PROGRAM SELECTION BASED UPON INTRINSIC CHARACTERISTICS OF AN INSTRUCTION STREAM

摘要

A programmable machine selects from among a plurality of branches on condition based upon intrinsic characteristics of the instruction stream in the machine. In a preferred form of the invention, an explicitly addressed machine selects from among a plurality of sets of branches on condition based upon the control memory address from which the branch instruction was fetched, such control memory address being an intrinsic characteristic. Such intrinsic characteristics may selectively include control memory addresses of other instruction words fetched from memory. An instruction decoder has plural decoder sections selectable in accordance with such intrinsic characteristics enabling one instruction word to be variably decoded in accordance with instruction stream characteristics.