User's Manual

18
DAT 72/DDS-4 Product Manual
Terminator Power (Pins 11 and 12)
Internal DAT 72 and DDS-4 drives are shipped with terminator power disabled (no
jumper across pins 11 and 12, as shown in Figure 6). You can enable terminator
power, if necessary, by placing a jumper across pins 11 and 12.
Note 1:
If the termination power jumper is installed, be careful not to short the
TERMPWR signal to ground (for example, by attaching the SCSI cable
upside down). If this occurs, the drive no longer supplies terminator power to
the bus. The fuse resets automatically after the short is corrected.
Note 2:
The internal DAT 72 and DDS-4 do not provide SCSI termination, and
therefore should not be installed as the last device in a SCSI chain. See
“Connecting the SCSI interface cable” for details.
DIP Switch Settings
Figure 7 shows the location of DIP switches on the
underside
of the internal drive.
Each of these switches is described in detail on the following pages.
If you change a DIP switch, the new setting does not take effect until you turn the
drive off, and then on again.
Data compression (DC)
SCSI DC control
Media recognition
Self Test
Wide/Narrow SCSI
Inquiry String support
1
2
3*
4
5
6
7
8
9
10
O
N
Default settings shown
Front of drive
Operating-system
configuration
switches
* Reserved on DAT 72
Figure 7. DIP Switch Settings for an Internal Drive
Data Compression (Switches 1 and 2)
If switch 1 is ON (the default setting), hardware data compression is enabled. If
switch 1 is OFF, hardware data compression is disabled.
If DIP switch 2 is ON (the default setting), SCSI commands can be used to enable or
disable hardware data compression. To prevent hardware data compression from
being enabled or disabled by SCSI commands, set DIP switch 2 to OFF.