| 摘要 |
<p>PURPOSE:To enlarge a memory larger than an address enable memory of a processor itself to cope with a memory increase request, by providing a circuit that gives a permission to the accesses given from an adaptor and a microprocessor to the regions excepting an enlarged region when the control signal is in another state. CONSTITUTION:Adaptors 4-7 are connected to a microprocessor MPU1 via a bus interface signal line 8, and at the same time memory banks 20-21 constituting a memory 2 are connected to the MPU1. An FF whose state can be controlled by the control given from the MPU1 plus a circuit that transmits a bank selection signal 9 capable of reflecting the state of the FF to the banks 20 and 21 when a permission signal of direct memory access DMA arrives from the MPU1 are provided to the adaptors 4-7. Then an address is attached to the enlarged region of the memory 2 with a partial overlap with another region, and an access is given to the enlarged region only when the signal 9 is in a specific state. Thus the banks 20 and 21 are enlarged larger than the address enable memory of the MPU1 itself.</p> |
