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8/8/2019 Itba Notes


Easy Storage and Once a document is in electronic form it is easy to store andmany, many documents can be stored on one computer in much less space thanin a file cabinet.

Easy to search

For programming

Most programming requires the use of computers

There are many, many tools available to programmers such as:

Editors: CodeWrite, SlickEdit, VIM, EMACS, Notepad, BBEdit...

Compilers: MSVC, Sun javac, GNU Compiler Collection (java, fortran, C, C++, andmore), Intel C Compiler...

Assemblers: NASM, MASM, TASM...

Interpreters: Ruby, Python, Lisp, Perl, bash, and countless others

For Research:

Access to the Internet has become invaluable as a research tool

Easily gather huge amounts of information and store/catalog it

Easily search for new information or search the information already acquired

Interact with other researchers to create/gather more research

Almost instant access to many remote or obscure locations of the globe andtheir researchers/experiences/knowledge.

Easily disseminate results of your own research.

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HISTORY AND DEVELOPMENT OF COMPUTERS:

y The first counting d ev ice was t he abacus, originally from Asia. It work e d on aplac e-v alu e notion m e aning t h at t he plac e of a b e ad or rock on t he apparatus

de te rmin e d h ow muc h it was wort h .

ABACUS

1600 : Jo h n Napi e r disco ve rs logarit h ms. Rob e rt Bissak e r in ve nts t he slid e rul e .

1642 : Blais e Pascal, a Fr e nc h mat he matician and p h ilosop he r, in ve nts t he firstm e ch anical digital calculator using g e ars, call e d t he Pascalin e . Alth oug h t h ismac h ine could p e rform addition and subtraction on w h ole numb e rs, it was tooex pe nsi ve and only Pascal h ims e lf could r e pair it.

PASCALINE

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1804 : Jos e ph Mari e Jacquard us e d punc h cards to automat e a w e av ing loom.

A PUNCH CARD COMPUTER

1812 : Charles P. Babbage, the "father of the computer", discovered that manylong calculations involved many similar, repeated operations. Therefore, hedesigned a machine, the difference engine which would be steam-powered,fully automatic and commanded by a fixed instruction program. In 1833,Babbage quit working on this machine to concentrate on the analytical engine.

Babbage s Difference engine

1840s: Augusta Ada. " The first programm e r" sugg e st e d t h at a binarysyst e m(0,1) s h ould b e us e d for storag e rat he r t h an a d e cimal syst e m(0 -9 ).

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1850s : G e org e Bool e deve lop e d Bool e an logic w h ich would lat e r b e us e d in t he de sign of comput e r circuitry.

18 9 0: Dr. H e rman Holl e rit h introduc e d t he first e le ctrom e ch anical, punc he d -

card data-proc

essing mac

hin

ew

hic

hwas us

ed to compil

einformation for t

he 18 9 0 U.S. c e nsus. Holl e rit h' s tabulator b e cam e so succ e ssful t h at he start e d h is

own busin e ss to mark e t it. His company would eve ntually b e com e Int e rnationalBusin e ss Mac h ine s (IBM).

19 06 : The v acuum tub e is in ve nt e d by Am e rican p h ysicist L ee De For e st.

A Vacuum Tube:

1939 : Dr. Jo h n V. Atanasoff and h is assistant Clifford B e rry build t he firste le ctronic digital comput e r. The ir mac h ine , t he Atanasoff -Be rry -Comput e r (ABC)pro v ide d t he foundation for t he ad v anc e s in e le ctronic digital comput e rs.

19 41 : Konrad Zus e (re ce ntly d e ce as e d in January of 1 99 6), from G e rmany,introduc e d t he first programmabl e comput e r d e sign e d to sol ve compl ex e ngin ee ring e quations. Th is mac h ine , call e d t he Z3 , was also t he first to work onthe binary syst e m inst e ad of t he de cimal syst e m.

19 43 : Britis h mat he maticians Alan Turing d eve lopp e d h ypot he tical d ev ice s, t he Turing mac h ine wh ich would b e de sign e d to p e rform logical op e ration and could

re ad and writ e . It would pr e sag e programmabl e comput e rs. H e also us e d v acuumte ch nology to build Britis h Colossus, a mac h ine us e d to count e ract t he Ge rmancod e scrambling d ev ice , Enigma.

