| 摘要 |
PURPOSE:To perform the service change without replacing ROM, by enabling to rewrite the designated address only from the backup memory, after the transfer of the content of the backup memory to the main memory. CONSTITUTION:The main memory 9 of RAM constitution writes in the data BD of the backup memory 3 to the address corresponding to the address signal AD while the control signal C2 is 1, and writes in the subdata SDD to the address corresponding to the subaddress signal SAD of the subbackup memory 4 while the control signal C3 is 1. In other casses, the memory 9 is controlled with the external address signal A and the control signal R/W and in case of write-in instruction, the data DI is written in to the address corresponding to the signal A. Normal memory access can be made by outputting the data DO from the address corresponding to the signal A in case of readout instruction. |
