Acer Altos 9100 Series User Manual page 139

Some versions of the backplane board come with a 6-pin J3 and J4 jumpers. The
two additional pins are for setting more hard disk IDs. Note that the hard disk ID
switches in these versions have only three on/off switches. See section 4 for details
on hard disk ID settings.
Figure B-3 shows the settings for backplane boards with a 6-pin J3 and J4 jumpers.
)LJXUH % -XPSHU 6HWWLQJV IRU SLQ - DQG -
SETTING 1
Terminator power comes from the
backplane
SETTING 2
Terminator power comes from the
SCSI cable
SETTING 3
Hard disk ID setting (ID3)
$SSHQGL[ %  'ULYH 7UD\ 0DQDJHPHQW 6\VWHP %