Abstract: A method of and apparatus for executing a family of instructions provides synchronization of processes in a multiprocessing system. Representations of processes awaiting data (information units) such as the completion of an asynchronous operation or the availability of a resource are stored in a memory in a first queue and representations of information units available to processes are stored in memory in a second queue. Transfer of information units between processes is controlled by data elements known as "semaphores" stored in the memory. Each semaphore contains a field having a numerical value identifying which of the two different kinds of queues is present.

Abstract: An information structure, or semaphore, serves as a signalling mechanism in process synchronization to connect a process and a non-simultaneously occurring event or resource. The semaphore is a data structure which stores representations of processes awaiting particular events or alternatively stores representations of events awaiting processes. Semaphore data structures are developed in two storage areas. First and second groups of process links are stored in the first storage area to establish, respectively, a first queue of processes ready to operate and a second queue, associated with the semaphore structure, of processes awaiting occurrences of a first particular event prior to being ready to operate. In the second storage area are stored first and second groups of message links to establish respectively a first queue, associated with a semaphore structure, representing second particular events and a second queue of unused links.

Abstract: A system and method for computer process dispatching in a multiprogramming/multiprocessing environment is disclosed. Each process in the multiprogramming/multiprocessing computer system may be in one of four states at any given time as follows:1. Running -- the process is in control of the computer system and is directing the operation of the central processing unit (CPU);2. ready -- the process is ready to run as soon as it is given control of the CPU;3. waiting -- the process is waiting for an external event to occur so it can either resume running or enter the ready state;4. Suspended -- the process has been temporarily stopped (from a source external to the process).The dispatcher is a firmware/hardware structure that controls the first three states of the process--i.e. running, ready and waiting states.