Patent ID: 6567877
Filing Date: 2003-05-20
Classification: G06F

Abstract:
A bus system for use in a computer system having an external periphery comprising:a small computer standard interface (SCSI) bus including a plurality of bus signal lines, the SCSI bus having an internal connector terminated by a fixed termination and a multi-pin external connector mounted to the external periphery of the computer system to interface with a removable, external termination device; and an apparatus coupled to each of the plurality of bus signal lines to automatically enable termination of the bus signal lines of the SCSI bus in parallel at the external connector when the external termination device is disconnected from the SCSI bus, the apparatus including a sensing line coupled to a pin of the external connector, the sensing line to sense whether the external termination device is coupled to the SCSI bus, the sensing line being common to the bus signal lines, a pull-up resistor coupled to the sensing line, the pull-up resistor driving the sensing line to a high voltage level if the external termination device is disconnected from the SCSI bus, at least one termination resistor coupled to each of the plurality of bus signal lines of the SCSI bus to provide a terminating impedance at the external connector of the SCSI bus, and a plurality of switches each including a transistor having a gate coupled to the sensing line, each of the plurality of switches coupled to one of the plurality of termination resistors and terminating a separate bus signal line of the SCSI bus if the sensing line is pulled to the high voltage level.