbers, letters, symbols, size etc. And it comesin various shapes & sizes depending upon the type of computerapplication.** - **[A computer can store, process & retrieve data as and when wedesired.]** - **The fact that computer process data is so fundamental that many peoplehave started calling as "DataProcessor".** - **A computer first it gets the Data, does Process on it and thenproduces Information**. - **DEFINATION OFCOMPUTER** - **A computer is an electronic device which takes input from theuser, processes it and gives the output as per user'srequirement.** - **So the main tasks of performed by the computerare:** - **Input** - **Process** - **Output** ###. WRITE DOWN THE CHARACTERISTICS OFCOMPUTER - DAT**Automatic:** - **Computers are automatic machines because it works by itselfwithout humanintervention.** - **Once it started on a job they carry on until the job isfinished.** - **Computer cannot startthemselves.** - ![](media/image2.png)**They can works from the instructions which are stored inside the systemin the form of programs which specify how a particular job is to bedone.** - **Accuracy:** - **The accuracy of a computer is veryhigh.** - **The degree of accuracy of a particular computer depends upon itsdesign.** - **Errors can occur by the computer. But these are due to humanweakness, due to incorrect data, but not due to the technologicalweakness.** - **Speed:** - **Computer is a very fact device. It can perform the amount of work infew seconds for which a human can take an entireyear.** - **While talking about computer speed we do not talk in terms ofseconds and milliseconds but inmicroseconds.** - **A powerful computer is capable of performing several billion (109)simple arithmetic operations persecond.** - **Diligence:** - **Unlike human beings, a computer is free from monotony, tiredness &lack ofconcentration.** - **It can continuously work for hours without creating any error &without grumbling.** - **If you give ten million calculations to performed, it will performwith exactly the same accuracy & speed as the firstone.** - **Versatility:** - **It is one of the most wonderful features about thecomputer.** - **One moment it is preparing the results of a particular examination, the next moment it is busy with preparing electricity bills and in between it may be helping an office secretary to trace an important letter inseconds.** - **Power ofremembering:** - **Computer can store and recall any amount of data because of itshigh storage capacity of its storagedevices.** - **Every piece of information can be retained as long as desired by theuser and can be recalled as and whenrequired.** - **Even after several years, if the information recalled, it will be asaccurate as on the day when it was filled to thecomputers**. - **NoI.Q.** - **A computer is not a magical device; it processes no intelligence of itsown.** - **Its I.Q. iszero.** - **It has to be told what to do & in whatsequence.** - **It cannot take its owndecision.** - **NoFallings:** - **A Computer has no feelings because they aremachines.** - **Based on our feelings, task, knowledge and experience we oftenmake certain judgments in our day todaylife.** - **But Computer goes exactly the way which we have given theinstructions**. 3. ###. EXPLAIN THE DATA PROCESSING CYCLE OFCOMPUTER. - **The computer Data Processing is any process that a computer program does to enter data &summarise, analyse or convert data into useable information.** - **The process may be automated & run on acomputer.** - **It involves recording, analysing, storing, summarising& storing data.** - **Because data are most useful when it is well presented & informative.** - **Data Processing cycle described all activities which are common to alldata processing systems from manual to electronicsystems.** - **These activities can be grouped in four functional categories, viz., data input, data processing, data output and storage, constituting what is known as adata processingcycle.** - **The main aim of data processing cycle is to convert the data intomeaningful information.** - **Data processing system are often referred to as InformationSystem.** - **The Information System typically take raw Data as Input to produceInformation asOutput.** **INPUT OUTPUT** **DATA PROCESS INFORMATION** - **The data processing cycle contains main fourfunctions:** - **Datainput** - ![](media/image2.png)**Dataprocess** - **Datastorage** - **Dataoutput** - **[DATAINPUT]** - **The term input refers to the activities required to recorddata.** - **It's a process to entered data in to computersystem.** - **So before we input any data, it is necessary to check or verify thedata context.** - **[DATAPROCESSING]** - **The term processing includes the activities like classifying,storing, calculating, comparing or summarising thedata.** - **The processing means to use techniques to convert the datainto meaningfulinformation.** - **[DATAOUTPUT]** - **It's a communication function which transmits the information tothe outsideworld.** - **After completed the process the data are converted into the meaningfulin** - **Sometimes the output also includes the decoding activity whichconverts the electronically generated information into human readableform.** - **[DATASTORAGE]** - **It involves the filling of data & information for futureuse.** ###. EXPLAIN THE CLASSIFICATION OF THE COMPUTER BY DATAPROCESSED 1. **Analogcomputers** 2. **Digitalcomputers** 3. **Hybridcomputers [Analogcomputers:]** - **In Analog Computers, data is represented as continuously varying voltage and operate essentially by measuring rathercounting.** - **Asthedataiscontinuouslyvariable,theresultsobtainedareestimatedandnot exactlyrepeatable.** - **It can able to perform multiple tasks simultaneously and also capable towork effectively with the irrational number. E.g. 1/8 = 0.125 and1/6=0.1666** - **Voltage, temperature and pressure are measured using analog deviceslike voltmeters, thermometers andbarometers**. - **The digit computer is a machine based on digital technology whichrepresents information by numericaldigit.** - **InDigitalComputersdataisrepresentedasdiscreteunitsofelectricalpulses.The data is measured in quantities represented as either the 'on' or 'off'state.** - **Therefore, the results obtained from a digital computer areaccurate.** - **Virtually all of today's computers are based on digitalcomputers. [HybridComputers]** - **It combines the good features of both analog & digitalcomputers.** - **It has a speed of analog computer & accuracy of digitalcomputer.** - **Hybrid Computers accept data in analog form and present output alsoin digitally.** - **The data however is processeddigitally.** - **Therefore, hybrid computers require analog-to-digital and digital-to-analog converters foroutput**. ###. EXPLAIN THE CLASSIFICATION OFTHECOMPUTER BY DATAPROCESSING: - **Microcomputer** - **Minicomputer** - **Mainframecomputer** - **Super computer[MicroComputer:]** - **Micro computers are the computers with having a microprocessor chip asit central processingunit.** - **Originated in late1970s.** - **First micro computer was built with 8 bitprocessor.** - **Microcomputer is known as personalcomputer.** - **Designed to use by individual whether in the form of pc's, workstationor notebookcomputers.** - **Small in size and affordable for generalpeople.** - **Ex: IBM PC, IBM PC/XT, IBMPC/AT** - **Mini computers are originated in1960s.** - **Small mainframes that perform limitedtasks.** - **Less expensive than mainframecomputer.** - **Mini computers are Lower mainframe in the terms of processingcapabilities.** - **Capable of supporting 10 to 100 userssimultaneously.** - **In 1970s it contains 8 bit or 12 bitprocessor.** - **Gradually the architecture requirement is grown and 16 and 32bit.** - **Minicomputers are invented which are known as superminicomputers.** - **Ex: IBM AS400 [MainframeComputer:]** - **A very powerful computer which capable of supporting thousands ofuser simultaneously.** - **It contains powerful data processingsystem.** - **It is capable to run multiple operatingsystems.** - **It is capable to process 100 million instructions persecond.** - **Mainframes are very large & expensive computers with having largerinternal storage capacity & high processingspeed.** - **Mainframes are used in the organization that need to process large numberof transaction online & required a computer system having massive storage & processingcapabilities.** - **Mainly used to handle bulk of data & information forprocessing.** - **Mainframe system is housed in a central location with several userterminal connected toit.** - **Much bigger in size & needs a large rooms with closely humidity& temperature.** - **IBM & DEC are major vendors ofmainframes.** - **Ex : MEDHA, SPERRY, IBM, DEC, HP,HCL [Super Computer:]** - **Most powerful & most expensivecomputer.** - **Used for complex scientific application that requires huge processingpower.** - **Used multiprocessor technology to perform the calculation veryspeedy.** - **They are special purpose computers that are designed to performsome specifictask.** - ![](media/image2.png)**The cost of the super computer is depended on its processing capabilities& configuration.** - **The speed of modern computer is measured in gigaflops, teraflopsand petaflops.** - **Gigaflops= 109 arithmetic operation persecond.** - **Teraflops=1012 arithmetic operation persecond.** - **Petaflops=1015 arithmetic operation persecond.** - **Ex: PARAM , EKA, BLUEGENE/P** ###. EXPLAIN THE GENERATION OF THECOMPUTERS. - **Duration: 1942-1955** - **Technology: vacuumtube** - **Used as a calculatingdevice.** - **Performed calculations inmilliseconds.** - **To bulky in size & complexdesign.** - **Required large room to placeit.** - **Generates too much heat &burnt.** - **Required continuously hardwaremaintenance.** - **Generates much heat so must air-conditioner rooms arerequired.** - **Commercial production is difficult &costly.** - **Difficult toconfigure.** - **Limited commercialuse.** - **ENIAC, EDVAC, EDSAC are example of 1^st^ generationcomputer.** - **Duration: 1955-1964** - **Technology: transistor** - **10 times Smaller in size than 1^st^ generationsystem.** - **Less heat than 1^st^ generationcomputers.** - **Consumed less power than 1^st^ generationsystem.** - **Computers were done calculations inmicroseconds.** - **Air-conditioner is alsorequired.** - **Easy to configure than 1^st^ generationcomputers.** - **More reliable ininformation.** - **Wider commercialuse.** - **Large & fast primary/secondary storage than 1^st^ generationcomputers.** - **Duration: 1965-1975** - **Technology: ICchip** - **Smaller in size than 1^st^& 2^nd^ generationcomputers.** - **Perform more fast calculations than 2^nd^ generationsystems.** - **Large & fast primary/secondary storage than 2^nd^ generationcomputers.** - **Air --conditioner isrequired.** - **Widely used for commercialapplications.** - **General purposecomputers.** - **High level languages like COBOL & FORTAN are allowed to writeprograms.** - **Generate less heat & consumed less power than 2^nd^ generationcomputer.