Switchable active termination for SCSI peripheral devices

摘要

A switchable active termination device internally mounted within a peripheral device and electrically connected to the end of a Small Computer Systems Interface (SCSI) bus cable. Through use of a pair of SCSI active terminator circuit chips, the termination device actively terminates the data lines of the bus cable in a first operating mode in response to a first digital command by providing precise resistive pull-up to a predetermined value on each data line. In a second mode of operation responsive to a second digital command, the termination device disconnects all terminating resistors. Activation of the termination modes is logically driven from an included switch, with visual indication of the presence of an active termination state provided by a light emitting diode.