Fundamentals

What is Computer? Computer is an advanced electronic device that takes raw data as from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use.

It can process both numerical and non-numerical (arithmetic and logical) calculations.

Characteristics of Computters 1) Automatic: Given a job, computer can work on it automatically without human interventions

2) Speed: Computer can perform data processing jobs very fast, usually measured in microseconds (10-6), nanoseconds (10-9), and picoseconds (10-12)

3) Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. Computer errors caused due to incorrect input data or unreliable programs are often referred to as Garbage-In-Garbage-Out (GIGO)

4) Diligence: Computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling

5) Versatility: Computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps

6) Power of Remembering: Computer can store and recall any amount of information because of its secondary storage capability. It forgets or looses certain information only when it is asked to do so

7) No I.Q.: A computer does only what it is programmed to do. It cannot take its own decision in this regard

8) No Feelings: are devoid of emotions. Their judgment is based on the instructions given to them in the form of programs that are written by us (human beings) A computer has four functions:

a. accepts data Input b. processes data Processing c. produces output Output d. stores results Storage

Input (Data): Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.

Process: Process is the operation of data as per given instruction. It is totally internal process of the computer system.

Output: Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use.

Computer System

All of the components of a computer system can be summarized with the simple equations. COMPUTER SYSTEM = HARDWARE + + USER

• Hardware = Internal Devices + Devices All physical parts of the computer (or everything that we can touch) are known as Hardware. • Software = Programs Software gives "intelligence" to the computer. • USER = Person, who operates computer. Generation of computer:

 In 1822, Charles Babbage built the ‘Difference Engine’. This could do only one kind of calculations.

 In 1833, Charles Babbage designed and worked on Analytical Engine. It was a general purpose computer designed to solve almost any type of problem. It contained most of the elements we find in modern digital computer systems. Hence, Charles Babbage is considered as Father of modern computer. First Generation (1940-56):  The first generation computers used vaccum tubes & language was used for giving the instructions.  These computer were large in size & their programming was difficult task.  The electricity consumption was very high.  Some computers of this generation are ENIAC, EDVAC, EDSAC & UNIVAC-1.

Second Generation(1956-63):  In 2nd generation computers, vaccum tubes were replaced by transistors. They required only 1/10 of power required by tubes.  This generation computers generated less heat & were reliable. The first developed in this generation.

The Third Generation (1964-71):  The 3rd generation computers replaced transistors with known as chip. From Small scale integrated circuits which had 10 transistors per chip, developed to MSI circuits with 100 transistors per chip.  These computers were smaller, faster & more reliable. High level languages invented in this generation.

The fourth Generation(1972- present):  LSI & VLSI were used in this generation. As a result came into existence. The computers using this technology known to be Micro Computers.  High capacity hard disk were invented. There is great development in data .

The Fifth Generation (Present & Beyond):  Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today.  The use of parallel processing and superconductors is helping to make artificial intelligence a reality.  Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. ARCHITECTURE OF COMPUTER

INPUT DEVICES Input devices accept data and instructions from the user.

Following are the examples of various input devices, which are connected to the computer for this purpose. 1. Keyboard 2. Mouse 3. Light 4. Optical/magnetic Scanner 5. Touch Screen 6. for voice as input 7. Track Ball

1. Keyboard  A keyboard is the most common . Several kinds of keyboards are available, but they resemble each other with minor variations.  Generally standard keyboard has 104 keys. Sr. Keys Description No.

These keys include the letter keys (A-Z) and digits 1 Typing Keys keys (0-9) which generally give same layout as that of typewriters.

It is used to enter numeric data or movement. Generally, it consists of a set of 17 keys that are laid 2 out in the same configuration used by most adding machine and calculators. The twelve functions keys are present on the keyboard. These are arranged in a row along the top 3 Function Keys of the keyboard. Each function key has unique meaning and is used for some specific purpose. These keys provide cursor and screen control. It includes four directional arrow key. Control keys 4 Control keys also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).

Keyboard also contains some special purpose keys 5 Special Purpose Keys such as Enter, Shift, Caps Lock, Num Lock, Space bar, , and Print Screen.

Control keys Left Arrow, Right Arrow, Up Arrow, or Down Arrow Move the cursor or selection one space or line in the direction of the arrow, or scroll a webpage in the direction of the arrow Home Move the cursor to the beginning of a line or move to the top of a webpage End Move the cursor to the end of a line or move to the bottom of a webpage Page Up Move the cursor or page up one screen Page Down Move the cursor or page down one screen Delete Delete the character after the cursor, or the selected text; in Windows, delete the selected item and move it to the Recycle Bin Insert Turn Insert mode off or on. When Insert mode is on, text that you type is inserted at the cursor. When Insert mode is off, text that you type replaces existing characters. Special Purpose Keys Shift Press Shift in combination with a letter to type an uppercase letter. Press Shift in combination with another key to type the symbol shown on the upper part of that key.

