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Computer Overview

Not to MissA computer can be made intelligent through the latest technology of Artificial Intelligence (AI). Robots that you see in movies is one of the application areas of AI.

Not to MissData v/s InformationData in computer terminology mean raw facts and figures. For example, “Raja”, 1987, ‘B’, –120.8, +76.2 are data. Data are processed to form information.Information is the processed form of data.

1.1 Introduction

Computers have played a great role in improving our lives in almost all spheres. They have gained immense importance by increasing the productivity and effi ciency of the work done. They are put to use for all sorts of applications ranging from simple activities such as teaching, printing books and playing games to complex calculations. The ease with which computers can store, process and retrieve data have made them inevitable in offi ce and business environments.

1.1.1 What is a Computer?Let’s formally defi ne the wonderful machine called computer.

A computer is an electronic device that can perform a variety of operations in accordance with a set of instructions called program. It processes the input data given by the programmer/user and provides the desired information as output. Data is a set of basic facts and entities which itself has no meaning, while information is the data which has some meaning or value. Instruction is a statement given to a computer to perform a task. Input is the data and instructions given to a computer to perform a task. Process refers to manipulation of data while output is the information obtained after processing of data.

1.2 Characteristics of a Computer

1.2.1 Strengths and Weaknesses of a ComputerComputers have made life easier for everyone in the world. They are being used everywhere in nearly all fi elds such as banking, railways, airways, hotels, schools, colleges, shops, industries, defence and designing. All the areas were working without computers previously have shifted from manual working to computerized working due to the various advantages off ered by a computer, such as greater precision, accuracy and consumption of less time. Some of the advantages of computers are described below.

1Let’s learn about

• Introduction• Characteristics of a Computer• Hardware and Soft ware• Components of a Computer System• Memory• Measuring Data• Input/Output Devices• Common Storage Devices• Types of Soft ware• Operating Systems• Language Translators, Application

Generators and CASE Tools• General Purpose Application

Soft ware• Customized Application Soft ware• Common Utility Soft ware• Computer Languages

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1. Speed: Computers are much faster as compared to human beings. A computer can perform a task in a minute that may take days if performed manually. A modern computer can execute millions of instructions in one second.

2. High Storage Capacity: Computers can store a large amount of information in very small space. The data and instructions stored by computers can be retrieved and recalled even after a number of years. A CD-ROM of 4.7 inch diameter can store all the 33 volumes of Encyclopedia Britannica and will still have space to store more information. Bubble memories can store 6,250,000 bits per square centimeter of space. New age Blu-Ray discs are capable of storing upto 100 GB of data.

3. Accuracy: Computers can perform all the calculations and comparisons accurately provided the hardware does not malfunction.

4. Reliability: Computers are immune to tiredness and boredom or fatigue. Thus, they are more reliable than human beings.

5. Versatility: Computers can perform repetitive jobs effi ciently. They can solve labour problem or do hazardous jobs in hostile environment. They can even work in the areas where human brain can err, for instance, observing motion of very fast moving articles. Also, they can work with diff erent types of data and information such as graphic, audio, visual and characters.

In spite of these benefi ts, there are some disadvantages of computers also. A computer is a machine and obviously has no intelligence of its own. It needs instructions to perform a task. So, it cannot take decisions on its own.

1.3 Hardware and Software

Hardware and software are the two broad categories of computer components. Hardware refers to any physical component of a computer. For example, Central Processing Unit (CPU), monitor, keyboard, hard disk, etc. are physical components and thus, are hardware. Software refers to the programs, which are required to operate the computer. For example, DOS (Disk Operating System), Windows, Oracle, Tally, etc. are all software. An analogy of hardware can be the book which you are reading and the software would be the text written on the book. Another analogy could be—‘brain’ is a hardware but ̒ memory stored in the brainʼ is a software.

Both hardware and software are dependent on each other. CPU, memory unit, hard disk, etc. are useless unless they are provided with instructions and data for storage and processing. Similarly, BASIC or COBOL languages have no importance unless they are used along with various hardware components of a computer.

1.4 Components of a Computer System

The internal architectural design of computers diff ers from one model to another, however the basic components of a computer remain the same for all models. A complete computer

Tech NotesComputer strengths• Speed• High storage capacity• Accuracy• Reliability• Versatility

Computer weaknesses• Lack of decision-making power• Zero IQ

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installation including the central processing unit, the peripherals such as hard disk drives, monitor, printer, mouse and operating system which are designed to work and interact with each other and with the user is called a computer system. A computer system has three main physical components: input/output unit, central processing unit and memory unit (See Fig. 1.1). Besides these main components, a computer system has other components such as motherboard and storage devices. All the devices of a computer except motherboard and CPU are called peripheral devices.

Input Unit Output UnitCentral Processing Unit (CPU)

Primary Memory

Fig. 1.1: Basic Structure of a Unit

1.4.1 Functional Components of a ComputerSince a computer follows input-process-output cycle, the fi rst stage is performed in computer by the input unit, second stage is performed by its central processing unit and the third stage is performed by the output unit (See Fig. 1.1).

The main memory holds the input and intermediate output during the processing.

1.4.2 Central Processing UnitCentral Processing Unit (CPU) is the main component or ʻbrainʼ of a computer, which performs all the processing of input data. Its function is to fetch, examine and then execute the instructions stored in the main memory of a computer. In microcomputers, the CPU is built on a single chip or Integrated Circuit (IC) and is called a microprocessor. The CPU consists of Arithmetic Logic Unit (ALU), Control Unit (CU), Registers, Buses and Clock. Letʼs discuss about these. 1. Arithmetic Logic Unit: The arithmetic 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 and greater than.

2. Control Unit: The control unit is responsible for controlling the transfer of data and instructions among other units of a computer. It is considered as the ʻCentral Nervous Systemʼ of a computer, as it manages and coordinates all the units of a computer. It obtains the instructions from the memory, interprets them and directs the operation of the computer. It also performs the physical data transfer between memory and the peripheral device.

3. Registers: Registers are small high-speed circuits (memory locations) which are used to store data, instructions and memory addresses (memory location numbers), when ALU

Not to MissA motherboard contains the CPU chip, Memory chip, I/O interface, expansion slots and many other logic circuits. Motherboard is so called as all the other boards (printed circuit boards having chips or other electronic components) of the computer are connected to this board.

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performs arithmetic and logical operations. Registers can store one word of data (1 word = 2 bytes and 1 byte = 8 bits) until it is overwritten by another word. Depending on the processorʼs capability, the number and type of registers vary from one CPU to another.

4. Buses: Data is stored as a unit of eight bits (BIT stands for Binary Digit, i.e., 0 or 1) in a register. Each bit is transferred from one register to another by means of a separate wire. This group of eight wires, which is used as a common way to transfer data between registers is known as a bus. In general terms, bus is a connection between two components to transmit signal between them.

5. Clock: Clock is another important component of CPU, which measures and allocates a fi xed time slot for processing each and every micro-operation (smallest functional operation). In simple terms, CPU is allocated one or more clock cycles to complete a micro-operation. CPU executes the instructions in synchronization with the clock pulse. The clock speed of CPU is measured in terms of Mega Hertz (MHz) or Millions of Cycles per second and Giga Hertz (GHz) or Billions of Cycles per second. CPU speed is also specifi ed in terms of Millions of Instructions Per Second (MIPS) or Millions of Floating-Point Operations Per Second (MFLOPS).

