Unit 6Resources:

Lesson 2: History of Internetworking

At a Glance

A course in networking is about communication, the sharing of ideas, information and messages with others. Specifically, it is about how people use networks of interconnected computers to enable communications between individuals, businesses and organizations. Advances in computer technology satisfy the demand for better communication while at the same time creating new demands. The high demand for new communications technologies is creating large shifts in employment to create and sustain this new “Information Age.”

Networking is not a new concept. From our earliest history, people have needed to communicate across vast distances. As we study the evolution of communication solutions, we will see that the concept of networking has been in existence throughout history. It is the technology that has changed and continues to change to meet demands.

What You Will Learn

After completing this lesson, you will be able to do the following:

  • Summarize the history of networking from the telegraph to modern computer technology
  • Describe the evolution of data transmission from Morse code to ASCII standards.
  • Identify emerging technologies in networking.
  • Describe Unified Networks and how they will improve global communications.

Student Notes:

Tech Talk

  • ASCII - American Standard Code for Information Interchange. A 7-bit coding scheme that assigns unique numeric values to letters, numbers, punctuation, and control characters.
  • Baudot Code - A 5-bit coding scheme used for transmitting data over a printing telegraph.
  • ENIAC - Electronic Numerical Integrator and Calculator. This early computer was developed for use by the US Government in 1946.
  • Ethernet - A local area network technology developed by DEC (Digital Equipment Corporation), Intel, and Xerox in the early 1970’s.
  • Internet - The world’s largest network spanning the globe with it’s origins dating back into the 1960’s.
  • Modem - Modulator-Demodulator. A modem converts between the digital signals used by computers and analog signals to allow data transmission over telephone lines.
  • Morse Code - A code of dots and dashes or long and short sounds used to transmit messages over a telegraph.
  • RAMAC - Random Access Method of Accounting and Control. This was the first hard disk developed by IBM in 1956.
  • Telegraph - An early communication device developed in the 1840’s using an electromagnet connected to a battery via a switch. The device has only two states, on or off. Morse code was developed to use the device to transmit information.
  • Telephone - A communication device that electrically transmits sound and voice. Alexander Graham Bell patented the telephone in 1876.
  • Teletypewriter - A printing telegraph that uses a typewriter style keyboard. The teletypewriter uses a modified Baudot code instead of Morse code.
  • Terminal - A terminal looks like a personal computer, but it cannot do anything unless it is connected to a host computer

History of Early Networking and Computers

Networks have long been in existence facilitating communication over time and space. Some of the earliest communications systems consisted of smoke signals, drumbeats, and lantern beacons. The Egyptians developed papyrus, one of the earliest forms of paper, to facilitate written communication. In 1455, Johann Gutenberg invented the printing press, revolutionizing written communication around the world.

By 1789, the United States created the postal service using the mass network of rail lines and roads to deliver messages across the country. However, in the late 19th century, the territories of the United States expanded beyond reliable roads and railways. In 1860, the firm of Russell, Majors, and Waddell formed the Pony Express to decrease the delivery time of mail over these new territories. The pony express service consisted of a network of relay stations between Missouri and California, with 190 way stations to provide fresh horses to the riders. Each rider rode about 75 miles in the relay system.

The pony express ended with the completion of the overland telegraph connections in 1861. With the birth of the telegraph in the 1840’s and the completion of the overland connections, networking moved into the electronic age.

The Telegraph and Morse Code

Recently coined the Victorian Internet, the telegraph was developed in the 1840’s, by Samuel Morse. Using an electromagnet connected to a battery via a switch, the telegraph provided an electronic solution to communication over large distances. Within the United States, the telegraph lines followed the developing train tracks across the country. There were over one million miles of telegraph lines across the country by the early 1900’s. Telegraph cable was laid across the Atlantic in 1858 and transatlantic service began in 1866.

The telegraph has only two states, on or off. When the switch is clsoed, the electric current from the battery flows through the wire into a sounder at the receiving end. When the switch is open, the electric current is shut off.

The Telegraph Moved Networking into the Electronic Age

Morse code was developed by Samuel Morse to use with the telegraph to transmit information over wire. The length and pattern of the on and off states of the telegraph are defined by Morse code into letters of the alphabet and numbers. Long “on” states are called dashes and short “on” states are called dots. The combinations of dots and dashes code for each letter of the alphabet and numbers.

The Morse Code Standard for “Call For Help” was SOS

The Telephone

On February 14, 1876, Alexander Graham Bell filed for a patent for the telephone. The telephone operates by changing sound waves into electrical pulses. Every telephone has a transmitter (mouthpiece) and a receiver (earpiece). Bell designed the telephone to use a membrane in the transceiver that was attached to a rod with a coil of wire. Sound struck the membrane, which moved the rod, causing the coil of wire to produce an electrical current.


