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Related Flashcards
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Cards In This Set
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The total time required to access data in secondary storage
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Access time
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A storage-saving and I/O saving technique that groups individual records into a block that's stored and retrieved as a unit
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Blocking
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Buffers
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Temporary storage areas residing in main memory, channels, and control units
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Channel status word (CSW)
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Contains info on the indicating the condition of the channel, with 3 bits for 3 components of the I/O system-channel, control unit, device
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C-LOOK
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A scheduling strategy for direct access storage devices thats an optimization of C-SCAN
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C-SCAN
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Scheduling strategy for direct access storage devices used to optimize seek time (circular-scan)
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Cylinder
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Describes virtual tube formed when two or more R/W heads are positioned at the same track, at the same position on the surface
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Dedicated device
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A device that can be assigned to only one job at a time
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Direct memory access (DMA)
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I/O technique that allows a control unit to access main memory directly and transfer data without the intervention of the CPU
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Direct access storage device (DASD)
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Any secondary storage device that can directly read or write to a specific place, sometimes called random access storage device
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First come first serve (FCFS)
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Simplest scheduling algorithm for direct access storage devices that satisfies track requests in the order in which they arrive
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Flash memory
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Type of nonvolatile memory used as a secondary storage device that can be erased ad reprogrammed in blocks of data
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Hamming code
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Error-detecting and error-correcting code that greatly imporves the reliability of data
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I/O channel
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Specialized programmable unit between the CPU and the control units; synchronizes the fast speed of the CPU with the slow speed of the I/O device
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I/O channel program
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Program that controls the channels
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