| 摘要 |
PURPOSE:To prevent trouble even when there is dissidence in backup state between doubled storage devices by making a signal which indicates a success or failure in backup on a reception side coincident with the signal of a transmission side when a copy of nonvolatile memory is taken between the doubled storage devices. CONSTITUTION:When a memory start request 142 from the inside of a CPU turns on, a request signal 49 to both system moemories also turns on. An address 144, a write specifying signal 145, and a write data signal 146 are transferred similarly to both system memories as signals 50, 51, and 52. The read data signals 53 from both system memories are checked by check circuits 131 and 133; when an error is detected, error signals 135 and 136 turn on. OR outputs between copy reception mode signals 54 and error signals from both system memories are read data unusable signals 137 and 138. Read data 140 is informed to te inside of the CPU; read data 53 on a side Ma is selected when the signal 137 is off, and read data 53 on a side Mb is selected when the signal is on. |
