Ethernet - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 150

The advances made in computer science also meant that i les became bigger;
because computers had more memory and could do faster calculations, the results
could also be bigger. Soon, disks became too small to exchange information.
Precious time was lost when data was to be retrieved; a desktop computer
simply could not store all the information it required, and when modii cations
were made to a i le on one computer, other computers would not be aware of
changes. It became obvious that this had to change and that computers had to
talk between themselves.
Serial communication had been used before computers existed and was an
early means of connecting two computers. However, its speed made this type of
link impractical. In addition, it could connect only two computers to each other.
Engineers designed some interesting ways to connect three or four computers
together using serial links, but the technology simply could not link computers
the way they are today.
Again, it was a military need that boosted the industry. In the late 1950s, one
of the i rst uses of networked computers was with military radar. Soon after-
ward, the aviation sector took over, and two airline-booking mainframes were
connected. The question remained, how many computers would need to be
connected? Dozens? Hundreds? Thousands, maybe? At the time, nobody could
have imagined the impact of what they were working on and could certainly not
have dreamed of the Internet. In 1969, three universities and a research center
were linked together using 50-kilobit network lines. Research notes could be
shared, and messages could be sent from researcher to researcher.
More and more companies and institutions saw the need to connect their ofi ces
and centers, and thousands upon thousands of machines were being networked
into small, independent networks. With the need for more and more computers
on the same network, the original networking designs could not keep up with
the rise in trafi c. Networking architectures became a system administrator's
nightmare; in some cases, adding a computer onto a network forced all the
other devices to disconnect before attempting to reconnect. Something needed
to be done, both in making networks larger and allowing them to connect over
greater distances. In 1973, the Ethernet standard was proposed in Xerox PARC.
It was commercially introduced in 1980 and standardized in 1983. The original
version proposed a high-speed throughput—10 megabits, or ten million bits
of data per second. This speed was later increased to 100 megabits and then
1 gigabit—the highest speed available in home networks. Ethernet supports
speeds up to 100 gigabits per second.
Ethernet
Ethernet describes the physical connection between two or more computers;
the electronic signaling between devices, and the physical format of the cables.