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2 INFORMATiCS PRACTCES 1.2 Computer System A Computer system comprises of five basic components (see Fig. ) : ) nput Unit. It is res...

2 INFORMATiCS PRACTCES 1.2 Computer System A Computer system comprises of five basic components (see Fig. ) : ) nput Unit. It is responsible for taking input for the computer. The input devices attached to the computer system make the input untt " ouPut Onit. It is responsible for producing output. The output devices attached to the Computer system make the output unit. ) Cental Processing Unit (CPU). It is responsible for processing the data and instructions. It comprises of tvo parts : (a) Aritlhmeticand Logic Unit (AL). It is responsible for carrving out the arithmetc instructions (add, subtract, multiply, divide) and making logic decisions (greater thn less than, equal to). (0) Control Unit. It is responsible for controlling and supervising the processing (0) Primary Memory. It is the internal volatile memory where data and instructions are stored during processing. () Secondary Storage Unit. It refers to the external storage devices which provide permanent memory to the computer system. Secondary Storage Central Processing Unit Control Unit Input Device Arithmetic/Logic Unit Output Device Primary Memory Fiqure 1.1 Components of a computer system. The components of acomputer system make the physical structure of a computer whereas the logical structure of a computer system is defined as Computer Organisation 1.2.1 Computer Organisation Computer organization refers to the logical structure of a computer describing how is comnonentsare connected to one another ; nOW they attect one another's funetionine and contribute to overall pertormance of the computer. Computers, as you must be Kiow onon e tr principle I.e'., Input ’ Process -Outut (acertain input is processed to generate specific output). Thus basic computer organization is as Siown in rig. 1.2. Io see the working of computer (Computer OTganization), scan this QR Code interconnetions with SIPO an ant hsik Chapter l: COMPUTER SYSTEM 3 CPU To see Computer Organization in action ALU Registers Control Memory Scan QR Code System Bus Input Output Storage unit unit unit Figure 1.2 Basic Computer Organization. NOTE Let us talk about these functional components of a System Bus connects various components computer, one by one. of a computer system, through which they communicate and work in tandem. 1.2.2 Input Unit (Input Devices) The input unit is formed by the input devices attached to the computer. Examples of input devices and media are : keyboard, mouse, magnetic ink character reader (MICR), optical mark reader (OMR), optical character reader (OCR), joystick etc. The input unit is responsible for taking input and converting it into computer understandable form (the binary code). NOTE All the inputs consisted of data (on which the action was to be An input unit takes the input and performed) as well as the instruction (the action to be taken). converts it into digital binary form SO that it can be The input unit is comprised of different input devices that understood by the computer. take the input in different forms and pass them in digital form to CPU for processing. Some common input devices are: () Keyboard. Keyboard is a typewriter like device which is used to type in the letters, digits and commands. For visually challenged people, Braille keyboards are also available these days. (i) Mouse. Mouse is pointing device with either a roller on its base or some laser mechanism. Mouse controls movement of pointer (also called mouse pointer) on screen. (iii) Microphone (Mic). We can send sound input to computer through a special input device called microphone or mic in short. A mic converts the sound received into computers format, which is called digitized sound or digital audio. Amic can work if your computer has a special hardware known as sound card. (iv) Scanner. A scanner is a device similar to a photocopier. A scanner creates an electronicform of the printed image, which can later be manipulated, charnged and modified according to the requirements. (7) Barcode Reader. A barcode reader is used to read barcodes which can be found on products in shops. The barcode uses lasers to identify the position and thickness of the bars. (v) Light Pen. A light-sensitive input device shaped like a pen, used to draw on the computer screen or to make menu selections.  INFORMATICS PRACTICES - YI 1.2.3 Output Unit (Output Devices) The output unit is formed by the output devices attached to the Computer. The output coming from the CPU is in the form of Output Unit converts the output in binary form to electronicbinary signals which needs which can be easily understood conversion in some fori human readable form. by human beings l.e characters, graphical or audio visual form. This function of conversion is performed by output unit. Some popular output devices are : () Monitors. Monitor (or "screen'") is the most common torm ot output rom a computer. It displays information in a similar way to that shown on atelevision screen. The picture on a montOr made up of thousands of tiny coloured dots called pixels. For visually challenged people, Braille monitors are also available these days. () Printers. Printers are the devices that deliver information by means of printed characters on paper. Printers come in variety of forms, e-g-. inkjet, laserjet, dotmatrix printers etc. Unlike old style printers, which printed on a paper, these days 3D printers are also available which can print/create 3D models. Laser Printer (i) Speakers. Speakers receive the sound in form of electric current from the sound card and then convert it to sound format audible to user. 1.2.4 The CPU (Central Processing Unit) The CPUor the Central Processing Unit is the main control centre and processing unit. It is also called brain of the computer as it guides, directs, controls and governs the performance of acomputer. The CPUhas some sub-components that help in carrying out the processing of a task. These are: () ArithmeticLogic Unit (ALU) (ii) Control Unit (CU) (ii) Registers (0) Arithmetic Logic Unit (ALU) The ALU performs all the four arithmetic (+, -,") and some logical (,=, A source code refers to the program-code written by ProgramMinglanguage (HLL) such as inC, Java, C++ etc code, a language > An object code refers to a code usuallyin machine language or binary that computer can understand easily and run'on hardware. codes into object So, youcan safely say that language Processors are software that convert source codes. There are three types of language processors : assembler, compiler and interpreter. assembly language (i) Assembler. This language processor converts the program written in into machine language. () mrerpreter. An interpreter is a tyne of system software that translates and exeCutes instructions written ina computer program line-by-line, unit by unit erc. (ii) Compiler. A Compiler is another type of system software that translates and executes instructions written in a computer program in one g0. The translated machine code runs fast (faster execution time) as now computer does not require any type of conversion to run it : unlike source code which requires conversion into object/machine code before it can be executed. 1.4.1C System Utilities Utility software are those helpful programs that ensure the smooth functioning of the computer. Utilities are meant to assist your computer. Some utilities help you back-up data, some help remove outdated files or recover data that has been accidentally erased. Some make it easier to find and arrange the information you need. And some help you avoid virus attacks or clean viruses, if any. In UTILITIES other words, the utility programs perform housekeeping Utilities are those functions. application programs that assist It is an established truth that everything comes with certain the computer by performing pros and cons. Softwares also are not an exception to it. housekeeping functions like Utilities bridge the gaps by helping to solve the problems and backing up disk or scanning / maximize your computer's potential. cleaning viruses or arranging information etc. 99 Some commonly used utility software are : > Antivirus Software. These software protect a attack. Some popular anti-virus software are computer Norton system from computer-virus Kaspersky Antivirus, McAfee Antivirus etc. Antivirus, Quick Heal Antivirus, > File Management Tools. These software help you in tasks find information, qick preview etc. One such tool is by like browse, search, arrange, Windows operating system, known as Windows default available to you in Total Commander, Explorer. Some other such popular file management tools are Directory > Compression Tools. This utility program facilitates Opus, Google Desktop etc. compression be compressed so that they take less storage area. When needed, of files. Large files can be exploded back to their original form. Some popular file these compressed files can WinRAR, 7-Zip, PeaZip etc. Compression tools are:  13 Disk Management Tools. As the natne suzyrsts, thee tords are es fos etfiaerty managing data m disks o as to have ixrezed periomance Most of thee tis are rOwadays inbuiit in operating systerrs Common disk maragernent tools are brefly being discussed beiora ? (i) Disk Cleanup Too. The Disk Clearnup utility allows yOu to free yoaur cesnputer froT temporary and unnecessary fies. (1) Disk Defragmenter. This utilities prograrm atternpts to minúsnáse the fragmeTitation on your disk. (i) Backup Utility. This utility prograrn faihtates the backing-up of disk Back-up of arv means dupicating the disk information (file/folders/drives) so that in casemav be data damage or data-loS5, this backed up data may be used. The backed up restored when needed í.e., ifvour original files are damaged or kost 1.4.1D Device Drivers of instructions tor the Device drivers or simply Drivers are prograrms or files that aontain sets hardware devie Each device operating system detailing how best to operate or drive a certain video device, scanner, camera, on your system has its own specific driver. Your audio device, modem etc. are some of the hardware components that require drivers. When you add a new device to your computer, the operating DEVICE DRIVERS system may not know what to do with it. However, when you Device Drivers are the install the device driver software, the operating system knows prograrms that store instructions to drive and use different exactly what it is and, more importantly, it understands how hardware devices to use it. 1,4.2 Application Software software that can This type of software pertains to one specific application. For instance, a perform railway reservation functions cannot prepare result APPLICATION SOFTWARE for aschool. An Applicotion Sofware is These are the programs written by programmers to enable the set of programs necessary to computer to perform a specific task such as processing words, carry out operations for a inventory control,handling calculations and figures, medical specified application. accounting, financial accounting, result preparation, railway reservation, billing etc. Application software can further be divided into following tuo sub-categories: (a) General purpose software (b) Customised software 1.4.2A General Purpose Software Only system software does not suffice for efficient use of computers because the system software exists mostly for the benefit of the computer. Other programs i.e., the appicathon software are required to make the computer useful for people. Application software has been written to do almost every task imaginable, from word processing to selecting a college to atend. feasible to design As applications may be numerous (from thousands to millions of them), it is not that may be used by software for each one of them. Rather some general software are designed general-appiication individual users in the manner it suits their needs and requirements. Such software are known as packages.  