Timer Operation
How does the OS prevent against runaway user programs (infinite loops)?
A timer can be set to generate an interrupt in a given time
Before it transfers to a user program, the OS loads the timer with a time to interrupt
When the time arrives, the executing program is interrupted and the OS regains control
This ensures that the OS can get the CPU back even if a user program erroneously or purposely continues to execute past some allotted time.