Using Voice Transmission, Telephones Connect the World

This design has been improved over the years. However, the basic technology of converting speech into electrical signals, transmitting the signals over copper wire, and converting them back into speech is still an important component of modern networking. Today’s telephone system links the entire globe. With the addition of wireless telephones, the limitations of the copper wire connections are eliminated, allowing individuals to communicate via telephone from nearly anywhere (e.g. the car, the park, or the elevator).

The Teletypewriter and The Baudot Code

At the same time that the telephone was being developed, the world was looking for a better communication technology. The telegraph was only able to transmit one message at a time and it required an operator present at both ends of the wire. The goal was to create a telegraph that was more efficient and less costly.

Emile Baudot, in 1874, created a new coding system that allowed up to six operators to share a single telegraph line. The Baudot code used a five-unit scheme that represented every character. Unlike Morse code, the electrical pulses created by the telegraph were of equal length. Baudot also created a printing telegraph where perforations were made on a tape corresponding to the code. An operator on the receiving end could then interpret the tape.

Through the combination of the telegraph and telephone technologies, the teletypewriter was created. Using an improved version of the Baudot code and the addition of a typewriter keyboard, an operator was able to type the correct sequences of electrical impulses directly to the telegraph line. On the receiving end, the teletypewriter was able to print the messages.

Often teletypewriters were connected in a round-robin circuit, allowing information to be relayed across a network of teletypewriters. Messages sent from the transmitting station were received along the network to the next closest station. In turn, each operator relayed the message to the next station, until the last station on the circuit received the message.

Since 1948, news services, such as the Associated Press, used the telegraph and later the teletypewriter to report news from around the globe. In the 1980s, the speed of computer and satellite technology surpassed the speed of wire services.

Teletypewriters Transmitted News from Around the World

Check Your Understanding

Networking is about communication. Explain how the pony express, the telegraph, the telephone, and the teletypewriter represent early networking.

Early Computers

Early computers were very large machines called mainframes. They were very slow and much more expensive compared to today’s computers, but they performed essentially the same functions. They represented huge improvements over previous manual methods of calculating and manipulating data. In the late 1940’s and 1950’s, computers were used only in government offices, and large corporations and institutions.

  • 1944: Harvard University and IBM released the Mark I. Mark I was powered by electromagnetic switches that could automatically do long involved mathematical calculations.
  • 1946: The U.S. government began using the ENIAC (Electronic Numerical Integrator and Calculator). The ENIAC calculated the trajectory of artillery weapons. It was powered by 18,000 vacuum tubes and was very large and complex to operate.
  • 1946: Bell Laboratories invented the transistor to enhance the speed and efficiency of telephone systems. Transistors become faster as they become smaller, and are more reliable than vacuum tubes. However, transistors are sensitive to heat.
  • 1954: Texas Instruments developed a silicon-based transistor that is less costly and more resistant to heat.

  • 1956: IBM introduced the RAMAC (Random Access Method of Accounting and Control). RAMAC was the first hard disk and consisted of 50 double-sided disks, two feet in diameter. RAMAC could only access 5 MB of data.
  • In 1959, Texas Instruments developed a silicon wafer that combines transistors, capacitors, resistors, and diodes.

Mainframes Were Enormous Compared to the PC

Early Computer Networking

In the 1960’s, the teletypewriter was adapted for use in the computer industry and communications satellites began to transfer telephone and television signals between continents. New technologies and products allowed mainframes to perform unrelated tasks for users from multiple terminals. A terminal looks like a personal computer, but it can not do anything unless it is connected to a host computer.

In 1962, Digital Equipment Corporation introduced the first time-share terminal for mainframes and the first minicomputer. A time-sharing system allows users at different terminals to use the same computer at the same time. AT&T introduced the Bell 103 modem which allowed mainframes and terminals to connect via telephone lines. The term modem is derived from its functions as a modulator and a demodulator. A modem converts between the digital signals used by computers and analog signals to allow data transmission over telephone lines

  • 1966: The Baudot code was replaced with ASCII (American Standard Code for Information Interchange). Unlike the Baudot code, ASCII uses a 7-bit code and defines 96 printable characters. ASCII also provided a validity test for received data.
  • 1968: IBM patented the Dynamic Random Access Memory (DRAM) which is a storage device for personal computers.
  • 1971: Intel introduced the first microprocessor. Minicomputers were developed to fill the need of smaller companies that could not afford to purchase the large mainframes. Several applications such as word processing became available.
  • 1977: Apple Computers introduced the first personal computer, the Apple II.
  • 1981: IBM introduced their minicomputer called the Personal Computer (PC). With this machine, the power of the computer was brought to the desktop.
  • 1984: Apple introduced the Macintosh computer during the Super Bowl.


