SCSI connector and Y cable configuration which selectively provides single or dual SCSI channels on a single standard SCSI connector

摘要

A SCSI controller card which includes a standard SCSI connector that can support either one or two SCSI channels, as desired. The connector can receive either a standard single channel cable or a specially designed dual channel "Y" cable to provide either one or two SCSI channels, respectively. The SCSI controller card includes logic that determines which cable is installed and switching logic which routes one or two SCSI channels to the connector accordingly. In the preferred embodiment, the SCSI adapter card includes two SCSI controllers which provide two SCSI channels. A first channel is connected directly to pins on the SCSI connector. A second channel is connected to switching logic, and a plurality of ground signals are also connected to the switching logic. The second channel is switched into the SCSI connector if the dual channel "Y" cable is attached to the connector, and the ground signals are switched into the SCSI connector if the "Y" cable is not detected. The SCSI adapter card continuously auto-senses which cable is installed at power-up, i.e., whether the dual channel "Y" cable is installed or a standard single channel cable is installed, and switches in either the second channel or ground signals accordingly. Thus the present invention provides increased connectivity from a single connector as well as modular and upgradable SCSI bus routing options. The single external SCSI connector is mechanically compliant with the SCSI standard, but allows external routing of either one or two SCSI channels.