Caps Lock Press Caps Lock once to type all letters as uppercase. Press Caps Lock again to turn this function off. Your keyboard might have a light indicating whether Caps Lock is on. Tab Press Tab to move the cursor several spaces forward. You can also press Tab to move to the next on a form. Enter Press Enter to move the cursor to the beginning of the next line. In a dialog box, press Enter to select the highlighted . Spacebar Press the Spacebar to move the cursor one space forward. Backspace Press Backspace to delete the character before the cursor, or the selected text. PrtScn (or Print Screen) pressing PrtScn captures an image of your entire screen (a "screen shot") and copies it to the Clipboard in your computer's memory. From there you can paste it (Ctrl+V) into Paint or another program and, if you want, print it from that program. ScrLk (or ) pressing these keys causes the document to scroll without changing the position of the cursor or selection. Esc Cancel the current task Application key Open a of commands related to a selection in a program. Equivalent to right-clicking the selection. Windows logo key Open the Pause/Break This key is rarely used. In some older programs, pressing this key pauses the program or, in combination with Ctrl, stops it from running. 2. Mouse  A mouse is an electro-mechanical, hand-held device. It is used as a pointer.  It can perform functions like selecting menu commands, moving icons, resizing windows, starting programs, and choosing options.

 The most common mouse uses an internal, magnetically coated ball, to detect the movement of the mouse across a flat surface, usually a desktop. Now a days Optical or laser mouse is used to detect the movement.

 Generally, it has two buttons called left and right button and scroll bar is present at the mid.

 Mouse can be used to control the position of cursor on screen, but it cannot be used to enter text into the computer.

 All windows based applications today are designed to work with a mouse. A mouse is used to replace hard -to-remember key combinations with easier "" actions. However, it cannot substitute all keyboard operations. It can be alternative for commands based operations.

Light pen  An input device that utilizes a light-sensitive detector to select objects on a display screen.  A is similar to a mouse, except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen.

Optical Scanner  These devices are used for automatic data collection.  The devices of this category completely eliminate manual input of data. For example, the bar-code reader is actually just a special type of .  An image scanner translates printed images into an electronic format that can be stored in a computer’s memory, and with the right kind of software, one can alter a stored image.  Another example of scanner is optical character recognition (OCR) device, used by banks to convert the scanned image of a typed or printed page into text that can be edited on the computer. Touch Screen  Touch panel displays and pads are now being offered as alternatives to keyboard.  Here the input can be given through the computer screen, that accepts the input through monitor; users touch electronic buttons displayed on the screen or they may use light pen.

Microphone  Microphone is an input device, which takes voice as input. The voice communication is more error-prone than information through keyboard. There are two types of available 1. Desktop Microphone 2. Hand held Microphone

Track Ball  , a , is a mouse lying on its back  To move the pointer, you rotate the ball with your thumb, your fingers, or the palm of your hand. There are usually one to three buttons next to the ball, which you use just like mouse buttons.  The advantage of over mouse is that the trackball is stationary so it does not require much space to use it.  In addition, you can place a trackball on any type of surface, including your lap. For both these reasons, trackballs are popular pointing devices for portable computers.

OUTPUT DEVICES Output devices return processed data that is information, back to the user. Some of the commonly used output devices are: 1. Monitor (Visual Display Unit) 2. Printers 3. 4. Speakers

1. Monitor  Out of all the output devices, monitor is the most important because people interact with this device most intensively than others.  Computer information is displayed, visually with a video card and monitor.  Information processed within the CPU, that needs to be visually displayed, is sent to video adapter. The video adapter converts information from the format used, in the same manner as a television displays information sent to it by a cable service

Two basic types of monitors are used with microcomputers, which are as follows: 1. CRT 2. LCD

Cathode Ray Tube (CRT):  CRT or Cathode Ray Tube Monitor is the typical monitor that you see on a .  It looks a lot like a television screen, and works the same way. This type uses a large vacuum tube, called cathode ray tube (CRT).

The basic CRT consists of four major components.

 Electron Gun  Focussing & Accelerating Anodes  Horizontal & Vertical Deflection Plates  Evacuated Glass Envelope

1. Electron Gun

It is used for producing a strain of electrons

2. Focussing & Accelerating Anodes

These are used for producing a narrow and sharply focus beam of electrons. 3. Horizontal and Vertical Deflection Plates

These are used for controlling the path of the beam.

