Tuesday, 10 July 2012

The History of Computer Data Storage


Nowadays we are used to having hundreds of gigabytes of storage capacity in our computers. Even tiny MP3 players and other handheld devices usually have several gigabytes of storage. This was pure science fiction only a few decades ago. For example, the first hard disk drive to have gigabyte capacity was as big as a refrigerator, and that was in 1980. Not so long ago!
Pingdom stores a lot of monitoring data every single day, and considering how much we take today’s storage capacity for granted, it’s interesting to look back and get things in perspective. Here is a look back at some interesting storage devices from the early computer era.

The Selectron tube

The Selectron tube had a capacity of 256 to 4096 bits (32 to 512 bytes). The 4096-bit Selectron was 10 inches long and 3 inches wide. Originally developed in 1946, the memory storage device proved expensive and suffered from production problems, so it never became a success.
Selectron tube
Above: The 1024-bit Selectron.

Punch cards

Early computers often used punch cards for input both of programs and data. Punch cards were in common use until the mid-1970s. It should be noted that the use of punch cards predates computers. They were used as early as 1725 in the textile industry (for controlling mechanized textile looms).
Punch card Fortran program
Above: Card from a Fortran program: Z(1) = Y + W(1)
Punch card reader and punch card writer
Above left: Punch card reader. Above right: Punch card writer.

Punched tape

Same as with punch cards, punched tape was originally pioneered by the textile industry for use with mechanized looms. For computers, punch tape could be used for data input but also as a medium to output data. Each row on the tape represented one character.
Punch tape
Above: 8-level punch tape (8 holes per row).

Magnetic drum memory

Invented all the way back in 1932 (in Austria), it was widely used in the 1950s and 60s as the main working memory of computers. In the mid-1950s, magnetic drum memory had a capacity of around 10 kB.
Magnetic drum memory
Above left: The magnetic Drum Memory of the UNIVAC computer. Above right: A 16-inch-long drum from the IBM 650 computer. It had 40 tracks, 10 kB of storage space, and spun at 12,500 revolutions per minute.

The hard disk drive

The first hard disk drive was the IBM Model 350 Disk File that came with the IBM 305 RAMAC computer in 1956. It had 50 24-inch discs with a total storage capacity of 5 million characters (just under 5 MB).
IBM Model 350, the first hard disk drive
Above: IBM Model 350, the first-ever hard disk drive.
The first hard drive to have more than 1 GB in capacity was the IBM 3380 in 1980 (it could store 2.52 GB). It was the size of a refrigerator, weighed 550 pounds (250 kg), and the price when it was introduced ranged from $81,000 to $142,400.
Really big hard disk drives
Above left: A 250 MB hard disk drive from 1979. Above right: The IBM 3380 from 1980, the first gigabyte-capacity hard disk drive.

The Laserdisc

We mention it here mainly because it was the precursor to the CD-ROM and other optical storage solutions. It was mainly used for movies. The first commercially available laserdisc system was available on the market late in 1978 (then called Laser Videodisc and the more funkily branded DiscoVision) and were 11.81 inches (30 cm) in diameter. The discs could have up to 60 minutes of audio/video on each side. The first laserdiscs had entirely analog content. The basic technology behind laserdiscs was invented all the way back in 1958.
Laserdiscs
Above left: A Laserdisc next to a regular DVD. Above right: Another Laserdisc.

The floppy disc

The diskette, or floppy disk (named so because they were flexible), was invented by IBM and in common use from the mid-1970s to the late 1990s. The first floppy disks were 8 inches, and later in came 5.25 and 3.5-inch formats. The first floppy disk, introduced in 1971, had a capacity of 79.7 kB, and was read-only. A read-write version came a year later.
Old floppy disks
Above left: An 8-inch floppy and floppy drive next to a regular 3.5-inch floppy disk.Above right: The convenience of easily removable storage media.

Magnetic tape

Magnetic tape was first used for data storage in 1951. The tape device was called UNISERVO and was the main I/O device on the UNIVAC I computer. The effective transfer rate for the UNISERVO was about 7,200 characters per second. The tapes were metal and 1200 feet long (365 meters) and therefore very heavy.
Old tape drives for OLD computers
Above left: The row of tape drives for the UNIVAC I computer. Above right: The IBM 3410 Magnetic Tape Subsystem, introduced in 1971.
And of course, we can’t mention magnetic tape without also mentioning the standard compact cassette, which was a popular way of data storage for personal computers in the late 70s and 80s. Typical data rates for compact cassettes were 2,000 bit/s. You could store about 660 kB per side on a 90-minute tape.
Compact cassette and Commodore Datasette.
Above left: The standard compact cassette. Above right: The Commodore Datassette is sure to bring up fond memories for people who grew up in the 80s.
There are so many interesting pictures from “the good old days” when you look around on the web. These were some of the best we could find, and we hope you liked them.