Early Personal Computers

Desktop computers became the norm, however there was still a need to share information from computer to computer. The need to share information and resources led to the next step, local area networks using transmission cables to connect computers together.

Check Your Understanding

Briefly describe the differences between the Baudot code and ASCII. What advantages does ASCII have over the Baudot code?

Ethernet

Robert Metcalfe of the Xerox Palo Alto Research Center (PARC) first coined the name “Ethernet” in 1973. Prior to the introduction of Ethernet, the University of Hawaii had developed a radio network for communication between the Hawaiian Islands called the Aloha network. Within the Aloha network, a workstation sent a transmission and then waited for an acknowledgement. If no acknowledgement arrived, the workstation assumed that another workstation had sent a transmission at the same time and caused a collision between the two transmissions. The workstations then retransmitted. This cycle continued until the transmission was received at the destination and an acknowledgement was received by the transmitting workstation.

Ethernet technology improved the Aloha system by the incorporation of a new protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). Within this protocol, the transmitting workstation listens to the activity over the network before it transmits. The workstation can detect collisions and Ethernet allows for multiple workstations to share a channel in the network. Ethernet is the most popular local area network technology due to the ease of installation, management, and troubleshooting. Currently, Ethernet technology allows for transmission rates up to 100 megabits per second (Mbps), but the future of Ethernet lies in the ability to transmit information in gigabits per second.

  • 1977- Robert Metcalfe received a patent on Ethernet.
  • 1978- The patent for the Ethernet repeater was issued.
  • 1980- Digital Equipment Corporation, Intel, and Xerox joined forces to introduce the 10 megabit per second Ethernet called DIX Ethernet standard.
  • 1982- DIX Ethernet Version 2 was released.
  • 1985- The Institute of Electrical and Electronics Engineers (IEEE) an IBM’s Token Ring alternative.

The Internet

The Internet is the world’s largest network, spanning the globe. Its origins date back to the 1960’s. It consists of a super network of interconnected government, education, and business networks.

In the 1960’s the U.S. Department of Defense (DOD) wanted a network that would allow communications throughout the United States even if the existing telecommunications lines were destroyed by enemy attack. Funded through the DOD’s Advanced Research Projects Agency, a new network was formed called ARPANet with only four computers, three located in California and one in Nevada. ARPANet was limited by the fact that different systems could not connect to each other. With funding from military sources, the universities and government contractors continued to improve on ARPANet.

  • 1973- Transmission Control Protocol (TCP) and Internet Protocol (IP)emerged, allowing various systems to interconnect.
  • 1975- The Defense Communications Agency became responsible for ARPANet.
  • 1979- Academic and research facilities were allowed to connect to ARPANet leading to a rapid growth of the network.
  • 1980- Tim Berners-Lee , a software engineer, developed HTML (HyperText Mark-up Language) used in the World Wide Web.
  • 1986- The National Science Foundation initiated their own high-speed network called NSFNet that connected various regional networks. The term “Internet” was adopted.
  • 1988- MCIMail was given permission to connect to the Internet.
  • 1989- The graphical interface for the Internet called the World Wide Web was proposed using HTML. CompuServe, ATTMail, and Sprintmail connected to the Internet. ARPANet was dismantled.
  • 1991- Tim Berners-Lee developed the HyperText Transfer Protocol (HTTP) and introduced the WWW on the Internet.

  • 1993- NSFNet began to be dismantled.
  • 1999- Over 150 million people use the Internet/WWW each week.

Today the Internet is the largest interconnection of networks in the world. The Internet allows communication and sharing of information between users all over the world through the use of connected computers and an extremely efficient technology called packet switching which moves huge quantities of data around the world. It has grown to thousands of interconnected networks with millions of users worldwide.

With the development of a graphical user interface for the World Wide Web, more people can access the web with less training. The demand for access has led to thousands of web servers linking the world to retail stores, on-line databases, research resources, government publications, public libraries, and more.

The Internet: The World’s Largest Network

What’s Next?

“As new and existing network applications evolve to embrace high-resolution graphics, video, and other rich media data types, pressure is growing at the desktop, the server, the hub, and the switch for increased bandwidth.” This statement from the Gigabit Ethernet Alliance sums up the ever growing demands of our society for faster, more efficient, and unified networks that will increase our productivity and yet reduce the cost of networking.