Location dependence for assuring the security of system-control operations

Abstract From the Canadian patent

Abstract of the Invention, A computer operating system security mechanism employing a non-penetrable hardware means for storing privileged instruction identification data for preventing direct unauthorized access to certain privileged instructions forming a part of the computer operating system; and further including memory address data boundary storage means for each said privileged instruction for preventing indirect access to such privileged instructions in memory by unauthorized branch instructions. The mechanism includes means associated with the computing system instruction register for recognizing privileged instruction and branch instructions. Storage means are included for each …