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Flashcards do conjunto (5)
- 1What is the purpose of base and limit registers?To define the logic address space that the user is permitted to use. The CPU must check every memory access generated to make sure it is within those bounds, sending a trap (address error) if they're not
- 2What is an input queue?The process on the disk that are waiting to be brought into memory for execution
- 3What does it mean to bind an instruction or data?Binding is when instructions, variables, etc... are bound to addresses in the memory. This can occur at:
-- Compile time: if you know at compile time where the process will reside in memory (absolute code). E.g. MS-DOS
-- Load time: If bindings aren't known at compile time, the compiler needs to generate relocatable code
-- Execution time: binding is delayed until run time if the process can be moved during its execution between memory segments (need hardware support for address maps, e.g. base and limit registesr) - 4What is the difference between logical and physical address space?Well, usually these are the same thing during compile and load time, they can be different during execution time.
A LOGICAL ADDRESS (aka VIRTUAL ADDRESS) is generated by the CPU
A PHYSICAL ADDRESS is the address as seen by the memory unit.
A logical / physical address space is the set of all logical / physical addresses generated by a program - 5What is the difference between static and dynamic linking, and why might we prefer dynamic linking?Under static linking, the loader (see image) links the system libraries and program code into the program image, but under dynamic linking this is postponed until execution time.
With dynamic linking,
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- Operating Systems FlashCards sobre Sem título, criado por Joel Pearson em 15-10-2018.
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- Joel Pearson
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