Editing Cambridge Ring (computer network)

{{Short description|Experimental local area network}}
{{Use dmy dates|date=April 2022}}

[[File:Cambridge Ring.jpg|thumb|upright|Cambridge Ring]]

The '''Cambridge Ring''' was an experimental [[local area network]] architecture developed at the [[Computer Laboratory, University of Cambridge]] starting in 1974<ref>{{cite web|url=http://www.cl.cam.ac.uk/conference/EDSAC99/history.html |title=A brief informal history of the Computer Laboratory |publisher=University of Cambridge |date=20 December 2001 |archiveurl=https://web.archive.org/web/20101113213834/http://www.cl.cam.ac.uk/conference/EDSAC99/history.html |archivedate=2010-11-13 |url-status=live }}</ref> and continuing into the 1980s. It was a [[ring network]] with a theoretical limit of 255 [[Node (networking)|node]]s (though such a large number would have badly affected performance), around which cycled a fixed number of [[network packet|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.<ref>{{cite book|title=Proceedings of the seventh symposium on Operating systems principles - SOSP '79|author=[[Roger Needham]]|chapter=Systems aspects of the Cambridge Ring |year=1979|pages=82–85|doi=10.1145/800215.806573|isbn=0-89791-009-5 }}</ref>
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]].<ref>[[John R. Pierce]], [https://archive.org/details/bstj51-6-1133/mode/1up Network for Block Switching of Data], Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1133-1145.</ref><ref>W. J. Kropfl, [https://archive.org/details/bstj51-6-1147/mode/1up An Experimental Data Block Switching System], Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1147-1165.</ref><ref>C. H. Coker, [https://archive.org/details/bstj51-6-1167/mode/1up An Experimental Interconnection of Computers Through a Loop], Bell System Technical Journal, Vol. 51, No. 6 (July–August, 1972); pages 1167-1175.</ref>  That network used [[T1 line]]s at bit rate of 1.544&nbsp;MHz and accommodating 522 bit messages (data plus address).

People associated with the project include [[Andy Hopper]], [[David Wheeler (computer scientist)|David Wheeler]], [[Maurice Wilkes]], and [[Roger Needham]].<ref>{{cite journal |title= The Cambridge Fast Ring Networking System |author1= Andrew Hopper |author2= Roger Needham |author2-link= Roger Needham |journal= Orl-88-1 |date= 1988 |volume= 37 |issue= 10 |pages= 1214–1223 |doi=10.1109/12.5983 |url= http://www.cl.cam.ac.uk/research/dtg/lce-pub/public/files/tr.88.1.pdf }}</ref><ref>{{cite AV media|title=Prof. Andy Hopper - The Cambridge Ring and the Computer Lab|via=[[YouTube]]|url=https://www.youtube.com/watch?v=euid1mj7ap8|year=2016|people=[[Andy Hopper]]|location=[[Cambridge, UK]]|publisher=[[Centre for Computing History]]}}</ref>
A 1980 study by [[Peter Cowley]] reported several commercial implementors of elements of the network, ranging from [[Ferranti]] (producing [[gate array]]s), [[Inmos]] (a [[semiconductor]] manufacturer), [[Mergenthaler Linotype Company|Linotype Paul]], [[Logica]] VTS, MDB Systems, and Toltec Data (a design company who manufactured interface boards).<ref>{{cite web|url=https://www.cl.cam.ac.uk/downloads/ring/ring-2005-01.pdf|publisher=[[Cambridge Computer Lab Ring]]|year=2005|title=The Ring|pages=12–13}}</ref>

In 2002, the Computer Laboratory launched a graduate society called the [[Cambridge Computer Lab Ring]] named after the Cambridge Ring.<ref>{{cite web|url=https://www.cst.cam.ac.uk/ring|title=Cambridge Computer Lab Ring|year=2024|publisher=[[Cambridge Computer Laboratory]]}}</ref>

==See also==
* [[Cambridge Distributed Computing System]]
* [[Internet in the United Kingdom|Internet in the United Kingdom § History]]
* [[JANET]]
* [[NPL network]]
* [[Packet switching]]
* [[Token Ring]]
* [[University of London Computer Centre]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20120716230723/http://koo.corpus.cam.ac.uk/projects/earlyatm/cr82/ Cambridge Ring Hardware]
* [https://web.archive.org/web/20120716230729/http://koo.corpus.cam.ac.uk/projects/earlyatm/earlyatm.html Cambridge Fast Ring]
* [https://web.archive.org/web/20120903174601/http://koo.corpus.cam.ac.uk/projects/earlyatm/backbone-ring/index.html Cambridge Backbone Ring Hardware]
* [https://web.archive.org/web/20120204061112/http://www.camring.ucam.org/cl/page?sp=25&sp=25 Cambridge Computer Lab Ring]
* {{cite web |title= Ring PCB |work= Relic Archive |publisher= University of Cambridge Computer Laboratory |url= http://www.cl.cam.ac.uk/cgi-bin/relicd?name=&machine=any&class=any&uid=34/97 |accessdate= 9 April 2011}}

{{DEFAULTSORT:Cambridge Ring}}
[[Category:1974 introductions]]
[[Category:Experimental computer networks]]
[[Category:History of computing in the United Kingdom]]
[[Category:Local area networks]]
[[Category:Network topology]]
[[Category:University of Cambridge Computer Laboratory]]