19 44 : Howard Aiken, in collaboration with engineers from IBM, constructed alarge automatic digital sequence-controlled computer called the Harvard Mark I.

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This computer could handle all four arithmetic operations, and had special built-in programs for logarithms and trigonometric functions.

19 45 : Dr. Jo h n v on N e umann pr e se nt e d a pap e r outlining t he stor e d - program

conce

pt. 1946 : The giant ENIAC (Electrical Numerical Integrator and Calculator)

machine was developed by John W. Mauchly and J. Presper Eckert, Jr. at theUniversity of Pennsylvania. It used 18, 000 vacuums, punch-card input, weighedthirty tons and occupied a thirty-by-fifty-foot space. It wasn't programmable butwas productive from 1946 to 1955 and was used to compute artillery firingtables.

That same year, the TRANSISTORwas invented by William Shockley, JohnBardeen and Walter Brattain of Bell Labs. It would rid computers of vacuumtubes and radios.

ENIAC

19 49 : Mauric e V. Wilk e s built t he EDSAC (Ele ctronic D e lay Storag e AutomaticComput e r), t he first stor e d -program comput e r. EDVAC (Ele ctronic Discr e te Variabl e Automatic Comput e r), t he se cond stor e d - program comput e r was built byMauc h ly, Eck e rt, and v on N e umann. A Wang d eve lop e d magn e tic -cor e m e morywh ich Jay Forr e st e r would r e organiz e to b e mor e e fficie nt.

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EDSAC

19 50 : Turing built t he ACE, consid e re d by som e to b e the first programmabl e digital comput e r.

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COMPUTER ARCHITECTURE:

Control flow:

y Any input given through the input devices will firstly enter the Control unit

and will be stored for temporary usage by the registers.

y It then goes through the Arithmetic Logic Unit(ALU) for processing and willbe stored in the memory(RAM).

y Finally, the processed and stored data will be displayed back to the user byan output device.

Input devices:

Any hardware peripheral used to provide data and control signals to aninformation processing system such as computer is called as an input device.

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An input device acts as an interface between a computer and a user.

Examples: Mouse, Keyboard, Joysticks, touch screens, webcams, Microphonesetc.

Mouse:

A Mouse is used for navigation through the monitor screen and it makesfacilitates the usage of the computer.

Types of Mouse:

1.Ball Mouse(tracks with a ball)

2.Laser Mouse(uses laser transmission)

3.Optical Mouse(uses optical transmission)

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Advantages of a mouse:

A mouse works very well for navigating a graphical user interface, such asWindows or Mac. With additional buttons and a scroll wheel, increasingly

complex functions can be done from a mouse. These include opening, closingand minimizing software; grouping, moving and deleting files; and even imageediting with software like Photoshop. In my experience, a mouse is better forfine movements and adjustments than most of the alternatives.

Threats:

Motion controller.

Keyboards:

These are the default input devices. A 'keyboard' is a human interface devicewhich is represented as a layout of buttons. Each button, or key, can be used toeither input a linguistic character to a computer, or to call upon a particularfunction of the computer. Traditional keyboards use spring-based buttons,though newer variations employ virtual keys, or even projected keyboards.

Types of keyboards:

1.Wireless keyboards

2.Wired keyboards

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Wireless Keyboards

The wireless keyboards use three basic types of connections, viz.

y Bluetooth Keyboardsy Infrared (IR) Keyboardsy Radio Frequency Keyboards

Wired keyboards:The PS/2 and USB are the two wired connections that connect the keyboardsto your desktop computers. The PS/2 keyboards are very commonly used

and they are called so because they use the PS/2 connection. They are one of the cheapest keyboards that are available in the market. The USB keyboardsuse a USB (Universal Serial Bus) to connect to the CPU. The PS/2 and USBkeyboards are usually plug and play. Other types of keyboards are a bitexpensive and require expensive software applications to be installed.

y Ergonomic Keyboards

The ergonomic keyboards are designed considering the ergonomic aspect of the keyboards. It is specially designed as per the comfort of the hands andwrist of the keyboard user. The ergonomic keyboards are designed toprevent the carpal tunnel syndrome, which causes numbness and tinglingsensation in hands and fingers after typing for a long duration. Thesekeyboards also help the keyboard user maintain a comfortable position.

