Editing Futurebus

{{Short description|Universal computer bus standard}}
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'''Futurebus''' ('''IEEE 896''') is a [[Bus (computing)|computer bus]] standard designed to replace all local bus connections in a computer, including the [[Central processing unit|CPU]], plug-in cards, and even some [[Local area network|LAN]] links between machines. The project started in 1979 and was completed in 1987, but then went through a redesign until 1994. It has seen little real-world use, although custom implementations are still designed.

== History ==
In the late 1970s, [[VMEbus]] was faster than the parts plugged into it. It can connect a [[Central processing unit|CPU]] and [[Random-access memory|RAM]] to VME on separate cards to build a computer. However, as the speed of the CPUs and RAM rapidly increased, Futurebus created a successor to VMEbus using [[asynchronous communication|asynchronous]] links. Though the ability to have several cards in the system as "masters", allowing Futurebus to build [[Multiprocessing|multiprocessor]] machines, required some form of "distributed arbitration" to allow the various cards to gain access to the bus at any point, as opposed to VME, which put a single master in slot 0 with overall control.

Typical [[Institute of Electrical and Electronics Engineers|IEEE]] standards start with a company building a device, then submitting it to the IEEE for the standardization effort. In the case of Futurebus, the whole system was being designed during the standardization effort. It took eight years before the specification was finally agreed on in 1987. [[Tektronix]] did make a few workstations based on Futurebus.<ref>{{cite magazine |last1=Marshall |first1=Martin |title=Tektronix Unveils Family Of Graphics Workstations |url=https://books.google.com/books?id=XToEAAAAMBAJ&pg=PT35 |magazine=InfoWorld |date=April 24, 1989}}</ref> It took another four years for the Futurebus+ Standard to be released. The IEEE 896 committee later split from the IEEE Microcomputer Standards Committee and formed the IEEE Bus Architecture Standards Committee (BASC).

Futurebus+ transceivers that meet the IEEE Standard 1194.1-1991 Backplane Transceiver Logic (BTL) standard are still made by [[Texas Instruments]]. Futurebus+ was used as the I/O bus in the [[DEC 4000 AXP]] and [[DEC 7000/10000 AXP|DEC 10000 AXP]] systems. Futurebus+ [[Fiber Distributed Data Interface|FDDI]] boards are still supported in the [[OpenVMS]] operating system.

==See also==
* [[InfiniBand]]
* [[QuickRing]]
* [[Scalable Coherent Interconnect]] (SCI)
* [[Bus topology]]
* [[FASTBUS]]

==References==
{{reflist}}

== Further reading ==
* ''The Futurebus+ Handbook'', John Theus, VITA
* ''Futurebus+ Handbook for Digital Systems'', [[Digital Equipment Corporation]]
* ''IEEE Standard Backplane Bus Specifications for Multiprocessor Architectures: Futurebus+'', [https://standards.ieee.org/ieee/896.1/1268/ IEEE Std 896.1-1987]
* ''IEEE Standard for Futurebus+(R) -- Logical Protocol Specification', [https://standards.ieee.org/ieee/896.1/1269/ IEEE Std 896.1-1991]
* ''IEEE Standard Backplane Bus Specification for Multiprocessor Architectures: Futurebus+'', [https://standards.ieee.org/ieee/896.2/1271/ IEEE Std 896.2-1991]

== External links ==
* {{webarchive|url=https://web.archive.org/web/20100212031335/http://www.cs.umass.edu/~weems/CmpSci635/635lecture12.html|date=February 12, 2010|title=Buses}}

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[[Category:Computer buses]]
[[Category:IEEE standards]]