** - **Duration: 1975-1989** - **Technology: Microprocessorchip** - **Based on LSI & VLSI microprocessorchip.** - **Smaller insize.** - **Much faster than previousgenerations.** - **Minimum hardware maintenance isrequired.** - **Very reliable as computer to previous generationcomputers.** - **Totally general purposecomputer.** - **Easy toconfigure.** - **Possible to use network concept to connect the computertogether.** - **NO requirement ofair-conditioners.** - **Cheapest inprice.** - **Duration: 1989 to Present** - **Technology: ULSI microprocessor chip** - **Much smaller &handy.** - **Based on the ULSI chip which contains 100 million electroniccomponents.** - **The speed of the operations isincreased.** - **Consumed lesspower.** - **Air-conditioner is notrequired.** - **More user friendly interface with multi-mediafeatures.** - **High level languages are allowed to writeprograms.** - **Larger & faster primary/secondary storage than previousgenerations.** - ![](media/image3.jpeg)**Notebook computers are the example of 5^th^ generationcomputers.** ###. EXPLAIN THE BLOCK DIAGRAMOFCOMPUTER OREXPLAIN THE SIMPLE MODELCOMPUTER. - - **InputDevices:** - **The devices which are used to entered data in the computer systemsare known as inputdevices.** - **Keyboard, mouse, scanner, mike, light pen etc are example of** **inputdevices.** - **[FUNCTION OF INPUTDEVICES]** - **Accept the data from the outsideworlds.** - **Convert that data into computer codedinformation.** - **Supply this data to CPU for furtherprocessing.** - **OutputDevices:** - **The devices which display the result generated by the computer are knownas outputdevices.** - **Monitor, printer, plotter, speaker etc are the example of outputdevices.** - **Accept the result form theCPU.** - **Convert that result into human readableform.** - **Display the result on the outputdevice.** - - **MemoryUnit:** - **The data & instruction have to store inside the computer before theactual processingstart.** - **Same way the result of the computer must be stored before passed tothe output devices. This tasks performed by memoryunit.** - **Store data & instruction received from inputdevices.** - **Store the intermediate results generated byCPU.** - **Store the final result generated byCPU.** - **Arithmetical & LogicalUnit:** - **The ALU is the place where actual data & instruction areprocessed.** - **All the calculations are performed & all comparisons are made inALU.** - **Performs all arithmetical & logicaloperations.** - **An arithmetic operation contains basic operations like addition,subtraction, multiplication,division.** - **Logical operations contains comparison such as less than, greater than,less than equal to, greater than equal to, equal to, not equalto.** - **ControlUnit:** - **It controls the movement of data and program instructions into and outof the CPU, and to control the operations of theALU.** - **In sort, its main function is to manage all the activities within thecomputer system.** - **Controls the internal parts as well as the external parts related withthe computer.** - **CPU:** - **The Unit where all the processing is done is called as Central ProcessingUnit.** - **It contains many other units underit.** - **Main of them are:- Control Unit And ALU (Arithmetic & LogicUnit)** ![](media/image2.png)UNIT: 2 INPUT DEVICES ========================================== 1. ###. WHAT ISINPUTDEVICES ? - **The Input devices are the devices which are used to enter the data inthe computersystem.** - **Keyboard, mouse, scanner, microphone are the example of inputdevices. [FUNCTIONS OF INPUTDEVICES:]** - **Accept the data from the outsideworlds.** - **Convert that data into computer codedinformation.** - **Supply this data to Central Processing Unit for furtherprocessing.** ### ### 2. ### EXPLAIN STANDARD INPUT DEVICE:KEYBOARD. - **Keyboard is most commonly used inputdevice.** - **It is similar like a type writer which is used to enter data in thecomputer.** - **It contains sets of keys such as alphabets, number & specialsigns.** - **There are two types ofkeyboard.** - **General purposekeyboard** - **Special purposekeyboard** ### GENERAL PURPOSE KEYBOARD: - **Standard keyboard which are used in personalcomputers.** - **It contains enough keys which are used in all types of applications so theyare known as general purposekeyboard.** - **Most popular general purpose keyboard contains 101keys.** - **The general purpose keyboard are divided into** ![](media/image2.png)**following parts:** - **[ALPHANUMERAICKEYPAD]** - **The centred part of the keyboard is known as alphanumerickeypad.** - **It contains alphabets, numbers & special signs such as \*,!, @, \#, \$, %,\*etc.** - **[NUMERAICKEYPAD]** - **The right most part of the keyboard is known as numerickeypad.** - **It contains 0 to 9 numbers & mathematical signs such as +, \*, -,/.** - **Mainly used for fast data entry in mathematicalapplications.** - **[ARROWKEYS]** - **Set of four keys up, down, left &right.** - **Used to move the cursor at left & right or up and down on thescreen.** - **They are referred as "cursor-control" or "cursor-movement" keys.** - **[FUNCTION KEYS]** - **The first line of the keyboard contains a Set of 12 keys with name f1 to f2are known as functionkeys.** - **Used to generate short-cuts in different softwarepackage.** - **[SPECIALKEYS]** - **There are lots of keys that are used for some specific task describesfollows:** - **TAB: used for gives multiple spaces or move the cursor to next definedposition.** - **ENTER: used for generate the output of anycommand.** - **SPACE: used to make one blank space between twowords.** - **BACKSPACE: used to remove the left-most character at cursorposition.** - **DELETE: used to remove the right-most character at cursorposition.** - **HOME: moves the cursor at the beginning of theline.** - **END: moves cursor at the end of theline.** - **PAGE UP: moves or scroll the screen up or previous page of the currentpage.** - **PAGE DOWN: moves the screen to the next page from the currentlydisplayed page.** - **PRINT SCREEN: used to print what is currently displayed on thescreen.** - **INSERT: used to enter text between twocharacters.** - **ESC: used to negate current command or terminate the execution ofthe program.** - **ALT: used to expand the functionality of keyboard. Basically used togenerate shortcuts in differentapplication.** - **CTRL: used to expand the functionality of keyboard. Basically used togenerate shortcuts in differentapplication.** - **NUMLOCK: used to on or off the numerickeypad.** - **CAPSLOCK: used to type the all inputted textcapitally.** - **Special purpose keyboard is used for special purpose applications which required faster data entry and rapid interaction with the computersystem.** - **For example ATM used in banks used special purpose keyboard which containsa fewkeys.** ###. EXPLAIN POINTINGDEVICES. 1. **.[MOUSE]** - **Mouse is Small hand-hold device Input device which is generally usedfor drawingpurpose.** - **It's a Pointingdevice.** - **It contains two or threebuttons** - **Left button is used to point out or select any item byclicking.** - **Right to generate contextmenu.** - **When user moves mouse across flat surface, the graphic cursor moves onscreen.** - **Graphic cursor contains verity of symbols such as arrow, wrist, pointingfinger etc.** - **Depending on application text & graphic cursors arechanged.** - **The following 5 techniques are used to carry out variousoperations:** - **POINT:** - **To move the mouse on top oficon** - **CLICK:** - **To press & release the left button of mouse atonce.** - **Used to open any currently selected icon,menu.** - **DOUBLECLICK:** - **To press & release the left button of mousetwice.** - **Used to open any application orprogram.** - **SIMULTANEOUS-CLICK:** - **Press & release left & right button togather.** - **Used in some software package to added somefunctionality.** - **DRAG:** - **Press the left button down & moved the mouse onscreen.** - **Used to move the graphics onscreen.** - **Many types of mouse are available such as mechanical mouse, optical mouse, serial mouse, wireless mouse which are used for differentpurpose.** 2. ###. TRACKBALL - **Trackball is a pointing device which is similar to amouse.** - **A ball is placed on the track ball device which is used to move the graphiccursor on thescreen.** - **Italsocontainsbuttonswhichareusedtoselectaparticularitemonthescreen.** - **To move the graphic cursor on screen, the ball is rolled with the fingers or thumb.** - **It needs not to move the whole device to move the cursor so it is oftenattached with somekeyboards.** - **Track balls come in various shapes with samefunctionality.** - **Commonly three shapes are used: ABALL, A SQUARE, and ASQUARE.** - **In case of ball we need to move it with the help offinger.** - **In case of button pushed with finger in desired direction of thecursor movement.** - **In case of button press finger to up or down & left or right to movecursor. [Advantages of trackball]** - **Takes less deskspace.** - ![](media/image6.jpeg)**Takes less arm movements thanmouse.** - **Doesn't require any mouse pad & large area to move themouse.** - **Less strain on thewrist.** - **Finger trip control which may offer more accuracy thanmouse.** 3. ###.JOYSTICK - **Joystick is a pointing device which is works on the same principle of trackball.** - **It contains a stick which is placed on the sphericalball.** - **The stick is used to move the cursor at desired position left or right orbackward orforward.** - **It also contain button that is clicked to make selection of currently pointeditem.** - **A joystick is similar to a mouse, except that with a mouse the cursorstops moving as soon as you stop moving themouse.** - **With a joystick, the pointer continues moving in the direction the joystick is pointing.** - **To stop the pointer, you must return the joystick to its uprightposition.** - **Some of the systems using joysticksare** - **Aircrafts, UAVs for flightcontrol** - **Motorized Wheelchairs as inputdevice** - **Microscopes** - **Submarines** - **SecuritySystems** - **VideoGames** - **Joysticks are widely used for videogames** - **[Advantages ofjoystick]** - **It is very easy to learn touse.** - **Very simple design so they can beinexpensive.** - **It has a big analogue stick in the middle so it's easier tocontrol.** ![](media/image1.png) 4. ###. LIGHTPEN - **Light pen is a pointing device which is used to draw directly draw on thescreen.** - **It is called light pen because it is similar to a pen & senseslight.** - **It's an input device in the form of light-sensitive stick used in conjunction witha CRTdisplay.** - **The light pen allows the user to point out or draw any object on thescreen.** - **The user brings the pen to the desired point on screen and presses thepen button to makecontact.** - **It has a switch on its top which allows the user to make contact withscreen.** - **It is useful for drawing or graphics in the program such as CAD (computeraided design).** - **An engineer, architect or fashion designer can draw directly onscreen.