Mirha Malik

 Input Devices The data is entered directly to the computer and sometimes indirectly. In first case,the data goes directly to the computer from the source and in the second case;we have to carry out some intermediate handling. In either case the task is to gather data to be processed by the computer. Types There are three general types of input devices. Keyboard Pointing devices S ource Data entry devices Keyboard The keyboard may look like a typewriter keypad to which some special keys have been added. The keys normally available on the keyboard are Numeric,Alphabetic,function and aditional special purpose keys. It has some additional keys between the main keypad and the numeric keys,and status lights in the upper right corner.The standard keyboard is also called "QWERTY"which describes the beginning keys in the top row of alphabetic letters. There are 101 Enhanced keyboard showing the layout of the various  key groups. Types There are 5 types of Keyboard. Alphabet Keys Numb...

 Protocols in TCP/IP suit Each layer of TCP/IP model has its own protocols. Every protocol is designed to perform some specific task. Some of the most widely used application layer protocols are; FTP HTTP SMTP FTP FTP stands for File Transfer Protocol. It is a standard TCP/IP protocol which is used for the purpose of transferring files from one computer to another. Example "If we want to transfer a document file to a remote computer,then we can use this protocol". HTTP HTTP stands for Hypertext Transfer Protocol. It is a protocol used by World Wide Web (WWW) to transfer web pages between a client and a web server. A web server is also called HTTP server. We use this protocol while browsing internet. For secure data transfer,we use HTTP. SMTP SMTP stands for Simple Mail Transfer Protocol. It is a standard protocol to transmit emails.

 Data Communication Data communication refers to exchange of messages between sending and receiving devices through some communication medium. These messages are actually the information which can be presented in many forms like text,numbers,images,audio and video. Components of communication system A communication system is used to transfer data from one point to other. The main components of communication system are discussed below; Sender  Receiver Message Protocol Transmission medium Sender Sender is a device that initiates the communication process. It sends messages consisting of text,numbers,pictures,etc. It is also called source or transmitter. Normally,computer is used as a sender in a communication system. Receiver Receiver is a device that receives a message. It is also called sink. The receiver can be a computer,printer or another device.The receiver must be capable of accepting a message. Message Message is the data or information to be communicated. It may consis...

Network Topologies Topology of a network is a geometric representation of the relationship among the interconnected devices. There are four basics Network Topologies. Bus Topology Star Topology Ring Topology  Mesh Topology  Bus Topology Bus Topology A Bus Topology connects all devices of the network through a single common cable having exactly two ends point.The cable is called backbone of the topology. Bus Topology offers a simple way to connect devices. All of the devices of the network are connected to common transmission medium which has exactly two endpoints. In this simple form of networking,failure of any single device does not affect other devices connected with the cable. However,if there is some problem in the shared communication cable,then all other devices can stop functioning. Star topology Star Topology A Star topology connects all devices using point to point connections with cables to  central point.The Central point is known as Hub or Switch. The central...

 Computer Network Acomputer network is a group of computer system and other computing hardware devices linked together through communication channel. Network of Networks Networks are connected together to make a larger network which is called network of networks. Example "The internet is a well known example of network of networks". Need of a Computer Network Acomputer network is established for the purpose of sharing resources. Examples of sharing resources File sharing Hardware sharing Application sharing Sharing a single internet connection User communication Increasing storage capacity File Sharing Networking of computer helps a network user to share files. It can be as accessing work files from your home computer or sharing your created documents on your web page. Examples If you need datesheet of your board examination,you can get the file from Internet  without visiting BISE(Board of Intermediate and Secondary Education) office. Morever we can sharing files with others...

 Computer "Computer is an electronic device that accept input,process the data,store the data and produce output". computer Classification of Computers Computers are classified into four based on their size. Mini computers Micro computers Mainframe computer Super computer Mini Computer Minicomputer A minicomputer is also called mid-range computer. Minicomputers are mainly multi users systems where more than one user can work simultaneously. Minicomputers was smaller,less expensive,and less power than mainframe or supercomputers but more expensive and more powerful than personal or microcomputers. Examples of minicomputer IBM's AS/400e, Honeywell200, TI-990,etc Micro Computer Microcomputers A microcomputer is a complete computer on a small scale,designed for use by one person at a time.  Microcomputer is also called Personal computer,or a device based on a single chip microprocessor. The microcomputer is small in size. The microcomputer is used to design different software...