4. Evacuated Glass Envelope With a phosphorecent screen which produces bright spot when struct by a high velocity electron beam. Working of CRT  Heater element is energized by alternating current to obtain high emission of electron from cathode.  Control grid is biased negative with respect to cathode it controls the density of electron beam to focus the electron beam on the screen focusing anode is used.  The focusing anode operate at a potential of twelve hundred (1200 V) and accelerating anode at 2000 V to accelerate the electron beam.  Two pairs of deflection plates provided in the CRT these deflection plates are mounted at right angle to each other to provide electron beam deflection along vertical and horizontal axis of the screen.  The screen consists of a glass which is coated by some florescent material lie zinc silicate. Which is semi transparent phosphor substance.  When high velocity electron beam structs the phosphorescent screen the light emits from it. The property of phosphor to emit light when its atoms are excited.  A CRT monitor contains millions of tiny red, green, and blue phosphor dots that glow when struck by an electron beam that travels across the screen to create a visible image.

Liquid Crystal Displays (LCD):  This type of monitors are also known as flat panel monitor. Most of these employ liquid crystal displays (LCDs) to render images. These days LCD monitor are very popular.  When people talk about the capabilities of various monitors, one critical statistic is the resolution of the monitor. Most monitors have a resolution of at least 800 x 600 .  High-end monitors can have resolutions of 1024 x 768 pixels or even 1280 x 1024 pixels. Thus monitors are available either in low resolution or in high resolution.

Dots/Pixels: The smallest changeable point on the screen. A dot can have any colour from the palette. Resolution Refers to two things: the clarity and the number of dots appearing on the screen.  A resolution is usually described with two numbers: number of dots across the display (x-axis) and the number of dots up and down (y-axis).  For example, 640x480 is 640 possible dots left and right; and 480 possible dots up and down.

Printer After a document is created on the computer, it can be sent to a for a hard copy (printout). Some printers offer special features such as colored and large page formats. Some of the most commonly used printers are: 1. Laser Printer 2. Jet Printer 3. Dot Matrix Printer 4. Line Printer

Laser Printer: A laser printer produces high quality print that one normally finds in publishing. It is extremely fast and quiet.

 Moreover, the operation of a laser printer is easy with automatic paper loading and no smudging or messing up of ink ribbons.

 The fastest laser printer can print up to 200 pages per minute in monochrome () and up to 100 pages per minute in colour.

Ink-Jet Printer: An ink-jet printer creates an image directly on paper by spraying ink through as many as 64 tiny nozzles.  Although the image it produces is not generally quite as sharp as the output of a laser printer, the quality of ink-jet images is still high.  In general, ink-jet printer offers an excellent middle ground between dot matrix and laser printer. Like laser printer, an ink-jet printer is quiet and convenient, but not particularly fast.  Typically, an ink-jet printer is more expensive than a dot-matrix printer, but costs only half as much as a laser printer.

Dot Matrix Printer: It is a very versatile and inexpensive output device.  In dot matrix printer the print head physically "hits" the paper through the ribbon and produces text (or images) by combinations of dots; hence the name dot matrix printer.  Its speed is measured in characters per second (CPS). Although it is less expensive, it is louder, slower and produces lower print quality. Line Printer: A line printer is generally used with large computer systems to produce text based data processing reports.  Line printers are high-speed printers with speeds ranging anywhere from 100 to about 3800 lines per minute.  In the past, print quality on line printers was not high. Developments in technology are improving the print quality on line printers. These are in the cost range of lacs of Rupees.

Plotter  A plotter is a special kind of output device that, like a printer, produces images on paper, but does so in a different way.  are designed to produce large or images, such as construction plans for buildings or blueprints for mechanical objects.  A plotter can be connected to the port normally used by a printer. An array of different colored in a clip rack and a robotic arm is part of plotter.  The instructions that a plotter receives from a computer consist of a color, and beginning and ending coordinates for a line.  With that information, the plotter picks up the appropriate pen through its arm, positions it at the beginning coordinates drops the pen down to the surface of the paper and draws to the ending coordinates. Plotters draw curves by creating a sequence of very short straight lines.

Plotters usually come in two designs:

1. Flat Bed: Plotters of small size to be kept on table with restriction of paper size. 2. Drum: These plotters are of big size using rolls of paper of unlimited length.

Speaker Speakers are another type of output device, which allow you to listen to voice like music, and conversation with people. (CPU)

 The main component to make a computer operate is the computer chip or . This is referred to as the Central Processing Unit (CPU) and is housed in the . Together, they are also called the CPU.  It performs arithmetic and logic operations. The CPU (Central Processing Unit) is the device that interprets and executes instructions.