** - **Used in application such as gaming, graphic arts, healthcare applicationsetc.** - **Light pen cannot scratch or damage ascreen.** ### Advantages of light pen; - **Less expensive than touchscreen.** - **give the user the full range of mouse capabilities, without the use of apad or any horizontalsurface** - **Cannot scratch or damagescreen.** - **Works on any sizescreen.** 5. ###. TOUCHSCREEN - **Touch screen is a pointingdevice.** - **It is most simple & easiest to learn of all inputdevices.** - **It allows the user to choose from available options by simply touching withtheir figure to the desired icon or menu item displayed on the computerscreen.** - **A touch screen is an electronic visual display that can detect the presenceand location of a touch within the displayarea.** - **The term generally refers to touching the display of the device with a fingeror hand.** - **Touch screens are common in devices such as computers, tablet computers& Smartphone.** - **The touch screen has two mainattributes::** - **First, it enables one to interact directly with what isdisplayed.** - **Secondly, it lets one do so without requiring any intermediate devicethat would need to be held in thehand** - **It's a very easy to operate device which users can use the system withoutany formaltraining.** - **Uses optical sensors that detect the touch of the finger onscreen.** - **Sensors communicate the position of touch to the computer which interpretsthe input made by theusers.** - **It contains pressure sensitive monitors which are placed inside the baseof computerscreen.** - **Pressure sensitive monitors contain sensors to measure the monitor's weightat manypoints.** - **When user touches the screen, the changes on weights & forcestransferred down to sensor which allows the device to detect the location of thetouch.** - **This type of monitors required little pressure to transmit the desiredinput.** - **Touch screen are commonly used in followingplaces.** - **An airport or railwaystation.** - **Large departmentalstores.** - **In large museums or zoos to guide visitors to the locations ofvarious attractions.** - **Self service checkout** - **In ATMmachines** - **In I-phones orPDA's** - **Computer basedtraining** - **Any type of touch screen contains Three maincomponents: [A touch screen sensorpanel:]** - ![](media/image8.png)**Which sits above the display & generate appropriate voltage accordingto where precisely it istouched?** - **Processes the signal received from the sensor & translates this touchevent data & passed to pc's processor via serial or USBinterface.** - **Provides an interface to the pc's operating system & which translates the touch event data into mouseevent.** 6. ###.DIGITIZER - **An inputdevice.** - **Used for converting pictures, map & drawing into digitalform.** - **Allows one to hand-draw images and graphics, similar to the way onedraws images with a pencil andpaper.** - **Also be used to capture data or handwrittensignatures.** - **The device consists of a flat surface upon which the user may \"draw\" animage using an attached stylus, a pen-like drawingtool.** - **These devices are usually connected via a Serialport.** - **Placed on the desk n connected with thecomputer.** - **Digitizer consists of graphic tablets which are associated with astylus.** - **The stylus is like a pen with abutton.** - **Stylus connected with a tablet and can press down at a point on the tabletto input (x, y) co-ordinates ofpoint.** - **It contains hundreds of copper wires forming a grid that receives electricpulsed.** - **When stylus moves on tables the cursor on screen movesssimultaneously.** - **Allows the user to draw sketchesdirectly.** - **Commonly used in CAD by architects &engineers.** - **Used in GIS (geographical information system) for digitizingmaps.** 7. ###.MICROPHONE - **It's an inputdevice.** - **Used to stores the voice data into the computersystem.** - **Microphones are a type of *transducer* - a device which converts energy fromone form toanother.** - **Microphones convert sound waves into electricalenergy.** - **Different types of microphone have different ways of convertingenergy.** - **All the microphones share one common thing: Thediaphragm.** - **Thin piece of material (such as paper, plastic or aluminium) which vibrates when it is struck by soundwaves.** - **When the diaphragm vibrates, it causes other components in the microphoneto vibrate.** - **These vibrations are converted into an electrical current which becomesthe audiosignal.** - **The microphones are divided in mainly two types The type of conversion technology theyuse** - **This refers to the technical method the mike uses to convert soundinto electricity.** - **The most common technologies are dynamic, condenser, ribbonand crystal.** - **Some mikes are designed for general use and others are muchspecialised purpose.** 8. ###. WEBCAMERA - **It's an inputdevice.** - **Used to feeds the image to a computer or computer network often via USBor Wi-Fi.** - ![](media/image2.png)**Web camera is a hardware camera connected to a computer that allows everyone to connect to internet to view either pictures or motionvideo.** - **Most Web cameras are embedded to display with laptop computer orconnected with USB or Wi-Fi with acomputer.** - **Simple web cam. Consists a digital camera attached to your computertypically throughUSB.** - **The camera part of web camera is just a digitalcamera.** - **Web camera comes with software which preset interval & transfer it toanother location ofviewing.** - **Web camera system allows you to using video also for that you have webcamera with high framerate.** - **Web camera is a digital camera which taking picture over & over & againone afteranother.** - **These images are stored image into the physical memory of camera in builtin.** - **After capture image & stored in memory it reduced the amount of data needto transmit.** - **Web camera software takes image & converts data in jpeg (compressingformat).** 9. ###. EXPLAIN SCANNER &ITSTYPES. - **Scanners are inputdevices.** - **They are capable of entering information directly into thecomputer.** - **The main advantage of direct entry of information is that users do not haveto key theinformation.** - **And another advantage is that through Scanners you can input GraphicalData into the computer.This** - **Provides faster and more accurate data entry.** **Important types ofscanners** ### Image scanner: - **It's an input device, which translates paper documents into an electronicformat which can b stored in acomputer.** - **The input document may be typed text, pictures, graphics or even handwritten material.** - **There are two types of imagescanner: [Flatbedscanner]** - **It's like a zerox machine which consist of box having a glass plate on itstop and a lid to covers the glassplate.** - **The document placed inside the glass plate & light source is situatedblow glass plate which moves horizontally from left to write & scanning document line byline.** - **It contains a set of light emitting diodes encased in small case which can be conveniently held inhand.** - **To scan a document the scanner is slowly dragged on thedocument.** - **The scanner has to be dragged carefully & steadily otherwisethe document cannot scanproperly.** - **Used when higher accuracy is notrequired.** ### 10. EXPLAIN THEOPTICALSCANNERS OMR (OPTICAL MARKREADER) - **OMR is a device that is capable of recognised pre-specified type of mark madeby pencil orpen.** - **The Optical Mark Reader is a device which can detect the presence or absence ofa mark on apaper.** - **The OMR recognise the marks by focusing a light on the paper being scanned& detect the reflected light pattern frommark.** - **The present mark is detected due to intensity of light being reflected from themark.** - **Pencil marks made with soft lead pencil reflect the light which allowing the OMRto determine which response aremark.** - **OMR is used in reading answers sheets,questionnaires.** - **[ADVANTAGES]** - **Speedy and accurate to generateresult.** - **Cheap incost.[DISADVANTAGES]** - **Cannot able to readcharacters.** - **Erasing or cancellation is notpossible.** - **Good quality expensive paper isrequired.** - **OCR capable of recognizing alphabets & numbers printed onpaper.** - **It can also capable of recognise shape & identify character directly fromsource document.** - **It is always used with character recognizedsoftware.** - **It converts bitmap images of character to equivalent ASCIIcode.** - **First it create bitmap image of document & OCR software translate into ASCIIcode which computer interprets letter, symbol ornumber.** - **The type of document must be type using OCRfonts.** - **The software design to recognised the standard OCR-A(American standard) & OCR- B(Europeanstandard)** - **Speedy entereddata.** - **Accept wide range of font using ordinarymark. [DISADVANTAGE]** - **Expensive** - **Scanned properly only if the characters are standardsize.** - **Dusty paper cant scannedproperly.** - **MICR systems use special ink which can be magnetized, to print characters that can then be read and decoded by special magneticdevices.** - **The common E13B font is used to write these special kinds ofcheques.** - **E13B font contains 0-9 numbers & 4symbols.** - **Detection of characters is a two stepprocess.** - **First MICR Reader-Sorter reads the data on cheques& sorts the chequesfor distribution for furtherprocessing.** - **The reading station is used to sense and identify the magnetic characters asthey passthrough.** - **Magnetized characters are read by the head. E.g. MICR is used in Banks tocheques the MICR systems use special ink which can be magnetized, to print characters cheques.** - ![](media/image2.png)**Speedy dataentry.** - **Accurateoutput.** - **Folded or roughly handled cheques are also scanned with same accuracy. [DISADVANTAGE]** - **MICR software isrequired.** - **Limited fonts are used so used in banking industriesonly.** - **Data can be coded in the form of small lines which are known as BarCodes.** - **Bar codes represent the alphanumeric data by combination of vertical lineswhich contains different width & spacing betweenthem.** - **Bar Code Reader is a device which are used to recognized bar codedata.** - **It scanned the barcode image & converted into alphanumeric value & fedto computer.** - **It uses laser-beam technology. Laser stroke across the pattern of bar whichsensed by light sensitive decoder & their reflection of light pattern are converted into electrical pulse which converted it into alphanumericvalue.** - **Various barcodes are available for differentuse.** - **Most common is UPC (UNIVERSAL PRODUCTCODE).** UNIT: 3 OUTPUT DEVICES ====================== 1. ###. WHAT IS OUTPUTDEVICE. - **The output devices are the devices which are used to display theresult generated by the computersystem.** - **Monitor, printer, plotter, speaker are the example of outputdevices. [FUNCTIONS OF INPUTDEVICES:]** - **Accept the result from theCPU.** - **Convert that result into human readableform.** - **Supply this result to outputdevice.