Apple Macintosh 6500 - Manual (Page 58)

Before you connect a device
Before you connect a SCSI device to your Macintosh, be sure to complete the
tasks explained in this section.
IMPORTANT This section contains general instructions for attaching SCSI
devices to your computer. Be sure also to follow the specific instructions that
came with your external hard disk drive or other SCSI device when
connecting the device to your Macintosh. The specific instructions that came
with the device tell how to change a device’s ID number and attach a SCSI
cable or terminator to the device.
Make sure each device has a unique ID number
Each SCSI device connected to your computer must have its own, unique ID
number from 0 to 6. The SCSI ID number helps the computer keep track of
the devices and sort out conflicts when more than one device in the SCSI
chain are communicating with the computer simultaneously.
The ID numbers in your computer are assigned as follows:
ID Device
3 Optional internal Apple CD-ROM drive
5 Optional internal Zip drive
7 Main logic board
Make sure other SCSI devices you add to the chain do not use ID numbers
that are already assigned. For example, if your computer came with an
internal CD-ROM drive, don’t use SCSI ID numbers 3 (which is assigned to
the optional CD-ROM drive) or 7 (which is assigned to your computer’s main
logic board). 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.
The SCSI devices can be in any physical order in the chain; it is not necessary
to arrange them in numerical order.
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