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y Compact Keyboard

The sizes of keyboard goes on increasing, especially, those of the ergonomickeyboards. The ergonomic keyboards are designed bigger to accommodatemany keys that perform special functions. The compact keyboards are slimand usually do not have the numeric keypad that is present on the right sideof the other keyboards. Some compact keyboards even include a rubber padthat can be used instead of the mice. These keyboards are not very small insize, but offer portability during travel and storage.

Different Types of Keyboards - Special Keyboards

y Internet KeyboardsThe internet keyboards are designed to increase the comfort level of theinternet user. The internet keyboards have hot-keys for the home page of the web browser, inbox and the favorites menu on your computer.

y Multimedia and Gaming Keyboards

The multimedia and gaming keyboards are designed for playing audio andhas hot-keys for volume control, play, stop and mute operations. The gaming

keyboards are designed for the convenience of the gamers and these typesof keyboards provide the required controls on the keyboards likebacklighting.

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Threats:

Touch screen and Virtual keyboards.

Audio and video input devices:

They provide the audio and visual data to the cpu.

Examples: Webcam, digicam, microphones ,midi keyboards etc.

Control unit:

Control Unit Co-ordinates the input and output devices of a computer system.

Functions of Control Unit:

A control unit can be described as a sort of circuitry that supervises and controlsthe path of information that runs over the processor and organizes the variousactivities of those units that lie inside it.

It carries out many tasks such as decoding, fetching, handling the executionand finally storing the results.

It controls the execution of instructions in a sequential order.

It guides the flow of data through the different parts of the computer.

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It interprets the instructions.

It regulates the time controls of the processor.

Arithmetic Logic Unit(ALU):

Arithmetic logic unit is that part of the computer which performs the differentlogic operations and arithmetic calculations like addition, subtraction,multiplication and division. It is the high speed digital circuit that solvescalculations and does comparisons.

Functions of Arithmetic Logic Unit:

Almost all the actions of the computer are done by it. It gets its data from acertain computer memory called processor register . After the data getsprocessed, its results get stored in output registers of the arithmetic logic unit .

The arithmetic logic unit can perform integer arithmetic operations likeaddition, subtraction, etc.

It can also perform bitwise logic operations like AND, OR, XOR, etc

Registers:

In computer architecture, a processor register (or general purpose register) is asmall amount of storage available on the CPU whose contents can be accessedmore quickly than storage available elsewhere. Typically, this specialized

storage is not considered part of the normal memory range for the machine.

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Memory device:

RANDOM ACCESS MEMORY (RAM):

Random Access Memory, RAM, also known as main memory or system

memory, is a term commonly used to describe the memory within acomputer. Unlike ROM, RAM is a volatile memory and requires power; if power is lost, all data is also lost. Below is an example image of a512MB DIMM memory stick.

Random access memory or RAM most commonly refers to computer chips thattemporarily store dynamic data to enhance computer performance. By storing

Memory

Random acc e ssm e mor RAM

Re ad onlym e mory(ROM)

STATICRAM

(SRAM)

DYNAMICRAM

(DRAM)

PROGRAMMABLEROM(PROM)

(EPROM)

ERASABLEPROM

(EEPROM)

ELECTRICALLY ERASE

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frequently used or active files in random access memory, the computer canaccess the data faster than if it to retrieve it from the far-larger hard drive.

SRAM AND DRAM:

There are two types of Random Access Memory or RAM, each has its ownadvantages and disadvantages compared to the other. SRAM (Static RAM) andDRAM (Dynamic RAM) holds data but in a different ways. DRAM requires thedata to be refreshed periodically in order to retain the data.

SRAM does not need to be refreshed as the transistors inside would continue tohold the data as long as the power supply is not cut off. This behavior leads to afew advantages, not the least of which is the much faster speed that data can be

written and read.

