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Definition of ARCNET in Network Encyclopedia.

What is ARCNET?

Acronym for Attached Resource Computer Network, an early local area network (LAN) architecture developed in 1976 by Datapoint Corporation.

ARCNET predates Ethernet and uses RG/62 93-ohm coaxial cabling, RS485 twisted-pair cabling, or fiber-optic cabling to transmit data at 2.5 Mbps and a maximum of 255 nodes.

ARCNET Adapter
ARCNET Adapter

A newer implementation called ARCNET Plus operates at a data rate of 20 Mbps and a maximum of 2047 nodes.

ARCNET is a baseband networking technology that is similar to standards for token-passing bus networks running over broadband cabling. ARCNET uses a token-passing bus architecture with nodes forming a logical ring but a physical bus or star pattern.

History of Arcnet

RCNET was developed by principal development engineer John Murphy at Datapoint Corporation in 1976 under Victor Poor and announced in 1977. It was originally developed to connect groups of their Datapoint 2200 terminals to talk to a shared 8″ floppy disk system. It was the first loosely coupled LAN-based clustering solution, making no assumptions about the type of computers that would be connected. This was in contrast to contemporary larger and more expensive computer systems such as DECnet or SNA, where a homogeneous group of similar or proprietary computers was connected as a cluster.

The token-passing bus protocol of that I/O device-sharing network was subsequently applied to allowing processing nodes to communicate with each other for file-serving and computing scalability purposes. An application could be developed in DATABUS, Datapoint’s proprietary COBOL-like language and deployed on a single computer with dumb terminals. When the number of users outgrew the capacity of the original computer, additional ‘compute’ resource computers could be attached via ARCNET, running the same applications and accessing the same data. If more storage was needed, additional disk resource computers could also be attached. This incremental approach broke new ground and by the end of the 1970s (before the first cassette-based IBM PC was announced in 1981) over ten thousand ARCNET LAN installations were in commercial use around the world, and Datapoint had become a Fortune 500 company. As microcomputers took over the industry, well-proven and reliable ARCNET was also offered as an inexpensive LAN for these machines.

Arcnet difficulty communicating with Windows 95 and Windows 98

A computer running Microsoft Windows NT on an ARCNET network will have difficulty communicating with computers running Windows 95 and Windows 98 on the same network. This is because Windows NT uses Raw ARCNET, while Windows 95 and Windows 98 use Encapsulated ARCNET. The workaround solution is to install the 16-bit TCP/IP stack with Novell Open Data-link Interface (ODI) drivers on the machines running Windows 95 and Windows 98.

The acronym ARCNET stands for Attached Resource Computer Network and it was fallowed by arcnet plus.

ARCNET today

Visit the ARCNET Resource Center website.