Output DevicesMonitor

Modem

Floppy diskKeyboard

Hard diskMouse

Optical diskScannerDigital camera

SoundVideo

Printer

Input Devices

Memory (Short term data)

Storage (Long term data)

CPU

1.4.3 Memory UnitMemory unit, also known as a main/primary/internal memory is used to store data, instructions and information before, during and after processing by ALU. It is actually a work area (physically a collection of integrated circuits) within the computer, where the CPU stores the data and instructions.

1.4.4 Storage UnitPrior to the advent of computer, all data were stored manually on paper. Nowadays when computer has become an essential part of every organization, most data are stored in computers. Primary memory stores the data, instructions and information temporarily during processing by CPU. When the computer is switched off , this memory gets erased. The storage unit stores the data, information and software permanently, so that they can be retrieved whenever required. The storage unit consists of diff erent storage devices such as hard disk drive, compact disk drive and pen drive. The storage unit is also called secondary memory unit.

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1.4.5 Input/Output UnitsComputer processes the input data according to a given set of instructions and gives the output. The unit used for getting the data and instructions into the computer and displaying or printing output is known as an input/output unit (I/O Unit). The input unit is used to enter data and instructions into a computer. There are many peripheral devices which are used as input/output units for a computer. Keyboard is the main input device. Monitor, printer and plotter are the main peripheral devices used as output units for a computer.

1.5 Memory

There are two types of memory in computers: primary memory and secondary memory. They are further divided into many types. Letʼs discuss various types of computer memory.

1.5.1 Primary MemoryPrimary memory is of mainly three types: ROM (pronounced as ʻRa-omʼ), RAM (pronounced as ʻR-aemʼ) and CMOS (pronounced as ʻC-mosʼ). 1. Read Only Memory (ROM): Read Only Memory is an essential component of the memory

unit. A computer, being a machine, itself has no intelligence or memory and it requires instructions, which are given by man. Whenever a computer is switched on, it searches for the required instructions. The memory, which has these essential instructions, is known as read only memory. This memory is permanent and is not erased when the system is switched off . So, ROM is a non-volatile memory. As is clear from its name, it is read type of memory, i.e., it can be read only and not be written by user/programmer.

ROM contains a number of programs (set of instructions). The most important program of ROM is the Basic Input/Output System (BIOS, pronounced as ̒ bye-Osʼ) which activates the hardware to communicate with the system and application software.

Types of ROM: There are many types of ROM available for microcomputers like Mask ROM, PROM, EPROM, EEPROM and EAPROM.

(a) Mask ROM: Mask ROM is the basic ROM chip. In this type of ROM, the information is stored at the time of its manufacturing. So, it cannot be altered or erased later on.

(b) PROM: PROM stands for Programmable Read Only Memory. In this type of ROM, the information is stored by programmers after its manufacturing. It also cannot be altered or erased later on.

(c) EPROM: EPROM stands for Erasable Programmable Read Only Memory. It is similar to PROM, but its information can be erased later on by ultra violet light and it can be reprogrammed.

(d) EEPROM: EEPROM stands for Electrically Erasable Programmable Read Only Memory. It is similar to EPROM, but its information can be erased by using a high voltage current.

(e) EAPROM: EAPROM stands for Electrically Alterable Programmable Read Only Memory. As compared to EPROM and EEPROM, the information stored in EAPROM can be altered later.

Not to MissThe most common form of input device is known as a terminal. A terminal has an electronic typewriter like device, called keyboard along with a display screen, called Visual Display Unit (VDU) or monitor.

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2. Random Access Memory (RAM): Random Access Memory is used to store data and instructions during the execution of programs. Contrary to ROM, RAM is temporary and is erased when a computer is switched off . So, RAM is a volatile memory. RAM is a read/write type of memory, and thus can be read and written by the user/programmer. As it is possible to randomly use any location of this memory, therefore, this memory is known as random access memory.

Types of RAM: There are two types of RAM used in PCs: Dynamic RAM and Static RAM. (a) Dynamic RAM (DRAM): The information stored in Dynamic RAM has to be refreshed

after every few milliseconds, otherwise it is erased. In other words, DRAM must be continuously rewritten in order to maintain its data. DRAM is used for most system memory because it is cheaper and has higher storage capacity than Static RAM.

(b) Static RAM (SRAM): The information stored in Static RAM need not be refreshed, but it remains stable as long as power supply is provided. SRAM is costlier but has higher speed than DRAM.

Not to MissThere are four types of RAM chips: SIP (Single Inline Package), DIP (Dual Inline Package), SIMM (Single Inline Memory Module) and DIMM (Dual Inline Memory Module).

3. Complementary Metal–Oxide–Semiconductor (CMOS) Memory: Complementary Metal–Oxide–Semiconductor memory is used to store the system confi guration, date, time and other important data. When the computer is switched on, BIOS matches the information of CMOS with the peripheral devices and displays error in case of mismatching.

1.5.2 Secondary Memory (Storage Devices)A computer stores the data, information and software permanently in its storage devices, which are also called secondary memory devices. Storage devices enable you to retrieve the data whenever you require it. There are many storage devices used with microcomputers. The most common storage devices currently used with a PC are hard disk, CD-ROM (Compact Disc Read Only Memory), DVD (Digital Versatile Disc) and Pen Drive, which are discussed in the later part of the chapter (Refer Section 1.8: Common Storage Devices).

1.6 Measuring Data

There are diff erent number systems used in arithmetic such as decimal, binary, octal and hexadecimal. Although we input numbers in decimal form, in a computer they are represented either in binary, octal or hexadecimal forms. In order to understand why computers use the binary system, you must fi rst understand that everything that occurs within a computer happens due to the presence or absence of an electronic signal. For instance, if a wire contains a signal, a specifi c operation may occur. If the wire does not have a signal, the event will not occur. At any given time, the wire either has a signal or it does not have it. To represent these two possible states, a computer uses the values 0 (for off ) and 1 (for on).

Not to MissIn a computer, characters are represented in codes such as BCD (Binary-coded Decimal), EBCDIC (Extended Binary Coded Decimal Interchange Code) and ASCII (American Standard Code for Information Interchange).

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BIT stands for Binary Digit. It is single digit in a binary number, which can be either 0 or 1. Within a computer, hardware devices such as the CPU, memory, and even disks, store data in terms of ones and zeros which are referred as binary digits (or bits). 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 store all alphabets, numbers and other characters used by a computer. A group of 8 bits is known as a byte. For example, when the user types A (1 byte) on the keyboard, the system delivers a signal, which sets the input location to the bit value 01000000. In memory, each byte occupies a unique address (storage location). Byte is considered the smallest unit of memory.

Not to MissUnit Short Name Full Name1 Bit Bit Binary Digit8 Bits 1 Byte Byte210, i.e., 1024 Bytes 1 KB Kilobyte210, i.e., 1024 KB 1 MB Megabyte210, i.e., 1024 MB 1 GB Gigabyte210, i.e., 1024 GB 1 TB Terabyte210, i.e., 1024 TB 1 PB Petabyte210, i.e., 1024 PB 1 EB Exabyte210, i.e., 1024 EB 1 ZB Zettabyte210, i.e., 1024 ZB 1 YB Yottabyte210, i.e., 1024 YB 1 Brontobyte Brontobyte210, i.e., 1024 Brontobytes 1 Geopbyte Geopbyte**Geopbyte is the highest memory measurement unit so far.

