4. Believe it or not, it
all began with a
satellite Sent by
the Soviet Union
President Dwight D. Eisenhower created the
Advanced Research Projects Agency
(ARPA) in 1958
ARPA's purpose was to give the United States a technological edge over other countries.
One important part of ARPA's mission was computer science.
5. In the 1950s, computers
were enormous devices
that filled entire rooms.
They had a fraction of
the power and
processing ability you
can find in a modern PC.
6. • In 1973, engineers began to look at
ways to connect ARPA NET to the
packet radio network (PRNET).
• Instead of sending data across phone
lines, the computers use radio waves.
• It took three years, but in 1976 engineers
successfully connected the two
networks.
Microchips are built layer by layer on a wafer of the semiconductormaterial silicon. The layers are built by a process called photolithography involving chemicals, gases, and light. First a layer of silicon dioxide is deposited on the surface of the silicon wafer, that layer is covered with a photosensitive chemical called a photoresist.The photoresist is exposed to ultraviolet light shined through a pattern, which only hardens the areas exposed to the light. Gas is used to etch into the remaining soft areas. This process repeated and modified builds the component circuitry.Conducting paths between the components are created by overlaying the chip with a thin layer of metal (aluminum). The photolithography and etching processes are used to remove the metal leaving only the conducting pathways.
Technicians joined the Satellite Network (SATNET) to the other two networks in 1977. They called the connection between multiple networks inter-networking, or the Internet for short. Other early computer networks soon joined. They included USENET, BITNET, CSNET and NSFNET.
