SCSI "Network"

SCSI devices inside the computer (internal) attach to the SCSI controller via a ribbon cable. The ribbon cable has a single connector at each end and may have one or more connectors along its length. Each internal SCSI device has a single SCSI connector. SCSI devices outside the computer (external) attach to the SCSI controller using a thick, round cable. You have already read about the different connectors used on these external cables. The cable itself typically consists of three layers:
• Inner layer - This is the most protected layer. It contains the actual data being sent.
• Media layer - The middle layer contains the wires that send control commands to the device. • Outer layer - This layer includes the wires that carry parity information, which ensures that the data is correct. External devices connect to the SCSI bus in a daisy chain, which refers to the method of connecting each device to the next one in line. External SCSI devices typically have two SCSI connectors -- one is used to connect to the previous device in the chain, and the other is used to connect to the next device in the chain. A good way to think of SCSI is as a tiny local area network (LAN). The SCSI controller is like the network router, and each SCSI device is like a computer on the network. The SCSI adapter built into each device is comparable to the Ethernet card in a computer. Without the adapter, the device can't communicate with the rest of the network. And just as the router in a LAN is used to connect the network to the outside world, the SCSI controller connects the SCSI network to the rest of the computer.