Computer Applications for Management

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Notes are Prepared by Virendra Singh Kushwah, Assistant Professor, Department of Computer Application, HIMCS, Mathura 1

MBA 017: Computer Applications in ManagementMax. Hours: 40

Unit I (10 Sessions)Basic Concepts of Computers :Introduction and definition of computer; functional components of acomputer system-(Input unit, CPU, Memory and output unit); Types of memory and memory hierarchy;Functioning inside a computer; characteristics, advantages and limitations of a computer; classification of computers;Essential Components of computerHardware: (a) Input devices - keyboard, printing devices, voice speech devices, scanner, MICR, OMR, Barcode reader, digital camera etc. (b) Output devices - Visual Display Unit, printers, plotters etc.(c) StorageDevices Magnetic storage devices, Optical storage devices, Flash Memory etc.Software: Introduction; Types of software with examples; Introduction to languages, compiler, interpreterand assembler.Operating System: Definition, Functions, Types and Classification, Elements of GUI based operatingsystem-Windows-Use of menus, tools and commands of windows operating system.

Unit II (12 Sessions)Use of MS-Office: Basics of MS-Word, MS-Excel and MS-PowerPoint; Application of these softwares fordocumentation and making reports; preparation of questionnaires, presentations, tables and reports (Practical)Database Management System: Overview of DBMS; Components of DBMS, Recent trends in database,RDBMS.MS Access: Overview of MS-Access. Creating tables, queries, forms and reports in MS-Access.

Unit III (Session 8)Computer Networks: Overview of Computer Network, Types of computer networks (LAN, WAN andMAN), Network topologies, Components of computer networks (servers, workstations, network interfacecards, hub, switches, cables, etc..)

Internet: Overview of Internet, Architecture & Functioning of Internet, Basic services over Internet likeWWW, FTP, Telnet, Gopher etc., IP addresses, ISPs, URL, Domain names, Web Browsers, InternetProtocols, Search engines, e-mail, Web browsing, searching, downloading & uploading from Internet.

Unit IV (Session 10)E-commerce: Introduction, Comparison between Traditional commerce and E-commerce; Advantages &disadvantages of e-commerce, Buying & Selling on Internet, Issues in Implementing Electronic Commerce.Applications of Information Technology: Information Technology (IT) applied to various functional areasof management, such as Production / Operations, Marketing, Human Resource, Finance and MaterialsManagement.

Suggested Readings

1. Cyganski - Information Technology: Inside and outside (Pearson, 1st

Edition).2. Basandra SK - Computers Today (Galgotia, 1

stEdition).

3. Leon A and Leon M - Introduction to Computers (Leon Vikas, 1st

Edition).4. Leon - Fundamentals of Information Technology, (Vikas)5. Kakkar DN, Goyal R Computer Applications in Management (New Age, 1

stEdition).


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In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to another.

Functional components of a computer system:

Historically, a computer is any device that can store and process data. Today it usually refers to anelectronic device with circuits that allow for data to be manipulated in binary form. So the maincomponents are software (memory and programs to process data) and hardware (devices used forthe storing and processing of that data). And, lastly, an array of components for humans to interactwith the electronic data 'machine.'

Modern computers usually contain the following components: A Motherboard - The backbone of the computer, designed to transfer information and power

to and from all of the major components. Other components are usually plugged into thisdevice, and it is almost always the largest board in the computer. Also called a "Mainboard"or "mobo". The motherboard contains the BIOS (Basic Input/output System) that allows allthe components to communicate with each other.

CPU (Central Processing Unit) - The Central Processing Unit that is usually attached directlyto the motherboard. It is comprised of a chip with usually dozens of pins which areconnected to the motherboard. They are usually obscured by a large heat sink (large metalcomponents which divert heat away from chips, which may or may not have an attached fan,depending on if it is a PC or a Mac).

RAM (Random Access Memory) - Usually Dual-Inline Memory Modules (DIMMs), theyare plugged directly into the motherboard as well. Some high-performance versions arecased in metal which help cool the chips on them. There are usually 8 chips on a stick of RAM (random access memory), sometimes there is a 9th "parity" chip, which helps check for errors within the memory.

ROM (Read Only Memory), usually on a Hard drive - This is usually a large metallicrectangular prism-shaped device about 3.5 inches wide. It stores data onto metal discs withinthe device and has recently come out with capacities as large as 1 TB (Terabyte, or 1000Gigabytes, 1,000,000 Megabytes etc). In the 'old days' these were cards, ticker tape, ormagnetic discs labeled as A drive or B drive. Now most computers have C drive, which isthe hard drive mentioned earlier.

A Power Supply - Computers need specific power voltages for each component and alwayshave a power supply which takes power from the wall and outputs power at specific voltageson specific cable formats within the computer.

The OS - This is the programmed Operating System that is the 'brain' of the computer. If it isa PC it will be a Microsoft derivative of the common Windows systems. It began its earlierdays as DOS (Disk Operating System) which was developed by Bill Gates for IBM. If it isan Apple Mac (Macintosh) computer it will likely be using a Mac OS system developed by


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Notes are Prepared by Virendra Si

Let's take a look at each o

System unit

The system unit is the cunderneath your desk. Insmost important of these cacts as the "brain" of youtemporarily stores informin RAM is erased when th

Almost every other part ointo specific ports (openithe system unit is someti

Storage

Your computer has onedisk. The disk preserves t

Hard disk drive

Your computer's hard diswith a magnetic surface.

serve as your computer'sThe hard disk drive is nor

gh Kushwah, Assistant Professor, Department of Compute

these parts.

ore of a computer system. Usually it's a ride this box are many electronic componentsmponents is the central processing unit (CPcomputer. Another component is random ation that the CPU uses while the computer

e computer is turned off.

f your computer connects to the system unitgs), typically on the back of the system unites called a peripheral device or device.

r more disk drivesdevices that store infoe information even when your computer is t

drive stores information on a hard disk, a riecause hard disks can hold massive amount

primary means of storage, holding almost almally located inside the system unit.

Application, HIMCS, Mathura 5

ectangular box placed on orthat process information. TheU), or microprocessor, whichccess memory (RAM), whichis on. The information stored

using cables. The cables plug. Hardware that is not part of

rmation on a metal or plasticrned off.

gid platter or stack of platterss of information, they usually

l of your programs and files.


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A mouse usually has twoMany mice also have a wscreens of information.

When you move the mou(The pointer's appearanceyou want to select an itebutton. Pointing and clicki

Keyboard

A keyboard is used mainlhas keys for letters and nu

The function keysthey are used.

The numeric keynumbers quickly.

The navigation k document or webp

You can also use your ke

Monitor

A monitor displays inforthat displays the informatshow still or moving pictu There are two basic typedisplay) monitors. Both tymuch thinner and lighter.


buttons: a primary button (usually the left beel between the two buttons, which allows y

se with your hand, a pointer on your screenmight change depending on where it's posit

m, you point to the item and then click (png with your mouse is the main way to inter

y for typing text into your computer. Like thmbers, but it also has special keys:, found on the top row, perform different f

ad, located on the right side of most ke

ys, such as the arrow keys, allow you toage.

Keyboard

board to perform many of the same tasks yo

ation in visual form, using text and graphicion is called the screen. Like a television sres.

of monitors: CRT (cathode ray tube) monpes produce sharp images, but LCD monitorCRT monitors, however, are generally more


tton) and a secondary button.ou to scroll smoothly through

moves in the same direction.ioned on your screen.) Wheness and release) the primaryct with your computer.

e keyboard on a typewriter, it

nctions depending on where

boards, allows you to enter

move your position within a

can perform with a mouse.

s. The portion of the monitorreen, a computer screen can

itors and LCD (liquid crystals have the advantage of beingffordable.


