What Is ARCNET?

ARCNET adapter

Date First Published: 27th May 2022

Topic: Computer Networking

Subtopic: Network Standards

Article Type: Computer Terms & Definitions

Difficulty Level: 7/10

Learn more about what ARCNET in this article.

Short for Attached Resource Computer Network, ARCNET is one of the oldest LAN technologies that was introduced by Datapoint Corporation in 1976. It used a coaxial cable to connect up to 255 computers per network and provide a data transfer rate of up to 2.5 Mb/s. It was the first networking system for microcomputers and became more popular in the 1980s for office automation tasks. Originally, it used the bus topology to connect the nodes together.

Note:

In response to greater bandwidth requirements, a new ARCNET specification, called ARCNET Plus was introduced to provide higher a data transfer rate of up to 20 Mb/s and connect up to 2047 node. It was backwards compatible with original ARCNET equipment.

How Does ARCNET Work?

ARCNET works by using a complex Token Ring scheme for Ethernet, meaning that during communication, each node had to have the token to communicate. The token is the portion of data that is passed from one computer to another on Token Ring networks. Nodes cannot send or receive data unless they have the token and if a node wants to communicate, it has to wait for its turn to catch the token. This causes the communication process to be delayed when nodes wait for a token.

The nodes are arranged on a bus. However, they are still logically organised into a ring. A token is passed among the stations and the node that wants to transfer data captures it. The node holds the token until the other node has finished transferring the data. Afterwards, the token is released and it is moved on the logical ring for its nearby node to reach it.

History

John Murphy, a development engineer at Datapoint Corporation developed ARCNET in 1976 to connect groups of their Datapoint 220 terminals to talk to a shared 8-inch floppy system. It was the first LAN-based clustering system that made no assumptions about the types of computers that would be connected to each other. This was different from more modern, larger, and more expensive computer systems such as DECnet or SNA, which connected a group of similar or identical computers together.

By the time ARCNET Plus products were for sale, Ethernet was already more popular, and users were discouraged from moving back to ARCNET, resulting in very few ARCNET products being produced. As of now, ARCNET is rarely used for general networks.

Eventually, ARCNET was standardised as ANSI ARCNET 878.1.