Dijkstra
God of computer science.
"Computer Science is no more about computers than astronomy is about telescopes." - E. Dijkstra
The first major advance in dealing with the problems of concurrent processes came in 1965 with Dijkstra’s treatise.
The fundamental principle is this: Two or more processes can cooperate by means of simple signals, such that a process can be forced to stop at a specified place until it has received a specific signal. Any complex coordination requirement can be satisfied by the appropriate structure of signals. For signalling, special variables called Semaphores are used. To transmit a signal via semaphore , a process executes the primitive . To receive a signal via semaphore , a process executes the primitive ; if the corresponding signal has not yet been transmitted, the process is suspended until the transmission takes place.