INFORMATICS PRACTICES 14 software (packages) are : Some major and most common general application (i) Word Processing Software,categories ot cg., MS-Word, Open Office Writer etc. (7) Spreadsheets, e.g., MS-Exccl, OpenOffice Calc etc. NOTE (ii) Database Management Systems, cg, MS-Access, MySQL etc. printed Ahard copy refers to a (7) Desktop Publishing Software, e.e.. Adobe InDestg or physical copy ofa document. QuarkExpressetc. while a soft copy is electronically on () Graphics, multimedia, and presentation applications, 8 stored copy of the document a storage device. CorelDraw, Photoshop, PoverPoint etc. (7) Web browsers, e.g., Google Chrome, Mozilla Firefox, Saari etc. form Or in Using these general purpose software, you can store your data either in softcopy hardcopy form. CUSTOMISEDSOFTWARE 1.4.2B Customised Software 66 Customised Software refers software. to specially developed Customised Software refers to specially developed software, which is created by software which is created by software programmers for an individual or programmers for the tasks business for the tasks specific to their needs. For example, if a specific to the needs of a specific business or application. boutique owner gets written asoftware to keep track of orders, deliveries and payments,then it will be a customised software. Although there are standard business software available in market, yet some companies prefer getting customized (tailor-made) software as per their specific requirements. However, such softwares cannot be directly installed at any other user's workplace as the requirements of the other users may differ from the originaluser and the software may not fit in the requiremernts of the new user. 1.4.3 Proprietary and Free and Open Source Software You should also know the categories of software based on their licensing and freedom to use. You should know what proprietary software, free software, freeware, open source software (OSS)and free and open source software (FOSS/FLOSS) mean. 1. OSS ond FLOSS OSS refers to open source software, which reters to software whose source code is available to customers and it can be modified and redistributed without any limitation. An OSS mav come free of cost or with a payment of nominal charges that its developers may charge in the name of development, support of software. FLOSS refers to Free Libre and Open Source Software or to Free Livre and Open Source Softrware. The s ET Oss is 1sed to refer to a software which is bOth free software as wel as open source software. Here the words libre (a Spanish word) and livre (a Portuguese word) mean freedom. Examples of FLOSS are :Linux 0S, BOSS Linux, My$QL, OpenOfice.org software and many more. 2. Proprietary Software open nor freely available. Its Proprietary software is the software that is neither use is regulated through alicense and further distribution and modification s eltner torbidden or requires special nomiscion bythe supplier or vendor. Source code of propretdry sotware iS normally notavailable Examples of proprietary software are : Microsoft Windows OS, Adobe Premier Pro, other Adobe software, Quick Heal Antivirus and Many more. Chapter 1: COMPUTER SYSTEM 15 3. Freeware The term freeware is generally used for software, which is available free of cost and which allows copying and further distribution, but not modification and whOse source code is not available. Freeware should notbe mistaken for open software or for free software. Freeware is distributed in binary form (ready to run) without any licensing fee. In some NOTE instances, the right to use the software is limited Freeware and Free Software are two different tocertain types of users, for instance, for private things. Freeware are the software, which permt and non-commercial purposes. Freeware is redistribution but not modification (and their source often used in marketing situations in order to code is not available). These packages are not free sell additional products and to gain market software;so don't uSe the word "freeware" to refer to free software. advantages. One example is Microsoft Internet Explorer, which is made available as freeware. 4. Free Software Free Software means the software is freely accessible and can be freely used, changed, improved, copied and distributed by all who wish to doso. And no payments are needed to be made for free software. LET US REVISE Computers can deliver performance because of anefficient combination of hardware and software. While hardware refers to physical electronic components of a computer, software represent the recorded instructions/software that govern its operation. * Computer organization refers to logical structure ofacomputer describing their interconnections nd work dependency. * The functional components of a computer include : input unit, CPU, Memory, Storage Uni, Output Unit. The Input unit is responsible for obtaining input from user and converting it to digital form. The CPU (Central Processing Uni) processes the received input as per a set of instructions ond produces output. The CPU has these sub-components : ALU, Control Unit and Registers. The ALU (Arithmetic of Logic Unit) is responsible for carrying out arithmetic operations and logic operations (e.g., comparing two values). The Control Unit controls or supervises the processing taking place. Registers are small data holding areas within CPUthat hold data, instructions and memory address during the processing. CheckPoint Themain memory or memory holds the data and proqrams for the processing. 1.2 Main memory can either be ROM or RAM. 1. How can computer software be classified ? ROM is read only memory that stores some prewritten instructioS. 2. What are the categories of system software ? *3 RAM is Randomdccess memorv that can be read and written and is used for manipulating data during processing. 3. What is an operating system ? What is its role ? The primary memory (RAM) is volatile in nature Os all contents 4. What is application software ? What are are erased us SOon as power goes of. the categories of application software ? The cache memory is aspecal high speed memory storing the 5. What is utility software? most recently aCceSsed data. 6. What are customized software ? Ihe storaqe unit stores the contents permunently.