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Printer

A printer transfers data frbut having one allows yoMany people also like bei

The two main types of ppopular printers for the hhigh-quality photographsable to handle heavy use.

Speakers

Speakers are used to playSpeakers allow you to list


LCD monitor (left); CRT monitor (right)

m a computer onto paper. You don't need au to print e-mail, cards, invitations, announg able to print their own photos at home.

rinters are inkjet printers and laser printersme. They can print in black and white or i

when used with special paper. Laser printers

Inkjet printer (left); laser printer (right)

sound. They may be built into the systemn to music and hear sound effects from your

Computer speakers


printer to use your computer,ements, and other materials.

. Inkjet printers are the mostfull colour and can produce

are faster and generally better

nit or connected with cables.computer.


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Modem

To connect your computereceives computer informbuilt into the system unit,

Components of a CoComponents of a compute

1. SoftwareSoftware refers to the proSystem), BASIC, COBOhardware can be the book on it. Another analogy coBoth hardware and softwuseless unless they are pBASIC or COBOL has noof computer.

2. HardwareHardware refers to anykeyboard, hard disk, floppHardware can be compareof blood and oxygen, ithardware. It is capable of

Thus, for computer both s


r to the Internet, you need a modem. A modation over a telephone line or high-speed cbut higher-speed modems are usually separat

Cable modem

puterr can be broadly divided into the following t

grams required to operate a computer. For eL, dBase, Accounting Software etc. arewhich you are reading and, in this case, softld be that brain is hardware but memoryare are dependent on each other. CPU, meovided with instructions and data for storaimportance unless they are used along with

physical component of computer. For exay disk, printer etc. are physical componentsd to a human body capable of doing any actiill not be able to do anything. The same i

doing many things but without software it ju

oftware and hardware components are essent


em is a device that sends andable. Modems are sometimese components.

o categories:

ample, DOS (Disk Operatingll software. An analogy of are would be the text writtentored in brain is software.

mory unit, hard disk etc. arege and processing. Similarly,various hardware components

ple, CPU, monitor (VDU),nd, thus, are all hardware.ity. But without the presencethe case with computer and

t cannot work.

ial.


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Organization of Computer

We will discuss the basic structure of a computer system. The diagram of a generalized architectureof a computer system is shown below. A computer system has the following main components: Input/output unit Central Processing Unit (CPU) Memory unit

Input/Output Unit

The computer is a machine which processes input data according to a given set of instructions andgives output. Before a computer does processing, it should be given data and instructions. Afterprocessing, output should be displayed or printed by computer. The unit used for getting the data

and instructions into computer and displaying or printing output is known as an Input/output Unit(I/O Unit).

There are many peripheral devices which are used as input/output units for a computer. The mostcommon form of an input device is known as terminal. A terminal has an electronic typewriter-like device called keyboard and has a display screen called Visual Display Unit (VDU) ormonitor. Keyboard is the main input device while the monitor can be considered both as an inputas well as an output device. There are some other common input devices like mouse, punch card,tape, joystick, scanner, modem etc. Monitor, printer and plotter are the main peripheral devices usedas output units for a computer.

Central Processing UnitCentral Processing Unit (CPU) is the main component or brain of a computer. It performs all theprocessing of input data. Its function is to fetch, examine and execute the instructions stored in themain memory of a computer. In microcomputers, CPU is built on a single chip or Integrated Circuit(IC) and is called a microprocessor. A CPU consists of the following distinct parts:

Arithmetic Logic Unit (ALU) Control Unit (CU) Registers Buses Clock

Arithmetic Logic Unit (ALU)The arithmetic and logic unit of CPU is responsible for all arithmetic operations like addition,subtraction, multiplication and division as well as logical operations, such as less than, equal to andgreater than. All calculations and comparisons are performed in arithmetic logic unit.


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ClockA clock is another important component of CPU. It measures and allocates a fixed time slot forprocessing each and every micro-operation (smallest functional operation). In simple terms, CPU isallocated one or more clock cycles to complete a micro-operation. CPU executes the instructions insynchronization with the clock pulse. The clock speed of CPU is measured in terms of Mega Hertz(MHz) or Millions of Cycles per second. The clock speed of CPU varies from one model to anotherin the range 4.77 MHz (in 8088 processor) to 266 MHz (in Pentium II). The speed of CPU is also

specified in terms of Millions of Instructions per Second (MIPS) or Million of Floating PointOperations per Second (MFLOPS).

Memory Unit

Memory unit is that component of a computer system which is used to store data, instructions andinformation before, during and after the processing by ALU. It is actually a work area (physically acollection of integrated circuits) within a computer where CPU stores data and instructions. It is alsoknown as a main/primary/internal memory.


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Input Devices

Input devices are used to input data, information and instructions into RAM. These devices can beclassified into the following two broad categories: Basic input devices Special input devicesThe structure and function of common input devices of these two categories are discussed below indetail.

Basic Input DevicesThe input devices which have now-a-days become essential to operate a PC (personal computer)may be called as basic input devices. These devices are always required for basic input operations.These devices include keyboard and mouse.

1. KeyboardKeyboard (similar to a typewriter) is the main input device of a computer. It contains three types of keys-- alphanumeric keys, special keys and function keys. Alphanumeric keys are used to type allalphabets, numbers and special symbols like $, %, @, A etc. Special keys such as , ,, , etc. are used for special functions. Function keys such as ,, etc. are used to give special commands depending upon the software used. The functionof each and every key can be well understood only after working on a PC. When any key is pressed,an electronic signal is produced. This signal is detected by a keyboard encoder that sends a binarycode corresponding to the key pressed to the CPU. There are many types of keyboards but 101 keyskeyboard is the most popular one.

2. MouseMouse (similar to a mouse) is another important input device. It is a pointing device used to movecursor, draw sketches/diagrams, select text/object/menu item etc. on monitor screen while workingon Windows (graphics-based environment of a computer). Mouse is a small, palm size boxcontaining three buttons and a ball underneath which senses the movement of the mouse and sendsthe corresponding signals to CPU on pressing the buttons.

Special Input DevicesThe input devices which are not essential to operate a PC are called as special input devices.These devices are used for various special purposes, and are generally not required for basic inputoperations. These devices include trackball, light pen, touch screen, joystick, digitizer, scanner,OMR, OCR, bar code reader, MICR and voice input devices.


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1. TrackballA trackball looks like a mouse. It has a roller on the top with selection buttons on the side . It is alsoa pointing device used to move the cursor and works like a mouse. For moving cursor in a particulardirection, the user spins the ball in that direction. It is sometimes considered better than a mousebecause it requires little arm movement and less desktop space. It is generally used with portablecomputers.

2. Light PenLight pen (similar to a pen) is a pointing device which is used to select a displayed menu item or

draw pictures on the monitor screen. It consists of a photocell and an optical system placed in asmall tube. When its tip is moved over monitor and pen button is pressed, its photocell-sensingelement detects the screen location and sends corresponding signal to CPU.

3. Touch ScreenSome special VDU devices have touch sensitive screens. These screens are sensitive to humanfingers and act as tactile input devices. Using touch screen, the user can point to a selection on thescreen instead of pressing keys. Touch screen helps users to get information quickly. It is mainlyused in hotels or airports to convey information to visitors.

