1. BASICS OF A COMPUTER - of a Computers: 1. First Generation: Vacuum Tubes (1946 – 1959) This generation used vacuum tubes as the basic components for memory and

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For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 1 | P a g e 1. BASICS OF A COMPUTER Computer Computer is an electronic machine that can manipulate date. It accepts and store input data and output the processed data in required format. History of Computer: Charles Babbage is called as Father of Computer His inventions: Difference Engine and Analytical Engine Specification: It can store the information on punch cards during 1800s Father of Modern Computer Science: Alan Turing First purpose electronic digital computer: ENIAC ENIAC means Electronic Numerical Integrator and Calculator Parts of a computer: Functional Unit of a Computer: Arithmetic and Logic Unit (ALU) ALU performs both logical and arithmetical operations like addition, subtraction, multiplication and division. Control Unit (CU) It controls the operations for all the parts of the computer. Fetching: It gets an instruction from the main memory Decoding: It translates instructions into computer commands Execution: It processes the commands Storage: It stores the results into the memory Central Processing Unit (CPU): CPU is the brain of a computer. It is a part of a computer where the entire work is performed. The combination of ALU and CU is called as CPU. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 2 | P a g e Processor Speed: It is usually measured in Megahertz (Mhz) or Gigahertz (Ghz). Generations of a Computers: 1. First Generation: Vacuum Tubes (1946 1959) This generation used vacuum tubes as the basic components for memory and circuitry or CPU. Input and Output devices: Punched cards, paper tape and magnetic tapes Operation system is basically a batch processing Programming language: Machine Coding 2. Second Generation: Transistors (1959 1965) Primary memory: Magnetic cores Secondary memory: Magnetic tape and magnetic disk Advantages: Cheaper and low power consumption More compact in size and more reliable It is faster than Vacuum Tubes Operating system: Batch processing and Multiprogramming In this generation assembly language and high-level programming languages like FORTRAN, COBOL were used. Classification of Computers: PC (Personal Computer) A personal computer (PC) is a small, relatively inexpensive computer designed for an individual user with less powerful microprocessor. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 3 | P a g e WorkStation A desktop computer terminal, typically networked and more powerful than a personal computer. Mini Computer It is a multi-user computer system which is capable of supporting hundreds of users simultaneously Main Frame A data processing system employed mainly in large organizations for various applications, including bulk data processing. Supercomputer It is an extremely fast computer which can execute hundreds of millions of instructions per second. 3. Third Generation : Integrated Circuits (1965 1971) Integrated Circuits (ICs) replaced usage of transistors Single IC consists of basic components like many transistors, resistors and capacitors along with the associated circuitry. Advantages: Smaller in size , reliable and efficient High level languages: FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 4. Fourth Generation: Microprocessors (1971 1980) It is also called as Very Large Scale Integrated (VLSI) circuits. A single microprocessor is having about 5000 transistors and other circuit elements. High level languages: C, C++, DBASE etc., were used For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 4 | P a g e 5. Fifth Generation: Artificial Intelligence (1981 to till date) The VLSI technology became ULSI (Ultra Large Scale Integration) The production of microprocessor chips having ten million electronic components High level languages: C, C++ , Java, .Net are used Inclusions: Robotics Neural Networks Game Playing Development of expert systems to make decisions in real time situations Some basic orders: Lowest to highest: Bit, Byte, Character, Field, Record and File Sequence of Operation in Booting Load BIOS -> Perform Post -> Load OS -> Check Configuration Settings Lowest to highest: Bit, Byte, Kilo Byte, Mega Byte, Giga Byte, Tera Byte, Peta Byte, Exa Byte, Zetta Byte 2. SOFTWARE There are two types of Softwares. They are 1. System Software 2. Application Software 1. System Software: The system software is a collection of programs designed to operate , control and extend the processing capabilities of the computer itself. It serves as the interface between hardware and the end users Examples: Operating System, Compilers, Interpreter, Assembler etc., For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 5 | P a g e Operating System: An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. Example: Windows XP and Windows 7 2. Application Software: It is the set of programs necessary to carry out operations for a specified application. Application software can be subdivided into three categories. They are Packages, Utilities and Customized Softwares. A. Packages: Word Processing: A package that process textual matter and creates organized and flawless documents. Spreadsheets An electronic spreadsheet is a program that accepts data in a tabular form and allow users to manipulate , calculate, analyze data in the desired manner. Database Management Systems DBMS is a package that can handle and manage bulk of stored data. Desktop Publishing Software Handles page layout by combining the functions of a traditional typesetter and a layout artist. Graphics, Multimedia and Presentation applications Application software that manipulates images is known as Graphics software B. Utilities: Utilities are also a application program It assists the computer by performing housekeeping functions like scanning viruses , backing up disk or etc. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 6 | P a g e Text Editor This program is used for creating, editing text files. Backup Utility This Program facility for the backing-up of disk by archives. Compression Utility Large files can be compressed so that it takes less storage area. Disk Defragmenter It speeds up disk access by rearranging the files and free space on your computer. Antivirus Software It scans yours disk for viruses and removes them if any virus is found. C. Customized Software: This type of software is tailor-made software according to a users requirements. Software Categories Freeware: A software that is available free of cost. The basic examples of freeware include Skype and Adobe Acrobat Reader. Shareware It is software that is distributed free on a trial basis with the understanding that the user may need or want to pay for it later. Examples: Trial version of Avast antivirus , games and other softwares Commercial software It is any software or program that is designed and developed for licensing or sale to end users or that serves a commercial purpose. Examples : MS Office, Windows XP For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 7 | P a g e Open source software It refers to any program whose source code is made available for use or modification as users or other developers see fit. Open source software is usually developed as a public collaboration and made freely available. Examples: LINUX and UNIX Special terms: Installation is the process of copying software programs from secondary storage media to the hard disk. 3. COMPUTER HARDWARE Computer hardware is the physical parts or components of a computer, such as the monitor, keyboard, computer data storage, hard disk drive (HDD), graphic cards, sound cards, memory (RAM), motherboard, and so on, Motherboard A motherboard is the main printed circuit board (PCB) found in general purpose microcomputers and other expandable systems. Microprocessor A single chip containing all the elements of a computer's CPU. A hard disk drive (HDD) It is a data storage device used for storing and retrieving digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. Graphics Card It is responsible for rendering an image to your monitor, it does this by converting data into a signal your monitor can understand. Sound Card A device which can be slotted into a computer to allow the use of audio components for multimedia applications. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 8 | P a g e SMPS A switched-mode power supply is an electronic power supply that includes a switching regulator to convert electrical power efficiently and effectively. Input Devices: Keyboard Mouse Joystick Scanner Microphone Touch Screen as well as Output Microphone Magnetic Ink Card Reader Optical Character Reader Bard Code Reader Output Devices: Visual Display Unit (VDU) or Monitor Printers Projector Speaker Plotter Peripheral Devices: Hardware that are connected externally are called peripherals. The basic examples are keyboards, USB mouse , Speakers, Monitor etc., The computer is able to work without the need of peripherals Memory Management: Types of Memory Primary Secondary Memory For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 9 | P a g e Primary Memory: It holds the data and instruction on which computer is currently working. It is also called as main memory and volatile memory It is faster than Secondary Memory Two types of Primary Memory 1.RAM (Random Access Memory) 2.ROM (Read Only Memory) 1. RAM (Random Access Memory) All the active data and programs are stored in RAM. So, they readily available and easily accessible by the CPU It is a volatile memory Two types of RAM Static RAM In this the memory retains its contents as long as power remains applied Dynamic RAM It must be continually refreshed in order for it to maintain the data 2. ROM (Read Only Memory) The storage of data in ROM is permanent. It is a non volatile memory It is more reliable and cheaper than RAM Types of ROM i. MROM (Masked ROM) ii. PROM (Programmable Read Only Memory) iii. EPROM (Erasable and Programmable Only Memory) For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 10 | P a g e The content in EPROM is erased only by exposing in Ultraviolet Radiation upto 40 minutes. iv. EEPROM (Electrically Erasable and Programmable Only Memory) Secondary Memory: It is also a permanent storage of data and information It is non-volatile memory It is not directly accessible to CPU. Transformation of information from the secondary memory to the primary memory first and then to the CPU Examples Of Secondary Memory: Magnetic Tape, Floppy Disk and Hard Disk Virtual Memory It is a memory on the hard disk that the CPU uses the extended RAM. Cache Memory: It is a small sized type of volatile computer memory It provides high speed data access to a processor It stores frequently used computer programs, applications and data Data storage is temporary It has limited capacity and very expensive Uninterrupted Power Supply (UPS) A battery powered backup system that provides enough electricity to a computer during a power outage so that a user can save files before shutting down the computer. Accumulator: A local storage area called a Register, in which the result of an arithmetic or logic operation is formed. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 11 | P a g e 4. COMPUTER NETWORK A computer network is a group of two or more computer systems linked together. Local Area Network A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link to a server. LANs can be built with relatively inexpensive hardware, such as hubs, network adapters and Ethernet cables. Metropolitan Area Network A metropolitan area network, or MAN, consists of a computer network across an entire city, college campus or small region. A MAN is larger than a LAN, which is typically limited to a single building or site. Personal Area Network A personal area network, or PAN, is a computer network organized around an individual person within a single building. This could be inside a small office or residence. A typical PAN would include one or more computers, telephones, peripheral devices, video game consoles and other personal entertainment devices. Wide Area Network A wide area network, or WAN, occupies a very large area, such as an entire country or the entire world. A WAN can contain multiple smaller networks, such as LANs or MANs. The Internet is the best-known example of a public WAN. Network Topology: a. BUS Topology Bus topology is a network type in which every computer and network device is connected to single cable. When it has exactly two endpoints, then it is called Linear Bus topology. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 12 | P a g e Features of Bus Topology It transmits data only in one direction. Every device is connected to a single cable Advantages of Bus Topology It is cost effective. Cable required is least compared to other network topology. b. RING Topology It is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbors for each device. Features of Ring Topology The transmission is unidirectional, but it can be made bidirectional by having 2 connections between each Network Node, it is called Dual Ring Topology. Data is transferred in a sequential manner that is bit by bit. Advantages of Ring Topology Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data. Cheap to install and expand Disadvantages of Ring Topology Troubleshooting is difficult in ring topology. Adding or deleting the computers disturbs the network activity. c. STAR Topology In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 13 | P a g e Features of Star Topology Every node has its own dedicated connection to the hub. Hub acts as a repeater for data flow. Can be used with twisted pair, Optical Fibre or coaxial cable. Advantages of Star Topology Fast performance with few nodes and low network traffic. Hub can be upgraded easily. Easy to troubleshoot. d. TREE Topology It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy. Features of Tree Topology Ideal if workstations are located in groups. Used in Wide Area Network. Advantages of Tree Topology Extension of bus and star topologies. Expansion of nodes is possible and easy. Disadvantages of Tree Topology Heavily cabled. Costly. e. HYBRID topology Hybrid topology is an integration of two or more different topologies to form a resultant topology which has many advantages of all the constituent basic topologies rather than having characteristics of one specific topology. f. MESH Topology For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 14 | P a g e It is a point-to-point connection to other nodes or devices. All the network nodes are connected to each other. Mesh has n(n-2)/2 physical channels to link n devices. There are two techniques to transmit data over the Mesh topology, they are : Routing - Routing logic to direct the data to reach the destination using the shortest distance. Flooding - The same data is transmitted to all the network nodes, hence no routing logic is required. 5. INTERNET: Internet The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to link several billion devices worldwide. It also known as network of networks. World Wide Web The World Wide Web commonly known as the Web is a system of interlinked hypertext documents that are accessed via the Internet. Web Browser A web browser is a software application for retrieving, presenting and traversing information resources on the World Wide Web. Hyperlink A link from a hypertext document to another location, activated by clicking on a highlighted word or image. A hyperlink, or simply a link, is a reference to data that the reader can directly follow either by clicking, tapping, or hovering followed by automatically. Downloading Download is to receive data from a remote system, typically a server such as a web server, an FTP server, an email server, or other similar systems. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 15 | P a g e Typically, downloading is the process of copying of files from the Internet. URL URL means Uniform Resource Locator. It serves major role to identify particular resources in the world wide web. Uploading Uploading refers to the sending of data from a local system to a remote system such as a server or another client Website A website is a set of related web pages served from a single web domain. IP address A unique string of numbers separated by full stops that identifies each computer using the Internet Protocol to communicate over a network. Domain Name System The Internet's system for converting alphabetic names into numeric IP addresses. Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. E-mail Messages distributed by electronic means from one computer user to one or more recipients via a network. The first email was sent by Ray Tomlinson to himself in 1971 Email attachment An email attachment is a computer file sent along with an email message. Spam Irrelevant or unsolicited messages sent over the Internet, typically to large numbers of users For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 16 | P a g e Phishing Phishing is the attempt to obtain sensitive information such as usernames, passwords, and credit card details, often for malicious reasons, by masquerading as a trustworthy entity in an electronic communication. Hot mail It is a free email service provided by Microsoft which was established in 1995. It was co founded by Indian American Entrepreneur Sabeer Bhatia along with Jack Smith in 1996. Domain Name The part of a network address which identifies it as belonging to a particular domain. Domain names are used to identify one or more IP addresses. HTML HTML stands for Hyper Text Markup Language. HTML is the standard markup language for creating Web pages. ISP ISP is Internet Service Provider. That is the private company or government organization that plugs into the vast Internet around the world. Bookmark A bookmark is a saved link to a Web page. It is also called as favorites or Internet shortcuts in Internet Explorer. Cookies A message given to a Web browser by a Web server. The browser stores the message in a text file. The message is then sent back to the server each time the browser requests a page from the server. Whaling Whaling involves a web page or email that masquerades/pretence as being legitimate and urgent. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 17 | P a g e Spooling Spooling is a specialized form of multi-programming for the purpose of mediating between a computer application and a slow peripheral, such as a printer. Email spoofing Email spoofing is the creation of email messages with a forged sender address. Hacktivism Hacktivism is the subversive use of computers and computer networks to promote a political agenda. HTTP 404 The 404 or Not Found error message is a Hypertext Transfer Protocol (HTTP) standard response code in computer network communications. Universal Serial Bus (USB) A common standard for connecting multiple peripherals to a computer as needed. Internet telephony An Internet telephony service provider (ITSP) offers digital telecommunications services based on Voice over Internet Protocol (VoIP) that are provisioned via the Internet. 6. COMMUNICATION PROTOCOLS: PROTOCOL A set of rules and regulations that coordinates the exchange of information over the network. TCP/IP TCP/IP, Transmission Control Protocol/Internet Protocol, is a suite of communications protocols used to interconnect network devices on the Internet. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 18 | P a g e TCP/IP implements layers of protocol stacks, and each layer provides a well-defined network services to the upper layer protocol. UDP UDP (User Datagram Protocol) is an alternative communications protocol to Transmission Control Protocol (TCP) used primarily for establishing low-latency and loss tolerating connections between applications on the Internet. POP Post Office Protocol (POP) is a type of computer networking and Internet standard protocol that extracts and retrieves email from a remote mail server for access by the host machine. FTP The File Transfer Protocol (FTP) is a standard network protocol used to transfer computer files between a client and server on a computer network. FTP is built on a client-server model architecture and uses separate control and data connections between the client and the server. HTTP HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. HTTPS HTTPS is a protocol for secure communication over a computer network which is widely used on the Internet. ICMP The Internet Control Message Protocol (ICMP) is one of the main protocols of the internet protocol suite. It is used by network devices, like routers, to send error messages indicating, for example, that a requested service is not available or that a host or router could not be reached. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 19 | P a g e IMAP In computing, the Internet Message Access Protocol (IMAP) is an Internet standard protocol used by e-mail clients to retrieve e-mail messages from a mail server over a TCP/IP connection. IMAP is defined by RFC 3501. Router The hardware device or software program that sends messages between networks is known as Router. Bandwidth: The amount of data that can be transmitted in a fixed amount of time. It is usually expressed in bits per second (bps) or bytes per second. Serial Port An outlet on a computer used to attach a device, such as a modem. A serial port sends data (bits) down the wire one at a time (in a series). Modem Modem (Modulator DE Modulator): Modem is a device attached to computers that can convert digital signals to analog signals and vice versa for communication via telephone cables. Router A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Network Interface Card A network interface card (NIC) is a circuit board or card that is installed in a computer so that it can be connected to a network. NIC is also referred to as an Ethernet card and network adapter. It is an expansion card that enables a computer to connect to a network. GPS GPS or Global Positioning System is a network of orbiting satellites that send precise details of their position in space back to earth. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 20 | P a g e The signals are obtained by GPS receivers, such as navigation devices and are used to calculate the exact position, speed and time at the vehicles location. CDMA CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies. Bandwidth Bandwidth is the total maximum transfer rate of a network cable or device. It is usually measured in bits per second. GSM GSM (Global System for Mobile communications) is an open, digital cellular technology used for transmitting mobile voice and data services. Gateway The gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. A machine that links two networks using different protocols is also called as gateway. In homes, the gateway is the ISP that connects the user to the internet. Server A computer or computer program which manages access to a centralized resource or service in a network. DSL DSL Stands for "Digital Subscriber Line." It is a communications medium used to transfer digital signals over standard telephone lines. ADSL Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines rather than a conventional voice band modem can provide. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 21 | P a g e Telnet A protocol for remote computing on the internet that allows a computer to act as a remote terminal on another machine, anywhere on the internet. Hub A network device that connects multiple computers on a LAN so that they can communicate with another network and the Internet Gopher A protocol used for locating and transferring information on the internet. It is an internet search tool that allows users to access textual information. PCI Peripheral Component Interconnect is an interconnection system between a microprocessor and attached devices in which expansion slots are spaced closely for high speed operation. Open system interconnection model (OSI) It is a conceptual model that characterizes and standardizes the internal functions of a communication system by partitioning it into abstraction layers. Seven layers of OSI model Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data link Layer Physical Layer 7. PROGRAMMING LANGUAGES: Program The set of instructions, which controls the sequence of operations, are known as Program. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 22 | P a g e Assembler The assembly language program is translated into machine code by a separate program known as an Assembler Spoofing attack It is a situation in which one person or program successfully represents oneself as another by falsifying data and thereby gaining an illegitimate advantage. Command An instruction that causes a program or computer to perform a function Debugging Debugging is the checking and correcting of errors in a program. Interpreter This language processor converts a HLL (High Level Language) program into machine language by converting and executing it line by line. Compiler It also converts the HLL program into machine language but the conversion manner is different. Multitasking. The ability of a computer to execute more than one program at a time. 8. SECURITY Antivirus Software Antivirus or anti-virus software is computer software used to prevent, detect and remove malicious software. This software was originally developed to detect and remove computer viruses. Virus A piece of computer code designed as a prank or malicious act to spread from one computer to another by attaching itself to other programs. Macro virus A type of virus that attaches itself to documents or word processing templates. