Arpanet
Forerunner of today's Internet, Arpanet was created by the Advanced
Research Projects Agency, an entity of the United States Defense
Department, and began operation in 1969.
Research
for it began in 1962 after the U.S. reacted with great concern to the 1957
launch of Sputnik, the world's first satellite, by the Soviet Union. The
nation felt it was in significant danger of nuclear attack, and the U.S.
Air Force hired the Rand Corp. to research ways to make a computer network
able to withstand a nuclear attack.
Before
Arpanet was created, computer networks had employed a "star"
topology. That is, they relied on a central computer to handle all
communications among the networked machines. Each machine was hooked only
to this central machine, which sat at the center of the "star."
This meant, of course, that if this one central computer were knocked out,
the entire network would cease to function.
What
Rand eventually recommended was an entirely new concept in networking, and
one that led directly to the development of the Internet, a network larger
than anyone at the time conceived possible. The key to its incredible
success was that its designers made a radical assumption: They assumed
from the start that it would fail, that whole chunks of the network could
disappear at any moment.
What
they came up with to solve this problem seems obvious and simple now. They
designed a decentralized network in which the computers were hooked to one
another somewhat at random, with many having connections to more than one
machine. Further, they made it so that only the computer sending
information and the one receiving it had to know or care that
communication was taking place.
In
this scenario, the computers left after a nuclear attack could continue to
function as a network, simply routing data around any missing computers.
This, from the Air Force's perspective, meant it still could use computers
for command and control of missiles and solved the problem.
It
actually solved many more problems than that. Before the development of
Arpanet and its communication protocols (rather like language dialects),
there were very few means for the room-sized computers of the day to
communicate. IBM mainframes could talk to other IBM mainframes, but they
couldn't talk to a Honeywell or a Digital Equipment Corp. machine. They
all were proprietary and used completely different "languages."
As
a result, whole corporations had to decide what manufacturer's computers
they would use at every one of their sites around the world. Since the
software was not cross-platform either, the decision often was made based
on the software available for a given computer. After Arpanet, which later
came to be called Darpanet (Defense Advanced Research Projects Network,
1972) and finally just, the Internet (date debatable, but about 1983),
machines of different manufacture could interact for the first time.
Arpanet
construction began in 1968, and it went into operation in 1969, connecting
computers at four U.S. universities: University of California at Los
Angeles, SRI (in Stanford), University of California at Santa Barbara, and
University of Utah. The network was wired together via 50 Kbps circuits.
Arpanet officially ceased to exist in 1990.