selected for external SCSI devices must not overlap with the addresses of thehost adapter or any other SCSI devices attached internally.Generally speaking, there can be no more than seven other SCSI devices attached,each with its own unique address and the total cable length must not exceed 20feet for single-ended and 80 feet for differential.ChecklistBefore applying power to your system, the following items should be completed andchecked:• The 50-pin SCSI ribbon cable is connected to the host adapter with properpin 1 orientation.• The host adapter is firmly seated in the host computer’s adapter slot.• The correct SCSI addresses are selected on all attached SCSI devices. Ad-dress 0 is reserved for the boot hard disk and address 1 is used for a secondhard disk.• The correct operating modes are selected on all attached SCSI devices.• Terminators are installed or removed on the drives and host adapter asrequired.• External SCSI devices are properly installed and cabled.TerminatorsThe SCSI bus must also be terminated correctly to ensure proper operation. The firstand last physical SCSI devices on the SCSI cable must have terminators installed.All other SCSI devices must have terminators removed. The AHA-1740A/1742A/1744host adapter is usually the first device on the SCSI Bus and has terminators in-stalled at the factory.System ConfigurationWhen it is being installed in an EISA system, the AHA-1740A/1742A/1744 requiresan EISA system configuration file. This may be part of the system software or may besupplied on a separate diskette. If it is separate, installation is easier if the contentsof the separate diskette are copied onto the main bootable system configuration disk.To perform system configuration:1. Place the bootable configuration diskette in an operative drive and reset the systemto boot from this diskette. This configuration diskette is normally supplied by theEISA system vendor.EISA-to-Fast SCSI Host Adapter Installation3-7