One complication is the much higher power used by DRAM memory, thisdifference is very significant in battery powered devices. SRAM modules arealso much simpler compared to DRAM, which makes it easier for most people tocreate an interface to access the memory.

Structurally, SRAM needs a lot more transistors in order to store a certainamount of memory. A DRAM module only needs a transistor and a capacitor forevery bit of data where SRAM needs 6 transistors.

Summary:

1. SRAM is static while DRAM is dynamic

2. SRAM is faster compared to DRAM

3. SRAM consumes less power than DRAM

4. SRAM uses more transistors per bit of memory compared to DRAM

5. SRAM is more expensive than DRAM

6. Cheaper DRAM is used in main memory while SRAM is commonly used incache memory

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READ ONLY MEMORY (ROM):

One major type of memory that is used in PCs is called read-only memory, orROM for short. ROM is a type of memory that normally can only be read, as

opposed to RAM which can be both read and written.

There are two main reasons that read-only memory is used for certain functionswithin the PC:

Permanence: The values stored in ROM are always there, whether the power ison or not. A ROM can be removed from the PC, stored for an indefinite periodof time, and then replaced, and the data it contains will still be there. For thisreason, it is called non-volatile storage. A hard disk is also non-volatile, for the

same reason, but regular RAM is not.

Security: The fact that ROM cannot easily be modified provides a measure of security against accidental (or malicious) changes to its contents. You are notgoing to find viruses infecting true ROMs, for example; it's just not possible. (It'stechnically possible with erasable EPROMs, though in practice never seen.)

Read-only memory is most commonly used to store system-level programs thatwe want to have available to the PC at all times. The most common example isthe system BIOS program, which is stored in a ROM called (amazingly enough)the system BIOS ROM. Having this in a permanent ROM means it is availablewhen the power is turned on so that the PC can use it to boot up the system.Remember that when you first turn on the PC the system memory is empty, sothere has to be something for the PC to use when it starts up.

TYPES OF ROM:

Programmable ROM (PROM):

This is a type of ROM that can be programmed using special equipment; it canbe written to, but only once. This is useful for companies that make their ownROMs from software they write, because when they change their code they cancreate new PROMs without requiring expensive equipment. This is similar to theway a CD-ROM recorder works by letting you "burn" programs onto blanks once

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and then letting you read from them many times. In fact, programming a PROMis also called burning, just like burning a CD-R, and it is comparable in terms of its flexibility.

Erasable Programmable ROM (EPROM):

An EPROM is a ROM that can be erased and reprogrammed. A little glasswindow is installed in the top of the ROM package, through which you canactually see the chip that holds the memory. Ultraviolet light of a specificfrequency can be shined through this window for a specified period of time,which will erase the EPROM and allow it to be reprogrammed again. Obviouslythis is much more useful than a regular PROM, but it does require the erasinglight. Continuing the "CD" analogy, this technology is analogous to a reusableCD-RW.

Electrically Erasable Programmable ROM (EEPROM): The next level of erasabilityis the EEPROM, which can be erased under software control. This is the mostflexible type of ROM, and is now commonly used for holding BIOS programs.

SECONDARY MEMORY DEVICES:

These are used for external storage.

Examples: CD s, Floppy s, DVD s, Pen drives, Memory cards etc.

Output devices:

They display the processed and stored data to the user.

These are Monitor, Printer, Scanner etc.

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SOFTWARE AND HARDWARE:

SOFTWARE:

What most people think of as a computer can actually be divided into two parts.The first part, computer hardware, does all of the physical work computers areknown for. The second part, computer software, tells the hardware what to doand how to do it. If you were to think of a computer as a living being, then thehardware would be the body that does things like seeing with eyes, liftingobjects, and filling the lungs with air; the software would be the intelligence,interpreting the images that come through the eyes, telling the arms how to liftobjects etc. Computer software is most commonly created by computerprogrammers using a programming language. The programmer writescommands in the programming language that are similar to what someonemight use in everyday speech. These commands are called source code. Anothercomputer program called a compiler is then used on the source code,transforming the commands into a language that the computer can understand.The result is an executable computer program, which is another name forsoftware.

