An instruction set where all (or most) instructions have the same format and all registers and addressing modes can be used interchangeably - the choices of op code, register, and addressing mode are mutually independent (loosely speaking, the choices are "orthogonal"). This contrasts with some early Intelmicroprocessors where only certain registers could be used by certain instructions. Examples include the PDP-11, 680x0, ARM, VAX. (2002-06-26)