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 23 | P a g e Piracy It is an illegal copying of software or other creative works. Password A users secret identification code, required to access stored material. A procedure intended to prevent information from being accessed by unauthorized persons. Malware Software that disrupts normal computer functions or sends a users personal data without the users authorization. Firewall A security system usually consisting of hardware and software that prevents unauthorized persons from accessing certain parts of a program, database or network. Authorization It is the function of specifying access rights to resources related to information security and computer security in general and to access control in particular. Authentication It is an act of confirming the truth of an attribute of a single piece of data or entity. It often involves verifying the validity of at least one form of identification. Cloud computing Delivery of storage or computing services from remote servers online (ie via the internet). Encryption The transformation of data to hide its information content. Hacker Someone who violates computer security for malicious reasons, kudos or personal gain. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 24 | P a g e Network firewall Device that controls traffic to and from a network. Outsourcing Obtaining services by using someone elses resources. Proxy server Server that acts as an intermediary between users and others servers, validating user requests. Spyware Malware that passes information about a computer users activities to an external party. Threat Something that could cause harm to a system or organization. Vulnerability A flaw or weakness that can be used to attack a system or organization. Worm Malware that replicates itself so it can spread to infiltrate other computers. Screen scraper A virus or physical device that logs information sent to a visual display to capture private or personal information. Intrusion prevention system (IPS) Intrusion detection system that also blocks unauthorized access when detected. Inspection certificate A declaration issued by an interested party that specified requirements have been met. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 25 | P a g e Identification The process of recognizing a particular user of a computer or online service. Adware Ad supported software, often called adware, is used when referencing any type of software that downloads or displays unwanted advertisement on a computer while the software is being used. Crackers An individual with extensive computer knowledge whose purpose is to breach or bypass internet security. Denial of Service (DoS) Attack A denial-of-service (DoS) attack involves an attempt to disrupt the normal functioning of a website or web service. Exploit An exploit is the use of software, data, or commands to exploit a weakness in a computer system or program to carry out some form of malicious intent, such as a denial-of-service attack. Key logger A key logger, also known as keystroke logging or key logging, is a method of tracking the strokes on a keyboard without the knowledge of the user. Spear-phishing Spear-phishing defines a more specialized phishing scheme targeting a specific employee in order to gain access to a companys information. Trojan A shortened form of "Trojan Horse", this type of malware appears to have a legitimate or at least benign use, but masks a hidden sinister function. Patch A patch is an update to a vulnerable program or system. For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 26 | P a g e Drive-by Download These attacks exploit vulnerabilities in your browser or its plug-in and helper applications when you simply surf to an attacker-controlled website. Plug in Plug-in or Ad on is a software component that adds a specific feature to an existing computer program. They are simply extensions that extends the usability of the program. 9. INTRANET AND EXTRANET Intranet An intranet is a network based on TCP/IP protocols (an internet) belonging to an organization, usually a corporation, accessible only by the organizations members, employees, or others with authorization. Secure intranets are now the fastest growing segment of the Internet because they are much less expensive to build and manage than private networks based on proprietary protocols. Extranet An extranet is a website that allows controlled access to partners, vendors and suppliers or an authorized set of customers normally to a subset of the information accessible from an organizations intranet. 10. MICROPROCESSORS AND MICROCONTROLLERS About Microprocessors: A microprocessor is a general purpose device which is called a CPU. A microprocessor do not contain on chip I/O Ports, Timers, Memories etc., Microprocessors are most commonly used as the CPU in microcomputer systems. Microcontroller 8051 A microcontroller is a dedicated chip which is also called single chip computer For more notes and career guidance visit www.careerwiz.in Share your feedback and suggestions at feedback@careerwiz.in 27 | P a g e A microcontroller includes RAM, ROM serial and parallel interface, timers and interrupt circuitry in a single chip. Microcontroller based system design is rather simple and cost effective. Salient Features 4 KB on chip program memory (ROM or EPROM) 128 bytes on chip data memory (RAM) 8 bit data bus 16 bit address bus 32 general purpose registers each of 8 bits Two 16 bit timers T0 and T1 Five interrupts (3 internal and 2 external) Four parallel port each of 8 bits with a total 32 I/O lines One 16 bit program counter One 8 bit stack pointer One Microsecond instruction cycle with 12 MHZ crystal One full duplex serial communication port ****** For More notes and wizards, visit us at www.careerwiz.in

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