4. JoystickJoystick is also a pointing device used to move cursor position on a monitor screen. It is a stick

having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket.It can be moved in all the four directions. The function of a joystick is similar to that of a mouse. Itis mainly used in Computer-Aided Designing (CAD) and playing computer games.


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5. DigitizerA digitizer is used to create drawings and pictures with the help of a digitizer tablet by a processcalled digitizing. Digitizing is a process by which graphic representations are converted into digitaldata. A digitizer consists of the following three main parts: A flat surface called tablet A small hand held mouse-like device called puck A special pen like device called stylus

The puck is used to input existing drawings into the computer. The stylus is used to trace existingdrawings placed on tablet. It is also used to draw new drawings on a piece of paper placed on tablet.The user makes contact to the tablet with stylus. As the stylus is connected to the tablet by a wire,the traced image is stored in RAM and displayed on monitor.

6. ScannerA scanner is widely used in Desktop Publishing (DTP) applications. It is used for digitizing imagessuch as photographs, forms, documents etc. in computer memory. There are many types of scannerswhich can also read text by converting them to digital code. The scanners are very useful forconverting the typed pages into word processing files. Graphic scanners convert a printed image intovideo image without converting it to digital code.

7. Optical Mark Reader (OMR)Optical Mark Reader (OMR) is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. Itis especially used for checking answer sheets of examination having multiple-choice questions. Theanswer sheet contains special marks such as squares or bubbles. The student fills in these squareswith soft pencil or ink to indicate the correct choice. The OMR detects these marks and sendscorresponding signals to the processor. If a mark is present, the amount of reflected light is reducedand, thus, OMR detects the presence of mark for each and every answer. These are widely used foralmost all competitive examinations having objective type questions.


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8. Bar Code ReaderBar code reader is an optidark lines). The bar codbetween them. The bar cwhich are then processenumbering the books, or e

9. Optical Character ReOptical Character Readercharacters typed or printilluminated by a low freqreflect it. The photocellcorresponding to dark anreading of passenger tickeservices.

10. Magnetic Ink CharaMagnetic Ink Charactercharacters mainly foundspecial ink called magnethem with special patternsprocessed in a day. It is w

11. Digital CameraA digital camera (alsophotographs, or both, digidigital still cameras cancentury cameras are digitaDigital cameras can do thithey are recorded, storingwith sound, and deletingelementary image editing.lens with a variable diapshutter admit the correct ais electronic rather than ch


cal scanner used for reading bar coded datad data consists of a number of bars of vde reader reads the bar coded data and co

d by computer. Bar coded data is generncoding ID or A/c numbers.

der (OCR)(OCR) is an optical scanner which is capaed on paper using an OCR font. The texency light source. The dark areas on the text

of OCR device receive this reflected lid light areas. OCR devices are used for lats, computer printed bills of credit card com

ter Recognition (MICR)Recognition (MICR) is used to recognion bank cheques. The magnetically chargic ink. MICR device reads the patterns of tstored in memory. Using MICR device, a la

idely used by banking industry for the proces

digicam or camera for short) is a camtally by recording images via an electronicrecord sound and moving video as well asl.ngs film cameras cannot: displaying imagesthousands of images on a single small me

images to free storage space. Some can croThe optical system works the same as in fi

hragm to focus light onto an image pickumount of light to the imager, just as with filemical.


(data in the form of light andrying thickness and spacingverts it into electrical pulseslly used in labeling goods,

le of detecting alphanumerict which is to be scanned isabsorb light while light areasht and provide binary data

rge volume applications likeanies and ZIP codes in postal

e the magnetically chargeded characters are written byhese characters and comparesrge volume of cheques can besing of cheques.

ra that takes video or stillimage sensor. Many compactstill photographs. Most 21st

on a screen immediately aftermory device, recording videop pictures and perform otherlm cameras, typically using a

device. The diaphragm andbut the image pickup device


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Voice-Input Devices

Voice-input devices are the latest input devices that can recognize human voice. They seem to bevery useful but are not popular due to storage of limited vocabularies and variations in the way of pronouncing words by different persons.

Output Devices

Output devices are hardware components which are used to display or print the processedinformation. The structure, working and uses of common output devices is discussed below.

1. MonitorVisual Display Unit (VDU), commonly known as monitor, is the main output device of a computer .It consists of a Cathode Ray Tube (CRT) which displays characters as an output. It forms imagesfrom tiny dots, called pixels. Pixels are arranged in a rectangular form. The sharpness of image(screen resolution) depends upon the number of pixels.

Types of MonitorsDepending upon the resolution, monitors can be classified as follows:(a) CGA (Color Graphics Adapter)b) MDA (Monochrome Display Adapter)(c) HGA (Hercules Graphics Adapter)(d) EGA (Enhanced Graphics Adapter)(e) VGA (Video Graphics Adapter)(f) SVGA (Super VGA)

The differences between these monitors are summarized below. Depending upon the color of display, monitors can be classified as monochrome (with single color/ black and white display) andcolor (with all colors display) monitors.


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2. PrinterPrinter is the most important output device. It is used to print information on paper. It is essential forgetting output of any computer-based application.

Types of PrintersPrinters can be broadly categorized into the following two types:

1. Impact PrintersThe printers that print the characters by striking against the ribbon and onto the paper are calledimpact printers. These are of two types:

(a) Character PrintersThese printers print one character at a time. These printers are further of two types:

(i) Daisy Wheel PrintersThese printers print the characters by a mechanism that uses a plastic or metal hub with spokes,called daisy wheel (refer to figure 2.20). The characters are embossed on the radiating spokes andprinted by striking these spokes against the ribbon and paper. These printers give a good quality butare more expensive than dot matrix printers.

(ii) Dot Matrix PrintersThese printers print the characters by putting dots onto paper. They do not give better printingquality than daisy wheel printers but are faster in speed. The printing speed of a dot matrix printercan be upto 360 cps (characters per second). They are widely used with microcomputers.

(b) Line PrintersThese printers print one line at a time. Their printing speed is much more than character printers.They are also of two types:

(i) Drum PrintersThese printers print line by a rotating drum having a ring of characters for each print position. Thehammers strike each character of the drum simultaneously so that entire line is printed in one fullrotation of the drum. These printers are also called as barrel printers. The printouts obtained fromthese printers have even character spacing but uneven line height.

(ii) Chain PrintersThese printers print the line by a rotating chain having ring characters for each print position. Theirprinting mechanism is similar to drum printers. The printouts, thus, obtained from these printershave uneven character spacing but even line height.


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2. Non-Impact PrintersThe printers that print the characters without striking against the ribbon and onto the paper are callednon-impact printers. These printers print a complete page at a time and, therefore, are also calledas page printers. Page printers are of three types:

(a) Laser PrintersThese printers look and work like photocopiers. They are based on laser technology which is thelatest development in high speed and high quality printing. In these printers, a laser beam is used towrite an image on a paper. First, the image is formed by electrically charged thousands of dots on apaper by laser beam. Then, the paper is sprayed with a toner having the opposite charge and ispassed over a heated roller to make the image permanent. Laser printers are very popular and havebecome an essential part of DTP. Although laser printers are costlier than dot matrix yet they aregenerally preferred in all offices due to their high quality of printing. There are many models of laser printers depending upon the speed and number of dots printed. The latest model of laser printeris 1200 DPI (dots per inch) which can print 10 pages per minute. Some high-speed laser printersgive a speed of upto 100 pages per minute.

