Tandberg Data VXA-320 (VXA-3) - Manual (Page 51)

O CTOBER 2006 VXA-320 T APE D RIVE 37
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This chapter provides an overview of the communication interface and
command protocol used by the VXA-320 (VXA-3) tape drive. It includes the
following topics:
 Communication interface versus command protocol
 SCSI communication interface
 SCSI interface requirements
 SCSI command protocol
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When a device is connected to a host computer, their interaction is
accomplished via a communication interface (for example, a parallel SCSI bus).
The communication interface is comprised of the physical interface (for
example, cables, connectors, and control circuitry) and the signaling protocol
used during communication.
The physical interface determines the number of devices that can be attached
to a bus or network loop, the maximum length of the cables, and the physical
characteristics of the cable itself (for example, the number of wires, shielding,
and so forth). The signaling protocol defines the electrical characteristics and
timing of signals carried by the cable, the message system requirements,
transmission speeds and maximum data transfer rates, as well as the encoding
and decoding of the individual bit patterns representing commands passing
between the individual devices.