Bluetooth

Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS232 data cables. It can connect several devices, overcoming problems of synchronization. It provides a wireless solution for reducing the cable clutter of peripherals. It is also a replacement for IrDA, and is a complimentary technology to Apple's AirPort (802.11b, g and n) solution for wireless networks, not a replacement for networking. On a technical level, Bluetooth is an open specification for a cutting-edge technology that enables short-range wireless connections between desktop and laptop computers and a host of other peripheral devices - on a globally available frequency band (2.4 GHz) for worldwide compatibility.

Apple's implementation of the Bluetooth Stack is based on the Bluetooth Special Interest Group (SIG) standard where Data transfers happen over a series of layered protocols including Baseband, L2CAP, RFCOMM and OBEX. Devices are identified by unique 6 byte addresses - like Ethernet.

Apple's Bluetooth Stack is integrated in Mac OS X starting with version 10.2, also known as "Jaguar", and the Bluetooth Software Developer's Kit.

Details in the Bluetooth SDK include how to extend our stack to support your hardware, how to add support for additional profiles required by your devices, and how to develop applications that take advantage of the unique attributes of Bluetooth.

Some basic terms of Computer

HARDWARE
All the physical part of the computer is called hardware. Example: keyboard, mouse, CPU, monitor etc. so input, output, storage and processing devices are all hardware of the computer. A physical component may be electronic, electrical, mechanical or optical.

SOFTWARE
The programs and instructions sets that operate the computer are called software or computer programs are collectively known as software. The main objective of software is to enhance the performance capability of hardware. There are two types of software designed to do different tasks they are: application and system software. E.g. oracle, word, LINUX etc

CPU (central processing unit):
CPU is the brain of a computer. Its primary function is to execute programs. Besides executing programs, the CPU controls the operation of all other components such as memory, input and output devices. Under its control, programs and data are stored in the memory and display on the CRT/LCD screen or printed on printer.

OS (Operating system):
The interaction between hardware and software which is managed by a program is called operating system. Example: DOS, LINUX, UNIX etc. it is allows user to format disk, print, copy, delete, control input/output operation etc.

5 PROGRAM
Programs are the collection of many commands together in sequence and in logical way. A program is written for specific purpose.

Computer virus

Computer viruses are the software programs that have the ability to clone itself and can operate without the knowledge or desire of the computer user. In other words, a computer virus is a program designed to spread to itself by first infecting executable files or the system areas of hard and floppy disks and then making copies of itself. It is a program inserted into another program. It gets activated by its host program. It infects data or program every time the user runs the infected program and it takes advantages and replicates itself. It is the intellectual destructive creation of computer programmers.

Virus in reference to computer was first used by David Gerrold in his book "When Harlie was one" in 1975. He named a computer program as ‘Virus’ which rang telephone randomly until it found another computer linked to the network. In 12975, John Burner used the term "worm" in his novel "The Shockwave Rider". The first viruses appeared at the University of Delaware in 1987. In 1997, over 9000 different variations of viruses were developed.

Virus spread from computer to computer through electronic bulletin boards, telecommunication systems, and shared floppy disks. Viruses are created by computer programmers for fun, but once they began to spread they take on a life own, creating disruption, dismay and paranoia in their wake. Antivirus software are developed to protect from virus. We should detect and stop the virus from spreading.

Viruses are created by computer programmer for the following purposes:
To protect software from software piracy.
To entertain the users during the use of the program by displaying vulgar pictures on the screen and by producing interesting messages.
Some programmers create computer viruses even to expose their programming capabilities.

DEVELOPMENT OF COMPUTER EXTENDED IN PRESENT DAYS...

The development of personal computer has taken a long period of time to extend the use of computer at present days. So, it passed through a various stages to become this stage at present days. The world without computers is unimaginable. A small, relatively inexpensive computer designed for an individual user is known as personal computer. In price, personal computers range from hundred dollars to thousands of dollars and are based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip. There are different types of computers according to their size. The smallest computer is micro computer where Personal computers also lie in this category and also popular to used as as personal. These computers are portable and can be use in personal life.

There were many ages in development of computer. Mainly there are three ages, age of mechanical calculators, age of electromechanical computers and age of electronic computers. The examples are Abacus, Slide rule, Pascal’s calculator, etc. The mechanical computers using electricity is known as electro mechanical computers. The examples are Mark-1, ABC, etc. And the computers which use the electronic devices in it are known as electronic computers. The examples are EDSAC, EDVAS, etc. The age of computer from electromechanical computers are also divided into different generations. The computer using vacuum tubes for circuitry and magnetic drums for memory having enormous size is known as first generation computers. They were very expensive, mechanical and used a great deal of electricity, generated a lot of heat, which often cause the malfunctions. E.g. MARK-1, UNIVAC, etc. the computers using the transistor are known as second generation computers. These computers still relied on punched cards for input and output. They moved from cryptic binary machine language to symbolic languages, which allowed programmers to specify instructions in words. High level programs were also developed in this time. E.g. IBM1401, ICL 2650 etc. the computers using IC know as third generation computers. Transistors were miniaturized and placed on silicon chips and were called as semiconductors. E.g. IBM 360, UNIVAC 9000 etc. the computers using microprocessor are known as fourth generation computers. The microprocessor brought the thousands of integrated circuits onto a single silicon chip. The personal computer also lies in this generation of computer. E.g. IBM PC, Pentium PC etc. are the some example of forth generation of computer.
People uses personal computer in different field. E.g. Business purpose like word processing, accounting, desktop, publishing, running etc. at home, the most popular use for personal computers is for playing games. People often use computers in home for drawing and painting pictures, designing pictures typing etc. due to smaller size it can be kept at any place of the home. It is also easy to use in comparison to other types of computer. No any special knowledge is required for it. People having basic knowledge and education can operate it easily. These types of computers are also as economical as compare to others. Thus, development of personal computers has extended the use of computer in present days.

