ACCESS METHOD FOR EXTENDED MEMORY AND ACCESS CONTROLLER FOR EXTENDED MEMORY

摘要

PURPOSE:To execute a continuous access processing at high speed by bringing a mapper value for mapping an extended address space to a window area on a physical address space to increment or decrement at every time of the increment or the decrement of the most significant digit of the output address information of a central processing unit. CONSTITUTION:A mapper value for mapping an extended address space to a window area on the physical address space is brought to increment or decrement by a circuit 16 which responds thereto at every time of the increment or the decrement of the most significant digit of output address information of the central processing unit 1. Accordingly, while bringing the output address information of the central processing unit 1 to the increment or the decrement continuously without switching the mapper value many times while being aware of the size of the window area by the program, a continuous area being larger than the window area on an extended memory 5 can be brought to access continuously. In such a manner, the delay of a memory access caused by an overhead for switching the mapper value, etc., is eliminated, and the access processing of the extended memory 5 can be executed at the high speed and efficiently.