Abstract: A computer system has a USB bus to which one or more USB-compatible devices can connect. One or more of the USB devices has an electrical interface that includes two transmitters and, if desired, a receiver for bidirectional data transmission. The transmitters preferably are dual output, differential transmitters. The transmitters include a slower transmitter and a faster transmitter. The faster transmitter can transmit data at a rate that is faster than the slower transmitter. The electrical interface also includes an electrical termination device that is disposed between the output terminals of the two transmitters. The termination device preferably comprises a pair of multi-purpose termination resistors that can provide serial termination or parallel termination depending whether the fast or slow transmitter is used.

Abstract: The present invention relates to a method of in-band communication, outside the standard SCSI communication protocol, between SCSI bus repeaters and initiator devices. The present invention implements the communication mode during the message phase of the SCSI protocol and allows initiators on a SCSI bus to determine the number, location and status of SCSI repeaters accessible on the SCSI bus.