** 2. ###. EXPLAIN THE VISUALDISPLAYUNIT OR - **The monitor is the common output device mostly used It is a softcopyoutput device.** - **It can be thought of as a high resolution TVset.** - **The monitor can also determine if the display will be colour, black and white,or include graphical objects(pictures).** - **Two types of monitors areused.** - **CRTmonitors.** - **Non CRTmonitors.** - **Most computer monitors are based on Cathode Ray Tube (CRT)technology.** - **The basic operation of these tubes is similar to that in televisionsets.** ![](media/image10.png) - - **In CRT display CRT is a specialised vacuum tube in which images areproduced when electron beam strikes a phosphorsurface.** - **CRT monitor contains cathode, control grid, acceleration anode, deflectionplates & phosphor coatedscreen.** - **Cathode: the cathode is heated by filament and produced high speed & large amount ofelectrons.** - **Control Grid: used to control the brightness of the screen. It controls thenumber ofelectrons.** - **Accelerating anodes: they are with focusing lens are applied withpositive electrons.** - **Horizontal deflection plate: moves electron side byside.** - **Vertical deflection: moves electrons up &down.** - **Screen: contains millions of tiny red, green, blue phosphor dot that glowwhen struck by electron beam that travels across screen to create a visibleimage.** - **Produce morecolours.** - **Price is lower than LCD &Plasma.** - **High contrastratio.** - **Can easily increase brightness of monitor by reflecting thelight. [DISADVANTAGES OF CRTDISPLAY]** - **High powerconsumed.** - **Heavy to pick up andcarry.** - **Large spacerequired.** ###. EXPLAIN THE NON CRTDISPLAY. - **In LCD, a liquid crystalline material is sandwiched between two glass or a plastic plates.** - **The front plate is transparent and the back plate isreflective.** - **There is a coating of thin film on the frontplate.** - **The coating is transparent and conductive. Its sections (segments) are inthe shape of desiredcharacters.** - **LCDs do not emit their own light. Therefore, a light source is to beused.** - **LCDs simply change the reflection of available light. Today, most LCDs usedare of the type that produces dark images on a silverbackground.** - **Light weight as compare toCRT.** - **Perfectly flatscreen.** - **Consumed low electricitypower.** - **Able to generate higher brightness inimages. [Disadvantages:]** - **Fixed resolution that cannot bechanged.** - **Expensive than CRTdisplay.** - **Limited viewingangle.** - **Shortlife.** - **In Plasma Displays, ionized gas is sandwiched between two glassplates.** - **A number of parallel wires run horizontally as well asvertically.** - **A small amount of current is passed through one horizontal and one verticalwire to cause the gas to glow at a spot at the intersection of thewires.** - **The IBM 581 display employs 960 horizontal and 768 vertical pixel ascompared to IBM-PC colour graphic adapter which is provided with 320 X 200 pixels in medium resolution and 640 X 200 in highresolution.** - **Large viewingangle.** - **Thinner inwidth.** - **Free standing or can be easily mounted onwall.** - **Clear image, brighter viewing angle, better colour quality & high contrastratio. [Disadvantages:]** - **The plasma displays screens arecostly.** - **These are available on the selected models of portablecomputers.** - **More electricity thanLCD.** - ![](media/image2.png)**As your plasma get older the brightness getdimmer.** ###. WHAT IS PRINTER? EXPLAIN THE TYPES OFPRINTER. - **The printer is a most commonly used outputdevice.** - **It is used to producing the hard copyoutput.** - **It prints characters, symbols & graphics on thepaper.** - **Printer can be categorised according to the technology used in printer,speed, and approach of printing, colours, language & the quality ofprinting.** - **Mainly printer can be classified in twotypes:** - **Impactprinter** - **Non impactprinter** **[IMPACTPRINTER:]** - **It works on the same mechanism oftype-writer.** - **It forms a character or image by striking mechanism such as hammer orwheel against to ink ribbon, leaving an image onpaper.** - **It is oldest technology and still is inused.** - **It can capable to print single character or line at the sametime.** - **Commonly types of impact printers are dot matrix, daisy wheel, chain,drum printer.** - **Physical contact with paper to produceoutput.** - **Lowcost** - **Verynoisy** - **Very slow inprinting** - **Low quality printout** - **Stand with dusty or extremeenvironment [NON IMPACTPRINTER:]** - **Non impact printer forms characters & images on paper without actuallystriking thepaper.** - **Paper & print head come in contact & hence the text or image isformed.** - **Ink jet & laser printer are example of non impactprinter. [CHARACTERISTICS OF NON IMPACTPRINTER]** - **Faster than impactprinter.** - **Ability to change type faceautomatically.** - **High qualityoutput.** - **Supporttransparency.** - **More expensive than impactprinter.** - **Less maintenance than impactprinter.** ###. EXPLAIN IMPACTPRINTERS. - **Characterprinter.** - **Capable to print single character at the sametime.** - **Forms characters & images as a pattern ofdots.** - **Contains a print head which moves horizontally acrosspaper.** - **Uses 5 × 7 matrix to form acharacter.** - **Print by hammering the pins on inked ribbon to leave ink impressions onthe paper.** - **Able to print 30 to 600 characters persecond.** - **[ADVANTAGES:]** - **Low cost & easilyavailable.** - **Cheap incost.** - **Can make carbon copy of printout.** - **Low maintenancecost.** - **Work with any type ofenvironment.** - **[DISADVANTAGES:]** - **Slow inspeed.** - **Verynoisy.** - **Cannot work perfectly ingraphics.** - **Characterprinter.** - **Able to print a single character at the sametime.** - **Contain a metal wheel on which the characters & numbers are raised on theeach petal.** - **The wheel is rotated very fast when the desired characters arrives atcorrect position a print hammer strike to produceoutput.** - **Different type of font face can be used by replacing the daisywheel.** - **Able to print bold letter by striking on specific characters twice orthrice.** - ![](media/image1.png)**Capable to print 10 to 50 characters persecond.** - **[ADVANTAGES:]** - **Lowcost.** - **Can make carbon copy of printout.** - **Low maintenancecost.** - **Printing quality is similar to a typewriter.** - **Able to print boldcharacters.** - **Allows using different font-face in samedocument.** - **[DISADVANTAGES:]** - **Very slow inspeed.** - **Verynoisy.** - **Cannot printgraphics.** - **It's a lineprinter.** - **Able to print a line at the sametime.** - **Consist of a solid cylindrical drum with characters embossed on it incircular band.** - **Each band consists of character set which contains 96characters.** - **Drum rotates fastlywhen desired characters arrives an appropriate hammer stike on ribbon & character is print onpaper.** - **Capable to print 300 to 2000 lines perminute.** - **[ADVANTAGES:]** - **Low cost than non impactprinter.** - **Can make carbon copy of printout.** - **Low maintenancecost.** - **Faster than other impactprinter.** - **Printing quality is similar to a typewriter.** - **[DISADVANTAGES:]** - **Very slow inspeed.** - **Verynoisy.** - **Large &heavy.** - **Cannot printgraphics.** **Only prints predefined set ofcharacters.** - **It's a lineprinter.** - - **Able to print a line at the sametime.** - **Consist of a metallic chain on which all characters of character set areembossed.** - **Character set contains 48, 64 or 96characters.** - **Characters are embossed severaltimes.** - **Chain rotates at high speed when the desired characters in correct positionthe hammer strikes & the characters are print onpaper.** - **Capable to print 400 to 2500 lines perminutes.** - **[ADVANTAGES:]** - **Low cost than non impactprinter.** - **Can make carbon copy of printout.** - **Chain can be easilychanged.** - **Allowed to print different typefont.** - **Printing quality is similar to a typewriter.** - **[DISADVANTAGES:]** - **Slower than non impactprinter.** - **Verynoisy.** - **Large &heavy.** - **Cannot printgraphics.** - **Only prints predefined set ofcharacters.** ###. EXPALAIN NON -IMPACTPRINTERS. - **It's non-impactprinter.** - **It's a characterprinter.** - **Forms characters and all kinds of images by spraying drops of ink on tothe paper.** - **Print head contains 64 tinynozzles.** - **To print a character the printer the printer selectively heats the appropriateset of nozzle as the print head moveshorizontally.** - **Inkjet printer can either colour ormonochrome.** - **Capable to print 30 to 400 characters perminutes.** - **[ADVANTAGES:]** - **High qualityoutput.** - **Silent during theoperation.** - **Able to printgraphics.** - **Able to print any characters &graphics.** - ![](media/image2.png)**Able to generate colour& monochromeoutput.** - **[DISADVANTAGES:]** - **Slower than dot matrixprinter.** - **Cannot make carbon copy of printout.** **Expensive than impactprinter.** - **It's non-impactprinter.** - **It's a pageprinter.** - **Three main components laser beam, a multi-sided mirror, aphotoconductive drum &toner.** - **To print page laser beam is focused on drum by spinning multisidedmirror.** - **Drum is electriccharged.** - **Toner which is composed of oppositely charged ink particles, stick to thedrum.** - **Then toner focused on the paper with heat & pressure to generateoutput.** - **Low speed laser printer can print 4 to 12 page per minute while high speedlaser printer Capable to print 500 to 1000 pages perminutes.** - **[ADVANTAGES:]** - **High qualityoutput.** - **Very faster inspeed.** - **Silent during theoperation.** - **Able to printgraphics.** - **Able to print any characters &graphics.** - **Able to generate colour& monochromeoutput.** - **[DISADVANTAGES:]** - **Veryexpensive.** - **Cannot make carbon copy of printout.** ###. WRITE DOWN THE DIFFERENCE BETWEENIMPACT& NON -IMPACT PRINTER. +-----------------------------------+-----------------------------------+ | **Noisy during printing** | | +===================================+===================================+ | **Able to produced carbon copy | | | output** | | +-----------------------------------+-----------------------------------+ | **e.g.:** | | | | | | **daisy wheel, drum, chain, dot | | | matrix** | | +-----------------------------------+-----------------------------------+ ###. WHAT IS PLOTTER? EXPLAIN ITSTYPE. - **Plotter is an output device which is capable to producing hardcopy outputof graphics.** - **Used to producing wide formatprinting.** - **It is an ideal output device for architects, engineers, city planners and otherwho need to generate hardcopy output of widely varying insizes.** - **Woks on the same mechanism of human holding pen & moving onpaper.** - **Contains multiple pens & pencil which can be easily changed out in orderto create drawing of differentcolours.** - **Normally generate output veryslowly.