Monitors vs Semaphores

Monitors are programming-language concept, the compiler must recognize them and arrange for the mutual exclusion somehow or other. Many programming languages do not have monitors.The same languages do not have semaphores either, but adding semaphores is easy: all you need to do is add two short assembly-code routines to the library to issue the up and down system calls. The compiler do not even have to know that they exist. Of course the operating system have to know about the semaphores, but at least if you have a semaphore-based operating system, you can still write the user programs for it in C or C++ or even assembly.With monitors, you need language that has them built in.