Difference between revisions of "Virtual address"

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Originally this protection was provided by '[[base and bounds]] [[register]]s', which allowed the entire memory of a user/process to be relocated into a contiguous block of main memory. Now, [[virtual memory]] is usually used, which provides this protection/relocation as one of its many benefits.
 
Originally this protection was provided by '[[base and bounds]] [[register]]s', which allowed the entire memory of a user/process to be relocated into a contiguous block of main memory. Now, [[virtual memory]] is usually used, which provides this protection/relocation as one of its many benefits.
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[[Category: CPU Basics]]

Latest revision as of 20:35, 15 December 2018

A virtual address is an address emitted by code running when it is not running on a 'bare machine' (i.e. the machine is not using a 1:1 correspondence between the addresses used by code running in the CPU, and the actual addresses of main memory, the latter often referred to as physical addresses).

When running a time-sharing operating system, the memory management hardware provides mapping of memory addresses emitting by code belonging to a user/process, to protect both the OS itself, and other users/processes, from errors or malicious behaviour.

Originally this protection was provided by 'base and bounds registers', which allowed the entire memory of a user/process to be relocated into a contiguous block of main memory. Now, virtual memory is usually used, which provides this protection/relocation as one of its many benefits.