** - **Mainly two types of plotters areused:** - **Drumplotter** - **Flatbed** - **In the case design has to be made is placed over adrum.** - **It consist one or more than penholders which are mounted to the drumsurface.** - **The drum plotter both the paper and the penmove.** - **The paper is contained on two rollers and passes over adrum.** - **The pen is driven along fixed arm set across the length of thedrum.** - **It is especially useful for plotting continuous linegraph.** - **The accuracy of the drum type depends on the paper transport mechanism, which in turn is dependent on the width of the paper and it can alsoproduce largerdrawings.** - **The Flatbed Plotter is generally more expensive and can produce verydetailed and accuratedrawings.** - **The paper is mounted on a stationaryflatbed.** - ![](media/image2.png)**The pen is mounted on a moveablearm.** - **Colour drawing can be produced by some plotters through interchangeable pens.** - **Able to draw output in small size as A4 size or can able to generate verylarge size can be up to 20ft by50ft.** - **Specially used in the design of cars, ships, aircrafts, buildings, highwaysetc.** 9. ###. WRITE A BRIEF NOTE ONSPEAKER. - **The speaker is output device which is connected to computer'ssoundcard.** - **The speaker output the sound generated by the soundcard.** - **Audio data is generated by computer is send to audio card which islocated inside extensionslot.** - **It can translate data into audio signal which are sending tospeaker.** - **The speaker can able to produced series of differenttones.** UNIT: 4 INTERNAL/EXTERNAL PARTS WITHCOMPUTER CABINATE ===================================================== 1. ### EXPLAIN TYPESOFPROCESSORS. DUALCORE - **Dual-core refers to a CPU that includes two complete execution coresper physical processor.** - **It has combined two processors and their caches and cache controllers onto a single integrated circuit (silicon chip)** - **Multi-core is similar to dual-core in that it is an expansion to the dual-core technology which allows for more than two separateprocessors.** - **Dual-core refers to a CPU that includes two complete execution coresper physicalprocessor.** - **It combines two processors and their caches and cache controllers onto asingle integrated circuit (siliconchip).** - **It is basically two processors, in most cases, rsesiding reside side-by-side onthe samedie.** - **Dual-core processors are well-suited for multitasking environmentsbecause there are two complete execution cores instead ofone.** - **Each with an independent interface to the front sidebus.** - **Since each core has its own cache, the operating system has sufficientresources to handle most compute intensive tasks inparallel.** - **Performance is faster than single-coreprocessors.** - **Able to divide information for processing by multipleunits.** - **Core processor uses slightly less power than two coupled single-coreprocessors** - ![](media/image2.png)**Multi-core chips also allow higher performance at lowerenergy.** ### CORE 2DUO - **Core 2 Duo is the name given by Intel to its second batch of dual coreprocessors.** - **Desktop PCs with the Intel® Core™2 processor family deliver fasterperformance, greater energy efficiency, and more responsivemultitasking.** - **Intel's dual core processors were simply 2 Pentium 3 processors thatwere fabricated in a singlechip.** - **Astheyrefinedtheirproductmore,theydecidedtodifferentiatetheirsecondset of processors from the Core Duo and decided to call it Core 2Duo.** - **The difference between dual core processors and the Core 2 Duo processorsis just in the semantics as Core 2 Duo is simply a name given to a more recent family of dual coreprocessors.** - **If we translate this to the single core processors, we can say that Core Duois Pentium 1 while Core 2 Duo is Pentium 2. But all these are still single core processors.** - **We can therefore say that Core 2 Duo is simply a subset of all the dualcore processors that are out in the markettoday**. - **With an Intel® Core™2 Duo processor you will get performance-richtechnologies,** - **Intel® multi-core processing provides greater multitasking performanceby combining two independent processor cores in one physicalpackage.** - **Execution improves execution time and energy efficiency with moreinstructions per clockcycle.** - **Power Capability enables smarter, more energy-efficientperformance.** - **Intel® Smart Memory Access improves system performance by optimizingthe use of the available databandwidth** - **Intel® Advanced Smart Cache enables higher performance and moreefficient cache subsystem by optimizing for multi-coreprocessors.** ### EXPLAIN PRIMORY STORAGEDEVICE. - **It's a temporarystorage.** - **It consists of somechips.** - **The data & instruction are resided in this memory when the CPUexecuting programs.** - **This memory can capable to store & retrieved data veryquickly.** - **Primary memory is only the memory that is directly access to theCPU.** - **The complete name of RAM is random access memory which is also knownas Primarymemory.** - **It is called read/write memory because data can be read as well as write inRAM.** - **It is called random access because you can directly access any data from RAMif you know row & columncell.** - **The RAM chip is fixed on the mother board & the mother board is designed in such a way that its memory capacity can be enhanced by adding more RAMchip.** - **RAM is a VOLETILEmemory.** - **RAM chips are of twotypes:** - **Dynamic Random Access Memory is a volatile memory that allows fast accessto data and is ideal for use as the primary store of computersystems.** - **However, the information is stored as electrical charges and the charges need to be constantly refreshed in order for the data to bemaintained.** - **Static Random Access Memory is also a volatilememory.** - **Once data is written into the chip, it is maintained as long as power is suppliedto it; it does not needrefreshing.** - **However, SRAM is slower than DRAM and it is also moreexpensive.** - **The complete name of ROM is read onlymemory.** - **The data stored permanently & can't be altered by theprogrammer.** - **Data stored in RAM chip can be read & used but cannot bechanged.** - **This memory also known a field storage permanent storage or deadstorage.** - **It is basically used to store manufacturer programmed & userprogram.** - **Most of the basic operations are carried out by electronic circuits whichare known as microprograms.** - **These programs are stored in ROM. For ex. System BootLoader.** - **Programmable Read Only Memory is a non-volatile memory which allowsthe user to program the chip with a PROMwriter.** - **The chip can be programmed once, thereafter, it cannot bealtered.** - **Erasable Programmable Read Only Memory and Electrically Erasable Programmable Read Only Memory chips can be electricallyprogrammed.** - **Unlike ROM and PROM chips, EPROM chips can be erased andreprogrammed.** ###. EXPLAINFOLLOWINGPORTS ### SERIALPORT - **Known as asynchronous port or RS-232-Cport.** - **This type of port is sends & receives data using only twoline.** - **Therefore this type of port is ideal for connection to the phone circuitswhich uses 2 datalines.** - **The communication process of data transfer isslower.** - **Due to this reason it is not used forprinter.** - **It has high signal travellingcapacity.** ### ### ### PARALLEL PORT - **Known as centronics or printerport.** - **It's a type of socket found on personal computer for connecting various typesof computerdevices.** - **Normally it is reserved forprinter.** - **They carry 8 bits at the same time so that communication becomes veryfaster.** - **Due to the faster data communication capability it is used in input &output devices.** - **The signal travel capacity is less than serialport.** ### USB PORT - **It's a new interface technology which are used to connect computerperipherals such as keyboard, mouse, scanner, joysticks, printer, web cameraetc.** - **USB operate at two speeds 1.5 mbps & 12mbps.** - **The speed is depending upon the devices which are attached with theport.** - **For example the devices such as mouse, keyboard Use the law band while digital camera use high speedchannel/** - **Main advantage is that when devices are attached the appropriate driversare loadedautomatically.** ### PS/2 PORT - **Developed by IBM for connecting mouse or keyboard toPC.** - **It supports the plug that contains 6pins.** - **Also called mouseport.** ### EXPLAIN FOLLOWING CABLES ### Serial Cable - ![](media/image2.png)**Serial Cables are typically used for RS-232communication.** - **A serial cable is a cable that can be used to transfer information betweentwo devices using serialcommunication.** - **The form of connectors depends on the particular serial portused.** - **The maximum working length of a cable varies depending on thecharacteristics of the transmitters andreceivers.** - **This cable has short transmission distance because of noise limiting the transmission of high numbers of bits per second when the cable is more than15 meterslong.** - **It is cheap to purchase and is simple to join andconnect.** - **It is suitable for unbalanced datastandards.** - **Only one device can be connected to thecable.** ### Parallel Cable - **On many legacy peripherals, the parallel cable utilized both the 25 pin Sub-D connector and the 36 pin Centronicsconnector.** - **This was a common printer interface and is still in service in greatnumbers.** - **With the advent of \"intelligent\" laser and ink jet printers, the IEEE-1284bi- directional printer cable wasintroduced.** - **This parallel interface allows for bi-directional communication resulting inspeeds up to 10 times faster than conventionalcables.** ### USB Cable - **To Connecting a USB device to a computer is simple \-- you find the USB connector on the back of your machine and plug the USB connector intoit.** - **If it\'s a new device, the operating system auto-detects it and asks for the driver disk.** - **If the device has already been installed, the computer activates it andstarts talking toit.** - **USB devices can be connected and disconnected at anytime.** 5. ###.SHORT NOTE: GRAPHIC CARDS. - **A graphics card is the component in your computer that handles generating the signals that are sent to the monitor or\"graphics\".** - **It is responsible for generating all the text and pictures that are displayedon yourscreen.** - **The images you see on your monitor are made of tiny dots calledpixels.** - **At most common resolution settings, a screen displays over a million pixels,and the computer has to decide what to do with everyone in order to create an image.** - **To do this, it needs a translator \-- something to take binary data from the CPU and turn it into a picture you cansee.** - **This task is performed by Graphic Card which is built intomotherboard.** - **A graphics card\'s job is complex, but its principles and components are easyto understand.** - **The CPU, working in conjunction with software applications, sendsinformation about the image to the graphicscard.