| 摘要 |
PROBLEM TO BE SOLVED: To enable memory protection by the addition of small hardware by devising memory arrangements in processing units to actualize memory protecting functions in the processing units. SOLUTION: For memory access, only X bits are taken out of the MSB of a program counter and denoted as a value A and only X bits are taken out of the MSB of a memory address to be accessed and denoted as a value B. The values A and B are compared with each other and when they are equal, the memory access is allowed to continue normal operation (case 1). When the values A and B are different, the A and B are compared and when A>B, the memory access is allowed to continue the normal operation (case 2). When A<B, on the other hand, an exception of memory protection violation is generated to inhibit the memory access and a process is trapped by an OS, etc., (case 3). Then the OS, etc., arranges a task in a proper memory space so that the memory protecting function correctly operates. |
