Instruction manual
Installation Page 4-13
Eagle 450 Installation and Technical Manual, Rev. 00
Switch Description
/ET Enable tolerant active negation
/EW
/EW:{id#}
Enable Wide SCSI negotiation for all devices
Enable Wide SCSI negotiation for SCSI device
ID#
/NQ
/NQ:{id#}
Disable Command Queuing for all devices
Disable Command Queuing for SCSI device
ID#
/NS
/NS:{id#}
Disable Synchronous Negotiation for all devices
Disable Synchronous Negotiation for SCSI device
ID#
/NP Disable Parity Checking (Parity still generated) on all devices
We recommend that all Eagle 450s use the /ET switch to enable tolerant active negation. Using active
negation improves bus integrity when using synchronous data transfers.
Never attach a device to or remove a device from the SCSI bus while system power is on.
This is
never a good idea, but active negation makes it even more likely that doing so will damage the
device, the SCSI controller, or both.
The most common of the other switches is /EW, to enable Wide SCSI operation when using the optional
Wide SCSI bus. For example, if you are using the Wide SCSI bus and have a Wide SCSI disk drive at ID
0, with narrow devices at other IDs, use this statement to enable Wide SCSI operation for just that drive:
SCZDSP SCZ138/ET/EW:0
If you have both Wide and narrow SCSI devices attached to the Wide bus, enable Wide SCSI operation
only for the Wide devices. Use /EW without a device ID (to enable Wide operation for the entire bus) if
all devices on the bus, both disk and tape drives, are Wide SCSI devices.
Do not use the /EW switch with the narrow SCSI bus, even if you have Wide SCSI devices attached to
the bus using the appropriate adapters.
Setting Write Buffering
To optimize SCSI bus performance, you may want to enable write buffering, in which blocks to be
written to the disk are held (buffered) in memory and written in groups, more efficiently than they could
be individually. For information on write buffering, including the modifications to make to your
initialization file to enable it, please see Appendix A.
Disabling Super I/O
If you want to disable Super I/O on some or all ports, see Appendix B for instructions. Disabling Super
I/O will decrease I/O performance; you should generally do this only if an application program will not
run on a Super I/O enabled port.