Apple Macintosh Performa 5400 Series - Manual (Page 41)

Before you connect a device
Before you connect a SCSI device to your Macintosh, be sure to complete
these tasks:
m Make sure each SCSI device connected to your Macintosh has its own,
unique ID number from 0 to 6. The computer itself (the main logic board)
has ID number 7 and the internal CD-ROM drive has the ID number 3,
making ID numbers 0, 1, 2, 4, 5, and 6 available for additional SCSI
devices. Make sure other SCSI devices you add to the chain do not use ID
numbers 3 or 7. See the instructions that came with each SCSI device for
information on checking and setting its SCSI ID number.
IMPORTANT If you use two or more devices attached to the same SCSI
interface with the same ID number, your equipment could malfunction and
you could lose data as a result.
m Make sure you have the appropriate cable for attaching the SCSI device to
your Macintosh.
If the device is the first or only one you’re connecting, use a SCSI system
cable to connect it to the computer’s SCSI port:
If the device is not the first one, use a SCSI peripheral interface cable to
connect it to the last device in the chain:
SCSI peripheral interface cable
SCSI system cable
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