Mutual Exclusion
https://en.wikipedia.org/wiki/Mutual_exclusion
Mutex (Mutual Exclusion) – binary semaphore
Semaphore (counting semaphore) is a main synchronization primitive in early operating system developed by Edsger W. Dijkstra (1965).
https://en.wikipedia.org/wiki/Semaphore_(programming)
https://os.mbed.com/users/takashikojo/notebook/r/