Generation of computer|Science and technology.

Generation of computer :

First Generation (1942-1955) Vacuum Tubes:
The early stage computers used vacuum tubes for circuitry Magnetic drums for memory, and were often enormous, big sized taking up entire rooms.The UNIVAC 1, ENIAC and Mark 1 Computers are examples of first generation computing devices.

Second Generation (1956-1963) Transistors:
Transistors replaced vacuum tubes and ushered in the second generation of computers.It was invented in Bell Laboratories.

Third Generation (1964-1971) Integrated
The development and use of the integrated circuit was the feature of the third generation of computers.Integrated circuits( IC) replaced the transistors, which was developed by J. S. Kilbi. Transistors were miniaturised and placed on silicon chips, called Semiconductors, which drastically increased the speed and efficiency of the computers.

Fourth Generation (1971-Present)
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip.In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Fourth generation computers also saw the development of GUIs, the mouse and handhold devices.

Apple Lisa Computer is the first home computer with a GUI (graphical user interface) in 1983. A graphical user interface (GUI), is a type of user interface that allows users to interact with electronic devices through graphical icons and visual indicators, Such as secondary notation, instead of text-based user interface, typed command labels or text navigation.

Fifth Generation (Present and Beyond) Artificial : Unlike all other generation computers, present generation of computers is characterized by the use of the technique used to reduce complex programming.
The fifth generation computers are based on artificial intelligence (AI) , are still in developmental stage, though there are Some applications, such as voice recognition, that are being used today.


Mobile technology is the technology used for Cellular communication. Code division multiple access (CDMA) technology has evolved rapidly over the past few years. Since the start of this millennium, a standard mobile device is not only used as a mode of communication but also used for other useful operations like GPS navigation, embedded web browser, messaging device and also as a game console.

A cellular network or mobile network is a communication network which is based on wireless communication system.The network is distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station. This base station provides the cell with the network coverage which can be used for transmission of voice, data and others. A cell might use a different set of frequencies from neighbouring cells, to avoid interference and provide guaranteed service quality within each cell. Radio waves are used to transfer signals to and from the mobile/cell phones.

There are number of types of cellular network:
✹Time division multiple access(TDMA) .
✹Frequency division multiple access(FDMA).
✹Code division multiple access(CDMA).
✹Orthogonal frequency division multiple access(OFDMA).
✹Global System for Mobile Communications(GSM).
✹ General Packet Radio Service (GPRS).
✹Evolution-Data Optimised (EV-DO).
✹Enhanced Data Rates for GSM Evolution (EDGE).
✹Universal Mobile Telecommunications System (UMTS).
✹Digital Enhanced Cordless Telecommunications (DECT).
✹Digital AMPS (IS-136/TDMA).
✹Integrated Digital Enhanced Network (IDEN).