Computer software falls into two primary categories:

System software and Application software.

System software represents programs that allow the hardware to run properly.Application software represents programs that allow users to do somethingbesides simply run the hardware. Some experts also include a third category,programming software, though others put those programs into one of the otherpreviously mentioned categories.

Hardware:

Everything you can see and touch in your PC is hardware. Hardware is thephysical interface of a computer on which software runs.

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It is tangible.

This following list represents a basic set of hardware found in most PCs.

PC Case

Motherboard

Power Supply

Hard Disk Drive (HDD)

Floppy Disk Drive (FDD)

Compact Disk Drive (CDD)

Digital Video Disk drive (DVD)

Monitors (CRT and LCD)

Keyboard

Mouse

Audio

Cables & Wires

Generations of Software:

Five Generations of Modern Computers

First Generation (1945-1956)

With the onset of the Second World War, governments sought to developcomputers to exploit their potential strategic importance.

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The Electronic Numerical Integrator and Computer (ENIAC), produced by apartnership between the U.S. government and the University of Pennsylvania.Consisting of 18,000 vacuum tubes, 70,000 resistors and 5 million soldered joints, the computer was such a massive piece of machinery that it consumed160 kilowatts of electrical power, enough energy to dim the lights in an entiresection of Philadelphia. Developed by John Presper Eckert (1919-1995) and JohnW. Mauchly (1907-1980), ENIAC, unlike the Colossus and Mark I, was a general-purpose computer that computed at speeds 1,000 times faster than Mark I.

ENIAC

Second Generation Computers (1956-1963)

By 1948, the invention of the transistor greatly changed the computer'sdevelopment. The transistor replaced the large, cumbersome vacuum tube intelevisions, radios and computers. As a result, the size of electronic machineryhas been shrinking ever since. The transistor was at work in the computer by1956. Coupled with early advances in magnetic-core memory, transistors led tosecond generation computers that were smaller, faster, more reliable and moreenergy-efficient than their predecessors. The first large-scale machines to take

advantage of this transistor technology were early supercomputers, Stretch byIBM and LARC by Sperry-Rand. These computers, both developed for atomicenergy laboratories, could handle an enormous amount of data, a capabilitymuch in demand by atomic scientists. The machines were costly, however, and

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tended to be too powerful for the business sector's computing needs, therebylimiting their attractiveness.

Third Generation Computers (1964-1971):

Though transistors were clearly an improvement over the vacuum tube, theystill generated a great deal of heat, which damaged the computer's sensitiveinternal parts. The quartz rock eliminated this problem. Jack Kilby, an engineerwith Texas Instruments, developed the integrated circuit (IC) in 1958. The ICcombined three electronic components onto a small silicon disc, which wasmade from quartz. Scientists later managed to fit even more components on asingle chip, called a semiconductor. As a result, computers became ever smalleras more components were squeezed onto the chip. Another third-generationdevelopment included the use of an operating system that allowed machines torun many different programs at once with a central program that monitoredand coordinated the computer's memory.

Fourth Generation (1971-Present)

After the integrated circuits, the only place to go was down - in size, that is.Large scale integration (LSI) could fit hundreds of components onto one chip. By

the 1980's, very large scale integration (VLSI) squeezed hundreds of thousandsof components onto a chip. Ultra-large scale integration (ULSI) increased thatnumber into the millions. The ability to fit so much onto an area about half thesize of a U.S. dime helped diminish the size and price of computers. It alsoincreased their power, efficiency and reliability. The Intel 4004 chip, developedin 1971, took the integrated circuit one step further by locating all thecomponents of a computer (central processing unit, memory, and input andoutput controls) on a minuscule chip.

Such condensed power allowed everyday people to harness a computer'spower. They were no longer developed exclusively for large business orgovernment contracts. By the mid-1970's, computer manufacturers sought tobring computers to general consumers. These minicomputers came completewith user-friendly software packages that offered even non-technical users an

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array of applications, most popularly word processing and spreadsheetprograms. Pioneers in this field were Commodore, Radio Shack and AppleComputers.