** - **The graphics card decides how to use the pixels on the screen to createthe image.** - **It then sends that information to the monitor through acable.** - **To make a 3-D image, the graphics card first creates a wire frame out ofstraight lines. Then, it rasterizes theimage.** - **It also adds lighting, texture andcolour.** - **The graphics card accomplishes this task using four maincomponents:** - **[A motherboard] connection for data andpower** - **[A processor] to decide what to do with each pixel on thescreen** - **[Memory] to hold information about each pixel and to temporarilystore completedpictures** - **[A monitor] connection so you can see the finalresult** ![](media/image12.jpeg)UNIT: 5 DATA STORAGE =========================================== 1. ### NOTE ON MAGNETICTAPE - **Sequentially access storagedevice.** - **Most popular storage medium for storage largedata.** - **Its plastic ribbon which is ½ or ¼ inch wide and 50 to 2400 feetlong.** - **It is coated with a magnetisable recordingmaterial.** - **In a magnetic tape data are recordedserially.** - **Information is recorded on the tape in the form of tiny invisible magnetizedand non magnetizedspots.** - **The tape ribbon is itself stored in reels or smallcassette.** - **Whenever we stored new data on the tape that contains old data the olddata are automatically erased and new data are recorded in the samearea.** - **In older tape contains 7 tracks and they used 6-bit BCD code format fordata recording.** - **Morden magnetic tape contains 9 tracks & used 8-bit EBCDIC code formatfor datarecording.** - **There are various types of magnetic tape are used. Most commonlyare:** - **½ inch tapereel** - **½ inch tapecartridge** - **¼ inch streamertape** - **4 mm digital audiotape** - **Large or unlimited storagecapacity.** - **Lowcost.** - **Light weight and compact insize.** - **Copying of data is easy andfast.** - **Possible to erase older data n store newdata.** [Disadvantages:] - **Cannot be accessed directly because it's a Sequential accessdevice.** - **Must be located in dust free environment otherwise it causeerrors.** - **Data are stored in coded form so cannot interpret or verifydirectly.** 2. ###. WRITE A NOTE ON MAGNETICTAPE - **Directly access storagedevice.** - **It's a thin circular plate that is made up with plasticmaterial.** - **Plate is coated both side with magnetic material such as ironoxide.** - **Information is recorded on the tape in the form of tiny invisible magnetizedand non magnetizedspots.** - **8-bit EBCDIC code is used for datarecording.** - **Like magnetic tapes, magnetic disks are also erased &reuse.** - **The disk is divided into number of circles calledtracks.** - **The tracks are further divided intosectors.** - **A sector typically contains 512bytes.** ![](media/image2.png) - **Two common types of magnetic disks are usedwidely.** - **Floppydisks** - **Harddisks** ### 3. ### SHORT NOTE: FLOPPYDISK - **Floppy disks were introduced by IBM in1972.** - **floppy disk is a round, flat piece of flexible plastic which is coatedwith magneticoxide.** - **It is encased in square plastic cover that gives protection to thedisk.** - **They are also referred asdiskettes.** - **The data is read and write in floppy disk is using a device called FLOPPYDISC DRIVE.** - **The long lit is provided for the read / writes head to access thedisk.** - **A hub in the centre is used for mounting the diskdrive.** - **A hole is used to sense indexmarking.** - **The floppy disks are available in twosizes.** - **5 ¼ inch (1.2MB)** - **3 ½ inch (1.44MB)** - **Cheap incost.** - **Convenient offline storage for small computerusers.** **[Disadvantages;]** - **Low storagecapacity.** - **A floppy disk drive device is required to use read/writedata.** ### A DETAILNOTEONHARDDISK - **Hard disks are most popular secondary storagedevice.** - **It supports the direct access of thedata.** - **It's a thin magnetic plate which is made of metal n both side coatedwith magneticmaterial.** - **The disk is divided in many tracks & the data is store in both side of thedisk.** - **The disk pack consists of multiple diskplates.** - **The disk drive pack has a separate read/write head for each disksurface.** - **The disk drive consists of motor to rotate the disk pack about its axis at aspeed of about 5400 revolution perminute.** - ![](media/image2.png)**The drive also has a set of magnetic heads mounted onarms.** - **The arm assembly is capable of moving in & out in radialdirection.** - **The hard disk drive has become the most indispensable secondary storage device inmicro-computers.** - **It is fast and speeds of less than 10 (ms) milliseconds areachievable.** - **Storage capacity is large and it is not uncommon formicro-computers.** 4. ###. SHORTNOTE: CD-ROM - **CD-ROM (Compact Disk -- Read Only Memory) is a non-erasable backing store which can hold large amounts ofdata.** - **It's a shiny silver colour metal disk of 5 ¼ inch and the storage capacity about650 megabytes.** - **Large volume production is achieved by automated processes similar to thatof audio compactdisks.** - **Many of today's micro-computers come with CD-ROM readers and as a result, CD-ROM is popularly used for distribution of software, digitized graphicimages as well as Multi-Mediamaterial.** - **Information is written on the disk surface by shining a laserbeam.** - **As a disk rotates the laser beam traces out a continuousspiral.** - **It's known as WORM (Write Once Read Many) disktechnology.** - **The data can be read time and again but, once the data is stored, it cannotbe erased orchanged.** - **Cost per bit isLow.** - **Need not have any mechanical read/write heads to read/writedata.** - **Compact insize.** - **Light weight[Disadvantages:]** - **Read only storagemedium.** - **Slower access speed than magneticdisk.** 5. ###. EXPLAININBRIEF: DVD - **DVD (Digital Versatile Disk) is optical diskstorage.** - **Basically it is used for storing large amount of data including movies withhigh video & soundquality.** - **Work on the same principle ofCDROM.** - **Data is recorded on each layer so that the storage capacity is becomelarge.** - **Total capacity of DVD is 8.5 GB [Advantages]** - **Larger capacity thanCD. [Disadvantages:]** - **Expensive thanCD.** - **Damaged if not handledproperly.** 6. ###.EXPLAININBRIEF: ZIPDISK - **It's a high capacity, removable magnetic disk which can be read or write byZIP drive.** - **It is similar to floppy disk except that much faster & largercapacity.** - **Zip disks are available in two size namely 100 megabytes & 250megabytes.** **[Advantages:]** - **Easy touse and carry** - **Large capacity than floppydisk.** - **Faster than floppydisk** **[Disadvantages:]** - **Expensive** - **Data transfer between drive & computer isslow.** 7. ### SHORTNOTE:PENDRIVE - **It consists of a small printed circuit board encased in a robust plastic ormetal casing.** - **It is easy to carry inpocket.** - **It uses standard-A type connection which allows it to directly connect withthe computer.** - **It contains followingcomponents:** - **[Male type-A USB connector]-provides an interface tocomputer.** - **[USB mass storage controller]- provides liner interface to blockoriented serial flashdevice.** - **[NAND flash memory chip]- storesdata.** - **[Crystal oscillator]- controls devicedata.** - **Portable insize.** - **Can easily work with all new operatingsystem.** - **More reliable than floppydisk** **[DISADVANTAGES:]** - **Expensive than opticaldisk** - **Do not provide protectmechanism.** 8. ### ![](media/image2.png). SHORTNOTE: BLUE RAYDISK - **Blue-Ray disk is an optical disc storage mediaformat.** - **It was developed by blue-ray discassociations.** - **It is mainly used to store high definition video anddata.** - **It has same dimensions as CD orDVD.** - **The violet coloured laser is used to read and write thedata.** - **Because of its shorter wavelength more data can be stored than DVDformat.** - **Its storage capacity is 50GB.** UNIT: 6 NUMBER SYSTEM ===================== - **All digital computers store numbers, letters, and other characters incoded form.** - **The code used to represent characters is the Binary Code -- i.e. a code made up of bits called BinaryDigits.** - **Every character is represented by a string of "0s" and "1s" -- the onlydigits found in the binary numberingsystem.** - **When data is typed into a computer, the key board converts each keystroke into a binary character code. This code is then transmitted to thecomputer.** - **When the computer transmits the data to the any device, each individual character is communicated in binary code. It is then converted back tothe specific character while displaying or printing thedata.** - **Numbers earlier consisted of symbols like I for 1, II for 2, III for 3 etc.Each** - **Symbol represented the same value irrespective of its position in thenumber.** - **This approach is called an additive approach. As time passed positional numbering systems were developed. In such a system the number of symbols is few and they represent different values depending on the position they occupy.** - **Now we know that numbers can be represented by arranging symbolsin variouspositions.** - **In the decimal system the successive positions to the left of the decimalpoint represent units, tens, hundreds, thousands etc. For example if weconsider** - **The number 7762, the digit 2 represents the number of units, 6 representsthe number of tens, 7 the number of hundreds and 7 the number ofthousands.** - **Thus as we move one position to the left, the value of the digit increases by ten times. We can see that the position of the number affects itsvalue.** - **These kinds of number systems are therefore called positionalnumber systems.** - **In other words the number of symbols used to represent numbers in the system is called the base of that system. In short we can say that the value of each digit in the number system is determinedby:** - **The digititself** - **The position of the digit in the numberitself** - **The base of thesystem.** - **The Roman numbering system uses symbols like I, II, III, IV, V etc.To represent the decimal numbers 1, 2, 3, 4, and5.** - **As we can see this follows an additive approach and hence is notconductive toarithmetic.** - **We now come to a different number system -- the Binary numbersystem.** - **This binary number system has a base of two, and the symbols used are"0" And"1".** - **In this number system, as we move to the left the value of the digit will be two times greater than its predecessor. Thus the values of the places are: 64 32 16 8 4 21** - **In conversion from decimal to any other number system, the steps tobe followedare:** - **Divide the decimal number by the base of2.** - **Note the remainder in one column and divide the quotient againwith the base. Repeat this process until the quotient is reduced to azero.** **2** **65** **1** ------- -------- ------- **2** **32** **0** **16** **0** **2** **8** **0** **2** **4** **0** **2** **2** **0** **1** - **The decimal number is65** - **The binary number of 65 is** - **The decimal number of 1000001 is[65 Octal Number System (Base8)]** - **A commonly used positional system is the Octal System. The octal systemhas a base of8.