| 摘要 |
PURPOSE:To improve reliability for a system, by providing a scan ring on each of plural units and channels, and detecting a mounting state by setting a prescribed data in a register, and performing a scan-in/out operation. CONSTITUTION:The scan rings SR1-SRN are provided on plural units 21-2n, and channels 31-3m, respectively, and a scan address register SAR4a, a scan address decoder SAD4b, and a scan data register SDR4c, are provided on a service processor SVP4, and the output of the SAR4a is decoded, and one of scan ring enable signal lines 41-4N is set as significant. Furthermore, the scan rings SR1-SRN are connected to the SDR4c through a scan-in line 4d, and the outputs of the scan rings SR1-SRN are connected to the SDR4c by a scan-out data line 4e, and only when the signal lines 41-4N connected by gates 91-9n are significant, the scan rings SR1-SRN are connected to the line 4e. |