Formative Assessment 1

1. Tick (✓) the correct option. (a) __________ has no meaning, while __________________ has some meaning. (i) Information, data (ii) Data, information (iii) Process, instruction (iv) Instruction, process (b) A computer has no __________________ of its own. (i) Memory (ii) Data (iii) Information (iv) Intelligence (c) Which of the following is not a part of CPU? (i) ALU (ii) Control Unit (iii) Memory Unit (iv) Registers (d) The storage unit is also called ____________________. (i) Primary memory unit (ii) Secondary memory unit (iii) Tertiary memory unit (iv) Hard disk drive (e) Which of the following is not a type of RAM chip? (i) SIP (ii) DIP (iii) SRAM (iv) SIMM

2. Fill in the blanks. (a) In microcomputers, the CPU is built on a single chip called ____________. (b) The group of eight wires used to transfer data between registers is called ____________. (c) A ____________ contains the CPU chip, memory chip, I/O interface, expansion slots

and many other logic circuits.

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(d) ____________ refers to any physical component of a computer. (e) Bit stands for ____________ ____________.

3. Circle six components of a computer in the following grid.B A S U D I J M A TC M B T O C L O C KX E A P B P L P N JY M Z A L U C U Y KA O R E G I S T E RP R I N T E R L M HD Y T W V S L W U FN K E Y B O A R D HO P S X E J G K I LQ R M O N I T O R M

4. Recall the features of various types of memories. From the following lists, sort the memory type and a feature of the memory and place them in the correct position in the given table.

Memory TypeROM

RAM

FeatureCan be erased by high voltage current

Needs to be refreshed

Need not be refreshed

Can be erased by UV light

Can’t be erased or altered later on

Name Memory Type FeatureEPROM

SRAM

EEPROM

DRAM

PROM

1.7 Input/Output Devices

Input devices are used to input data, information and instructions into a computer. Common input devices include keyboard, mouse, joystick, scanner, microphone, Optical Character Reader (OCR), Magnetic Ink Character Recognition (MICR), light pen, barcode reader and digital camera. Output devices are hardware components, which are used to display or print the processed information. Common output devices include monitor, printer, speaker and plotter.

1.7.1 Input Devices1.7.1.1 Keyboard

Keyboard, the most common and essential input device of a computer is similar to a typewriter. However, there are more keys present on a computer keyboard than on a

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typewriter. Most commonly used keyboards (such as QWERTY keyboard) have 105 keys and more (See Fig. 1.2).

Not to MissA QWERTY keyboard is so called as in this type of a keyboard the leftmost six letters in the topmost row are Q, W, E, R, T and Y.

Fig. 1.2: QWERTY Keyboard

1.7.1.2 Mouse

A mouse is a pointing device, which is used to point out the location where you want to input the information. It is basically used to move the cursor, draw sketches/diagrams and select items visible on the screen in all Graphical User Interface (GUI) or Windows based programs. There are mainly three types of mouse: Mechanical, Opto-mechanical and Optical (See Fig. 1.3). Mechanical mouse has a rubber or a metal ball on its underside that can roll in all directions. Mechanical sensor detects the direction of the rolling ball and makes a movement of the screen painter accordingly. Opto-mechanical mouse is similar to a mechanical mouse except that it uses optical sensor to detect the movement of the ball on the mouse pad. Optical mouse, which is most commonly used has no mechanical moving parts, as it uses laser beam to detect the movement of the mouse on the mouse pad.

Mechanical mouse Opto-mechanical mouse Optical mouse

Fig. 1.3: Types of Mouse

1.7.1.3 Joystick

A joystick is a pointing device that consists of a small, vertical lever mounted on a base or a keyboard (See Fig. 1.4). It is used to steer the screen cursor around for drawing diagrams in computer-aided design (CAD) applications and playing computer games. A joystick can be moved in all directions.

1.7.1.4 Scanner

A scanner reads text, photographs or graphics from paper, which are then converted into bit patterns for processing, storage and output. Scanners are widely used for Desktop Publishing (DTP) and graphics applications. Generally there are three types of scanners: Hand-held, Sheet-fed and Flatbed (See Fig. 1.5).

Hand-held scanner Sheet-fed scanner Flatbed scanner

Fig. 1.5: Types of Scanners

Fig. 1.4: Joystick Mounted on a Base

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1.7.1.5 Microphone

A microphone (See Fig. 1.6) is a special multimedia input device that is used to store voice data consisting of a recorded message or synthesized sound using a GUI operating system such as Windows.

Not to MissMicrophone converts sound waves into analog electrical signals, which are further converted to digital form in a PC.

1.7.1.6 Optical Character Reader (OCR)

Optical Character Reader (OCR) device (See Fig. 1.7) is used to input the printed matter on paper or any other object. The text that needs to be scanned is illuminated by a low-frequency light source. The dark areas on the text absorb the light while the light areas refl ect it. OCR devices are used in application areas like reading PIN codes in postal services and reading of passenger tickets.

1.7.1.7 Magnetic Ink Character Recognition (MICR) Device

Magnetic Ink Character Recognition (MICR) device (See Fig. 1.8) is used to recognize the magnetically-charged characters given at the bottom of a cheque, which are written by a special ink called Magnetic Ink.

Fig. 1.8: MICR Device

1.7.1.8 Light Pen

A light pen is a small pen-shaped pointing device, which contains light sensors (See Fig. 1.9). It is used to choose objects or commands on the screen either by pressing it against the surface of the screen or by pressing a small switch on its side. This sends a signal to the computer, which then works out the light penʼs exact location on the screen.

1.7.1.9 Barcode Reader

Barcode Reader (See Fig. 1.10) is an optical scanner that reads the bar-coded data (data in the form of light and dark lines) and converts it into electrical pulses, which are then processed by the computer. Bar-coded data is generally used for labelling goods, numbering books or encoding identifi cation or account numbers.

Fig. 1.10: Barcode Reader

Fig. 1.6: Microphone

Fig. 1.8: MICR De

n

Fig. 1.7: OCR Device

Not to MissOther areas where MICR device is used are in correction of large volume of examination answer sheets, in market surveys, reading ordinary forms, etc.

Fig. 1.9: Light Pen

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1.7.1.10 Digital Camera (Webcam)

Digital Camera or Webcam (See Fig. 1.11) is used to capture and store data in the form of still and video images. It has become very popular on the Internet for chatting.

1.7.2 Output Devices1.7.2.1 Monitor

Monitor, also known as Visual Display Unit (VDU) is the most important output device. The screen of monitor is made up of tiny dots called pixels, which are arranged in a rectangular form. The resolution (sharpness of an image) of the monitor depends upon these pixels. Inside the monitor, there is either a Cathode Ray Tube (CRT) or an Liquid Crystal Display (LCD). Therefore, monitors are either of CRT type or LCD (See Fig. 1.12).

Not to Miss

Based on the quality of resolution, monitors are classified into many categories such as Color Graphics Adapter (CGA), Enhanced Graphics Adapter (EGA), Video Graphics Array (VGA) and Super Video Graphics Array (SVGA). However, today only SVGA monitors are available in the market. An SVGA can display both text and video graphics with graphics resolution of 800 × 600 pixels.

