Definitions for "System call"
A C language function that is used to request services from the UNIX kernel.
A system call is a function that is called by the user that requires the operating system to perform some work on behalf of the caller. Systems call cause the UNIX kernel to perform some operations on behalf of the user. Many common UNIX 'C' functions are system calls.
A request by an active process for a service performed by the UNIX system kernel, such as I/O or process creation. All system operations are allocated, initiated, monitored, manipulated, and terminated through system calls. System calls allow a user-level program to do work that the program would not normally be able to do.
an instruction that interrupts the program being executed and passes control to the supervisor
Keywords:  opportunity, memory, address
an opportunity to address memory