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(1) Disable auto spin up
This jumper controls how the drive starts when power is applied. If the jumper is NOT installed then the drive will spin up automatically after power-on reset. If the jumper IS installed the drive will NOT spin up unless the host system issues a 'START UNIT' command to the drive.
(2) SCSI terminator on
When this jumpers is installed, the on-card SCSI bus terminator is enabled.
(3) Unit attention disable
When this jumper is installed the drive will not generate a unit attention following a power on reset (POR) or SCSI bus reset. Any pending unit attention conditions will also be cleared at POR or SCSI bus reset.
(4) Enable TI-SDTR/Enable TI-SDTR/WDTR
When the jumper is installed the drive will initiate synchronous data transfer spped negotiation and initiate wide data transfer request following a SCSI bus reset or power on event.
(5 & 6) Auto start delay and delay start
The auto start delay and delay start pins control when and how the drive can spin up, with the combination of auto spin up option (1).
When in auto spin up and start delay mode the drive start will be delayed by a period of time multiplied by its own SCSI address. If auto spin up is disabled, these jumpers will be ignored.
| Disable auto spin up |
Auto start delay |
Auto start delay 6/12 |
| (1) |
(5) |
(6) |
Option |
| on |
don't care |
don't care |
Drive will NOT spin up requires start command |
| off |
off |
off |
Spin up immediately after POR |
| off |
on |
off |
Spin up six seconds multiplied by SCSI address after POR |
| off |
on |
on |
Spin up twelve seconds multiplied by SCSI address after POR |
(7) Disable SCSI parity
When this jumper is installed, the drive's SCSI parity checking is disabled.
(8) External activity (LED) pins
The LED pins can be used to drive an external light emitting diode. Up to 8mA of sink current capability is provided. The LED anode must be tied to the current limited +5V source provided on pin # 1 of the option jumper block. The LED cathode is then connected to the pin # 2 to complete the circuit.
Each device on the SCSI cable is either an end of the chain or a link in the middle. This SCSI drive has a terminator jumper which can be set to on or off (see graphic to the right), depending whether the device is an end or a middle link in the chain. Generally, your systems SCSI host adapter is at one end of the chain, and a terminated device is at the other. All other devices are middle links. The SCSI host adapter can be set so you can boot from any device on the SCSI BUS.
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