In 1981, IBM introduced its personal computer (PC) for use in the home, officeand schools. The 1980's saw an expansion in computer use in all three arenas asclones of the IBM PC made the personal computer even more affordable. Thenumber of personal computers in use more than doubled from 2 million in 1981to 5.5 million in 1982. Ten years later, 65 million PCs were being used.Computers continued their trend toward a smaller size, working their way downfrom desktop to laptop computers (which could fit inside a briefcase) topalmtop (able to fit inside a breast pocket). In direct competition with IBM's PC

was Apple's Macintosh line, introduced in 1984.

As smaller computers became more powerful, they could be linked together, ornetworked, to share memory space, software, information and communicatewith each other. As opposed to a mainframe computer, which was one powerfulcomputer that shared time with many terminals for many applications,networked computers allowed individual computers to form electronic co-ops.Using either direct wiring, called a Local Area Network (LAN), or telephone lines,

these networks could reach enormous proportions. A global web of computercircuitry, the Internet, for example, links computers worldwide into a singlenetwork of information.

Fifth Generation (Present and Beyond)

Defining the fifth generation of computers is somewhat difficult because thefield is in its infancy. The most famous example of a fifth generation computer isthe fictional HAL9000 from Arthur C. Clarke's novel, 2001: A Space Odyssey. HAL

performed all of the functions currently envisioned for real-life fifth generationcomputers. With artificial intelligence, HAL could reason well enough to holdconversations with its human operators, use visual input, and learn from itsown experiences. (Unfortunately, HAL was a little too human and had apsychotic breakdown, commandeering a spaceship and killing most humans onboard.)

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Major Types of Software:

Programming Software: This is one of the most commonly known and popularlyused forms of computer software. These software come in forms of tools that

assist a programmer in writing computer programs. Computer programs are setsof logical instructions that make a computer system perform certain tasks. Thetools that help the programmers in instructing a computer system include texteditors, compilers and interpreters.

System Software: It helps in running the computer hardware and the computersystem. System software is a collection of operating systems; devise drivers,servers, windowing systems and utilities. System software helps an applicationprogrammer in abstracting away from hardware, memory and other internalcomplexities of a computer.

Application Software: It enables the end users to accomplish certain specifictasks. Business software, databases and educational software are some forms of application software. Different word processors, which are dedicated forspecialized tasks to be performed by the user, are other examples of applicationsoftware.

Apart from these three basic types of software, there are some other well-known forms of computer software like inventory management software, ERP,utility software, accounting software and others. Take a look at some of them.

Inventory Management Software: This type of software helps an organization intracking its goods and materials on the basis of quality as well as quantity.Warehouse inventory management functions encompass the internalwarehouse movements and storage. Inventory software helps a company inorganizing inventory and optimizing the flow of goods in the organization, thusleading to an improved customer service.

Utility Software: Also known as service routine, utility software helps in themanagement of computer hardware and application software. It performs asmall range of tasks. Disk defragmenters, systems utilities and virus scannersare some of the typical examples of utility software.

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Data Backup and Recovery Software: An ideal data backup and recoverysoftware provides functionalities beyond simple copying of data files. Thissoftware often supports user needs of specifying what is to be backed up.

y SYSTEM AND APPLICATION SOFTWARES

The Operating System is the System Software that makes the Computer work.We can say that an Operating System (OS) is Software that acts as an interfacebetween you and the hardware. It not only contains drivers used to speak thehardware's language, but also offers you a very specific graphical user interface(GUI) to control the computer. An OS can also act as an interface (from thehardware) to the other software. A complex OS like Windows or Linux or MacOS offers the services of an OS, but also has applications built in. Solitaire, Paint,Messenger, etc. are all applications.

Application software is the software that you install onto your OperatingSystem. It consists of the programs that actually let you do things with yourcomputer. These Applications are written to run under the various OperatingSystems. These include things like your word processing programs, spread

sheets, email clients, web browser, games, etc. Many programs, such as most of the Microsoft Office suite of programs, are written in both Mac and Windowsversions, but you still have to have the right version for your OS.

***The End***

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