Closely related are instructions that modify an entire status word or status register. The more powerful version is a privileged instruction and includes access to portions of the status register that can control or modify other processes. Machine control instructions directly affect the entire processor. Stop or halt instructions bring the processor to an orderly halt, remaining in an idle state until restarted by interrupt, trace, reset, or external action. Reset instructions reset the processor.
Trap generating instructions generate a system trap.
This includes a transition to a privileged state and turns control over to a routine with supervisor permission. This allows user processes to communicate with and make requests of the operating system. Note that it is common for some parts of an operating system to run in normal user mode so as to limit potential damage if something goes wrong. Memory management instructions control memory and how memory is mapped and accessed by user and system routines. For those with high speed connections, the very large single file summary is still on line.