Cables and Connectors Tape, removable, hard, and optical drives along with scanners can all use SCSI connections. Most SCSI Host Adapters must be set to SCSI ID 7. 50 feet is the maximum length that a serial cable should be.
Connector resembles a small phone jack.
Twisted pair cables use RJ45 connectors. Connector resembles a fat phone jack. COM Ports COM1 and COM3 use IRQ4. COM2 and COM4 use IRQ3. The majority of PC's have only 2 COM port connectors.