System call

<operating system, programming> The mechanism used by an application program to request service from the operating system.

System calls often use a special machine code instruction which causes the processor to change mode (e.g. to "supervisor mode" or "protected mode").

This allows the OS to perform restricted actions such as accessing hardware devices or the memory management unit.

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system administration
system administrator
system analysis
system analyst
system board
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Devil Book
system catalog
System Control Language
System F
system management
System Management Bus