1.7.2.2 Printer

Printers are the output devices that give a hardcopy of the input. They can be classifi ed into two broad categories: Impact Printers and Non-impact Printers. An impact printer makes a contact with the paper to produce the result (an image) while a non-impact printer does not strike characters against ribbon or paper when it prints.Another diff erence between impact and non-impact printers is that an impact printer prints one character in one line at a time, while a non-impact printer prints the entire page at one time. So, a non-impact printer is also called page printer.

1. Impact Printers: Impact printers are generally of three types: Solid Font Printer, Character/Serial Printer and Line Printer.

Solid Font Printer: In this printer, a complete character, such as on a typewriter key, strikes a carbon ribbon or other inked surface against the paper to produce an image of the character. It gives the best quality formed character images, but it is slower than other types. The commonly used solid font printer is the daisy wheel printer (See Fig. 1.13), which contains a plastic or metal hub with spokes, called daisy wheel. The characters are embossed on the radiating spokes, which strike against the ribbon on the paper during printing mechanism. Fig. 1.13: Daisy Wheel Printer

CRT monitor LCD monitor

Fig. 1.12: Types of Monitors

Fig. 1.11: Digital Camera

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Character/Serial Printer: It prints one character at a time by putting a sequence of dots. The commonly used character or serial printer is the dot matrix printer (See Fig. 1.14). Each character printed by a dot matrix printer consists of a number of dots. Although the dot matrix printer is faster than daisy wheel printer, the printing quality of the former is poorer than the latter.

Line Printer: It prints an entire line in a single operation without necessarily printing one character at a time. Line printers are generally electro-mechanical devices, which print complete lines of print. A line printer (See Fig. 1.15) is used primarily in the mini/mainframe-processing environment. Line printers are of three types: Chain Printer, Band Printer and Drum Printer. Chain printer is a high-speed printer in which the types are caused by the lines of a revolving chain. Its speed is very high but noise is very low. Band printer uses band type characters as its printing mechanism. In this printer, the paper is momentarily stopped and the desired characters pass over a given column while the hammer activates by pressing the ribbon against the paper to form the image. In Drum printer, all the characters for printing are placed around the surface of a cylinder and the entire character set is placed around the cylinder at each print position.

Tech NotesSolid Font Printer• Complete character strikes a carbon ribbon• Gives best quality formed character images• Daisy wheel, the most commonly used solid font printer

Character/Serial Printer• Prints one character at a time• Dot matrix printer, the commonly used character/serial printer• Each character consisting of a number of dots

Line Printer• Prints an entire line in a single operation• Generally electro-mechanical devices• Used primarily in the mini/mainframe-processing environment

2. Non-impact Printers: They are of the four types: Inkjet Printer, Laser Printer, Thermal Printer and Electrostatic Printer.

Inkjet Printer: An inkjet printer (See Fig. 1.16) uses the technique of projecting droplets of ink on paper to form the required image.

Laser Printer: It is a non-impact printer (See Fig. 1.17) that creates a latent image by means of a laser beam. Then it makes the image visible using a toner and transfers and fi xes it on paper. The speed of a laser printer is very high with a very low level of noise.

Fig. 1.14: Dot Matrix Printer

Fig. 1.15: Line Printer

Fig. 1.16: Inkjet Printer

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Not to MissAn inkjet printer provides a print resolution of around 360 dots per inch (DPI). The resolution of laser printers is 600 DPI both horizontally and vertically. Some high model laser printers have resolution of 1200 DPI.

Fig. 1.17: Laser Printer

Thermal Printer: In this printer, heat elements produce dot-matrix images on heat sensitive paper. The output of thermal printer fades quality when exposed to light.

Electrostatic Printer: In this printer, the parts of paper which are to be printed are electrostatically charged and attract a fi ne dust which is then focused on the paper by the application of heat.

1.7.2.3 Speaker

Speaker (See Fig. 1.18) is one of the essential output devices of a multimedia PC. It is used to produce sound and music. It is generally available in pairs and various models based on size, quality and volume capacity.

1.7.2.4 Plotter

A plotter is an important device, which is used to print high quality graphics and drawings such as a construction plan for building or blueprints. Plotters are of mainly three types: Flatbed, Drum and Inkjet. Flatbed plotter (See Fig. 1.19) uses a bed or tray to hold paper in a fi xed position. A movable pen is usually held by a single arm that can move the pen both horizontally and vertically. It takes a lot of time to generate a graphic. Drum plotter (See Fig. 1.20) has a single arm that can move across the drum horizontally. The drum itself moves the paper forward or backward to enable the pen to draw in any vertical direction. Inkjet plotters (See Fig. 1.21) use inkjets in place of pens.

Fig. 1.19: Flatbed Plotter Fig. 1.20: Drum Plotter Fig. 1.21: Inkjet Plotter

1.8 Common Storage Devices

Some of the common storage devices of a microcomputer are Hard Disk, Floppy Disk, CD-ROM, DVD, Blu-ray Disc, Pen/Flash Drive and Memory Stick.

1.8.1 Hard DiskHard Disk or Hard Disk Drive (HDD) is the most common magnetic, mass-storage device of present-day microcomputers, which is fi xed inside a computer and is not easily removable.

Fig. 1.18: Speakers

Not to MissInkjet plotters are faster than flatbed plotters and can print multi-coloured large drawings.

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A hard disk is made up of disk platters, which are used to read and write to the disk. These platters are sealed inside a box (See Fig. 1.22). There are diff erent types of hard disks available in the market with diff erent storage capacities such as 80 GB, 160 GB, 250 GB, 300 GB and 500 GB.

Not to Miss

A hard disk is also known as ‘Winchester Disk’ because this device was first made by IBM at Hursley Laboratory located near Winchester in England.

1.8.2 Floppy DiskFloppy disk was once a common storage device of PC. It is made of a plastic disk coated with magnetic material, which is sealed inside a square plastic jacket. Data can be written on or read from this disk by a drive, called Floppy Disk Drive (FDD) fi xed inside the CPU (See Fig. 1.23). There are 3 types of fl oppy disks based on their sizes: 8 inch, 5¼ inch and 3½ inch. The 3½ inch fl oppy disk, the latest one (See Fig. 1.24) can store maximum 1.44 MB data. However, all types of fl oppy disks are outdated now.

Fig. 1.23: Floppy Disk Drive Fig. 1.24: 3½ inch Floppy Disk

1.8.3 CD-ROMCompact Disc Read Only Memory (CD-ROM) is an optical storage media. It is round in shape and is 5" in diameter (See Fig. 1.25). Earlier CDs were of read-only type but now writable CDs are available with the relevant drives (such as CD Writer) to write on them. A single optical disk stores nearly 640 MB of data on one side. A large multimedia software and data such as audio/video fi les can be stored on the CDs.

1.8.4 DVDDigital Versatile Disc Read Only Memory (DVD-ROM) and Digital Versatile Disc Random Access Memory (DVD-RAM) are optical discs having storage capacity of 4.7 GB and 5.22 GB respectively (See Figs. 1.26 and 1.27). DVD-ROMs are the higher capacity removable media for multimedia applications.