Friday, 6 July 2012

Introduction to the Internet


Introduction to the Internet

What is Internet?


Internet is (1) network of networks, (2) TCP/IP collection of networks, (3) community of people and services utilizing the global TCP/IP and other interconnected networks
References:
The Internet: Mini Course
Internet Society Home Page
Internet Timeline

Where did it all start?

The "unreliable network"

Adapted from
  • Short History of the Internet by Bruce Sterling, bruces@well.sf.ca.us, rom THE MAGAZINE OF FANTASY AND SCIENCE FICTION, February 1993
  • Hobbes Internet Timeline v. 1.3 by Robert H'obbes' Zakon, hobbes@hobbes.mitre.org
  • "A Brief History of the Internet and Related Networks."
  • RFC1462 What is Internet?"
Early 1960s: RAND Corporation charged with development of communication network able to survive and function during and after a nuclear war. No matter how well the wiring itself is protected, it's always vulnerable to impact of atomic bombs. Any central c ommand and control center of such a network would be the first logical target. Obviously, a conventioal network idea would not work.
Paul Baran of RAND published a paper "On Distributed Communications Networks" in 1962-64. The prososal featured a network "designed from the beginning to operate while in tatters."
  • The network itself would be assumed to be unreliable at all times. It would be designed from the get-go to transcend its own unreliability.
  • All the nodes in the network would be equal in status to all other nodes, each node with its own authority to originate, pass, and receive messages.
  • The messages themselves would be divided into packets, each packet separately addressed.
  • Each packet would begin at some specified source node, and end at some other specified destination node. Each packet would wind its way through the network on an individual basis.
  • The particular route that the packet took would be unimportant. Only final results would count. Basically, the packet would be tossed from node to node to node, more or less in the direction of its destination, until it ended up in the proper place. If big pieces of the network had been blown away, that simply wouldn't matter; the packets would still stay airborne, lateralled wildly across the field by whatever nodes happened to survive. This rather haphazard delivery system might be "inefficien t" in the usual sense (especially compared to, say, the telephone system) -- but it would be extremely rugged.

Pentagon's Advanced Research Projects Agency (ARPA) [becomes DARPA: Defence ARPA in 70's], formed in 1956 in response to Sputnik launch by the USSR, decided to implement a decentralized, blastproof, packet-switching network in the USA. The objective was to develop communication protocols which would allow networked computers to communicate transparently across multiple, linked packet networks. This was called the Internetting project and the system of networks which emerged from the research was known a s the "Internet." The nodes of the network were to be high-speed supercomputers. First node was installed in 1969 in UCLA. Stanford Research Institute, UCSB and U of Utah soon followed. The netword was named ARPANET, after it's sponsor.
The four computers could transfer data on dedicated high-speed transmission lines. Scientists and researchers could share one another's computer facilities by long-distance. In 1971 there were fifteen nodes in ARPANET; by 1972, thirty-seven nodes.
By the second year of operation, however, an odd fact became clear. ARPANET's users had warped the computer-sharing network into a dedicated, high-speed, federally subsidized electronic post-office. The main traffic on ARPANET was not long-distance c omputing. Instead, it was news and personal messages. Researchers were using ARPANET to collaborate on projects, to trade notes on work, and eventually, to downright gossip and schmooze. People had their own personal user accounts on the ARPANET co mputers, and their own personal addresses for electronic mail. Not only were they using ARPANET for person-to-person communication, but they were very enthusiastic about this particular service -- far more enthusiastic than they were about long-distance computation.
Soon a first mailing list was invented - a mechanism in which an identical message could be sent automatically to large numbers of network subscribers. Interestingly, one of the first really big mailing-lists was "SF-LOVERS," for science fiction fans. Discussing science fiction on the network was not work-related and was frowned upon by many ARPANET computer administrators, but this didn't stop it from happening.
Throughout the '70s, ARPA's network grew. In 1971 ARPANET consisted of 15 nodes (23 hosts): UCLA, SRI, UCSB, U of Utah, BBN, MIT, RAND, SDC, Harvard, Lincoln Lab, Stanford, UIU(C), CWRU, CMU, and NASA/Ames.
Its decentralized structure made expansion easy. Unlike standard corporate computer networks, the ARPA network could accommodate many different kinds of machine. As long as individual machines could speak the packet-switching lingua franca of the new, anarchic network, their brand-names, and their content, and even their ownership, were irrelevant.

