1. A general purpose video special effects system and method using random access memory (RAM) means in combination with one or more input sources, at least one being a video source, and with at least one video output destination comprising the steps of: providing a plurality of processing modules each having a predetermined function; connecting said modules in accordance with said associated functions to provide a composition of functions which determines said special effects; specifying connections representing signal flow between said input source and said processing modules and said output destination and said processing modules; pre-computing said special effects for substantially all possible values of permutations of said input sources; storing said pre-computations in said RAM means at addresses determined by said values of said input sources; and allowing said input sources to drive the address inputs of said RAM and read out said stored pre-computation contents of said RAM, in real time, to said video output destination.