Fig. 1.26: DVD-ROM Disc Fig. 1.27: DVD-RAM Disc

Fig. 1.22: Hard Disk Drive

Fig. 1.25: CD-ROM Disc

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1.8.5 Blu-ray DiscBlu-ray Disc (BD) is an optical plastic disc of the same size as DVDs and CDs (See Fig. 1.28). The storage capacity of a conventional Blu-ray disc is 25 GB per layer, with dual layer disks having a capacity of 50 GB. The major application of Blu-ray discs is as a medium for storage of video data such as feature fi lms. Blu-ray disc is associated with a set of multimedia formats that allow the video and audio fi les to be stored on it with greater defi nition than on DVD.

Not to MissBlu-ray disc is so called because blue laser is used to read the disk which allows information to be stored at a greater density than is possible with red laser used for DVDs.

1.8.6 Pen/Flash DrivePen drive is a portable Universal Serial Bus (USB) fl ash memory device. It is so called as it resembles a small pen (See Fig. 1.29). It is small enough to fi t into a pocket and can store a large amount of data such as 4 GB, 8 GB and 16 GB. It is used as a standard storage for data transfer from one computer to another.

1.8.7 Memory StickMemory stick is another standard storage device for data transfer in small digital electronic products. It is smaller than a stick of chewing gum (See Fig. 1.30). It is available in 4 MB, 8 MB, 16 MB, 32 MB, 64 MB and 128 MB storage sizes, and as a kit with a PC card adapter. The 8 MB memory stick has more than fi ve times the storage capacity of a standard 3.5 inch fl oppy disk.

Formative Assessment 2

1. Tick (✓) the correct option.

(a) QWERTY is a type of _____________. (i) Keyboard (ii) Mouse (iii) Monitor (iv) Printer

(b) Which of the following type of mouse uses laser beam to detect movement and has no ball?

(i) Mechanical mouse (ii) Optical mouse (iii) Opto-mechanical mouse (iv) Both (ii) and (iii)

(c) A ____________ converts sound waves into analog electrical signals. (i) Speaker (ii) Microphone (iii) Light pen (iv) None of these

(d) Which of the following is not a type of monitor? (i) CRT (ii) LCD (iii) SVGA (iv) GUI

Fig. 1.28: Blu-ray Disc

Fig. 1.29: Pen Drive

Fig. 1.30: Memory Stick

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(e) Which of the following is not an optical storage device? (i) Memory stick (ii) Blue-ray disc (iii) CD (iv) DVD

2. State true (T) or false (F).

(a) An OCR device can be used to read PIN codes in postal service. (b) Barcode reader is used to read magnetically-charged characters given at the

bottom of a cheque.

(c) Inkjet printer is an impact printer.

(d) Chain printer is a type of line printer.

(e) DVD ROM and DVD RAM are same.

3. Match the following. (a) Daisy wheel printer (i) Line printer (b) Dot matrix printer (ii) Non-impact printer (c) Drum printer (iii) Character/Serial printer (d) Thermal printer (iv) Solid font printer

4. Identify the device and classify it as Input (I), Output (O) or Storage (S) device.

(a) I/O/S (b) I/O/S (c) I/O/S (d) I/O/S

(e) I/O/S (f ) I/O/S (g) I/O/S (h) I/O/S

(i) I/O/S (j) I/O/S (k) I/O/S (l) I/O/S

5. Write any two facts that come to your mind about the following devices. (a) OCR (b) Light pen (c) VDU (d) Inkjet printer (e) Drum plotter (f ) CD-ROM

1.9 Types of Software

Software are broadly classifi ed into three types: System Software, Application Software and Utility Software.

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1.9.1 System Software System software are required to control the working of hardware and aid in eff ective execution of a general userʼs applications such as fi le editing, storage management, resource accounting, I/O management and database management. Some of the examples of system software are Disk Operating System (DOS), Windows, BASIC Interpreter and C Compiler.

Not to Miss

BASIC stands for Beginner’s All Purpose Symbolic Instruction Code. It is a programming language mostly used by students for learning programming and developing simple applications.

System software can be further categorized into two types: System Management Software (Operating Systems) and System Development Software (Language Translators, Application Generators and CASE Tools). We will discuss these software later in the chapter.

1.9.2 Application Software Application software consists of programs that are required to perform specifi c type of work for end users on computer. They are required for general and special purpose applications such as database management, word processing and accounting. Some examples of application software are Microsoft Word (MS Word), MS Excel, Adobe PageMaker and Tally. Application software can be further classifi ed into following two types:

General Purpose Application Software and Customized Application Software. We will discuss these software later in the chapter.

1.9.3 Utility SoftwareSystem software utilities or Utility software support the operation of a computer. They provide many features including fi le management capabilities, data compression, diagnostic routines, virus detection and removal, text editing, performance monitoring and spooling. There are many types of utilities for carrying on diff erent tasks. We will discuss these software later in the chapter.

1.10 Operating Systems

The hardware of a computer system cannot function on its own. When a computer is switched on, it needs to be instructed by the user what to do next. A computer needs instructions for every operation and we know that a computer understands only machine language. There is an interface between a user and a computer through which a computer can be instructed to perform the required operation. That interface is nothing but an operating system software. The operating system acts as an intermediary between a user and a computer. It provides environment to the user. DOS, Windows, Unix and Linux are examples of some common operating systems.

Not to MissCASE stands for Computer-aided Software Engineering.

Not to MissApart from providing the environment, the operating system software performs many other tasks as well. It manages the memory, the CPU time and also the file systems.

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1.10.1 BootingIt is not possible to use a computer without an operating system. An operating system makes a computer ready to use by a process called booting. The term ʻbootingʼ comes from the word ʻbootstrapʼ. As a bootstrap help us to get our boots on, similarly booting helps a computer to get ready. When we switch on a computer, the instructions stored in ROM are automatically executed. These instructions help the computer to load the operating system from the external storage device (disk) to internal storage (RAM). The process of loading of operating system from disk to RAM is called booting.

1.10.2 Types of Operating SystemsOperating systems are basically of two types—Single-user and Multi-user. Single-user operating systems are designed only for the use of a single user. In these systems, there is only one terminal on which the operating system is installed and can be accessed by a single user only. MS-DOS, PC DOS and OS/2 are examples of single-user operating systems. Multi-user operating systems are designed for multiple users, which are used for computers having many terminals. Unix, Xenix, Windows and OS/400 are some examples of multi-user operating systems.

1.11 Language Translators, Application Generators and CASE Tools

Besides operating system, we also need some system software such as language translators, application generators and CASE tools which assist us in development of other system software and application software. Letʼs discuss these.

1.11.1 Language TranslatorsWe give instructions to computer using a language. A set of instructions is called a Program and the language using which we give the instructions is called the Programming Language or Computer Language or simply Language. There are many types of computer languages such as Machine Language and High Level Language which we will discuss in concluding part of this chapter (Refer Section 1.15 – Computer Languages). Although we can give instructions to computer using any language, internally it understands only the machine language. The machine language consists of two numbers only, i.e., 0s and 1s. Regardless of the programming language used (except machine language), the symbolic instructions have to be translated into a form that can be executed by computer. The software which converts the codes of other languages into machine code are collectively called Language Translators. Language Translators are categorized into three types—Interpreters, Compilers and Assemblers. 1. Interpreters: Instructions of a high-level language

are coded in many statements. At the time of their execution, they are converted statement by statement into machine code by using a system software called interpreter. There are certain disadvantages of interpreters. As instructions are

Not to MissPrograms written in BASIC language are executed by using BASICA or GW-BASIC interpreters.

