Brief Computer History 1. First-Generation: Classification by hardware technology Huge, typically 8 feet tall, 50 feet long Unreliable, Slow, Used Vacuum Tubes and/or Electromechanical Relay switches. Some examples: Mark-I: Arguably first general-purpose automatic Digital computer developed in 1943 for US Navy by a team of Harvard and IBM and US War Department. ENIAC (Electronic Numerical Integrator and Calculator) to calculate the trajectory table of US Army artillery, completed 2 months after WW-2 ended. 80 feet long 30 ton 18000 vacuum tubes UNIVAC (Universal Automatic Calculator) in 1951 developed by the same team of ENIAC above "Stored-Program" computer and first General-purpose commercial computer. Used by US Census Bureau in 1951. Stored Program (due to John von Neumann) Idea to store both the program and data inside the computer's main memory for faster and more efficient execution. 2. Second Generation Transistor invented by Bell Lab. in 1948 marks the start of 2nd generation computers. IBM650: first computer built on transistors in 1953. Smaller size and higher speed and more reliable. 3. Third Generation Integrated Circuits invented separately by Jack Kilby of TI and Robert Noyce of Fairchild Corp in 1959 and 1958 mark the start of these computers. IBM360 and IBM370. Even smaller, faster and more reliable. 4. Fourth Generation Ted Hoff of Intel Corp. invented Micro Processor, a single computer chip, in 1969. This started personal/home computers with Apple-II (first personal computer) in 1976 IBM PC in 1981 and MacIntosh in 1984 and Mini-Computers such as DEC-10 in 1970. Very small , high performance, faster and inexpensive. 5. Distributed Network Computing and WWW. a. WWW invented in 1990 by Tim Berners Lee of CERN (European Laboratory for Particle Physics) for distributed information exchange system. b. Web pages have become a worldwide standard due to standardization of TCP/IP and adoption of HTML. TCP (Transmission Control Protocol) Data transmission stardards for all different computers to be able to communicate. IP (Internet Protocol) Standard for specifying addresses of host computers to correctly deliver E-messages to proper destinations as well as correctly identifying senders. HTML (Hyper Text Markup Language) Standard language to write WWW documents that all browsers understand. c. Web Browsers Netscape, Mozilla Firefox and Microsoft Internet Explorer. Software to mediate between client computers and server computers in displaying WWW documents (web pages). BRIEF HISTORY OF COMPUTER NETWORK 1. ARPANET in 1969, Cold war era. Advanced Research Projects Agency (DOD) Initial goal: Experimental computer network to support research. In particular, research about how to build computer Network that can withstand partial outages (like bomb attacks) and still function. It soon adopted the IP Protocol and required the minimum of information from client computers. 2. Other networks adopted IP protocol and joined ARPANET soon including Five supercomputer centers NSFNET CSNET and THEnet (Texas Higher Education) 3. In 1990 it became InterNet (A network of networks) a. Packet switching, no dedicated channels for particular transmission like telephone switching system. A packet: a piece of message of about 1500 characters b. IP addressing system Each host computer has a unique address made up of four numbers, each up to 256, (28 ) Possible number of addresses: roughly 4,000,000,000 c. DNS (Domain Name System) To use names instead of numbers for IP addresses. This allows an IP address to be specified by a series of domain names such as HAL.LAMAR.EDU where 'EDU' is the highest domain name. Originally, there were six highest domain names: COM EDU GOV MIL (military establishments) ORG (Non-profit organization) NET (network resources) 4. Internet-2 a. US Government and MCI initiated in 1998. b. Goal: To provide much faster access speed of some 9.6 billion bits per second, enough speed to transmit all 30 volumes of Encyclopedia Britannica in one second. 5. Some issues of Internet/WWW Privacy Security Censorship Criminal Activities Appropriate Net Behavior Lack of Central Control, No Government Control (1997 Communication Decency Act declared unconstitutional by the Supreme Court)