Abstract: The disclosure describes improved apparatus for setting the states of storage elements in a data-processing system and for responding to the data read out of the storage elements. The apparatus includes a first error detector which enables an initial setting circuit to initially set a first storage element to a predetermined condition in response to an error. The initial setting circuit also disconnects the outputs of a second storage element while that element is receiving reference data and reconnects the outputs of the second storage element after the data has been written into that element. A second error detector monitors the outputs of the first and second storage elements as test signals are conducted to the storage elements.

Abstract: The disclosure described improved apparatus for testing a data processing system including first and second functional members. First and second microprograms for testing the first and second functional members, respectively, are held in a read only store. If an error is detected in the first functional member while the data processing system is processing data, a circuit transmits the starting address of the first microprogram to an address register for the store, so that the first microprogram tests the defective first functional member. As the first functional member is tested, the symptoms needed to diagnose the defect are collected. If the first microprogram is completed without all of the symptoms required for diagnosis being collected, another circuit transmits the first address to the address register so that the first microprogram is executed again. The first microprogram continues to be executed until all of the symptoms needed for diagnosis are collected.

Abstract: The disclosure describes a device for locating faults in a working storage arranged in rows and columns.The device includes an auxiliary storage which holds a sequence of test words and means for cyclically writing the test words into the working storage and reading the test words out of the working storage. A bit for bit word comparator compares the words read out of the working storage with the words read into the working storage and detects bits of the words which do not match in order to identify defective components. First and second registers record the row and the column to which the defective component belongs.