Adaptec AHA-2740W User Manual

Also see for AHA-2740W: Installation guide Installation guide

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Adaptec AHA-2740W User Manual Manual pdf 41 page image

2-15Getting StartedAHA-2740W/2742W/2744W User’s GuideStock Number: 510647-00, Rev. A Page: 2-15Print Spec Number: 492897-00Current Date: 8/3/94 ECN Date: 8/9/94AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA50-pin and 68-pin Internal Connectors, and 68-pin External ConnectorThis is an invalid setup; only two of the three SCSI connectors canhave SCSI devices connected at any one time.Note: Any configuration utilizing all three SCSI connectorswill result in an improperly terminated SCSI bus.SCSI ID SettingEach SCSI device (including the host adapter) located on the SCSIbus must be set to a unique SCSI ID. The SCSI ID serves two pur-poses: it uniquely defines each SCSI device's address on the bus, andit determines the device's priority on the bus during the Arbitrationphase. The Arbitration phase determines which device will own thebus when two or more devices simultaneously request to use it.Note: If any SCSI device is connected to the 50-pin internalSCSI connector, the host adapter must be assigned a SCSI IDthat ranges from 0 to 7; SCSI ID 7 is recommended.When selecting the SCSI ID, consider the following:n The default value for your host adapter is SCSI ID 7. Normally,the host adapter should always be set to SCSI ID 7, which is theID that has the highest priority on the SCSI bus.n Standard 8-bit SCSI devices can be assigned IDs that rangefrom 0 to 7; SCSI ID 7 has the highest priority, and SCSI ID 0has the lowest.n 16-bit Wide SCSI devices and the host adapter can be assignedIDs that range from 0 to 15. SCSI IDs 0-7 have higher priorityover SCSI IDs 8-15. SCSI ID 7 has the highest priority, and SCSIID 8 has the lowest.n You only need to change a device's SCSI ID if it conflicts withthe SCSI ID of another device or another host adapter (assum-ing they are on the same SCSI bus).n SCSI ID 0 is best reserved for the SCSI hard disk drive that willbe used as your computer's boot device.