CPU consists of two parts (i) Arithmetic and Logic Unit (ALU) and (ii) Control Unit

Arithmetic and Logic Unit (ALU) : It is the part of the CPU that does all the arithmetic and logical operations like addition, subtraction, multiplication, division operations such as X > Y etc.

Control unit : It coordinates all the operations of the computer. It controls the input and output devices, the ALU and the memory. It also ensures that instructions in the software are carried out.

Memory:  It facilitates the remembrance power to computer system.  It refers to the physical devices used to store programs (sequences of instructions) or data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital electronic device.  The term primary memory is used for the information in physical systems which are fast (i.e. RAM), as a distinction from secondary memory, which are physical devices for program and data storage which are slow to access but offer higher memory capacity.  Primary memory stored on secondary memory is called virtual memory.

Primary Memory can be categorized as Volatile Memory & Non- Volatile Memory.

Volatile memory (RAM)

 Volatile memory is that requires power to maintain the stored information. Most modern semiconductor volatile memory is either Static RAM or dynamic RAM.  SRAM retains its contents as long as the power is connected and is easy to interface.  Dynamic RAM is more complicated to interface to and control and needs regular refresh cycles to prevent its contents being lost.

 SRAM is used for cache memories..

Non Volatile Memory (ROM)  Non-volatile memory is computer memory that can retain the stored information even when not powered.  Examples of non-volatile memory are and ROM/PROM/EPROM/EEPROM memory (used for such as boot programs).  Cache Memory:  Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM.  As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous of data), it does not have to do the more time-consuming reading of data from larger memory.  It is of two types- L1 cache is on the same chip as the microprocessor. L2 is usually a separate static RAM (SRAM) chip.

Secondary Memory:

 All the data and programmes which are not running on the CPU are stored in the secondary memory. They are copied into the RAM whenever they are required.  The commonly used secondary memory storage devices are disks and tapes. There are three types of disks- Hard Disk, and Compact Disk.  Hard disks are fitted into the computer whereas the floppy disks, compact disks can be taken out and kept outside.  A floppy can hold only 1.44 MB of information whereas compact disks can hold about 600 MB of data.  The floppy drive is referred to as 'A' drive. If there is a second floppy drive on the computer it is referred to as 'B' drive and the hard disk is termed as 'C' drive. The alphabets D,E, F etc., are reserved for additional hard drives that the computer may have.

Some storage devices. : A. Hard Disk (Local Disk) B. Optical Disks: CD-R, CD-RW, DVD-R, DVD-RW C. Pen Drive D. Floppy Disks F. Memory Cards G. External Hard Disk H. Blu Ray Disk

1. Floppy disk – 3 ½ inch diameter (previously we had 5 ¼ inch floppy disks also) :  It is divided into concentric circles called tracks and the tracks are further divided into sectors.  There is a small hole on the disk called index hole which denotes the starting point of the first sector. The 3 ½ inch floppy disks can store 1.44 MB or 2.88 MB of information.

2. Hard Disk : The disk consists of a containing hard disks/platters stacked onto one another.  A single hard disk is made of metal and coated on both sides with metallic oxide.  Hard disks can store large volumes of data as compared to floppy disks. Today we can see hard disks of capacity of 40 GB to 200 GB and even more. Portable (external) hard disks are also available now.

3. Digital Audio Tape (DAT) : This is widely used in our Bank for taking backups particularly in Bankmaster branches. It looks like an audio cassette and can store large volume of data ranging from 2 GB to 20 GB and even more.

4. CD ROM : These are also widely used now-a-days for data storage, storing music, video (cinemas) etc. Compact Disk (CD) can store up to 700 MB of data on it. Rewritable CDs are also available. This is a form of optical storage.

5. DVD (Digital Versatile Disk) : also look like CDs but can store much more data than that in CD. They can store 4.7 GB data on it. Dual layer DVDs can store almost double the data that can be stored on a normal DVD (single layer) i.e., up to 8.5 GB. Data recording is accomplished by burning the laser beam on CDs and DVDs.

6. Pen Drives / Flash Drives: These are also storage media ranging from 256 MB to 8 GB and more. These are very small and portable and easy to carry volume of data.

7.Blu-Ray Disk: . Blu-ray (not Blue-ray) also known as Blu-ray Disc (BD), is the name of a new format. . The format offers more than five times the storage capacity of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc. . While current optical disc such as DVD, DVD±R, DVD±RW, and DVD-RAM rely on a red laser to read and write data, the new format uses a blue-violet laser instead, hence the name Blu-ray.