LINUX

Linux is a Unix-like computer operating system. Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone.

The name "Linux" comes from the Linux Kernel started in 1991 by Linus Torvalds. The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. The GNU contribution is the basis for the alternative name GNU/Linux.
Predominantly known for its use in servers, Linux is supported by corporations such as Dell, Hewlett-Packard, IBM, Novell, Oracle Corporation, Red Hat, and Sun Microsystems. It is used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers, video game systems, such as the PlayStation 2 and PlayStation 3, several arcade games, and embedded device such as mobile phones, routers, and stage lighting systems.
Linux is a remarkably complete operating system, including a graphical user interface and other components usually found in comprehensive UNIX system. Although copyright are held by various creators of Linux’s components, it is distributed using the Free Software Foundation’s copy left stipulations that mean any modified version that is redistributed must in turn be freely available.

Linux is sometimes suggested as a possible publicly-developed alternative to the desktop predominance of Microsoft Windows. Although Linux is popular among users already familiar with UNIX, it remains far behind Windows in numbers of users. However, it use in business enterprises is growing daily,

Uses
As well as those designed for general purpose use on desktops and servers, distributions may be specialized for different purposes including: computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.

Linux is a widely ported operating system. While the Linux kernel was originally designed only for Intel 80386 microprocessors, it now runs on a more diverse range of computer architectures than any other operating system: in the hand-held ARM –based iPAQ and the mainframe IBM system z9, in devices ranging from mobile phones to supercomputers. Specialized distributions exist for less mainstream architectures. The ELKS ernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the μclinux kernel fork may run on systems without a memory management unit. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers, PADs, video games consoles, portable music players, and mobile phones.

INTERNET

INTRODUCTION
Internet is traditionally written with a capital first letter, as it is a proper noun. The internet society, the Internet Engineering Task Force, the Internet Corporation for Assigned Names and Numbers, the World Wide Web Consortium, and several other Internet-related organizations use this convention in their publications.

The Internet is a worldwide, publicly accessible series of interconnected Computer networks that transmit data by packet switching using the standard Internet protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked web pages and other resources of the World Wide Web (WWW).

History of the Internet
In the 1960s, computer researchers, J.C.R. Licklider and Robert W. Taylor pioneered calls for a joined-up global network to address interoperability problems. Concurrently, several research programs began to research principles of networking between separate physical networks, and this led to the development of packet switching. These included Donald Davies (NPL), Paul Baran (RAND corporation), and Leonard Kleinrock (MIT)'s research programs,
This lead to the development of several packet switched networking solutions in the late 1960s and 1970s, including ARPANET, and X.25. Additionally, public access and hobbyist networking systems grew in popularity, including UUCP. They were however still disjointed separate networks, served only by limited gateways between networks. This lead to the application of packet switching to develop a protocol for inter-networking, where multiple different networks could by joined together into a super-framework of networks. By defining a simple common network system, the Internet protocol suite, the concept of the network could be separated from its physical implementation. This spread of inter-network began to form into the idea of a global inter-network that would be called ‘The Internet’, and this began to quickly spread as pre-existing networks were converted over to become compatible with this. This spread quickly across the advanced telecommunication networks of the western world, and then began to penetrate into the rest of the world as it became the de-facto international standard and global network. However, the disparity of growth lead to a Digital divide that is still a concern today.
Following commercialization and introduction of privately run Internet Service Providers in the 1980s, and its expansion into mass popular use in the 1990s; the Internet has had a drastic impact on culture and commerce. This includes the rise of near instant communication by e-mail, text based discussion forums, the World Wide Web. Investor speculation in new markets provided by these innovations would also lead to the inflation and collapse of the Dot-com bubble, a major market collapse. But despite this, growth of the internet continued, and still does.

Terminology
The Internet and the World Wide Web are not synonymous. The Internet is a collection of interconnected computer networks, linked by copper wires, fiber-optic cables, wireless connections, etc. In contrast, the Web is a collection of interconnected documents and other resources, linked by hyperlinks and URLs. The World Wide Web is one of the services accessible via the Internet, along with various others including e-mail, file sharing, online gaming and others.

C Programming

Introduction of C Programming

C is programming language developed at AT and T’s laboratories of USA in 1972. it was designed and written by a man because it was reliable, simple and easy to use. C stands in between high level language and low level language. That is why it is often called a middle level language. Since, it was designed to have both: Relatively good programming efficiency (as compared to machine oriented language) and relatively good machine efficiency.

When we start to learn any language, first of all, we learn alphabet in those languages. Each and every alphabet and punctuation symbols are called token. After that, we learn how it makes words by combining those alphabets. Words when arranged in a sequence according to the grammer of that language, becomes sentence. The same rule applies when we learn the any programming language. Learning C is similar and much easier. Therefore, before starting the program straightway, we first of all learn tokens, commands and their syntax (Grammar of rules).

Step in learning c language
When we write and compile a program in c, the compiler collects each and every character, symbols, operator etc and makes tokens. Such tokens are then compared to the vocabulary the ANSI C, it classifies such tokens in to six types: Keywords, identifier, constant, string, operator and punctuators. For example, we have written two lines of codes as follows:
Int a
Inta
The vocabulary of c has only the definition of the keyword\data type under "int", so int is valid and "a" is considered to be a variable name but on second line of code, inta is considered to a single token. It can’t be found on the internal vocabulary of c, so any error is given by the compiler.