Arrangement for on-line diagnostic testing of an off-line standby processor in a duplicated processor configuration

摘要

Under normal operating conditions in an on-linne active/off- line standby duplicated processor system, only the on-line active processor is permitted access to the system's bus structure. The off-line standby processor is disconnected from the system buses. A technique is shown that allows the off-line standby processor diagnostic access to the system peripherals via the bus structure. The standby processor may then perform diagnostic testing to determine its communication ability with the system's peripheral devices. The diagnostic testing is done rapidly to avoid any loss of processor throughput. This technique also assures that the diagnostic testing will not cause faults or after the system configuration during this testing. As a result, when the off-line processor is put into active service, this transition will be made smoothly since this processor's operation has been previously verified.