Units of Memory:

The smallest unit is bit, which mean either 0 or 1. 1 bit = 0 or 1 1 Byte = 8 bit 1 Nibble = 4 bit 1 Kilo Byte = 1024 Byte = 210 Byte 1 Mega Byte = 1024 KB = 210 KB 1 Gega Byte = 1024 MB = 210 MB 1 Tera Byte = 1024 GB = 210 GB 1 Peta Byte = 1024 TB = 210 TB 1 Exa Byte = 1024 PB = 210 PB 1 Zetta Byte = 1024 EB = 210 EB 1 Yotta Byte = 1024 ZB = 210 ZB

Booting The process of loading the system files of the operating system from the disk into the computer memory to complete the circuitry requirement of the computer system is called booting. Types of Booting: There are two types of booting: • Cold Booting: If the computer is in off state and we boot the computer by pressing the power switch ‘ON’ from the CPU box then it is called as cold booting.

• Warm Booting: If the computer is already ‘ON’ and we restart it by pressing the ‘RESET’ button from the CPU box or CTRL, ALT and DEL key simultaneously from the keyboard then it is called warm booting. Types of Computer On the basis of working principle a) An analog computer is a form of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. Eg: Thermometer, Speedometer, Petrol pump indicator, Multimeter b) Digital Computer A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system. c) Hybrid Computer (Analog + Digital)  A combination of computers those are capable of inputting and outputting in both digital and analog signals.  A hybrid computer system setup offers a cost effective method of performing complex . The instruments used in medical science lies in this category.

On the basis of Size

a) Super Computer  The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations.  For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy research, and petroleum exploration.  PARAM, Pace & Flosolver are the supercomputer made in India.

b) Mainframe Computer  A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously.  In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers.  In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe. c) Mini Computer  A midsized computer. In size and power, minicomputers lie between and mainframes.  But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously. Generally, servers are comes in this category. d) Micro Computer i. Desktop Computer: a personal or micro-mini computer sufficient to fit on a .

ii. Computer: a portable computer complete with an integrated screen and keyboard. It is generally smaller in size than a desktop computer and larger than a notebook computer.

iii. Palmtop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer. Palmtops have no keyboard but the screen serves both as an input and output device. e) Workstations A terminal or desktop computer in a network. In this context, is just a generic term for a user's machine (client machine) in contrast to a "server" or "mainframe."

Software

 Software, simply are the computer programs. The instructions given to the computer in the form of a program is called Software.  Software is the set of programs, which are used for different purposes.  All the programs used in computer to perform specific task is called Software. Types of software 1. System software: a) Operating System Software DOS, Windows XP, , /, MAC/OS X etc. b) Utility Software Windows Explorer (File/Folder Management), Compression Tool, Anti Virus Utilities, Disk Defragmentation, Disk Clean, BackUp, WinZip, WinRAR etc… c) Language Processors Compiler, Interpreter and Assembler 2. Application software: a) Package Software Ms. Office 2003, Ms. Office 2007, Macromedia (Dreamweaver, Flash, Freehand), Adobe (PageMaker, PhotoShop) b) Tailored or Custom Software School Management system, Inventory Management System, Payroll system, financial system etc.

Operating system  Operating system is a platform between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of a computer.  It hosts the several applications that run on a computer and handles the operations of .

Functions of operating System:  Management  Memory Management  File Management  Device Management

Types of Operating System:

 Real-time Operating System: It is a multitasking operating system that aims at executing real-time applications. Example of Use: e.g. control of nuclear power plants, oil refining, chemical processing and traffic control systems

 Single User Systems: Provides a platform for only one user at a time. They are popularly associated with Desk Top operating system which run on standalone systems where no user accounts are required.

Example: DOS.

 Multi User Systems: Provides regulated access for a number of users by maintaining a database of known users.

Refers to computer systems that support two or more simultaneous users. Another term for multi-user is time sharing. Ex: All mainframes are multi-user systems.

Example: UNIX

 Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run at a time, the system is grouped under the single-tasking system category, while in case the operating system allows for execution of multiple tasks at a time, it is classified as a multi-tasking operating system.  Distributed Operating System: An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system.

Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.

Commonly used operating system

UNIX: a popular multi-user, multitasking operating system developed at Bell Labs in the early 1970s. UNIX was one of the first operating systems to be written in a high-level programming language, namely C. This meant that it could be installed on virtually any computer for which a C compiler existed.

LINUX: A freely-distributable open source operating system that runs on a number of hardware platforms.  The Linux kernel was developed mainly by Linus Torvalds and it is based on UNIX. Because it's free, and because it runs on many platforms, including PCs and .

Windows: is a series of graphical interface operating systems developed, marketed, and sold by Microsoft.

 Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs).  Microsoft Windows came to dominate the world's market with over 90% market share, overtaking Mac OS, which had been introduced in 1984.

