| 摘要 |
PURPOSE:To confirm the propriety of an access decided by a hierarchical structure at a stored program control system processor, by applying a key code which can identify the position of the hierarchical structure of a program module to be stored in a memory block. CONSTITUTION:When a central processing unit 2 executes an instruction within a program module M112, an instruction address is transmitted to a memory controller 3 from an instruction control part 21. An access originating key setting part 33 in the controller 3 refers to a key holding part 31 to extract and set a key code SK112 and reads out and sends back the instruction. Then an arithmetic control part 22 delivers a reading request for data within a memory block 1-1, an access designating key setting part 34 refers to the part 31 to extract and set a key code SK100 from the received data address. This code SK100 is collated with the access originating key code through a collating part 35. Then the access propriety is decided from the fact that the 1st codes of both codes are 1 and that the codes 2 and 3 of the access originating key code are 0 respectively. |
