A–6 AlphaServer 300 User’s Guide
Table A-6 Motherboard Jumper Locations
(continued)
Jumper
Setting
Function
Description
J4
(1 to 2) (D)
(2 to 3)
Enables flashROM
writes.
Disables writes.
Leave at factory default.
J7
(1 to 2) (D)
(2 to 3)
267 MHz CPU.
Not used.
Leave at factory default.
J21
(1 to 2)
(3 to 4)
(5 to 6)
Hang off 1 (D)
Hang off 3 (D)
Hang off 5 (D)
Not used.
Leave at factory default.
J25
(1 to 2) (D)
Removed
87332 Super I/O chip.
87312 Super I/O chip.
Leave at factory default.
J26
(1 to 2) (D)
Removed
87332 Super I/O chip.
87312 Super I/O chip.
Leave at factory default.
J27
(1 to 2)
Hang off 1 (D)
Disables sensing for
presence of external
cable.
Enables sensing for the
presence of an external
SCSI cable.
J27 controls the automatic SCSI
bus terminator. If an external SCSI
cable is attached to the SCSI
connector, the automatic SCSI
terminator turns off. Therefore, the
SCSI bus must be terminated at the
end of the external bus. When
sensing is disabled (J27 1 to 2
installed), an external SCSI
terminator is always required, even
if no external SCSI devices are
present.
J32
(1 to 2) (D)
(2 to 3)
267 MHz CPU.
Unused.
Leave at factory default.
(D)= Default setting.
