The ALOHAnet was the first radio computer network. It was based on ALOHA minutes and connected the many islands around Hawaii with the university of Honolulu, Hawaii. Even if it is today no more in enterprise, then one of the basic principles of ALOHA minutes is basis of the Ethernet.

Overview

As that ARPANET was financed the ALOHAnet with means the DARPA. But while that used ARPANET rented voice grade channels, used the ALOHAnet pack radio with the ARPANET could a knot with several other knots, over lines, communicates, while with the ALOHAnet all used the same radio frequency, with which it became necessary to recognize and treat collisions on this communication medium.

With the ALOHAnet two radio links were used: a Broadcast channel (413,475 MHz) and a random ACCESS channel (407,350 MHz). On the latter the individual stations would send their packets to the central computer. This confirmed the receipt of each package on the Broadcast channel. If two stations tried to send at the same time, then none of the two messages arrived correct. The central computer would not send confirmation, and the transmitters tried it, independently, after a coincidentally selected time interval again. The chances that both transmitters produced a collision with the next transmission attempt again, were minimized in such a way.

History

The ALOHAnet was developed 1970 under the direction of Norman Abramson at the university by Hawaii and taken in the same year in enterprise. It served pure research purposes.

It was the first local network, which permitted it to access over transmitting straining a central computer. It had a data transmission rate of 9600 bpses and connected the central computer on the island Oahu with seven locations on four islands. It was expanded by use of Repeatern soon since other Hawai islands. The ALOHA net has a star shaped topology. The central computer was originally a 2100-Minicomputer von Hewlett-Packard, who functioned as concentrator. This minicomputer received on the one hand data from teleprinters, terminal installations for data transmission, other minicomputers, etc., on the other hand one it conveyed these data to a Mainframe the data networks attached by IBM or to. Later extensions made possible that the terminals cannot only access the large computer, but also arbitrary terminals over the central computer with one another communicate.

For the data communication over radio so-called terminals control university width unit were developed, consisted those of tax logic and UHF radio.

1972 were connected it by a satellite connection with the ARPANET. This was also the first time that another computer network was connected with the ARPANET.

Related links

• The beginnings of the Internet
• Of ALOHANET to the Ethernet
• Development OF the ALOHANET

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