(b) Inkjet PrintersThese printers print characters by spraying electrically charged ink on paper. These printers givebetter quality than character printers but not better than laser printers. They are cheaper than laserprinters and hence used widely in many offices. They also offer an option of using color cartridgesfor multi-color printing.

(c) Thermal PrintersThese printers print characters by melting a wax-based ink off a ribbon onto a special heat sensitivepaper. They give letter-quality printing but are relatively expensive in maintenance than otherprinters.

PlotterPlotter is an important output device which is used to print high quality graphics and drawings.Although the graphics can be printed on printers yet the resolution of such printing is limited.Plotters are generally used for printing/drawing graphical images such as charts, drawings, maps etc.of engineering and scientific applications.


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Some important types of plotters are discussed below:

1. Flat Bed PlottersThese plotters print the graphical images by moving the pen on stationary flat surface material. Theyproduce very accurate drawings.

2. Drum PlottersThese plotters print graphical images by moving both the pen and the drum having paper. They donot produce as accurate drawings as printed by flat bed plotters.

3. Inkjet PlottersThese plotters use inkjets in place of pens. They are faster than flat bed plotters and can print multi-colored large drawings.

Computer Output MicrofilmComputer Output Microfilm (COM) is a technique to produce output on a microfilm media(microfilm reel or microfiche card). (Refer to figure 2.30) A microfilm is a continuous filmstrip thatcan store several thousand miniaturized document pages. A microfiche card is a 4 x 6 inch filmsheet which can store several hundred pages. The process of producing microfilm or microfichetakes place on a special COM unit. The information recorded on the microfilm is read with the helpof a microfilm viewing system. It is generally easier to read a microfiche than microfilm. COM isparticularly useful for organizations which need to store and manipulate large amount of data. Ithelps them in tremendous savings in paper and document handling costs.

Storage Devices1. Magnetic storage devicesMagnetic storage and magnetic recording are terms from engineering referring to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in amagnetizable material to store data and is a form of non-volatile memory. The information isaccessed using one or more read/write heads. As of 2009, magnetic storage media, primarily harddisks, are widely used to store computer data as well as audio and video signals. In the field of computing, the term magnetic storage is preferred and in the field of audio and video production,the term magnetic recording is more commonly used. The distinction is less technical and more amatter of preference. Other examples of magnetic storage media include floppy disks, magneticrecording tape, and magnetic stripes on credit cards.


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2. Optical storage devices Optical storage is a term from engineering referring to the storage of data on an optically readablemedium. Data is recorded by making marks in a pattern that can be read back with the aid of light. Acommon modern technique used by computers involves a tiny beam of laser light precisely focusedon a spinning disc. An older example, that does not require the use of computers, is microform.There are other means of optically storing data and new methods are in development. Opticalstorage differs from other data storage techniques that make use of other technologies such asmagnetism or semiconductors. Optical storage can range from a single drive reading a single CD-ROM to multiple drives reading multiple discs such as an optical jukebox. Single compact discs canhold around 700MB (megabytes) and optical jukeboxes can hold much more. Ex: the TeraStack Solution from Hie Electronics can hold 78TB (terabytes) and the DISC7000 from DISC can hold25.5 to 34.5TB. The term optical drive usually refers to a device in a computer that can read CD-ROMs or other optical discs.

3. Flash memoryFlash memory is a non-volatile computer storage technology that can be electrically erased andreprogrammed. It is primarily used in memory cards, USB flash drives, and solid-state drives forgeneral storage and transfer of data between computers and other digital products. It is a specifictype of EEPROM (electrically-erasable programmable read-only memory) that is erased andprogrammed in large blocks; in early flash the entire chip had to be erased at once. Flash memorycosts far less than byte-programmable EEPROM and therefore has become the dominant technologywherever a significant amount of non-volatile, solid state storage is needed. Example applicationsinclude PDAs (personal digital assistants), laptop computers, digital audio players, digital camerasand mobile phones. It has also gained popularity in console video game hardware, where it is oftenused instead of EEPROMs or battery-powered static RAM (SRAM) for game saves data.

Since flash memory is non-volatile, no power is needed to maintain the information stored in thechip. In addition, flash memory offers fast read access times (although not as fast as volatile DRAMmemory used for main memory in PCs) and better kinetic shock resistance than hard disks. Thesecharacteristics explain the popularity of flash memory in portable devices. Another feature of flashmemory is that when packaged in a "memory card," it is extremely durable, being able to withstandintense pressure, extremes of temperature, and even immersion in water.


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Binary Logic

Binary logic deals with binary variables and logical operations. The binary variables are denoted byx, y, z, A, B, C etc. that can have only two distinct values (e.g., 1 and 0, true or false, yes or no etc.).There are three basic logical operations-- AND, OR and NOT. In binary logic, if x and y are twobinary variables, x.y (read as x AND y) represents AND operation and x+y (read as x OR y) ORoperation. The NOT operation is represented by x'.

It follows that for each combination of the values of x and y, there is a value for x+y, x.y, and x' asspecified by the definition of logical operations. The definitions of AND, OR and NOT logicaloperations is demonstrated in tables, called truth tables.

Bits and BytesBit stands for binary digit. It is a single digit in binary number which can be either 0 or 1. Withina computer, a single bit can be stored in many ways, generally by using transistor, multi-vibrator(flip-flops-- circuits made of logic gates), or a capacitor as on/off switch. If a bit is OFF, its valueis considered 0 and if it is ON, its value is 1. Bit is the smallest unit of data in a computer.

A single bit alone does not provide much information but a combination of 8 bits is enough to storeall alphabets, numbers and other characters used by computer. The group of 8 bits is known as abyte. For example, when a user types A (1 byte) on the keyboard, the system delivers a signalwhich sets input location to the bit value 01000000. In memory, each byte occupies a unique address(storage location). Byte is considered as the smallest unit of memory. There are higher units of memory such as word, kilobyte, megabyte, gigabyte and terabyte. These are illustrated in table 2.2given below:

Unit of Memory Equivalent UnitsByte 8 bitsWord 2 bytesDouble word 4 bytesQuad word 8 bytesParagraph 16 bytesKilobyte (K) 1024 bytesMegabyte (MB) 1024 KGigabyte 1024 MBTerabyte 1024 GBPetabyte 1024 TB


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Characteristics of Computer

Now-a-days computer is playing a main role in everyday life it has become the need of people justlike television, telephone or other electronic devices at home. It solves the human problems veryquickly as well as accurately. The important characteristics of a computer are described below:

1. Speed The computer is a very high speed electronic device. The operations on the data inside the computerare performed through electronic circuits according to the given instructions. The data andinstructions flow along these circuits with high speed that is close to the speed of light. Computercan perform million of billion of operations on the data in one second. The computer generatessignals during the operation process therefore the speed of computer is usually measure in megahertz (MHz) or gega hertz (GHz). It means million cycles units of frequency is hertz per second.Different computers have different speed.

2. Arithmetical and Logical Operations A computer can perform arithmetical and logical operations. In arithmetic operations, it performsthe addition, subtraction, multiplication and division on the numeric data. In logical operation itcompares the numerical data as well as alphabetical data.

3. Accuracy In addition to being very fast, computer is also very accurate device. it gives accurate output resultprovided that the correct input data and set of instructions are given to the computer. It means thatoutput is totally depended on the given instructions and input data. If input data is in-correct then theresulting output will be in-correct. In computer terminology it is known as garbage-in garbage-out.

