Serial port Yost standard combines DSR and DCD. Some serial ports on motherboards or add-in cards provide jumpers that select whether pin 1 of the DE-9 connector connects to DCD or a power supply voltage, and whether pin 9 of the DE-9 connector connects to RI or a power supply voltage. The power supply voltage can be +5V, +12V, +9V, or ground. (Selection varies by vendor.) The power is intended for use by point-of-sale equipment. Makers include Dell, HP, and others (This is not an official standard.) Operating systems usually create symbolic names for the serial ports of a computer, rather than
Parallel SCSI of the standard has ever specified what kind of connector should be used. Specific types of connectors for parallel SCSI devices were developed by vendors over time. Connectors for serial SCSI devices have diversified into different families for each type of serial SCSI protocol. See the SCSI connector article for a more detailed description. Although parallel SCSI-1 devices typically used bulky Blue Ribbon Amphenol connectors, and SCSI-2 devices typically used Mini-D connectors, it is not correct to refer to these as "SCSI-1" and "SCSI-2" connectors. One valid rule is that connectors for wide SCSI buses have more pins and wires