| 摘要 |
PURPOSE:To extend the address space without losing the continuous property of a program, by detecting whether a processor is in the interruption state or not and selecting a memory bank according to the result of detection. CONSTITUTION:An address space extending system comprises an interruption detecting circuit 21 of a processor, a bank selecting circuit 22 plus memory banks 23 and 24. A call of the system program is possible from a user program and by an interruption of software. Whether or not the processor is in the interruption state is detected 21 at the outside of the processor. According to the result of detection, the circuit 22, if it is in the interruption state, selects the bank 23 where the system program is stored and otherwise selects the bank 24 respectively. The user program is stored in the bank 24, and both banks 23 and 24 have the same address. |
