Difference between revisions of "Virtual address"
(A decent start) |
m (Avoid redir) |
||
| Line 1: | Line 1: | ||
| − | A '''virtual address''' is an address emitted by code running when | + | 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 [[Central Processing Unit|CPU]], and the actual addresses of [[main memory]]) (often referred to as '''physical addresses'''). |
When running a [[time-sharing]] [[operating system]], the 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. | When running a [[time-sharing]] [[operating system]], the 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. | 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. | ||
Revision as of 20:46, 21 September 2017
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) (often referred to as physical addresses).
When running a time-sharing operating system, the 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.
