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Operating systemsA counter operating system creates a hierarchy of levels of abstraction, so that at a given level all details concerning lower levels can be ignored. This hierarchical structure separates functions according to their complexity, characteristic time scale, and level of abstraction. The lowest levels include the system's hardware; concepts associated explicitly with the coordination of multiple tasks appear at intermediate levels, which conduct 'primitive processes'. Software semaphore is the mechanism controlling primitive processes that must be synchronized. At higher levels lie, in rising order, the access to the secondary storage devices of a particular machine, a 'virtual memory' scheme for managing the main and secondary memories, communication between processes by way of a mechanism called a 'pipe', access to external input and output devices, and a hierarchy of directories cataloguing the hardware and software objects to which access must be controlled.
Document ID
19840061883
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Denning, P. J.
(NASA Ames Research Center Moffett Field, CA, United States)
Brown, R. L.
(NASA Ames Research Center Research Institute for Advanced Computer Science, Mountain View, CA, United States)
Date Acquired
August 12, 2013
Publication Date
September 1, 1984
Publication Information
Publication: Scientific American
Volume: 251
ISSN: 0036-8733
Subject Category
Computer Programming And Software
Accession Number
84A44670
Distribution Limits
Public
Copyright
Other

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