4. Reliability The electronic components in modern computer have very low failure rate. The modern computercan perform very complicated calculations without creating any problem and produces consistent(reliable) results. In general, computers are very reliable. Many personal computers have neverneeded a service call. Communications are also very reliable and generally available wheneverneeded.

5. Storage A computer has internal storage (memory) as well as external or secondary storage. In secondarystorage, a large amount of data and programs (set of instructions) can be stored for future use. Thestored data and programs are available any time for processing. Similarly information downloadedfrom the internet can be saved on the storage media.

6. Retrieving data and programs The data and program stored on the storage media can be retrieved very quickly for furtherprocessing. It is also very important feature of a computer.


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7. Automation A computer can automatically perform operations without interfering the user during the operations.It controls automatically different devices attached with the computer. It executes automatically theprogram instructions one by one.

8. Versatility Versatile means flexible. Modern computer can perform different kind of tasks one by one of simultaneously. It is the most important feature of computer. At one moment your are playing gameon computer, the next moment you are composing and sending emails etc. In colleges anduniversities computers are use to deliver lectures to the students. The talent of computer isdependent on the software.

9. Communications Today computer is mostly used to exchange messages or data through computer networks all overthe world. For example the information can be received or send throug the internet with the help of computer. It is most important feature of the modern information technology.

10. Diligence A computer can continually work for hours without creating any error. It does not get tired whileworking after hours of work it performs the operations with the same accuracy as well as speed asthe first one.

11. No Feelings Computer is an electronic machine. It has no feelings. It detects objects on the basis of instructionsgiven to it. Based on our feelings, taste, knowledge and experience: we can make certain decisionsand judgments in our daily life. On the other hand, computer cannot make such judgments on theirown. Their judgments are totally based on instructions given to them.

12. Consistency People often have difficulty to repeat their instructions again and again. For example, a lecturer feelsdifficulty to repeat a same lecture in a class room again and again. Computer can repeat actionsconsistently (again and again) without losing its concentration:

To run a spell checker (built into a word processor) for checking spellings in a document. To play multimedia animations for training purposes. To deliver a lecture through computer in a class room etc.

A computer will carry out the activity with the same way every time. You can listen a lecture orperform any action again and again.

13. Precision Computers are not only fast and consistent but they also perform operations very accurately andprecisely. For example, in manual calculations and rounding fractional values (That is value withdecimal point can change the actual result). In computer however, you can keep the accuracy andprecision upto the level, you desire. The length calculations remain always accurate.


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Advantages and Disadvantages of a computer

Advantages

1. It helps you automate various tasks that you cannot do manually.2. It helps you organize your data and information in a better way.3. It has much more computing and calculating power then an ordinary human.4. It may help your work to be a lot easier.5. It may be the storage of your important data and files.6. It may be your hand book.7. It may help you solve problems faster than an ordinary human being can do.8. It has speed, storage, reliability, consistency and communications.9. It helps you to find useful information using the Internet. 10. It helps in businesses, factories,offices, schools and homes.

Disadvantages

1. It destroys your social life and interactions with humans if you do not maintain the balance.2. It may effect to the destruction of your eye sight due to radiation.3. It may cause pimples and wrinkles.4. It may damage your studies and life.5. Too much time in front of monitor may adverse effect your eye sight and can also make you fat.6. The way it distracts and can deviate our thoughts and activities towards unproductive activities.7. It could cause violation of privacy, impact on labor force, health risks, impact on environment,distraction from work, and possible antisocial influences.8. Getting away from their real life and getting into bad lines


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Classification of computers

Computers can be classified, or typed, many ways. Some common classifications are summarizedbelow.

Classes by Size

1. Microcomputers (Personal computers)Microcomputers are the most common type of computers in existence today, whether at work inschool or on the desk at home. The term "microcomputer" was introduced with the advent of singlechip microprocessors. The term "microcomputer" itself, is now practically an anachronism.These computers include:

Desktop computers Laptop and notebook computers Tablet PC Palmtop computers Personal digital assistants (more commonly known as PDA's) Programmable calculator

2. Minicomputers (Midrange computers)A minicomputer (colloquially, mini ) is a class of multi-user computers that lies in the middle rangeof the computing spectrum, in between the largest multi-user systems (mainframe computers) andthe smallest single-user systems (microcomputers or personal computers). The contemporary termfor this class of system is midrange computer, such as the higher-end SPARC, POWER and Itanium-based systems from Sun Microsystems, IBM and Hewlett-Packard.

3. Mainframe ComputersThe term mainframe computer was created to distinguish the traditional, large, institutionalcomputer intended to service multiple users from the smaller, single user machines. Thesecomputers are capable of handling and processing very large amounts of data quickly. Mainframecomputers are used in large institutions such as government, banks and large corporations. Theseinstitutions were early adopters of computer use, long before personal computers were available toindividuals. "Mainframe" often refers to computers compatible with the computer architecturesestablished in the 1960s. Thus, the origin of the architecture also affects the classification, not justprocessing power.

Mainframes are measured in millions of instructions per second or MIPS. An example of integeroperation is moving data around in memory or I/O devices. A more useful industrial benchmark istransaction processing as defined by the Transaction Processing Performance Council. Mainframesare built to be reliable for transaction processing as it is commonly understood in the businessworld: a commercial exchange of goods, services, or money. A typical transaction, as defined by theTransaction Processing Performance Council, would include the updating to a database system forsuch things as inventory control (goods), airline reservations (services), or banking (money). Atransaction could refer to a set of operations including disk read/writes, operating system calls, orsome form of data transfer from one subsystem to another.


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4. SupercomputerA supercomputer is focused on performing tasks involving intense numerical calculations such asweather forecasting, fluid dynamics, nuclear simulations, theoretical astrophysics, and complexscientific computations. A supercomputer is a computer that is at the frontline of current processingcapacity, particularly speed of calculation. The term supercomputer itself is rather fluid, and today'ssupercomputer tends to become tomorrow's ordinary computer. Supercomputer processing speedsare measured in floating point operations per second or FLOPS. Example of floating point operationis the calculation of mathematical equations in real numbers. In terms of computational capability,memory size and speed, I/O technology, and topological issues such as bandwidth and latency,Supercomputers are the most powerful. Supercomputers are very expensive and not cost-effective

just to perform batch or transaction processing. Transaction processing is handled by less powerfulcomputer such as server computer or mainframe.

Classes by function

1. ServersServer usually refers to a computer that is dedicated to providing a service. For example, a computerdedicated to a database may be called a "database server". "File servers" manage a large collectionof computer files. "Web servers" process web pages and web applications. Many smaller servers areactually personal computers that have been dedicated to providing services for other computers.

2. WorkstationWorkstations are computers that are intended to serve one user and may contain special hardwareenhancements not found on a personal computer.

3. Embedded computersEmbedded computers are computers that are a part of a machine or device. Embedded computersgenerally execute a program that is stored in non-volatile memory and is only intended to operate aspecific machine or device. Embedded computers are very common. Embedded computers aretypically required to operate continuously without being reset or rebooted, and once employed intheir task the software usually cannot be modified. An automobile may contain a number of embedded computers; however, a washing machine and a DVD player would contain only one. Thecentral processing units (CPUs) used in embedded computers are often sufficient only for thecomputational requirements of the specific application and may be slower and cheaper than CPUsfound in a personal computer.


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Types of memory and memory hierarchy

A personal computer must have a means of storing information (data) and instructions so that it canperform processing tasks on the data. Personal computers have two types of memory. These arediscussed below.

