PPT Slide
Semaphore - an RTOS mechanism which can be used for synchronization of otherwise asynchronous tasks in order to coordinate resource usage such as shared memory, or to simply indicate a condition such as data is available on an interface.
Semaphore Take - a semaphore operation which allows a thread to check and see if a resource is available - if not, the RTOS can either block the calling thread until it is, or simply return an error code.
Semaphore Give - a semaphore operation which allows a thread to indicate that a resource is available - if another thread is blocking on this resource, then this will un-block that thread.