** - **The values increase from left to right as 1, 8, 64, 512,4096,....** - **In conversion from decimal to any other number system, the steps tobe followedare:** - **The decimal number is224** **8** **224** **0** ------- --------- ------- **8** **28** **4** **3** **3** - **The octal number of 224 is** - **The octal number is340** - **The decimal number of 340 is** **000** **0** ----------- ------- **001** **1** **010 2** **011** **3** **100** **4** **101** **5** **110** **6** **111** **7** - ![](media/image1.png)**The binary number must be divided into groups of three from the octalpoint** - **Example** - **Binary101010101010100** [101 010 101 010 100] 5 2 5 2 4 - **So, is the Octal equivalent of binary101010101010100** - **Each octal digit is replaced with the appropriate 'triple' of binarydigits.** - **The binary equivalent of the Octal number 65 is[110101 Hexadecimal Number System (Base16)]** - **There is another commonly used positional system, hexadecimalsystem.** - **The hexadecimal system has a base of 16, so the value increases from left to right as 1, 16, 256, 65536,....** - **We need to keep a simple table in mind before we attempt anyconversion from hexadecimal orvice-versa.** - **In conversion from decimal to any other number system, the steps tobe followedare:** - **The decimal number is370** **16** **370** **2** -------- --------- ------- **16** **23** **7** **16** **1** **1** **0** - **The hexadecimal number of 370 is** - **The decimal number of 172 is** - **Each hexadecimal digit is represented by 4 binarydigits. BinaryHexadecimal** **0000** **0** ------------------------ --------------------- **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **[A]** **** **[B]** **** **[C]** **** **[D]** **** **[E]** **** **[F]** - **To convert a binary number to its hexadecimal equivalent we split the quantity into groups of four onwards, asbefore.** - **Each of this group of four is directly converted into theirhexadecimal equivalent.** - **We may add zeros to the left of the number ifnecessary.** - **example** - **So, the hexadecimal equivalent of binary 10101011000010 will be[2AC2]** - **The conversion from hexadecimal to binary consists of writing off thebinary** - **e.g.** - **Thus the required binary number can be writtenas: ** - **Write 4 digit binary numbers for eachhexadecimal.** - **Arrange the entire number sequence into group of 3 bitsection.** - **If any bit is missing add 0 on leftmostsection.** - **Now write down octal equivalent of each 3 bitsection.** - **Example:** - **The hexadecimal number is2A35. 2 A 35** - **The octal number is25065** - **Write 3 digit binary number for eachoctal.** - **Arrange the entire number sequence into group of 4 bitsection.** - **If any bit is missing add 0 on leftmostsection.** - **Now write down hexadecimal equivalent of each 4 bitsection.** - **Example:** - **The octal number is25065. 2 5 0 65** 2 A 3 5 Binary Arithmetic ----------------- **\ ** - - - - **All the arithmetic operations are possible in binary numbering systemlike addition, subtraction, multiplication and division All the Arithmetic operations are done in binary number system are explained asunder:** - **For binary addition the following rules of binary addition are tobe considered:** - **1 + 1 = 0 (carry 1 to the next column to theleft)** - **1 + 1 + 1 = 1 (carry 1 to the nextcolumn)** - **e.g. 1 Add two binary numbers 11011 and111** - **Carry 1 1 11** - **Though there are other methods of performing subtraction, we willconsider the method of subtraction know as complementarysubtraction.** - **This is a more efficient method of subtraction while using electroniccircuits. We will be following three steps to performsubtraction:** - **Find the complement of the number you aresubtracting.** - **To the complement of the number we obtained in step 1, we addthe number we are subtractingfrom.** - **If there is a carry of 1 add the carry to the result of the addition elsere complement the sum and attach a negativesign.** - **How do we find the complement of a binary number ? We have to invertall the bits. e.g. NumberComplement** - **Consider the following example ofsubtraction:** - **Step-1. Find the complement of1001100 0110011** - **Step-2. Add the number you are subtractingfrom Carry 1 1 1 0 1 11** 1 0 1 0 1 01 \+ 0 1 1 0 0 11 - **Step-1. Find the complement of11100101 00011010** - **Step-2. Add the number you are subtractingfrom Carry 0 1 11** 0 0 1 0 1 1 00 \+ 0 0 0 1 1 0 10 - **Step-3. Since there is no carry we are complement theresult 10111001** - **- 10111001 (Answer) [Multiplication]** - **Multiplication** - **Multiplication in binary follows the same rules that are followed inthe decimal system. The table to be rememberedis:** - **0 x 0 =0** - **0 x 1 =0** - **1 x 0 =0** - **1 x 1 =1** - **e.g.** 1010 x1001 - **The answer is(1011010)** - **Table for binary division is given asunder:** - **0 / 1 =1** - **1 / 1 =1** - **The steps for binary divisionare:** - **Start from the left of thedividend.** - **Perform subtraction in which the divisor is subtracted fromthe dividend** - **If subtraction is possible put a 1 in the quotient and subtract thedivisor from the corresponding digits of the dividend else put a 0 in the quotient** - **Bring down the next digit to the right of theremainder.** - **Execute step 2 till there are no more digits left to strating downfrom thedividend.** - **e.g.** ![](media/image1.png) - **Most computers do not represent characters as pure binarynumbers.** - **They use a coded version of true binary to represent letters and specialsymbols as well as decimalnumbers.** - **Coding of characters has been standardized to enable transfer of data between computers.** - **Codes usedare:** - **BCD** - **ASCII** - **EBCDIC** - **BCD stands for Binary CodedDecimal.** - **BCD code is one of the early computercodes.** - **It is based on the idea of converting each digit of a decimal number into its binary equivalent rather than converting the entire decimal into binaryform.** - **All decimal digits are represented in BCD by 4bit.** - **Each decimal digit is independently converted into a 4 bit binary number &so the conversion process is veryeasy.** - **4 bit BCD can be used to represents only decimal numbers because 4 bitsare insufficient to represent variouscharacters.** - **By using 4 bit BCD only 16 possible characters arerepresented.** - **So the BCD code was extended from 6-bit code and it is possible to represent64 characters.** - **ASCII stands for American Standard Code for InformationInterchange.** - **In this form of representation, each character (which includes alphabets,digits and symbols) is assigned a particular pattern ofbits.** - **For example, A is represented as binary 1000012, B as 10000102 and soon.** - **The standard ASCII character set uses 7 bits and can be used to represent 128 differentcharacters.** - **It uses one extra parity bit for paritycheck.** - **Other forms of ASCII codes use an extra bit to extend the representation to256 characters.** - **However, characters represented from binary are not universally agreedupon.** - **The most popular form is the set used byIBM.** - **ASCII is commonly used to exchange data between data processingand communicationsystems.** - **EBCDIC stands for Extended Binary Coded Decimal InterchangeCode.** - **It uses 8 bits and can represent 256 distinctcharacters.** - **It also uses one extra parity bit for paritycheck.** - **The EBCDIC code is used in IBM mainframe models and other similarmachines.** - **Electronic Circuits are available to transform characters from ASCII to EBCDIC and vice-versa and can also be achieved using computerprograms.** - **With the onset of globalization through Internet, there emerged a need to Cater for data interchange of the more common languages of thedifferent nationalities like Chinese, Korea andJapanese.** - **ASCII, EBCDIC and other forms of representation provedinsufficient.** - **The Unicode/ISO 10646 standard was devised to overcome thisproblem.** - **The 16 bits used by Unicode can represent 65536 symbols, one extra parity bit for parity check, which is more than enough to represent all the worldswritten characters.** - **Although Unicode solves the problem of multi-language data representation, it is not the perfect solution as there remain issues to beaddressed.** - **Problems include the wastage of storage space, time needed fordata transmission and the lack of support of current operatingsystems.** - **Furthermore, Unicode does not guarantee a particular sortorder.** - **A parity check is a technique to detect the correctness of characterstransmitted.** - **For each character transmitted, a bit knows as the parity bit isadded.** - **In an Even Parity System, a parity bit is added such that the total number of '1's, inclusive of the parity bit, iseven.** - **In an Odd Parity System, the total number of '1' bits transmitted must beodd.** - **The parity check is not fool proof. It will fail when an even number of bits were incorrectlyreceived.** - **This cannot be recognized by this system. That if they are incorrectly receivedor not.** UNIT:7 LANGUAGES, OPERATING SYSTEM &SOFTWARE PACKAGES ===================================================== ### Introduction - **A computer can only do what a programmer asks it todo.** - **To perform a particular task programmer writes a sequence, called theprogram.** - **An instruction command given to the computer to perform a certainspecified operation on the givendata.** - **Now as we know only human languages and computer knows only machine language, we need some media through which we can communicate with the computer.** - **So we can complete our desired task. That media isLanguage.** - **Languages are tools human can use to communicate with the hardware ofa computersystem.** - **Each language has a systematic method of using symbols of thatlanguage.** - **In English, this method is given by the rules ofgrammar.** - **Similarly, the symbols of particular one computer language must also be usedas per set of rules which are known as the "Syntax" of that language, the language which you areusing.** - **Computer Languages can be classified into three broadcategories:** **ASSEMBLY LANGUAGES** **HIGH-LEVEL LANGUAGES** 1. ###.WHAT IS MACHINE LANGUAGE? - **Computer programs are written using many different computer Languages but the language which is understood by the computer without translatingprogram is called machinelanguage.** - **Machine language is normally written as string of binary 1s and0s.** - **A machine language instruction has two partformat.** -- -- -- -- - **The 1^st^ part is the operation code which tells the computer what function tobe performed.** - **The 2^nd^ part is the operand which tells the computer where to find & storedata to bemanipulated.** - **So each instruction tells the computer what operation to perform & the length& location of the data field which are involved in theoperation.