Abstract: The present invention is directed to a diagnostic system which utilizes a microprocessor within the power module to control the diagnostic function of all field replaceable modules powered thereby; additional diagnostic hardware being located on each replaceable module which may be utilized in normal operation for functions of the module and, on an interrupt basis, it is utilized in diagnostic functions; the diagnostic hardware in the power module serving to collect the diagnostic test data from all the functional modules powered thereby, the data being transmitted thereto over a diagnostic data bus. If a plurality of power supplies are present in the system, each power supply has a microprocessor for control, each such microprocessor being coupled to the replaceable modules and the diagnostic circuitry therein; a bus being provided between the processors in the power supplies so that one such microprocessor can become a master diagnostic to process all the diagnostic messages from the system.

Abstract: A peripheral controller is provided for controlling data transfers between peripheral devices operably on one type of data bus to devices operable on a second data bus. An intermediate buffer is utilized so that data is read into one memory block from the sending data bus and read out of another memory block to the receiving data bus. Controls are provided to prevent overwriting data which has not been transmitted and to prevent data transfers from the buffer until at least one block of memory has been filed.

Abstract: A pulsed power supply having a filter output and a battery backup includes electronic apparatus to sense when the AC source is failing. When the pulsed supply output has the same pulses as that which would be produced by the battery, the supply switches to battery backup mode. As the AC source returns, the supply switches to AC supply mode when the AC is at a level where the pulses produced by the supply would be the same as are actually being produced by the battery backup.