Avago Technologies LSI53C120 - Manual (Page 16)

8 LSI20101/LSI20102 SCSI Bus Boards
2.4.3 Subsystem Interface Connector J4
A-Side and B-Side SE termination circuitry provides termination for the
SCSI buses. Onboard termination for each of the two physical buses is
controlled in one of two ways: by switches or by the subsystem interface
(J4).
Switches – The LSI20101 board contains the following four switches at
location U4. See
Table 3 .
Termination Interface – The termination control on the LSI20101 board
permits the connection of the subsystem harness for external control of
the onboard SCSI terminators.
Connecting the Disable SE-A-TERM or Disable SE-B-TERM pins on J4
to ground turns off the onboard termination for the indicated physical bus.
See
Table 4 .
Table 3 U4 Switches
Switch Position Condition Description
SW1
ON Supplied by LSI20101 A-Side
OFF Not supplied by LSI20101 TERMPWR
SW2
ON Supplied by LSI20101 B-Side
OFF Not supplied by LSI20101 TERMPWR
SW3
ON Disabled A-Side
OFF Enabled Termination
SW4
ON Disabled B-Side
OFF Enabled Termination