Internet Timeline

1973
 First international connections to ARPANET: England nad Norway.
1976
 UUCP (Unix-to-Unix CoPy) developed at AT&T Bell Labs and distributed with UNIX one year later.
1979
Meeting between U of Wisconsin, DARPA, NSF, and computer scientists from many universities to establish a Computer Science Department research computer network.
 USENET established using uucp between Duke and UNC by Tom Truscott and Steve Bellovin.
1981
 BITNET, the "Because Its Time NETwork"
  • Started as a cooperative network at the City University of New York.
  • Provides electronic mail and listserv servers to distribute information.
  • Unlike USENET, where client s/w is needed, electronic mail is the only tool necessary.
CSNET (Computer Science NETwork) built by UCAR and BBN through seed money granted by NSF to provide networking services (specially email) to university scientists with no access to ARPANET. CSNET later becomes known as the Computer and Science Network.
Minitel (Teletel) is deployed across France by French Telecom.
1982
 The ARPA's original standard for communication was known as NCP, "Network Control Protocol," but as time passed and the technique advanced, NCP was superceded by a higher-level, more sophisticated standard known as TCP/IP, d etailsofthe design of which were specified in the paper by Vint Cerf and Bob Kahn "A Protocol for Packet Network Internetworking" in 1974. TCP, or "Transmission Control Protocol," converts messages into streams of packets at the source, then reassembles them back into messages at the destination. IP, or "Internet Protocol," handles the addressing, seeing to it that packets are routed across multiple nodes and even across multiple networks with multiple standards -- not only ARPA's pioneering NCP standa rd, but others like Ethernet, FDDI, and X.25.
 InterNetworking Working Group (INWG), created in 1972, establishes the Transmission Control Protocol (TCP) and Internet Protocol (IP), as the protocol suite, commonly known as TCP/IP, for ARPANET.
  • This leads to one of the first definition of an "internet" as a connected set of networks, specifically those using TCP/IP, and "Internet" as connected TCP/IP internets.
  • DoD declares TCP/IP suite to be standard for DoD (:vgc:)
EUnet (European UNIX Network) is created by EUUG to provide email and USENET services.
1983
 Name server developed at U of Wisconsin, no longer requiring users to know the exact path to other systems.
 Cutover from NCP to TCP/IP (1 January)
CSNET / ARPANET gateway put in place
ARPANET split into ARPANET and MILNET; the latter became integrated with the Defense Data Network created the previous year.
 Desktop workstations come into being, many with Berkeley UNIX which includes IP networking software.
Need switches from having a single, large time sharing computer connected to Internet per site, to connection of an entire local network.
Berkeley releases 4.2BSD incorporating TCP/IP
EARN (European Academic and Research Network) established.
FidoNet developed by Tom Jennings.
1984
 Domain Name Server (DNS) introduced.
# of hosts breaks 1,000
JUNET (Japan Unix Network) established using UUCP.
JANET (Joint Academic Network) established in the UK using the Coloured Book protocols.
1986

