Abstract: A drive for use in a secondary storage facility that includes a controller and a drive bus that interconnects the controller and one or more drives. Each drive includes various circuits for monitoring predetermined conditions within the drive and for generating a status signal whenever one of these conditions changes from a normal state. The controller contains circuitry for generating, in a recurring sequence, an address that identifies each drive connected to it. Polling lines of the drive bus convey these addresses to all the drives in parallel. Each drive monitors these polling lines concurrently with other operations it may be performing. When the polling lines identify the drive, the drive examines the status signal and generates an attention signal onto a common attention line that is conveyed back to the controller where it is stored in such a fashion that there is no ambiguity as to the source of the attention signal.

Abstract: A drive for use with a secondary storage facility that includes a controller and a drive bus that interconnects one or more drives with the controller. During the transfer of data between the drive and the controller, the drive transmits sector and index pulses to the controller over a INDEX/SECTOR PULSES line of the drive bus. Each drive contains circuitry for monitoring the signals on this line. If this circuitry senses a signal on the line that is not transmitted by the drive, the circuitry generates an error signal that indicates that more than one drive connected to the drive bus is active.