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Main memory (Swapping (Backing store (Fast disk large enough to…
Main memory
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Paging
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To run a program of size N pages, need to find N free frames and load program
Address binding
Programs on disk, ready to be brought into memory to execute form an input queue
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Dynamic Linking
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Small piece of code, stub, used to locate the appropriate memory-resident library routine
Stub replaces itself with the address of the routine, and executes the routine
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Contiguos allocation
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Limited resource, must allocate efficiently
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Fragmentation
External
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Compaction is possible only if relocation is dynamic, and is done at execution time
Internal
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This size difference is memory internal to a partition, but not being used
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Dynamic allocation
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Best-fit
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Must search entire list, unless ordered by size
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Page table
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Structure
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Inverted Page Tables
Rather than each process having a page table and keeping track of all possible logical pages, track all physical pages
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Memory protection
implemented by associating protection bit with each frame to indicate if read-only or read-write access is allowed
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Base & limit registers
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CPU must check every memory access generated in user mode to be sure it is between base and limit for that user
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