In 1984 the National Science Foundation got into the act, through its Office of Advanced Scientific Computing. The new NSFNET set a blistering pace for technical advancement, linking newer, faster, shinier supercomputers, through thicker, faster links, up graded and expanded, again and again, in 1986, 1988, 1990. NSFNET today provides a major backbone communication service for the Internet. With its 45 megabit per second facilities, the NSFNET carries on the order of 12 billion packets per month between th e networks it links. The National Aeronautics and Space Administration (NASA), the National Institutes of Health, and the U.S. Department of Energy contributed additional backbone facilities such as the NSINET and ESNET.
 NSFNET created (backbone speed of 56Kbps)
  • NSF establishes 5 super-computing centers to provide high-computing power for all (JVNC@Princeton, PSC@Pittsburgh, SDSC@UCSD, NCSA@UIUC, Theory Center@Cornell).
  • ARPANET bureaucracy keeps it from being used to interconnect centers and NSFNET comes into being with the aid of NASA and DOE.
  • This allows an explosion of connections, especially from universities.
Cleveland Freenet (start of NPTN) comes on-line.
Network News Transfer Protocl (NNTP) designed to enhance Usenet news performance over TCP/IP.
Mail Exchanger (MX) records developed by Craig Partridge allowing non-IP network hosts to have domain addresses.
1987
 NSF signs a cooperative agreement to manage the NSFNET backbone with Merit Network, Inc. (IBM and MCI involvement was through an agreement with Merit). Merit, IBM, and MCI later founded ANS.
Merit Network, Inc. is a non-profit corporation which is owned by 11 public universities in Michigan. It was formed 25 years ago by the University of Michigan, Michigan State University, and Wayne State University. Merit staff are administratively hosted by the University of Michigan in Ann Arbor.Merit's main purpose has always been to provide network connectivity for the state's higher education community. Originally, this meant connecting academic mainframe computers together so that users at different universities could access each others compu ters, data files could be shared, and printed output could be electronically submitted. More recently, Merit has operated MichNet, an IP backbone network interconnected at 45 Mbps to the rest of the Internet. Merit is the largest Internet service provider in Michigan with connections provided to over 200 organizations including businesses, health care organizations, state go vernment, and educational institutions.Merit is also involved in many other networking activities, most notably as the lead partner since 1987 on the NSFNET Cooperative Agreement between the National Science Foundation, Merit, ANS, IBM, MCI, and the State of Michigan. Currently, Merit has cont racts with the NSF for routing database work associated with the new Internet Network Attachment Points, with the FAA for routing protocol work, with the Society of Manufacturing Engineers on a TRP-funded projecct to train small businesses in the use of t he Internet, and with the Corporation for Research and Educational Networking (CREN) for BITNET III.
UUNET is founded with Usenix funds to provide commercial UUCP and Usenet access.
# of hosts breaks 10,000
# of BITNET hosts breaks 1,000
1989
# of hosts breaks 100,000
NSFNET backbone upgraded to T1 (1.544Mbps)
RIPE (Reseaux IP Europeens) formed (by European service providers) to ensure the necessary administrative and technical coordination to allow the operation of the pan-European IP Network.
 First relay between a commercial electronic mail carrier (Compurserve) and the Internet through Ohio State University.
1990
ARPANET ceases to exist.
 Second relay between a commercial electronic mail carrier (MCI Mail) and the Internet through the Corporation for the National Research Initiative (CNRI)
Electronic Frontier Foundation is founded by Mitch Kapor
1991
Commercial Internet eXchange (CIX) Association, Inc. formed by General Atomics (CERFnet), Performance Systems International, Inc. (PSInet), and UUNET Technologies, Inc. (AlterNet)
 WAIS released by Thinking Machines Corporation
 Gopher released by University of Minnesota
US High Performance Computing Act (Gore 1) establishes the National Research and Education Network (NREN)
1992
 Internet Society is chartered
 World-Wide Web released by CERN
 # of hosts breaks 1,000,000
 NSFNET backbone upgraded to T3 (44.736Mbps)
 First MBONE audio multicast (March) and video multicast (November)
1993
 InterNIC created by NSF to provide specific Internet services:
  • directory and database services (AT&T)
  • registration services (Network Solutions Inc.)
  • information services (General Atomics/CERFnet)

 US White House comes on-line:
  • President Bill Clinton: president@whitehouse.gov
  • Vice-President Al Gore: vice-president@whitehouse.gov
  • First Lady Hillary Clinton: root@whitehouse.gov
Internet Talk Radio begins broadcasting
 United Nations and World Bank come on-line
US National Information Infrastructure Act
Businesses and media really take notice of the Internet
 Mosaic takes the Internet by storm; WWW proliferates at a 341,634% annual growth rate of service traffic. Gopher's growth is 997%.
1994
Communities begin to be wired up directly to the Internet
US Senate and House provide information servers
First flower shop taking orders via the Internet
Shopping malls arrive on the Internet
Mass marketing finds its way to the Internet with mass e-mailings
FUTURE
The Next Generation Internet

MCI is pushing the limits of information technology with the very high speed Backbone Network Service (vBNS). Created under a five year cooperative agreement between MCI and the National Science Foundation (NSF), the vBNS will enable scientists to explore advanced routing technologies and protocols, taking high performance computing and applications research to new heights. 
The Network: See how the vBNS has combined advanced switching and fiber optic technologies, know as Asynchronous Transer Mode (ATM) and Synchronous Optical Network (SONET) with the Internet Protocol (IP). The vBNS will initially run at 155 Mbps, and in 19 96 MCI will increase network speeds to 622 Mbps. 

HOW BIG IS THE INTERNET?

