About SCSI Components

The SCSI system is composed of the following components.

•Initiator

This is the host computer system used to transfer commands. The system consists of the application software, the operating system, the device driver, the SCSI adapter card, etc.

•Bus

By connecting the SCSI cables to the SCSI adapter card, the library and other devices, a path (or a bus) is created for transferring commands.

•Targets

The AIT library and the AIT drive are peripheral devices (or targets) that receive commands from the host computer. Up to 16 devices (including the host computer) can be connected to the Wide SCSI bus. Also, up to 8 devices can be connected to the Narrow SCSI bus.

About SCSI Bus

When you are setting up the AIT library using a SCSI bus, please note the following precautions

LVD SCSI

The AIT library is an LVD SCSI device. All SCSI devices connected to the AIT library on the SCSI bus must be LVD SCSI devices.

Wide SCSI

The interface of the AIT library is Wide SCSI. In order to connect the AIT library to a Narrow SCSI bus, use a 50-pin to 68-pin LVD SCSI adapter. Also, make sure every unused data lines are terminated by an adapter.

SCSI ID

Set a unique SCSI ID for each device on a SCSI bus. The host computer uses these SCSI IDs to differentiate between the devices. Also, the SCSI IDs are used to prioritize the order of communication when several devices are communicating with the host computer.

Caution

The SCSI ID of a device has nothing to do with its physical location.

SCSI Bus Termination

If the AIT library is the device connected to the end of the SCSI bus, you must attach a terminator to the unused SCSI connector to terminate the SCSI bus. The AIT library can supply electric power to the terminator. For information about details, refer to“Setting the DIP Switches” (page 18) in Chapter 2, “Installation”.

Appendix 97