ARCNET
ARCNET (Attached Resource Computer NETwork) is one of the earliest local area network (LAN) protocols, designed to connect computers and peripherals in a local environment. Here's a detailed look into its history, functionality, and context:
History
- ARCNET was developed by Datapoint Corporation in the late 1970s, specifically by a team led by John Murphy. Its initial release was in 1977, making it one of the first LAN technologies.
- The technology was originally designed to connect IBM System/32 minicomputers, but its use quickly expanded to other systems.
- In 1980, the IEEE started to standardize ARCNET under the designation IEEE 802.4, although this standard was never widely adopted.
Functionality and Features
- ARCNET uses a token-passing protocol to manage network access. This method ensures that each node gets an opportunity to transmit data, reducing collisions and improving efficiency compared to contention-based protocols like Ethernet.
- The network can operate over various physical media including coaxial cable, twisted pair, and even fiber optics, with speeds typically ranging from 2.5 Mbit/s to 10 Mbit/s.
- It supports both star and bus topologies, although the star topology became more common due to its ease of troubleshooting and expansion.
- ARCNET has deterministic performance, meaning it can guarantee a certain level of service, which was particularly useful in industrial applications where timing was critical.
Context and Usage
- Despite its early adoption and reliability, ARCNET was eventually overshadowed by Ethernet due to the latter's lower cost, higher speeds, and broader compatibility.
- It found niche applications in environments where its deterministic nature was advantageous, such as manufacturing, automation, and in certain government installations.
- ARCNET was also used in some embedded systems and industrial control systems where its robustness and predictable performance were highly valued.
Legacy
- While ARCNET is no longer a mainstream networking technology, its principles have influenced other networking protocols, particularly in terms of token-passing schemes.
- Some of the design principles of ARCNET can be seen in modern industrial Ethernet variants like PROFINET and EtherCAT, which also emphasize determinism and real-time capabilities.
References
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