VARIEGATED MANUFACTURING PROCESS TEST METHOD AND APPARATUS

A manufacturing test method and apparatus for testing devices, preferably magnetic disk drives, assembled or processed at ones of a plurality of stations in a variegated process stream from components originating from a plurality of sources of components, to determine failure statistics for selected ones of the plurality of stations or ones of the sources of components. The method comprises establishing a unit history record for each device, the unit history comprising entries for indicating the stations at which the device has been processed and the sources of components specific to the device; detecting the results of selected test/operation processes for devices in the stream; reading the unit history record for the device for which the results were detected to determine a "trace to" stations at which the device has been processed; logging the detected results, by updating a log for each of selected ones of the test/operation process and stations at which a device was processed as determined from the unit history record for the device, with the detected results for the device; calculating at least one "trace to failure" statistic for selected ones of the results and/or stations; updating the unit history record with the results for the device; and comparing the "failure" statistic to an alarm threshold and actuating an alarm if the threshold is exceeded.