History of Computer

1. Generations of computer:

• First Generation - 1940-1956: Vacuum Tubes: The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. A magnetic drum,also referred to as drum, is a metal cylinder coated with magnetic iron-oxide material on which data and programs can be stored. Magnetic drums were once use das a primary storage device but have since been implemented as auxiliary storage devices.
• Second Generation - 1956-1963: Transistors:
  
  Transistors replaced vacuum tubes and ushered in the second generation computer. Transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit. Invented in 1947 at Bell Labs, transistors have become the key ingredient of all digital circuits, including computers. Today's latest microprocessor contains tens of millions of microscopic transistors.
• Third Generation - 1964-1971: Integrated Circuits:
  
  The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

• Fourth Generation - 1971-Present: Microprocessors: Three basic characteristics differentiate microprocessors:
  
  • Instruction Set: The set of instructions that the microprocessor can execute.
  • Bandwidth: The number of bits processed in a single instruction.
  • Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.
• Fifth Generation - Present and Beyond: Artificial Intelligence:
  Fifth generation computing devices, based on artificial intelligence, are still in development,though there are some applications, such as voice recognition, that are being used today.
  There are several programming languages that are known as AI languages because they are used almost exclusively for AI applications. The two most common are LISP and Prolog.

2. History of the Internet:
Although the history of the Internet arguably begins in the 19th century with the invention of the telegraph system, the modern history of the Internet starts in the 1950s and 1960s with the development of computers. This began with point-to-point communication between mainframe computers and terminals, expanded to point-to-point connections between computers and then early research into packet switching. Packet switched networks such as ARPANET, Mark I at NPL in the UK, CYCLADES, Merit Network, Tymnet, and Telenet, were developed in the late 1960s and early 1970s using a variety of protocols. The ARPANET in particular lead to the development of protocols for internetworking, where multiple separate networks could be joined together into a network of networks.