 The most recent client version of Windows is ; the most recent server version is R2; the most recent mobile version is Windows Phone 7.5.

SOLARIS: Solaris is a Unix operating system originally developed by .

 It superseded their earlier SunOS in 1993. Oracle Solaris, as it is now known, has been owned by Oracle Corporation since Oracle's acquisition of Sun in January 2010.

BOSS: BOSS (Bharat Operating System Solutions) GNU/Linux distribution developed by C-DAC (Centre for Development of Advanced Computing) derived from Debian for enhancing the use of Free/ Open Source Software throughout India. This release aims more at the security part and comes with an easy to use application to harden your Desktop.

Mobile OS: A mobile operating system, also called a mobile OS, is an operating system that is specifically designed to run on mobile devices such as mobile phones, , PDAs, tablet computers and other handheld devices.  The mobile operating system is the software platform on top of which other programs, called application programs, can run on mobile devices.

Symbian: Symbian is a mobile operating system (OS) targeted at mobile phones that offers a high-level of integration with communication and personal information management (PIM) functionality.  Symbian OS combines middleware with through an integrated mailbox and the integration of Java and PIM functionality (agenda and contacts).  The Symbian OS is open for third-party development by independent software vendors, enterprise IT departments, network operators and Symbian OS licensees.

Android: Android is a Linux-based mobile phone operating system developed by Google.  Android is unique because Google is actively developing the platform but giving it away for free to hardware manufacturers and phone carriers who want to use Android on their devices.

LANGUAGE PROCESSORS: Since a computer hardware is capable of understanding only machine level instructions, So it is necessary to convert the HLL into Machine Level Language.

Computer languages are broadly classified as:

1. Low Level Language: The term low level means closeness to the way in which machine understand. The low level languages are: a. Machine Language: . This is the language (in the form of 0’s and 1’s, called binary numbers) understood directly by the computer. . It is machine dependent. It is difficult to learn and even more difficult to write programs. b. Assembly Language: . This is the language where the machine codes comprising of 0’s and 1’s are substituted by symbolic codes (called mnemonics) to improve their understanding. . It is the first step to improve programming structure. . Assembly language programming is simpler and less time consuming than machine level programming, it is easier to locate and correct errors in assembly language than in machine language programs. . It is also machine dependent. Programmers must have knowledge of the machine on which the program will run.

2. High Level Language  We know that low level language requires extensive knowledge of the hardware since it is machine dependent. To overcome the limitation, high level language has been evolved which uses normal English like, easy to understand statements to solve any problem.  Higher level languages are computer independent and programming becomes quite easy and simple.

Various high level languages are given below:

BASIC (Beginners All Purpose Symbolic Instruction Code): It is widely used, easy to learn general purpose language. Mainly used in microcomputers in earlier days.

COBOL (Common Business Oriented language): A standardized language used for commercial applications.

FORTRAN (Formula Translation): Developed for solving mathematical and scientific problems. One of the most popular languages among scientific community.

C: Structured Programming Language used for all purpose such as scientific application, commercial application, developing etc.

C++: Popular object oriented programming language, used for general purpose.

There are three Language processors:

A. Compiler: It is translator which coverts the HLL language into machine language in one go. A Source program in High Level Language get converted into Object Program in Machine Level Language.

B. Interpreter: It is a translator which converts the HLL language into machine language line by line. It takes one statement of HLL and converts it into machine code which is immediately executed. It eliminate the need of separate compilation/run. However, It is slow in processing as compare to compiler.

C. Assembler: It translate the assembly language into machine code.

Microprocessor: A microprocessor is a semiconductor chip, which is manufactured using the Large Scale integration (LSI) or Very Large Scale Integration (VLSI), which comprises , Control unit and Central Processing Unit (CPU) fabricated on a single chip.

Terminologies:

Registers: . A register is a very small amount of very fast memory that is built into the CPU (central processing unit) in order to speed up its operations by providing quick access to commonly used values. . All data must be represented in a register before it can be processed. . For example, if two numbers are to be multiplied, both numbers must be in registers, and the result is also placed in a register.

Bus: . A collection of wires through which data is transmitted from one part of a computer to another. . This is a that connects all the internal computer components to the CPU and main memory. . All buses consist of two parts -- an address bus and a data bus. The data bus transfers actual data whereas the address bus transfers information about where the data should go. . The control bus is used by the CPU to direct and monitor the actions of the other functional areas of the computer. . It is used to transmit a variety of individual signals (read, write, , acknowledge, and so forth) necessary to control and coordinate the operations of the computer. . The size of a bus, known as its width, is important because it determines how much data can be transmitted at one time. For example, a 16-bit bus can transmit 16 bits of data, whereas a 32-bit bus can transmit 32 bits Clock speed: Also called clock rate, the speed at which a microprocessor executes instructions. . Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. . The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.