Not to MissMS-DOS, developed by ‘Microsoft Inc.’ in 1981, has been the most widely used operating system of IBM-compatible microcomputers.

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translated and executed simultaneously using interpreters, they are very slow for executing large programs. Hence, interpreters are not suitable for most application developments.

2. Compilers: In contrast to interpreters, compilers provide faster execution speed. Compilers do not translate and execute the instructions at the same time. They translate the entire program (source code) into machine code (object code) at one time. Using linker, the object code is converted into executable code. As compared to interpreters or assemblers, compilers are preferred in the development of application software.

3. Assemblers: Assemblers translate the assembly language code which are called mnemonic code (source program) into machine language code (object program). After assembling, a linker program is used to convert the object program into an executable program. Assemblers are used mainly in the development of system software.

1.11.2 CASE ToolsDevelopment of application software is very complex to plan, design, develop and manage. Software engineering is the systematic approach in designing, development, operation and maintenance of such software. Its basic aim is to produce high quality software at low cost. Computer-aided Software Engineering (CASE) tool is a group of diff erent software tools that are integrated and used in software engineering.

CASE tools simplify all stages of project planning, analysis and design of an application. They include many important features like graphics library, data dictionary, design methodology, screen/report designing and systems documentation. CASE tools incorporate modeling techniques for representing the data and processes.

1.12 General Purpose Application Software

General Purpose Application Software are needed for general purposes like word processing, spreadsheets, presentations and database management. MS Offi ce having MS Word, MS Access and MS Excel are some common general purpose application software.

1.12.1 Word Processing SoftwareWord processing programs enable you to write, edit, format, save and print a document with ease. Using a word processing software, you can produce a high quality document in much less time than if you use a typewriter because word processing software separates document creation from document printing. Word processing is the most widely used

Not to MissCompilers are widely used in translating codes of high level languages (e.g. COBOL, FORTRAN, PASCAL, Turbo/Quick BASIC, Turbo/Microsoft C, etc.) and fourth generation languages (e.g. FoxPro).

Not to MissThe Microsoft Macro Assembler program (MASM) and Borland Turbo Assembler program (TASM) are two popular assemblers.

Not to MissDesigner/2000 is Oracle’s suite of CASE tools that address the different stages of application development.

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technique for typing, editing, storing, formatting, manipulating and printing documents with the assistance of computer and printer. It is the most effi cient means of generating documents electronically. Word processing off ers several advantages over typewriting. Using the word processing technique, the user can edit the text as and when required, move or copy any part of the text from one location/fi le to another location/fi le, and insert or delete the spaces/text. There is a wide range of word processors available for both DOS and Windows environment. MS Word is the most popular word processor.

1.12.2 Spreadsheet PackagesBusiness applications require a lot of calculation work. In manual system, it is done on a sheet of paper with rows and columns, which is called a ʻspreadsheetʼ. Spreadsheet packages use the concept of an electronic spreadsheet. An electronic spreadsheet (or worksheet) is a very big sheet consisting of thousands of rows and columns, which is used to store information in the memory of a computer. For example, databases and electronic spreadsheets have now become an essential tool in developing a computerized management information system. Income statements, annual reports, balance sheet, cost analysis and budgets are some of the applications where worksheets are typically used. There are many products of spreadsheet packages. MS Excel is the most popular spreadsheet program.

1.12.3 Presentation SoftwareLetʼs say you are given a task of designing presentation on drug addiction. Now, you have two ways of going about it—one is doing it manually by making charts and posters, and second is computerizing the presentation by use of diff erent presentation packages like Microsoft PowerPoint. Microsoft PowerPoint has many powerful features, which help us to design an eff ective presentation with animation eff ects.

1.12.4 Database Management PackagesBusiness processes are always associated with a huge amount of data. To store, manipulate and process such data, some software packages are needed, which are collectively known as Database Management Packages/Software/Systems (DBMS). Database Management System is defi ned as software that organizes and maintains the data in a database for providing the information. Many database management packages are available in the market. MS Access, Paradox, Oracle, Ingres, Sybase and Informix are the major products of database management systems.

1.13 Customized Application Software

Although general purpose application software are exclusively used by all users for general applications, there are certain software which are meant for some special applications and organizations. Besides general purpose application software, some organizations also need software for desktop publishing, graphics, multimedia, animations, fi nancial accounting, sales and marketing, inventory, export documentation, etc. These software are collectively known as Special Purpose Application Software.

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Not to MissEvery business consists of many functions which are organized into different departments like Finance, Marketing, Inventory, Production, Research and Development (R & D) and Human Resource Development (HRD). For computerizing these departments, special kind of application software are needed, which are collectively called Business Application Software.

1.13.1 Computerized Reservation SoftwareIndian Railways and various airlines use computerized reservation systems for booking of tickets online. They have developed special software for operating and managing all functions related to reservation. Indian Railways has developed a Passenger Reservation System (PRS) that provides reservation services to nearly 1.5 to 2.2 million passengers per day on over 2500 trains running throughout the country. The PRS application software, Country-wide Network for Computerized Enhanced Reservation and Ticketing (CONCERT) is the worldʼs largest online reservation application, developed and maintained by Centre for Railway Information Systems (CRIS). Airline reservation software are used by various airline companies for booking tickets for a particular airline. They interface with a Global Distribution System (GDS) which supports travel agencies and other distribution channels in making reservations for most major airlines in a single system.

1.13.2 Accounting Management SoftwareAccord, EX and Tally are some examples of popular standard fi nancial accounting software packages among Indian users. Accord, developed by EDP Corporation, is a comprehensive accounting software for preparing Management Information Systems (MIS) and other reports. EX developed by Tata Consultancy, Services, provides business accounting capabilities along with inventory and invoicing features. Tally, developed by Peuronics Pvt. Ltd., is the accounting and book keeping software along with capabilities of invoicing/inventory accounting.

1.13.3 Human Resource Management SoftwareHuman Resource Management Software (HRMS) is a special purpose application software used by HR department for managing complete details of the employees of an organization. It basically supports HR managers in managing employee related functions such as appointment, training, attendance, salary and compensation and pensions. HRMS is used for data entry, data tracking, and data information needs of the human resources, payroll management, and accounting functions within a business. HRMS is also called Human Resources Information System (HRIS). Attendance system is a subsystem of HRIS, which manages the attendance records of all employees of the organization. It also keeps records of overtimes and leaves of the employees and provides input to the payroll system for generation of pay slips. Payroll is another subsystem of HRIS that manages salary and compensation records of the employees for generating pay slips, payroll reports, PF statements and other related MIS reports.

Not to MissManagement Information System is an application software that provides managers with information required for basic functions of management like planning, controlling, directing and decision-making.

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1.13.4 Inventory Control SystemAll organizations need an effi cient system to maintain and control the optimum level of investment in all types of inventories. Inventory refers to the stock of raw materials and fi nished goods available in the fi rm for production and sale. Inventory control system is a special purpose software for maintaining an optimum level of raw materials and fi nished goods inventory in an organization. This system helps managers in preparation of purchase orders, inventory status reports and MIS reports accurately and on time. Generation of MIS reports helps management to make eff ective and timely decisions.

