====== Additional Lock Calls ======

Additional lock calls exist in the system that are not available to MFS programmers. These are calls that the system uses to initialize and reset itself; as a result, these calls are passed only via direct calls at system initialization and reset time.

System lock calls are:

  * LOCK.SEMAPHORE
  * UNLOCK.SEMAPHORE
  * SET.USER.SEMAPHORE

An MFS will never receive these calls, and should therefore simply execute a RETURN for the CODE values of 23, 24, and 25.