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Revision Date Username Comment
929 Dec 2015 - 17:55ThomasMisa 
829 Dec 2015 - 17:46ThomasMisa 
729 Dec 2015 - 17:11ThomasMisa 
603 Oct 2013 - 15:41norqu036? 
519 Apr 2013 - 11:25NicLewis 
412 Mar 2013 - 10:44NicLewis 
305 Mar 2013 - 10:07NicLewis 
225 Feb 2013 - 10:41NicLewis 
121 Feb 2013 - 09:24NicLewis 

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You are here: UMWiki>CBI_ComputerSecurity Web>Systems>SystemsCmmpHydra (revision 4)



Developed in 1971, the C.mmp was a Carnegie Mellon University multiprocessor computer system meant to demonstrate the cost/performance advantages of multiprocessor-based computers derived from the relatively inexpensive minicomputers that were then becoming available. "C" in the system name stood for "CPU," while "mmp" stood for "Multi-Mini-Processor." The C.mmp employed sixteen DEC PDP-11 minicomputers as its processing components, all interconnected through a crossbar switch. This allowed each of the sixteen modules to share resources, including memory and peripherals.(1)(2) Carnegie Mellon extensively modified the PDP-11 hardware to meet the needs of the project, attempting to overcome limitations of hardware that was not intended for multiprocessor compatibility. Hydra was the C.mmp's object-oriented multi-user operating system, with system resources represented as objects. Hydra was an early fault-tolerant system, as it would remove a memory block from system use upon the detection of a fault. Likewise, the hardware attempted to increase system reliability through monitoring of each processing element. Upon detection of abnormal behavior, a processor would be removed from system use, and would conduct diagnostics until its performance proved satisfactory. However, reliability remained an issue with C.mmp, mostly due to the number of linked computers increasing the likelihood of failure, and timing errors in the modified hardware causing system errors.(3)


1 : lock Chapter6.pdf, pp. 103-105. - Ch.6, "The Hydra System," of Henry M. Levy's Capability-Based Computer Systems. (Login required)

2 , 3 : http://en.wikipedia.org/wiki/C.mmp

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Topic revision: r4 - 12 Mar 2013 - 10:44:29 - NicLewis
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