Read Only Memory (ROM)

ROM is a small area of permanent memory that provides startup instructions when the computer isturned on. You cannot store any data in ROM. The instructions in ROM are set by the manufacturerand cannot be changed by the user. The last instruction in ROM directs the computer to load theoperating system.Every computer needs an operating system. This is a special computer program that must be loadedinto memory as soon as the computer is turned on. Its purpose is to translate your instructions inEnglish into Binary so that the computer can understand your instructions. The operating systemalso translates the results generated by your computer into English when it is finished so that we canunderstand and use the results. The operating system comes with a computer.

Random Access Memory (RAM)

This is the area of memory where data and program instructions are stored while the computer is inoperation. This is temporary memory. NOTE: The data stored in RAM is lost forever when the

power is turned off. For this reason it is very important that you save your work before turning off your computer. This is why we have peripheral storage devices like your computers hard disk andfloppy diskettes.

Permanent Memory (Auxiliary Storage)

Your files are stored in permanent memory only when saved to your disk in a: drive or saved to yourcomputer's hard disk,When an electric current flows through a circuit, the circuit is on. When no electricity flows, thecircuit is off. An on circuit is represented by the number one (1) and an off circuit is representedby the number zero (0). The two numbers 1 and 0 are called bits. The word bit comes from binarydigit. Each time a computer reads an instruction, it translates that instruction into a series of bits,1s and 0s. On most computers every character from the keyboard is translated into eight bits, acombination of eight 1s and 0s. Each group of eight bits is called a byte.

Byte The amount of space in memory or on a disk needed to store one character. 8 bits = 1 Byte

Since computers can handle such large numbers of characters at one time, metric prefixes arecombined with the word byte to give some common multiples you will encounter in computerliterature.

Kilo means 1000 Kilobyte (KB) = 1000 BytesMega means 1,000,000 Megabyte (MB) = 1,000,000 BytesGiga Means 1,000,000,000 Gigabyte (GB) = 1,000,000,000 Bytes


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There are many types of computer memory modules available. In this day and age, computers(laptops, PCs, etc.) generally do not use a single type of memory; rather, a combination of memorychips and modules are normally found in today's computers, depending on requirements andapplications. The following is an overview of the types of computer memory:

SIMM (Single In-Line Memory Module) Dating back to the days of 286, 386, and 486 PCs,SIMMs are generally plug-in memory modules that are inserted into the CPU motherboard (or anextended memory board). A SIMM can be comprised of BEDO (Burst Extended Data Out DynamicRandom Access Memory), DRAM (Dynamic Random Access Memory) or EDO (Extended DataOut Dynamic Random Access Memory), with the memory chips (one or more) soldered on a PCB(printed circuit board). As mentioned above, it is the SIMM that is plugged into the CPUmotherboard or memory extend card to expand the memory capability of the computer. Generally,when one is adding memory to a computer, it is in the form of a SIMM. Early SIMMs handled 8data bits at a time in a 30-pin configuration; later, when CPUs were processing 32-bits, newergeneration SIMMs was constructed in a 72-pin configuration.

DIMM (Dual In-Line Memory Module) DIMMs have two rows of DRAM, BEDO, or EDOmemory chips. DIMMS allow for double the memory on the same size printed circuit board. Atypical DIMM would be constructed in a 168-pin configuration and handle 64 data bits at a time.

SODIMM (Small Outline Dual In-Line Memory Module) SODIMMs are generally found innotebook computers and are smaller than standard DIMMs. In general, there are 2 types of SODIMMs the first handling 32 data bits at a time with a 72-pin configuration, and the secondhandling 64 data bits with a 144-pin configuration. RIMM (Rambus In-Line Memory Module)Rambus Inc. in coordination with Intel developed a new memory technology called Direct RDRAM,with the in-line modules known as RIMMs. RIMMs have a 184-pin configuration and deliver a peak transfer rate of 1.6 Gigabytes per second (in 16 data bit segments). SORIMM (Small OutlineRambus In-Line Memory Module) SORIMMs have a similar outline as a SODIMM, but use theRambus memory technology. Different Types of Memory Chips:

DRAM (Dynamic Random Access Memory) The most common type of computer memory.DRAMs hold data for a relatively brief period of time and need to be refreshed at regular intervals.DRAMs are measured by access time (in nanoseconds, or ns) and storage capacity (in megabytes, orMB). EDO (Extended Data Out) Memory Higher-performing memory than DRAM, with a gain inperformance of roughly 10-15% over DRAM. BEDO (Burst Extended Data Out) Memory Higher-performing memory than EDO, with a gain in performance of roughly 13% over EDO. SDRAM(Static Dynamic Random Access Memory) A memory chip that retains memory and does not needrefreshing. Another advantage of SDRAM is that it synchronizes with the CPU timing. Althoughfaster than DRAM, it is also more expensive; available in speeds from 66 to 266 MHz. DDRSDRAM (Double Data Rate Synchronous Dynamic Random Access Memory) A memory integratedcircuit that permits transactions on the rising as well as the falling edges of the clock cycle, with abus clock speed of 100 MHz with a data transfer rate of 200 MHz.

OTHER MEMORY TYPES VRAM (Video Random Access Memory) VRAM is a video versionof fast page mode memory and is found primarily in video accelerator cards.


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Flash Memory A memorandom access memory amemory. Advantages of reason, flash memory is u

Shadow RAM (Randominstructions to start the co(basic input output systemtransfer of selected segme


y chip that is non-volatile, re-writable thatnd a hard disk drive. In the case of powerflash memory include low voltage, durabiled in printers, pagers, digital cameras, audio

Access Memory) During the booting up of amputer and video are stored in ROM (read o). Since ROM normally executes slowly, Shnts of the BIOS code from ROM to RAM m


functions like a combinationbeing lost, data is retained inity and high speed; for thisrecorders and cell phones.

computer, a minimal set of ly memory), known as BIOSdow RAM allows for themory (which is faster).


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Introduction of Software

Computer software , or just software , is the collection of computer programs and related data thatprovide the instructions telling a computer what to do. The term was coined to contrast to the oldterm hardware (meaning physical devices). In contrast to hardware, software is intangible, meaningit "cannot be touched". Software is also sometimes used in a more narrow sense, meaningapplication software only. Sometimes the term includes data that has not traditionally beenassociated with computers, such as film, tapes and records.

Types of software

Practical computer systems divide software systems into three major classes: system software,programming software and application software, although the distinction is arbitrary, and often

blurred.System softwareSystem software helps run the computer hardware and computer system. It includes a combinationof the following:

device drivers operating systems servers utilities window systems

The purpose of systems software is to unburden the applications programmer from the oftencomplex details of the particular computer being used, including such accessories ascommunications devices, printers, device readers, displays and keyboards, and also to partition thecomputer's resources such as memory and processor time in a safe and stable manner. Examples are- Microsoft Windows, Linux, and Mac OS X.

Programming softwareProgramming software usually provides tools to assist a programmer in writing computer programs,and software using different programming languages in a more convenient way. The tools include:

compilers debuggers interpreters linkers text editors

An Integrated development environment (IDE) is a single application that attempts to manage allthese functions.

