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.