** - **Programs can be executed immediately upon completion because it doesn't require anytranslation.** - **Now extra storage space isneeded.** - **Programmer has complete control over the performance of thehardware. [Disadvantage]** - **Tedious toprogram** - **Difficult toprogram** - **Difficult tomodify** - **Time consuming tocode** - **Errorprone** - **Operation codes have to bememorised** - **Assignment of memory is done byprogrammer** - **Time consuming fordevelopment** - **Programs development are machinedependent** - **Preparation of programs was slow andcostly.** 2. ###.EXPLAIN ASSEMBLY LANGUAGE. - **Assembly language is a language which allows instruction & storage locationto be represented by letters & symbols, instead ofnumber.** - **A program written in an assembly language is called [assembly languageprogram or symbolicprogram.]** - **Assembly language was introduced in1952.** - **Machine language was tedious to code and errors were expected to arise inbulk.** - **To solve these problems mnemonic codes and symbolic addresseswere developed.** - **It allows using alphanumeric mnemonic codes instead of numeric code forthe instructions in instruction set. For example using ADD instead of 1110 or 14 to add.** - ![](media/image2.png)**The storage locations are to be represented in the form ofalphanumeric addresses instead of numericaddress.** - **Format of assembly language is similar to machinelanguage:** -- -- -- -- - **This instruction adds value of NUM1 to the AX (AccumulatorRegister).** - **The symbolic language made program writing so much easier for the Programmers but it must be translated into machine code before being used for operation.** - **The translation is actually done by a special translatingprogram. [Assembler]** - **Assembler is a special program (translator) which translates symbolic operation codes into machine codes, and symbolic address is addressed into an actual machineaddress.** - **Easier to use, code andunderstand.** - **Easier to correcterror.** - **Easier tomodify.** - **No worry aboutaddresses.** - **Easilyrelocatable.** - **Efficiency of machinelanguage.** - **Can use Macros (Macro is a bunch of instruction referred as a singlename)** - **Machinedepended.** - **Programs have to be translated beforeexecution.** - **Translation of programs takes uptime.** - **Knowledge of hardware isrequired.** - **Additional storage area needed for the source programs and objectcode.** - **Microsoft Assembly Language (MASM), TurboAssembler** 3. ###.WRITE A NOTE ON HIGH LEVELLANGUAGE. - **The machine language & assembly language requires a good knowledgeof internal structure ofcomputer.** - **The both languages are machine dependent & it is difficult to solveerror.** - **To remove this limitation the high level language areintroduced.** - **The high level languages machine independent so it can be easily ported& executed on anycomputer.** - **The high level language programs do not require any knowledge of internal structure of computer so the programmer concentrate on the logic ofproblem rather than internal structure ofcomputer.** - **It enables the programmer to write instructions using English words &familiar mathematical symbols & expression so the program makes easier to code & understand.** - **It requires a translator program to convert high level program intomachine language.** - **Compiler is a special program (translator) which translates high levelprograms into machinecodes.** - **Machineindependent.** - **Easier to learn, use andunderstand.** - **Easier to correcterror.** - **Easier tomaintain.** - **Less time &efforts.** - **Easilyrelocatable.** - **Program preparation cost islow.** - **Lessflexible.** - **Lowerefficiency.** - **Require more time & storagespace.** 4. ###.SHORT NOTE:ASSEMBLER - **A computer can directly execute only machine language programs so the assembly language program must be converted into its equivalentmachine language program before can beexecuted.** - **This translation is done with the help of a translator program which is knownas assembler.** - **Assembler is a special program (translator) which translates symbolic operation codes into machine codes, and symbolic address is addressed into an actual machineaddress.** - **As shown in figure that the input to assembler is the assembly language program (source program) and the output is the machine language program (object program).** - **Assembler translates each assembly language instruction intoequivalent machine languageinstruction.** - **There is [one to one correspondence] between the assembly language instructions of source program & the machine language instruction of its equivalent object program.** - **In case of assembly language program the computer not only has to runthe program but also must first run assembler program to translate the original assembly language program into machine languageprogram.** - **So the computer has to spend more time in getting desiredanswer.** 5. ### WRITE A NOTE ON COMPILER - **A computer can directly execute only machine languageprograms.** - **So the high level language program must be converted into itsequivalent machine language program before can beexecuted.** - **This translation is done with the help of a translator program which is knownas compiler.** - **A compiler is a translator program which translates a high levellanguage program into equivalent machine languageprogram.** - **The process of translating is shown in belowfigure:** Program program **(SourceProgram) ONE TOMANYCORRESPONDENCE (ObjectProgram)** - **As shown in figure that the input to compiler is the high level languageprogram (source program) and the output is the machine language program (object program).** - **High level language instructions are macroinstructions.** - **The compiler translates each high level language instruction into set ofmachine language instructions rather than a single machine languageinstruction.** - **There is [one to many correspondence] between high level languageinstructions of source program into equivalent objectprogram.** - **During the translation the source program is [only translates notexecuted.]** - **A compiler can translates only those source programs which have written inthe language for which compiler isdesigned.** - **A compiler can also detect & indicates the syntax errors during thecompilation process but[cannot able to detect logicalerrors].** 6. ### WRITE A NOTE ON INTERPRETER. - **Aninterpreterisanothertypeoftranslatorwhichisusedfortranslatingprogram written using high levellanguages.** - **It takes one statement of high level language[, translates into machinelanguage & immediately executes]the resulting machine languageinstructions.** - **The main difference between compiler & interpreter is that compilercan translates the entire code but not involve inexecution.** - **As shown in figure that the input to an interpreter is a source program &the output is the result of an executionprogram.** - **Interpreter translates & executes a high level language program statement-by- statement.** - **A program statement is reinterpreted every time it is encounteredduring programexecution.** - **The main advantage of interpreter is that interpreter makes it easier & fasterto correctprograms.** - **The main disadvantage is that interpreter is slower than compilers whenrunning a finishedprogram.** 7. ###. WHAT IS O PERATINGSYSTEM? - **An operating system is a software program that provides an interfacebetween user & the computer and manages thousands ofapplications.** - **It's a collection of system software that co-ordinates between thehardware, provides a platform for software to runon.** - **An operating system is an integrated set of programs that the resources (the CPU, memory, I/O devices etc) of computer system & provides an interfaceto the user to run themachine.** - **The main two primary objective of operating systemare:** **Making a computer system convenient touse** ![](media/image2.png)**Managing the resources of a computersystem** 1. **[PROCESSMANAGEMENT]** - **The process management of OS taking care about the creation &deletion of user & system process, providing mechanism for process synchronization & processcommunication.** 2. **[MEMORYMANAGEMENT]** - **The memory management of OS taking care about the allocation &deallocation of memory space to the various programs in need ofthis resource.** 3. **[FILEMANAGEMENT]** - **The file management of OS is taking care about the file relatedactivities such as creation, storing, retrieving, naming, sharing & organization of files.** 4. **[SECURITY]** - **The security model of OS protects the resources & information ofa computer system against destruction & unauthorizedaccess.** 5. **[COMMANDINTERPRETATION]** - **This model taking care of interpreting user commands & directingthe system resources to handle therequests.** 8. ### WHAT IS BATCH OPERATINGSYSTEM. - **In Batch operating system, data is collected over a period of time andthe processing of the data is deferred to a latertime.** - **This approach was used very commonly in the past when punch cards served as data storage media and is used as input into the computer system forprocessing.** - **In batch processing, the data have first to be captured, normally as a form of source documents, like time cards, or alternatively, by RJE (Remote Job Entry) where data is gathered through remoteterminals.** - **The data will then be transmitted to the computer or the source document will be physically transported to the data centre where transcription (conversionof source document data into machine readable form) isperformed.** - **The data is processed by the computer and the resulting output is given tothe users.** - **Batch processing is suitable in application where there are large amounts of data and when the turnaround times are notcritical.** - **As data are transcribed into machine readable form before submitting for processing, the speed of processing is therefore determined by the computerand not by theoperator.** - **Payroll processing is suitable for batch processing as it is only performed on a regular basis. ( for example everymonth)** - **Lesscomplicated.** - **After input process is over, while processing is going on, user can attendother jobs.** - **Long turnaroundtime.** - **Access to one is notpossible.** - **Difficult to provide priorityscheduling.** - **Not convenient for programdevelopment.** 9. ### EXPLAIN REALTIME OPERATINSYSTEM. - **Real-Time systems are always on-line but on-line systems need not be real-time systems.** - **However, further constraints are placed in terms of response time and availability of thesystem.** - **By definition, a real time system receive data and process it quickly enoughto produce output which can be used to control or affect the outcome of an ongoing activity ofprocess.** - **In general, real-time systems handle small volumes of data at any one time and the turnaround time iscritical.** - **Feedback is essential in real-time systems so that process

COS 101 Notes on Introduction to Computer Sciences

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