1.13.5 Invoicing or Billing SystemInvoicing or billing system is a subsystem of sales and marketing system, which is used by the sales department to generate bills or invoices for the sales made. It is generally integrated with inventory and accounting system to update the stock status of items and to maintain accounts related records respectively.

Formative Assessment 3

1. Tick (✓) the correct option.

(a) ___________ software are required to control the working of hardware. (i) System (ii) Application (iii) Utility (iv) Operating system

(b) Which of the following is not an application software? (i) MS Word (ii) Adobe PageMaker (iii) DOS (iv) Tally

(c) The process of loading of operating system from ___________ to ___________ is called booting.

(i) RAM, disk (ii) Disk, RAM (iii) ROM, RAM (iv) RAM, ROM

(d) MS-DOS is an example of _______________________. (i) Single-user operating system (ii) Multi-user operating system (iii) Utility software (iv) System development software

(e) Which of the following is/are database management package(s)? (i) MS Access (ii) Oracle (iii) Paradox (iv) All of these

2. Classify the following software into System (S) or Application (A) software.

(a) DOS (b) MS Word (c) Tally

(d) Adobe PageMaker (e) MS PowerPoint (f ) MS Windows

(g) HRMS (h) MIS

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3. Recall the various types of software and complete the following crossword.

P E A

W

T

D B

W

1 2 3

4

5

6

8

7

Across

1. A special purpose software required for DTP (9)

4. A word processing software (4)

6. Disk operating system (3)

7. A programming language (5)

8. Most essential system software required for booting (7)

Down

1. An application software used for presentation purposes (10)

2. A spreadsheet software (5)

3. A database software developed by Microsoft (6)

5. An accounting software (5)

1.14 Common Utility Software

Disk/Folder/File Management, Virus Scanner/Cleaner and Data Compression Tools are some of the utilities which are commonly used. Letʼs discuss these.

1.14.1 Disk/Folder/File ManagementDisk, folder and fi le management utilities provide fi le management capabilities like copying, comparing, searching, listing and sorting the fi les. Although these features are off ered by many operating systems, utility programs provide better user-friendly environment along with some additional features. Norton Utilities (NU) and PC TOOLS are the most commonly used fi le management utilities. Norton utilities are widely used utility programs for DOS, Windows and Macintosh operating systems developed by Symantec (originally called Central Point Software). PC Tools is another popular comprehensive package of PC utilities from Symantec. It includes DOS shell, fi le management, backup, data recovery, data compression and antivirus utilities.

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1.14.2 Virus Scanner/CleanerVirus scanner and cleaner utilities are used to detect and eradicate the diff erent types of viruses. Virus is an unauthorised software that is used to invade and disrupt the normal working of a computer. Like biological viruses, computer virus spreads from one computer to another generally through fl oppy disks, CDs and pen drives. There are many problems caused by viruses such as damage of data, loss of user interface, unexpected screen messages and system crashes. There are many utilities, such as Norton Antivirus, McAfee, SmartDog and Dr Solomonʼs Antivirus Toolkit that can detect and remove most of the viruses and are popularly called Virus Scanners.

1.14.3 Data Compression ToolsData compression utilities compress or decompress fi les that are stored on fl oppy and hard disks. As compressed fi les take up very less space in disks, data compression utilities are widely used during copying of data from hard disks to fl oppy disks. WinZip is a popular data compression program available as a utility with Microsoft Windows operating systems.

1.15 Computer Languages

One man communicates with another in a language which another man can understand. Similarly, man communicates with computer in a language which machine can understand. This language which consists of a set of commands, understandable by computer directly or after translating, is known as Computer Programming Language. There are many types of computer languages which can be categorized into following four types. 1. Low-level Languages (First and Second Generation Languages) 2. High-level Languages (Third Generation Languages) 3. User-friendly Languages (Fourth Generation Languages) 4. Object-oriented Languages (Fifth Generation Languages)

Letʼs discuss these.

1.15.1 Low-level Languages/Machine Language/Binary LanguageIn early days of computers, only those languages were used for programming which could be directly executed on computer. Languages which computer can understand directly and are machine dependent are called Low-level Languages. For example, Machine Language and Assembly Language are two important low-level languages. Machine language is the oldest and most diffi cult of all the languages. It is also known as First Generation Language. In machine language, all Fig. 1.31: Hard Disk Drive

Not to MissVirus scanners and cleaners must be upgraded from time to time for detection and removal of new viruses.

Not to MissData compression tools are also required when you want to send a large file through e-mail on Internet.

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the instructions are given to computer in binary digits, and hence are directly understood by the computer. On the other hand, assembly language is easier than machine language, and is known as Second Generation Language. In assembly language, instructions are given using mnemonic operation codes (such as ADD and MUL) instead of binary digits.

1.15.2 High-level LanguagesDevelopment of applications using low-level languages requires a deep understanding of the hardware. In order to facilitate the programmers to write programs without knowing the internal details of computer components, many languages were developed. These languages use common English words and are translated into low-level languages before processing by the computer. These languages, which computer cannot understand directly and are not machine dependent, are called High-level Languages (HLL). These languages are also known as Third Generation Languages. Some popular high-level languages are as follows.• Beginner’s All Purpose Symbolic Instruction Code (BASIC)• Common Business-Oriented Language (COBOL)• Formula Translator (FORTRAN)• Algorithmic Language (ALGOL)• Pascal and C• LOGO, Ada and LIST Processing (LISP)• Programming Language One (PL/I) and Programming Language for Microcomputers

(PL/M)

High-level languages were widely used for applications development, but most of them are now outdated due to popularization of 4GLs. The uses of diff erent 3GLs are summarized in Table 1.1.

Table 1.1: Uses of 3GLs

Language Uses

BASIC Used for all purposes (commercial, scientifi c, educational, graphics, and symbolic) by beginners

COBOL Mainly used for development of commercial applications on all types of computers

FORTRAN Used for development of scientifi c (mathematical) applications

ALGOL Used to refl ect mathematical algorithms

PASCAL Used for both commercial and scientifi c applications

C Very powerful language for development of both system and application software

LOGO Used by young children to make drawings on computer

Not to MissLow-level languages are mainly used for development of system software.

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ADA Used to develop embedded applications for defence

LISP Used to develop artifi cial intelligence application

PL/I and PL/M Used to develop system software, mainly operating systems

1.15.3 User-friendly LanguagesAlthough high-level languages are simpler to codify than low-level languages, they still require a lot of time to learn programming syntax. Hence, these languages are beyond the reach of many computer users, who do not want expertise in programming. Therefore, new categories of languages have been developed which are user-friendly, very easy to codify and simple to learn. These languages are called User-friendly Languages and are popularly known as Fourth Generation Languages (4GLs). Fourth generation languages may be classifi ed into two categories — XBase and structured query language.

1. XBase: XBase is a generic term denoting any of the programming environment based on the original dBASE programming language. XBase languages include dBASE, FoxBase, Clipper and FoxPro.

2. Structured Query Language: Structured Query Language (SQL), developed by IBM, is a standard data defi nition and data manipulation language (DDL/DML) of relational databases. It is designed to defi ne, access, query, organize and update the data and information in relational databases. It is now provided with most RDBMS and non-relational DBMS. SQL is generally hidden by user-friendly interfaces in an end-user environment. It is an English-like query language, intended for interactive use by untrained end users.

