© Thomas Kunz 2000
SCE 574
171
Desirable Hardware Features
äMemory
protection
ädo
not allow the memory area containing the monitor to be altered by user
programs
äTimer
äprevents
a job from monopolizing the system
äan
interrupt occurs when time expires
äPrivileged
instructions
äcan
be executed only by the monitor
äan
interrupt occurs if a program tries these instructions
äInterrupts
äprovides
flexibility for relinquishing control to and regaining control from user
programs
ämanage
resource contention
äeither
hardware support through special instructions (lock, swap, …)
äsoftware
support: semaphores, monitors, ….