 
As of 1 Feb 1995, the Internet consisted of more than 50,000 networks in 90 countries. Gateways that allow at least Email connectivity extend this reach to 160 countries. At the end of 1994, 5 million computers were indicated as actually reachable - with an estimated total of 20-40 million users. Network growth continues at around 10 percent per month.

Internet, Inc.?

As the time went on, many very different social groups found themselves in possession of powerful computers. It was fairly easy to link these computers to the growing network-of-networks. As the use of TCP/IP became more common, entire other networks fell into the digital embrace of the Internet, and messily adhered. Since the software called TCP/IP was public-domain, and the basic technology was decentralized and rather anarchic by its very nature, it was difficult to stop people from barging in an d linking up somewhere-or-other. In point of fact, nobody *wanted* to stop them from joining this branching complex of networks, which came to be known as the "Internet." Connecting to the Internet cost the taxpayer little or nothing, since each node w as independent, and had to handle its own financing and its own technical requirements.
The Internet's "anarchy" may seem strange or even unnatural, but it makes a certain deep and basic sense. It's rather like the "anarchy" of the English language. Nobody rents English, and nobody owns English. As an English-speaking person, it's up to you to learn how to speak English properly and make whatever use you please of it (though the government provides certain subsidies to help you learn to read and write a bit). Otherwise, everybody just sort of pitches in, and somehow the thing evolves on its own, and somehow turns out workable. And interesting. Fascinating, even. Though a lot of people earn their living from using and exploiting and teaching English, "English" as an institution is public property, a public good. Much the same g oes for the Internet. Would English be improved if the "The English Language, Inc." had a board of directors and a chief executive officer, or a President and a Congress? There'd probably be a lot fewer new words in English, and a lot fewer new idea s.People on the Internet feel much the same way about their own institution. It's an institution that resists institutionalization. The Internet belongs to everyone and no one.

WHAT IS THE INTERNET SOCIETY?

The Internet Society is the international organization for global cooperation and coordination for the Internet and its internetworking technologies and applications.

WHO ARE ITS MEMBERS?

Its members reflect the breadth of the entire Internet community and consist of individuals, corporations, non-profit organizations, and government agencies.

WHAT IS ITS PURPOSE?

Its principal purpose is to maintain and extend the development and availability of the Internet and its associated technologies and applications - both as an end in itself, and as a means of enabling organizations, professions, and individuals worldwide to more effectively collaborate, cooperate, and innovate in their respective fields and interests.
Its specific goals and purposes include:
  1. development, maintenance, evolution, and dissemination of standards for the Internet and its internetworking technologies and applications;
  2. growth and evolution of the Internet architecture;
  3. maintenance and evolution of effective administrative processes necessary for operation of the global Internet and internets;
  4. education and research related to the Internet and internetworking;
  5. harmonization of actions and activities at international levels to facilitate the development and availability of the Internet;
  6. collection and dissemination of information related to the Internet and internetworking, including histories and archives;
  7. assisting technologically developing countries, areas, and peoples in implementing and evolving their Internet infrastructure and use;
  8. liaison with other organizations, governments, and the general public for coordination, collaboration, and education in effecting the above purposes.

HOW DOES IT OPERATE?

The Internet Society operates through its international Board of Trustees, its International Networking Conferences and developing country workshops, its regional and local chapters, its various standards and administrative bodies, its committees, and its secretariat. The Board of Trustees is headed by a President with the assistance of several officers. The Board consists of 18 eminent individuals drawn from every region of the world - most of whom were instrumental in creating and evolving different components of the Internet and the technology.

WHY WAS IT CREATED?

The Internet Society was announced in June 1991 at an international networking conference in Copenhagen and brought into existence in January 1992 by a worldwide cross-section of individuals and organizations who recognized that the Society was a critical component necessary to evolve and globalize the Internet and internet technologies and applications, and to enhance their availability and use on the widest possible scale.
The Internet Engineering Task Force (IETF) is the protocol engineering and development arm of the Internet. The IETF is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Inte rnet architecture and the smooth operation of the Internet. It is open to any interested individual. The actual technical work of the IETF is done in its working groups, which are organized by topic into several areas (e.g., routing, network management, security, etc.). Much of the work is handled via mailing lists, however, the IETF also holds meetings three times per year.

What is the IETF?