1.15.4 Object-oriented LanguagesWe have discussed that the object-oriented programming is the latest approach in programming. The languages which are based on object-oriented programming (OOP) approach are called object-oriented languages. They may be classifi ed into Fifth Generation Languages. Object-oriented languages are specially useful for development of GUI (Graphical User Interface) applications. These languages also off er a unique feature of Reusable Code. Some of the popular object oriented languages are Smalltalk, C++, Object COBOL, Object Pascal, Simula, Eiff el, Java and Visual J++.

Not to MissC++, Java and Visual J++ are widely used nowadays for development of Windows-based Web applications.

Not to MissSQL was originally spelled SEQUEL (Structured English Query Language). Although SEQUEL consists of basic vocabulary of English-like words like SELECT, INSERT, DELETE actually it has not much resemblance with English language. Therefore, now it is generally pronounced as SQL.

Not to MissAll xBase languages are out-dated now.

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Keywords

Application Generator: A software tool that can generate a complete or part programApplication Software: Programs that can perform specifi c type of work for end usersAssembler: A type of language translator software that converts the assembly language code into machine language codeBinary Digit (Bit): A single digit (0 or 1) in a binary numberBooting: Process of loading of operating system from disk to RAMCASE Tool: A computer-aided software engineering toolCentral Processing Unit (CPU): The main component of a computer that processes dataCompiler: A type of language translator software that converts the entire program into machine code at one timeComputer: A fast electronic device used to process data Data: A set of basic facts having no meaning Hardware: Any physical component of a computerHigh-level Language: A computer language which uses common English wordsInformation: Data which has some meaning or valueInput Device: A peripheral device of a computer used to input dataInterpreter: A type of language translator that converts a high-level language code into machine code statement by statementLanguage Translators: The software which converts the codes of other languages into machine codeLow-level Language: Binary language which computer can understand directlyObject-oriented Language: A computer language based on object-oriented programmingOperating System: A system that acts as an interface between user and computerOutput Device: A peripheral device of a computer used to display or print information Primary Memory: Internal memory of computer such as ROM and RAMRandom Access Memory (RAM): A volatile memory of a computer that can be read as well as written Read Only Memory (ROM): A non-volatile memory of a computer that can be read only Secondary Memory: Storage device of computer such as hard disk, CD-ROM and pen driveSoftware: Programs that are required to operate a computerSystem Software: Software that controls the working of hardware User-friendly Language: A computer language which is very easy to codify and simple to learn

Let’s Recall

• A computer is fast, accurate and diligent with very high memory.• A computer system has three main physical components—Input/Output Unit, Central

Processing Unit (CPU) and Memory Unit. • The CPU consists of Arithmetic Logic Unit (ALU), Control Unit (CU), Registers, Buses and Clock. • Primary memory and secondary memory are two major categories of computer memory. • Primary memory is of mainly three types—ROM, RAM and CMOS.• Secondary memory devices include hard disk, CD-ROM, DVD and pen drive.

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• Byte, kilobyte, megabyte, gigabyte, terabyte, petabyte, exabyte, zettabyte, yottabyte, brontobyte and geopbyte are various units of memory.

• Common input devices include keyboard, mouse, joystick, scanner, microphone, OCR, MICR, light pen, barcode reader and digital camera.

• Common output devices include monitor, printer, speaker and plotter.• Common storage devices include hard disk, fl oppy disk, CD-ROM, DVD, blu-ray disc, pen drive

and memory stick.• Software are broadly classifi ed into system software, utility software and application software. • Operating systems can be either single-user or multi-user.• Application software can be either general purpose or special purpose.• Language translators are categorized into three types: interpreters, compilers and assemblers.• Application generators are available for diff erent third and fourth generation languages.• Computer languages are of four types: low-level, high-level, user-friendly and object-oriented.

Summative Assessment

1. Name any software used for the following tasks. (a) Typing and editing a document (b) Preparing a balance sheet (c) Creating presentation slides (d) Maintaining data for generating reports (e) Scanning and cleaning a virus (f ) Creating data fi les and programs

2. Defi ne the following terms. (a) Booting (b) CASE tool (c) Application software (d) HLL (e) Utility software (f ) Word processing

3. Write the function of the following devices. (a) OCR (b) Blu-ray Disc (c) Scanner (d) Joystick

4. Diff erentiate between the following terms. (a) ROM and RAM (b) Impact printer and Non-impact printer (c) CD-ROM and DVD (d) EPROM, EEPROM and EAPROM (e) Dynamic RAM and Static RAM (f ) Interpreter, Compiler and Assembler

5. Write short notes on the following. (a) Types of memory (b) Types of printers (c) General purpose application software (d) Common storage devices (e) Application generators (f ) Fourth generation languages

6. Answer the following questions. (a) What is CPU? Describe its main components along with their functions. (b) Explain the diff erence between character, line and page printers. Give examples. (c) What is a trackball? How does it diff er from mouse and joystick? (d) Describe in brief the architecture of a computer system. (e) What are the advantages of a word processor? (f ) What is electronic spreadsheet? Discuss the advantage of electronic spreadsheets. (g) Discuss the various types of computer languages. (h) Describe some of the common special purpose application software. (i) Describe the common utility software.

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7. Think and answer. (Application-based HOTS questions) (a) Swati bought a new PC having 500 GB hard disk. How much data (in bytes) can be

stored on this disk? (b) Abhishek works in the computer department of a bank. Name the input device he uses

to recognize the magnetically-charged character given at the bottom of a cheque. (c) Sahil is an architect. Name the output device he uses to print construction maps for

buildings. (d) Shahid Khan is unable to boot his computer. Name the software he would need to

reinstall on the computer.

8. Answer orally. (Viva Voce) (a) What are the various parts of CPU? (b) What is ROM? How does it diff er from RAM? (c) What is the diff erence between 1 Megabyte and 1 Gigabyte? (d) Which input device is used to recognize the magnetically-charged characters given at

the bottom of a cheque? (e) How is a line printer diff erent from a plotter? (f ) Which operating system is generally used on a PC? (g) How is Bios diff erent from SMPS? (h) Name the latest highest unit of measurement of data.

9. Value-based/Life Skills-based questions. (a) Rajat has a pen drive. He uses it to copy data from his friendʼs PC without taking

permission. Is he doing the right thing? Discuss. (b) Tanya has a CD of songs. She runs this CD on her school PC to listen to songs during her

practical class. What would you suggest to her?

Projects and Applications

1. There are many types of input, output and storage devices of a computer. Make a project report on ʻInput/Output and Storage Devicesʼ by downloading the required information from the Internet.

2. Many diff erent types of operating system and application software are available in the market. Download the required information from the Internet and make a project report on operating system and application software.

3. Make a list of software installed in your school or home PC and write their uses in your project fi le.

4. Make a list of hardware available in your computer lab and write their uses in your project fi le.

In the Lab

1. Visit your computer lab and identify the various components and devices of a computer. Draw/Paste their pictures in your practical notebook.

2. Boot a PC and scan its hard disk for viruses. With the help of your teacher, remove the viruses if found. In your practical notebook, write a paragraph on the virus scanner software used.