Two atomic operations permissible on Semaphores are __________ and __________.

Answer: wait and signal

Explanation: Semaphores provide two atomic operations commonly named wait (also called P or down) and signal (also called V or up).

• wait (P/down): Decrements the semaphore value. If the result indicates no available resource (implementation commonly checks if value < 0), the calling process blocks until another process performs a signal.

• signal (V/up): Increments the semaphore value. If there are processes blocked waiting on the semaphore, one is typically awakened.

These two operations are atomic and provide mutual exclusion and synchronization between processes or threads.