Clock speeds are expressed in megahertz (MHz) or gigahertz ((GHz).

16 bit Microprocessor: It indicates the width of the registers. A 16-bit microprocessor can process data and memory addresses that are represented by 16 bits. Ex. 8086 processor

32 bit Microprocessor: It indicates the width of the registers. A 32-bit microprocessor can process data and memory addresses that are represented by 32 bits. Ex. Intel 80386 processor, Intel 80486

64 bit Microprocessor: It indicates the width of the registers; a special high- speed storage area within the CPU. A 32-bit microprocessor can process data and memory addresses that are represented by 32 bits. Ex. Pentium dual core, core 2 duo.

128 bit Microprocessor: It indicates the width of the registers. A 128-bit microprocessor can process data and memory addresses that are represented by 128 bits. Ex. Intel core i7

PORTS :  A port is an interface between the and an external device. Different types of port are available on motherboard as , , PS/2 port, USB port, SCSI port etc.  A can also be programmatic docking point through which information flows from a program to computer or over the internet. Characteristics

 External devices are connected to a computer using cables and ports.

 Ports are slots on the motherboard into which a cable of external device is plugged in.

 Examples of external devices attached via ports are mouse, keyboard, monitor, microphone, speakers, etc.

Following are few important types of ports:

Serial Port

 Used for external modems and older .

 Serial ports send and receive one bit at a time via a single wire pair

 Two versions: 9 pin, 25 pin model.

 Data travels at 115 kilobits per second.

Parallel Port  Used for scanners and printers  Also called printer port.  25 pin model.  Also known as IEEE 1284-compliant Centronics port.

 PS/2 Port

 Used for old computer keyboard and mouse

 Also called mouse port.

 Most of the old computers provide two PS/2 ports, each for mouse and keyboard.  Also known as IEEE 1284-compliant Centronics port.

Universal Serial Bus (or USB) Port

 Can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc.

 Introduced in 1997.

 Most of the computers provide two USB ports as minimum.

 Data travels at 12 megabits per second.

 USB compliant devices can get power from a USB port.

VGA Port

 Connects monitor to a computer's .  Has 15 holes.

 Similar to serial port connector but serial port connector has pins, it has holes.

 Power Connector

 Three-pronged plug

 Connects to the computer's power cable that plugs into a power bar or wall socket.

Firewire Port

 Transfer large amounts of data at very fast speed.  Connects and video equipments to the computer

 Data travels at 400 to 800 megabits per second.

 Invented by Apple

 Three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector and 9-Pin FireWire 800 connector

Modem

 Connects a PC's modem to the telephone network.

Ethernet Port

 Connects to a network and high speed Internet.  Connects network cable to a computer.

 This port resides on an Card.  Data travels at 10 megabits to 1000 megabits per second depending upon the network bandwidth.

Game Port

 Connect a PC to a .

 Now replaced by USB.

Digital Video Interface, DVI port

 Connects a Flat panel LCD monitor to the computer's high-end video graphic cards.

 Very popular among video card manufacturers.

Sockets

 Connect microphone, speakers to of the computer

Infrared Port: . An IR port is a port which sends and receives signals from other devices. . It is a wireless type port with a limited range of 5-10ft. :

. Bluetooth uses short-range frequencies to transmit information from fixed and mobile devices. . These devices must be within the range of 32 feet, or 10 meters for Bluetooth to effectively work.

. A Bluetooth port enables connections for Bluetooth-enabled devices for synchronizing.

. Typically there are two types of ports: incoming and outgoing. The incoming port enables the device to receive connections from Bluetooth devices while the outgoing port makes connections to Bluetooth devices.

Internal Storage encoding of Characters:

ASCII( American standard code for information interchange): ASCII code is most widely used alphanumeric code used in computers. . It is a 7- bit code, and so it has 27 =128 possible code groups. . It represents all of the standard keyboard characters as well as control functions such as Return & Linefeed functions.

ISCII(Indian standard code for information interchange) : To use the Indian language on computers, ISCII codes are used. . It is an 8-bit code capable of coding 256 characters. . ISCII code retains all ASCII characters and offers coding for Indian scripts also.

Unicode: . It is a universal coding standard which provides a unique number for every character, no matter what the platform, no matter what the program, no matter what the language. . Unicode version 3.1 represented 94,140 characters.