Application softwareApplication software allows end users to accomplish one or more specific (not directly computerdevelopment related) tasks. Typical applications include:


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Advantages of Machine Languagei) It makes fast and efficient use of the computer.ii) It requires no translator to translate the code i.e. directly understood by the computer

Disadvantages of Machine Language: i) All operation codes have to be rememberedii) All memory addresses have to be remembered.iii) It is hard to amend or find errors in a program written in the machine languageiv) These languages are machine dependent i.e. a particular Machine language can be used on onlyone type of computer

Assembly Language: It was developed to overcome some of the many inconveniences of machinelanguage. This is another low level but a very important language in which operation codes andoperands are given in the form of alphanumeric symbols instead of 0s and ls. These alphanumericsymbols will be known as mnemonic codes and can have maximum up to 5 letter combination e.g.ADD for addition, SUB for subtraction, START, LABEL etc. Because of this feature it is alsoknown as Symbolic Programming Language. This language is also very difficult and needs a lot of practice to master it because very small English support is given to this language. The languagemainly helps in compiler orientations. The instructions of the Assembly language will also beconverted to machine codes by language translator to be executed by the computer.

Advantages of Assembly Languagei) It is easier to understand and use as compared to machine language.ii) It is easy to locate and correct errors.iii) It is modified easily

Disadvantages of Assembly Languagei) Like machine language it is also machine dependent.ii) Since it is machine dependent therefore programmer should have the knowledge of the hardwarealso.

2. High Level LanguagesHigh level computer languages give formats close to English language and the purpose of developing high level languages is to enable people to write programs easily and in their own nativelanguage environment (English). High-level languages are basically symbolic languages that useEnglish words and/or mathematical symbols rather than mnemonic codes. Each instruction in thehigh level language is translated into many machine language instructions thus showing one-to-many translation

Types of High Level LanguagesMany languages have been developed for achieving different variety of tasks, some are fairlyspecialized others are quite general purpose.

These are categorized according to their use as


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Disadvantages of High Level Language A high-level language has to be translated into the machine language by a translator and

thus a price in computer time is paid. The object code generated by a translator might be inefficient Compared to an equivalent

assembly language program

Compiler, Interpreter and Assembler

1. Compiler: A compiler is a computer program (or set of programs) that transforms source codewritten in a programming language (the source language ) into another computer language (thetarget language , often having a binary form known as object code ). The most common reason forwanting to transform source code is to create an executable program.

A program that translates from a low level language to a higher level one is a decompiler . Aprogram that translates between high-level languages is usually called a language translator , sourceto source translator , or language converter .

2. Interpreter: A program that executes instructions written in a high-level language. There are twoways to run programs written in a high-level language. The most common is to compile theprogram; the other method is to pass the program through an interpreter.

An interpreter translates High-level instructions into an intermediate form, which it then executes. Incontrast, a compiler translates high-level instructions directly into machine language. Compiledprograms generally run faster than interpreted programs. The advantage of an interpreter, however,is that it does not need to go through the compilation stage during which machine instructions aregenerated. This process can be time-consuming if the program is long.

3. Assembler: A program that translates programs from assembly language to machine language.An assembler converts machine-manipulation coding directly into binary machine instructions.Produces the most efficient executables, but is the most difficult (for humans) to work with.


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Definition of Operating System

An Operating System is a software program or set of programs that mediate access between physicaldevices (such as a keyboard, mouse, monitor, disk drive or network connection) and applicationprograms (such as a word processor, World-Wide Web browser or electronic mail client).

Some characteristics of an Operating System are: Whether multiple programs can run on it simultaneously: multi-tasking Whether it can take advantage of multiple processors: multi-processing Whether multiple users can run programs on it simultaneously: multi-user Whether it can reliably prevent application programs from directly accessing hardware

devices: protected Whether it has built-in support for graphics. Whether it has built-in support for networks.

Some popular Operating System's are: UNIX: multi-tasking, multi-processing, multi-user, protected, with built-in support for

networking but not graphics. Windows NT: multi-tasking, multi-processing, single-user, protected, with built-in support

for networking and graphics. Windows 95/98: multi-tasking, multi-processing, single-user, unprotected, with built-in

support for networking and graphics. Windows 3.x: single-tasking, single-processing, single-user, unprotected, with built-in

support for graphics but not networking. DOS: single-tasking, single-processing, single-user, unprotected with no built-in support for

graphics or networking. NetWare: multi-tasking, multi-processing, single-user, unprotected, with built-in support for

networking but not graphics.


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Functions of Operating System

Today most operating systems perform the following important functions:1. Processor management , that is, assignment of processor to different tasks being performed by thecomputer system.2. Memory management , that is, allocation of main memory and other storage areas to the systemprogrammes as well as user programmes and data.3. Input/output management , that is, co-ordination and assignment of the different output and inputdevice while one or more programmes are being executed.4. File management , that is, the storage of file of various storage devices to another. It also allowsall files to be easily changed and modified through the use of text editors or some other filesmanipulation routines.

5. Establishment and enforcement of a priority system. That is, it determines and maintains the orderin which jobs are to be executed in the computer system.6. Automatic transition from job to job as directed by special control statements.7. Interpretation of commands and instructions.8. Coordination and assignment of compilers, assemblers, utility programs, and other software to thevarious user of the computer system.9. Facilities easy communication between the computer system and the computer operator (human).It also establishes data security and integrity.

Type and Classification of Operating System

Operating systems that create a link between users and the applications form the core of computersystems. It dissociates the programs and the hardware and simplifies resource management. Let uslook at the different types of operating systems.

An operating system is a software component of a computer system that is responsible for themanagement of various activities of the computer and the sharing of computer resources. It hosts theseveral applications that run on a computer and handles the operations of computer hardware. Usersand application programs access the services offered by the operating systems, by means of systemcalls and application programming interfaces. Users interact with operating systems throughCommand Line Interfaces (CLIs) or Graphical User Interfaces known as GUIs. In short, operating

system enables user interaction with computer systems by acting as an interface between users orapplication programs and the computer hardware. Here is an overview of the different types of operating systems.

Real-time Operating System: It is a multitasking operating system that aims at executing real-timeapplications. Real-time operating systems often use specialized scheduling algorithms so that theycan achieve a deterministic nature of behaviour. The main object of real-time operating systems istheir quick and predictable response to events. They either have an event-driven or a time-sharingdesign. An event-driven system switches between tasks based of their priorities while time-sharingoperating systems switch tasks based on clock interrupts.


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Multi-user and Single-user Operating Systems: The operating systems of this type allow amultiple users to access a computer system concurrently. Time-sharing system can be classified asmulti-user systems as they enable a multiple user access to a computer through the sharing of time.Single-user operating systems, as opposed to a multi-user operating system, are usable by a singleuser at a time. Being able to have multiple accounts on a Windows operating system does not makeit a multi-user system. Rather, only the network administrator is the real user. But for a Unix-likeoperating system, it is possible for two users to login at a time and this capability of the OS makes ita multi-user operating system.

Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run ata time, the system is grouped under a single-tasking system, while in case the operating systemallows the execution of multiple tasks at one time, it is classified as a multi-tasking operatingsystem. Multi-tasking can be of two types namely, pre-emptive or co-operative. In pre-emptivemultitasking, the operating system slices the CPU time and dedicates one slot to each of theprograms. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking.Cooperative multitasking is achieved by relying on each process to give time to the other processesin a defined manner. MS Windows prior to Windows 95 used to support cooperative multitasking.

Distributed Operating System: An operating system that manages a group of independentcomputers and makes them appear to be a single computer is known as a distributed operatingsystem. The development of networked computers that could be linked and communicate with eachother, gave rise to distributed computing. Distributed computations are carried out on more than onemachine. When computers in a group work in cooperation, they make a distributed system.