The Internet Engineering Task Force is a loosely self-organized group of people who make technical and other contributions to the engineering and evolution of the Internet and its technologies. It is the principal body engaged in the development of new I nternet standard specifications. Its mission includes:
  • Identifying, and proposing solutions to, pressing operational and technical problems in the Internet;
  • Specifying the development or usage of protocols and the near-term architecture to solve such technical problems for the Internet;
  • Making recommendations to the Internet Engineering Steering Group (IESG) regarding the standardization of protocols and protocol usage in the Internet;
  • Facilitating technology transfer from the Internet Research Task Force (IRTF) to the wider Internet community; and
  • Providing a forum for the exchange of information within the Internet community between vendors, users, researchers, agency contractors and network managers.
The 1st IETF meeting was held in January, 1986 at Linkabit in San Diego with 15 attendees. The 4th IETF, held at SRI in Menlo Park in October, 1986, was the first at which non-government vendors attended. The concept of working groups was introduced at the 5th IETF meeting at the NASA Ames Research Center in California in February, 1987. The 7th IETF, held at MITRE in McLean, Virginia in July, 1987, was the first meeting with over 100 attendees.

Technical Issues

  1. Network
    • HARDWARE (1)
    • SOFTWARE (2-3)
      • Hardware Protocol (2)
      • Software Protocol (3)
      • information transmitted is (4)
  2. TCP/IP - Language of the Internet
  3. Client-Server Issues

Connecting to the Internet

There are basically four kinds of access provided:
host access where end-users connect their computers to become part of the Internet, orterminal access where end users connect to a host computer which is directly connected to the Internet, ornetwork access where a network of computers become a part of the Internet, orgateway access where another kinds of computer networks, on-line services, or email services are indirectly interconnected.

Types of Access
  • Direct ("on the net")
  • Dial-up
    • MX records (directs mail to a "holding" host)
    • SL/IP (Serial line Internet Protocol)
    • PPP (Point-to-Point Protocol)
Telephone Service Grades
  • Standard line: 0-19.2 KB, possibly higher with compression technology, ~50 KB
  • Leased line: 56-64 KB
  • T1 line: 1.544 MB
  • T2 line: 6 MB (rare)
  • T3 line: 45 MB
Other Means of Communications
  • Packet radio -- portable networking
  • Satellite
Coming Technologies
  • Integrated Services Digital Network (ISDN; DOA?)
    • All-digital telephony
    • 1 16 KB "control" (A) channel
    • 2 64 KB "data" (B) channels
    • With multiplexing technology, ~=300 KB today
    • Sun already ships ISDN port on all workstations
    • Baby Bells slow in deployment
  • Frame Relay
  • CABLE MODEM!!! ~=500 Kb
  • Asymmetric (mixed) technologies (example: cable in, telephone out)

Internet Services

 
I prefer to think of the Internet services a little differently. We'll look at a "main" service and a "navigational enhancement" to it. Sometimes, the service lends itself to implementation of navigational enhancements to it (WWW and various WWW search en gines); but more often, the "navigational enhancement" grows into a service of its own (FTP and Archie, Gopher and Veronica).
  1. E-Mail
    • Addressing conventions
      • Hierarchical Addressing. The IP address looks like WWW.AGORANET.COM What it really means is 198.70.185.3 Obviously, the "word" address has many advantages over the numbers. A computer is reading the address in order to "translate" the "word" address i nto the"number" address. Remember DNS - a database of domain names and their addresses? The "word" address is read backwards, just like an address on an postal envelope. Domain area first (COM), then doman name (AGORANET), and, finally, the name of a comp uter (WWW).E-Mail address, in addition to the address of a computer, has to specify the name of a particular user. That's done in a folloing way: user@computer.
      • Top-Level Domains
        • COM Commercial
        • EDU Educational
        • GOV Government
        • MIL Military
        • NET Backbone Systems
        • ORG Non-profit Organizations
        • INT International Organizations
        • Regional CA, AU, IT, SU, RU
    • SMTP
    • MIME - (Multimedia Internet Mail Extensions) - text, images, audio, video
  2. Telnet and HYTELNET
  3. FTP and Archie, archiving and compression issues
  4. Distributed Database
    • Gopher & GopherVR and Veronica
    • WAIS
    • WWW
  5. USENET
  6. The MBone--which stands for "multicast backbone"--is a technology that enables you to more easily access audio and video broadcasts over the Internet. MBone uses a decentralized structure for routing files, so it's well suited for handling the huge amount of information contained in video and sound files. One caveat: only 10 percent of Internet users currently have computers powerful enough--and connections fast enough...
  7. Other
    • On-line, real-time: IRC, TALK
    • Database: Whois, Netfind, X.500, etc.
    • Finger, Ping
  8. PUSH MEDIA

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