NUMBER SYSTEM:

 As the computer is an electronic device, it works on the presence/absence of electronic signals. Electrical energy is used only to carry information.  Computer uses a number system which is different from our usual decimal system for storing data.  It can just recognize two states – ON or OFF and numbers are represented by using these two states i.e., by using the ON position to represent ‘1’ and the OFF position to represent ‘0’.  Therefore, a number can be simulated easily within the computer under a number system which uses two digits only i.e, ‘0’ and ‘1’. This system is called Binary system. Binary Number system :  The binary digits (0 and 1) are used to represent data in a computer. In computer terminology, the binary digit is called as a ‘bit’.  As the computer works on electricity, the number 1 represents power on and 0 represents power off.  Computers do not understand letters of decimal numbers. They only understand 1s and 0s. This is called the binary system.  All the letters of the alphabet, all numbers and all signs like +, -, = etc are converted into 0s and 1s if the computer has to work with them.

Decimal Number System

A positional number system Has 10 symbols or digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Hence, its base = 10  The maximum value of a single digit is 9 (one less than the value of the base)  Each position of a digit represents a specific power of the base (10) We use this number system in our day-to-day life

Table to remember Decimal Binary Hexadecimal Octal 0 0 0 0

1 1 1 1

2 10 2 2

3 11 3 3

4 100 4 4

5 101 5 5 6 110 6 6

7 111 7 7

8 1000 8 10

9 1001 9 11

10 1010 A 12

11 1011 B 13

12 1100 C 14

13 1101 D 15

14 1110 E 16

15 1111 F 17

16 10000 10 20 Octal Number System  Uses eight digits: 0, 1, 2, 3, 4, 5, 6, 7.  Also called base 8 number system. Hexadecimal Number System  Uses 10 digits and 6 letters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.  Letters represent numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15.  Also called base 16 number system.

Shortcut Method for Converting a Binary Number to its Equivalent Octal Number Method Step 1: Divide the digits into groups of three starting from the right Step 2: Convert each group of three binary digits to one octal digit using the method of binary to decimal conversion

Example 11010102 = ?8 Step 1: Divide the binary digits into groups of 3 starting from right 001 101 010 Step 2: Convert each group into one octal digit 2 1 0 0012 = 0 x 2 + 0 x 2 + 1 x 2 = 1 2 1 0 1012 = 1 x 2 + 0 x 2 + 1 x 2 = 5 2 1 0 0102 = 0 x 2 + 1 x 2 + 0 x 2 = 2 Hence, 11010102= 1528 Shortcut Method for Converting an OctalNumber to Its Equivalent Binary Number: Method Step 1: Convert each octal digit to a 3 digit binary number (the octal digits may be treated as decimal for this conversion) Step 2: Combine all the resulting binary groups (of 3 digits each) into a single binary number

Example 5628 = ?2 Step 1: Convert each octal digit to 3 binary digits 58 = 1012, 68= 1102, 28 = 0102 Step 2: Combine the binary groups 5628 = 101 110 010 5 6 2 Hence, 5628 = 1011100102

Shortcut Method for Converting a Binary Number to its Equivalent Hexadecimal Number Method Step 1: Divide the binary digits into groups of four starting from the right Step 2: Combine each group of four binary digits to one hexadecimal digit Example 1111012 = ?16 Step 1: Divide the binary digits into groups of four starting from the right 0011 1101 Step 2: Convert each group into a hexadecimal digit 3 2 1 0 00112 = 0 x 2 + 0 x 2 + 1 x 2 + 1 x 2 = 310 = 316 3 2 1 0 11012 = 1 x 2 + 1 x 2 + 0 x 2 + 1 x 2 = 1310 = D16 Hence, 1111012 = 3D16

Shortcut Method for Converting a Hexadecimal Number to its Equivalent Binary Number Step 1: Convert the decimal equivalent of each hexadecimal digit to a 4 digit binary number Step 2: Combine all the resulting binary groups (of 4 digits each) in a single binary number Example 2AB16 = ?2 Step 1: Convert each hexadecimal digit to a 4 digit binary number 216 = 210 = 00102 A16 = 1010 = 10102 B16 = 1110 = 10112 Step 2: Combine the binary groups 2AB16 = 0010 1010 1011 2 A B Hence, 2AB16 = 0010101010112

Formation of Fractional Numbers in Binary Number System Example 2 1 0 -1 -2 -3 110.1012 = 1 x 2 + 1 x 2 + 0 x 2 + 1 x 2 + 0 x 2 + 1 x 2 = 4 + 2 + 0 + 0.5 + 0 + 0.125 = 6.62510

Formation of Fractional Numbers in Octal Number System Example 2 1 0 -1 -2 127.548 = 1 x 8 + 2 x 8 + 7 x 8 + 5 x 8 + 4 x 8 = 64 + 16 + 7 + 5/8 + 4/64 = 87 + 0.625 + 0.0625 = 87.687510