Embedded System: The operating systems designed for being used in embedded computer systemsare known as embedded operating systems. They are designed to operate on small machines likePDAs with less autonomy. They are able to operate with a limited number of resources. They arevery compact and extremely efficient by design. Windows CE, FreeBSD and Minix 3 are someexamples of embedded operating systems.

The operating systems thus contribute to the simplification of the human interaction with thecomputer hardware. They are responsible for linking application programs with the hardware, thusachieving an easy user access to the computers.

Operating System Types

There are many types of operating systems. The most common is the Microsoft suite of operatingsystems. They include from most recent to the oldest:

Windows XP Professional Edition - A version used by many businesses on workstations. Ithas the ability to become a member of a corporate domain.

Windows XP Home Edition - A lower cost version of Windows XP which is for home useonly and should not be used at a business.

Windows 2000 - A better version of the Windows NT operating system which works wellboth at home and as a workstation at a business. It includes technologies which allowhardware to be automatically detected and other enhancements over Windows NT.


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Windows ME - An upgraded version from windows 98 but it has been historically plaguedwith programming errors which may be frustrating for home users.

Windows 98 - This was produced in two main versions. The first Windows 98 version wasplagued with programming errors but the Windows 98 Second Edition which came out laterwas much better with many errors resolved.

Windows NT - A version of Windows made specifically for businesses offering bettercontrol over workstation capabilities to help network administrators.

Windows 95 - The first version of Windows after the older Windows 3.x versions offering abetter interface and better library functions for programs.

There are other worthwhile types of operating systems not made by Microsoft. The greatest problemwith these operating systems lies in the fact that not as many application programs are written forthem. However if you can get the type of application programs you are looking for, one of thesystems listed below may be a good choice.

UNIX - A system that has been around for many years and it is very stable. It is primaryused to be a server rather than a workstation and should not be used by anyone who does notunderstand the system. It can be difficult to learn. UNIX must normally run on a computermade by the same company that produces the software.

Linux - Linux is similar to UNIX in operation but it is free. It also should not be used byanyone who does not understand the system and can be difficult to learn.

Apple Macintosh - Most recent versions are based on UNIX but it has a good graphicalinterface so it is both stable (does not crash often or have as many software problems asother systems may have) and easy to learn. One drawback to this system is that it can only berun on Apple produced hardware.

Graphical User Interface (GUI)

A graphical user interface (GUI), often pronounced gooey, is a type of user interface that allowsusers to interact with programs in more ways than typing such as computers; hand-held devices suchas MP3 players, portable media players or gaming devices; household appliances and officeequipment with images rather than text commands.

A GUI offers graphical icons, and visual indicators, as opposed to text-based interfaces, typedcommand labels or text navigation to fully represent the information and actions available to a user.The actions are usually performed through direct manipulation of the graphical elements.

Graphical user interfaces, also known as GUIs, offer a consistent visual language to representinformation stored in computers. This makes it easier for people with little computer skills to work with and use computer software.


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Elements of GUI based operating system-Windows-Use of menus

1. WindowA window is an area on the screen that displays information, with its contents being displayedindependently from the rest of the screen. An example of a window is what appears on the screenwhen the "My Documents" icon is clicked in the Windows Operating System. It is easy for a user tomanipulate a window: it can be opened and closed by clicking on an icon or application, and it canbe moved to any area by dragging it (that is, by clicking in a certain area of the window usuallythe title bar along the tops and keeping the pointing device's button pressed, then moving thepointing device). A window can be placed in front or behind another window, its size can beadjusted, and scrollbars can be used to navigate the sections within it. Multiple windows can also beopen at one time, in which case each window can display a different application or file this is veryuseful when working in a multitasking environment. The system memory is the only limitation tothe amount of windows that can be open at once. There are also many types of specialized windows.

A Container Window a window that is opened while invoking the icon of a mass storagedevice, or directory or folder and which is presenting an ordered list of other icons that couldbe again some other directories, or data files or maybe even executable programs. Allmodern container windows could present their content on screen either acting as browserwindows or text windows. Their behavior can automatically change according to the choicesof the single users and their preferred approach to the graphical user interface.

A browser window allows the user to move forward and backwards through a sequence of documents or web pages. Web browsers are an example of these types of windows.

Text terminal windows are designed for embedding interaction with text user interfaceswithin the overall graphical interface. MS-DOS and UNIX consoles are examples of thesetypes of windows.

A child window opens automatically or as a result of a user activity in a parent window. Pop-up windows on the Internet can be child windows.

A message window, or dialog box, is a type of child window. These are usually small andbasic windows that are opened by a program to display information to the user and/or getinformation from the user. They usually have a button that must be pushed before theprogram can be resumed.

2. MenusMenus allow the user to execute commands by selecting from a list of choices. Options are selectedwith a mouse or other pointing device within a GUI. A keyboard may also be used. Menus areconvenient because they show what commands are available within the software. This limits theamount of documentation the user reads to understand the software.

A menu bar is displayed horizontally across the top of the screen and/or along the tops of some or all windows. A pull-down menu is commonly associated with this menu type. Whena user clicks on a menu option the pull-down menu will appear.


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5. TabsA tab is typically a rectangular small box which usually contains a text label or graphical iconassociated with a view pane. When activated the view pane, or window, displays widgets associatedwith that tab; groups of tabs allow the user to switch quickly between different widgets. This is usedin the web browsers Firefox, Internet Explorer, Konqueror, Opera, and Safari. With these browsers,you can have multiple web pages open at once in one window, and quickly navigate between themby clicking on the tabs associated with the pages. Tabs are usually placed in groups at the top of awindow, but may also be grouped on the side or bottom of a window. Tabs are also present in thesettings panes of many applications. Windows for example uses tabs in most of its control paneldialogues.


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Questions based on Unit I

1. Distinguish between Primary Storage devices and Secondary Storage devices. 2. Distinguish between a Multiprogramming and a Time-Sharing Operating System. 3. What are the basic features of the Window Operating System? Why has it become so

popular? 4. Discuss the Menus, Tools and Commands of WINDOWS 98 Operating System. 5. Discuss the different applications of single and a multi-user operating systems.6. Differentiate between the following :

(i) Primary and Secondary memory,(ii) CPU and control unit,(iii) RAM and ROM,

7. What is buffer?8. What is the role of memory buffer and input/output buffer in computer?

9. Explain the advantages of working with graphics interface.10. Explain any four points to differentiate between a compiler and an interpreter.11. What is an operating system? What are its important functions?12. Discuss the different types of operating system by giving one example for each.13. What type of interface is provided by Windows operating system? How it differs with the

previously used interface (Command Line Interface) for computers?14. What do you understand by the compiler for a high level language? How it differs with the

interpreter used for high level language?15. Discuss the role of an operating system as a resource manager and coordinator of devices.16. Differentiate between RAM and ROM. Discuss various types of RAM and ROM in detail.17. Draw a block diagram to illustrate the basic organization of a computer system and explain

the function of the various units.18. What is operating system? Give various services provided by the OS. Distinguish between

single user and multiuser operating systems.19. What is the role of taskbar in Windows? List the steps to perform the following actions in

windows:(i) Start a program (ii) Open a recently used document(iii) Search a file (iv) Delete a file or folder permanently.

20. Write the role of following :(i) My computer (ii) Network neighborhood(iii) My document (iv) Recycle bin (v) My briefcase.

21. Write steps to create a folder in D: drive and to put a shortcut of this folder on Desktop inWindows based system.

Computer Applications for Management

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Transcript of Computer Applications for Management