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)