Cambridge Ring (computer network)

Cambridge Ring

The Cambridge Ring was an experimental local area network architecture developed at the Computer Laboratory, University of Cambridge starting in 1974^[1] and continuing into the 1980s. It was a ring network with a theoretical limit of 255 nodes (though such a large number would have badly affected performance), around which cycled a fixed number of packets. Free packets would be "loaded" with data by a sending machine, marked as received by the destination machine, and "unloaded" on return to the sender; thus in principle, there could be as many simultaneous senders as packets.

The network ran over twin twisted-pair cabling (plus a fibre-optic section) at a raw data rate of 10 megabits/sec.^[2] There are strong similarities between the Cambridge Ring and an earlier ring network developed at Bell Labs based on a design by John R. Pierce.^[3][4][5] That network used T1 lines at bit rate of 1.544 MHz and accommodating 522 bit messages (data plus address).

People associated with the project include Andy Hopper, David Wheeler, Maurice Wilkes, and Roger Needham.^[6][7] A 1980 study by Peter Cowley reported several commercial implementors of elements of the network, ranging from Ferranti (producing gate arrays), Inmos (a semiconductor manufacturer), Linotype Paul, Logica VTS, MDB Systems, and Toltec Data (a design company who manufactured interface boards).^[8]

In 2002, the Computer Laboratory launched a graduate society called the Cambridge Computer Lab Ring named after the Cambridge Ring.^[9]

See also

• Cambridge Distributed Computing System
• Internet in the United Kingdom § History
• JANET
• NPL network
• Packet switching
• Token Ring
• University of London Computer Centre

References

1. "A brief informal history of the Computer Laboratory". University of Cambridge. 20 December 2001. Archived from the original on 13 November 2010.
2. Roger Needham (1979). "Systems aspects of the Cambridge Ring". Proceedings of the seventh symposium on Operating systems principles - SOSP '79. pp. 82–85. doi:10.1145/800215.806573. ISBN 0-89791-009-5.
3. John R. Pierce, Network for Block Switching of Data, Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1133-1145.
4. W. J. Kropfl, An Experimental Data Block Switching System, Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1147-1165.
5. C. H. Coker, An Experimental Interconnection of Computers Through a Loop, Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1167-1175.
6. Andrew Hopper; Roger Needham (1988). "The Cambridge Fast Ring Networking System" (PDF). Orl-88-1. 37 (10): 1214–1223. doi:10.1109/12.5983.
7. Andy Hopper (2016). Prof. Andy Hopper - The Cambridge Ring and the Computer Lab. Cambridge, UK: Centre for Computing History – via YouTube.
8. "The Ring" (PDF). Cambridge Computer Lab Ring. 2005. pp. 12–13.
9. "Cambridge Computer Lab Ring". Cambridge Computer Laboratory. 2024.

External links

• Cambridge Ring Hardware
• Cambridge Fast Ring
• Cambridge Backbone Ring Hardware
• Cambridge Computer Lab Ring
• "Ring PCB". Relic Archive. University of Cambridge Computer Laboratory. Retrieved 9 April 2011.