SCSI and I/O 8-49
checks the logic state of pins 1, 3, 5 and 7. A ground on a pin indicates an asserted low state, while an open
circuit, high impedance or +5 V indicates a negated high state. The drive user can install jumper plugs to
connect pins 2, 4, 6 and 8 to pins 1, 3, 5 and 7, respectively, in the desired ID pattern. See Figures 8-5 and
8-6. The drive only connects ground to pins 2, 4, 6 and 8 during the 250 ms initialization period. The user
may install a cable on J6 or J1-auxiliary in order to connect the drive ID pattern to pins 1, 3, 5 and 7 through
some external switching circuit. The drive ID should be applied for at least the 50 ms period. During the
remaining operational time of the drive, the drive does not poll pins 1, 3, 5 and 7 for drive ID, unless a reset
occurs.
Table 8-16 provides the definitions and default setting for the J2, J1-Auxiliary, and J6 positions.
Underlined (On
or Off) indicates the HP default setting.
Table 8-19 J2, J1, and J6 Descriptions
J2 Jumper Function Description
RES
Off
/ On Reserved. Default is no jumper installed.
DS ME
Off Off
Off On
On Off
On On
Spindle starts immediately after power up - Default setting.
Drive spindle does not start until Start Unit command received from host.
Spindle Start-up is delayed by SCSI ID times 12 seconds after power is applied, i.e., drive 0
Spindle starts immediately when power is applied, drive 1 starts 12 seconds later, etc.
Drive spindle starts when Start Unit command received from host. Delayed start feature is
overridden when the ME jumper is installed.
WP
On
Off
Entire drive is write protected.
Drive is not write protected. (Default setting)
PE
On
Off
Parity checking and parity error reporting by the drive is enabled. (Default setting)
Drive does not report result of parity checking to host.
TE
On
Off
On-board (non-removable) terminator circuits are enabled.
Terminator circuits not enabled. (Default setting)
TP TP
Off Off
On Off
Off On
On On
No terminator power is connected to drive terminators or SCSI bus pin 26.
Drive supplies terminator power to internal terminator circuits only.
Drive supplies power to SCSI bus pin 26, none to internal circuits.
Drive supplies terminator power to SCSI bus pin 26 and internal circuits. (Default setting)
J1-Auxiliary;J6
A3,A2,Al,A0
Jumper Function Description
Drive ID on SCSI Bus (J1-auxiliary or J6 may be used, as the ID circuits are wired in paral-
lel). The drive ID is binary coded positionwise i.e., A3 = ID8, A2 = ID4, Al= ID2, A0 =
ID1.
SSP Not used in this application.
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