The Unibus was the earliest of several computer bus and backplane designs used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation (DEC) of Maynard, Massachusetts. The Unibus was developed around 1969 by Gordon Bell and student Harold McFarland while at Carnegie Mellon University.[1]
The name refers to the unified nature of the bus; Unibus was used both as a system bus allowing the central processing unit to communicate with main memory, as well as a peripheral bus, allowing peripherals to send and receive data. Unifying these formerly separate busses allowed external devices to easily perform direct memory access (DMA) and made the construction of device drivers easier as control and data exchange was all handled through memory-mapped I/O.[2]
Unibus was physically large, which led to the introduction of Q-bus, which multiplexed some signals to reduce pin count. Higher performance PDP systems used Fastbus, essentially two Unibusses in one. The system was later supplanted by Massbus, a dedicated I/O bus introduced on the VAX and late-model PDP-11s.
^Gardner Hendrie, Interviewer (June 23, 2005). "Bell (Gordon) Oral History". Reference number: X3202.2006. Computer History Museum. Retrieved May 20, 2011. {{cite web}}: |author= has generic name (help)
The Unibus was the earliest of several computer bus and backplane designs used with PDP-11 and early VAX systems manufactured by the Digital Equipment...
with the baseband signal. The Digital Equipment Corporation minicomputer Unibus systems used terminator cards with 178 Ω pullup resistors on the multi-drop...
Wallace, David Foster. "E Unibus Pluram: Television and U.S. Fiction". Review of Contemporary Fiction. 13 (2): 151–194. "E Unibus Pluram: Television and...
misinterprets the motto at the end of Roman Legion Hare: "E Pluribus Uranium". "E unibus pluram" is the title of a 1996 essay by David Foster Wallace which appears...
the route was dropped due to low passenger numbers.[citation needed] The Unibus brand is used for services U1, U2, U12 and U17, operating predominantly...
and Sun Microsystems computers.: 9 This was followed quickly by DEC's Unibus to Ethernet adapter, which DEC sold and used internally to build its own...
London bus services. During 1997, it also bought the Denmark-based operator Unibus, becoming its first venture based outside the United Kingdom. During November...
contemporary fiction, writer David Foster Wallace predicted, in his 1993 essay "E Unibus Pluram: Television and U.S. Fiction", a new literary movement which would...
Bournemouth. During the summer of 2016, the services were rebranded as 'Unibus', with new Alexander Dennis Enviro 400 MMC's arriving in a new livery, all...
a fibre optic cable with a maximum length of 300 meters to a Unibus card named the Unibus Window Module. Application logic ran on the host's VAX CPU, and...
The University of Bunia (UNIBU) is a public higher education institution located in the city of Bunia, in the Ituri province of the Democratic Republic...
the devices appeared to be memory locations. This was implemented in the Unibus of the PDP-11 around 1969, eliminating the need for a separate I/O bus....
controlling the system. Interface cards that plugged into the PDP-11's Unibus slots (the Digital Audio Interface, or DAI) provided analog and digital...
the performance issues. A major advance in the PDP-11 design was DEC's Unibus, which supported all peripherals through memory mapping. This allowed a...
routes in Canterbury, as well as long-distance services. Its bio fuel 'Unibus' service operates between the city centre and University of Kent. Canterbury...
configuration-free synchronous bus used on DEC's later VAX computers. Like the Unibus and Q-Bus before it, it uses memory-mapped I/O but has 32-bit address and...
Neopentyl glycol Non Processor (DMA) Grant, part of the early computer bus Unibus Network participating group, a functional group of Link 16 participants...
and PDP-6. Other architectural contributions were to the PDP-5 and PDP-11 Unibus and General Registers architecture. After DEC, Bell went to Carnegie Mellon...
original on 9 October 2017. Retrieved 26 April 2018. Wallace, David Foster. "E Unibus Pluram: Television and U.S. Fiction". Review of Contemporary Fiction. 13...
line of Ethernet "front end processor" boards for Multibus, VMEbus, Q-Bus, Unibus, and IBM AT Bus systems. The cards were equipped with their own processor...
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