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AHA-3940U/3940UW/3940UWD User's Guide
Enabling Wide Negotiation
Wide Negotiation is enabled (set to yes) by default on the
AHA-3940U/3940UW/3940UWD. For each 16-bit SCSI device con-
nected to the host adapter, Wide Negotiation should normally be
enabled to allow for 16-bit data transfer instead of 8-bit. See SCSI
Device Configuration on page 3-11.
Note:
Even when Wide Negotiation is disabled on the host
adapter, the host adapter will still switch to Wide Negotia-
tion if it receives a request for it from the SCSI device.
Disabling the Channel BIOS
Disabling the channel BIOS saves you 16 KBytes of memory address
space and can also shorten boot-up time by as much as 60 seconds.
Reset SCSI Bus at IC Initialization on page 3-15 explains how to
change the Channel BIOS option in SCSISelect.
You should disable the channel BIOS if the peripherals on the SCSI
bus (for example, CD-ROM drives) are controlled by device drivers
and do not need the BIOS.
Enabling SCSI Parity Checking
SCSI Parity Checking, which is Enabled by default, verifies the accu-
racy of data transfer on the SCSI channel. To use this option, make
sure that parity checking is enabled on each SCSI device and on the
SCSI channel. SCSI Parity Checking on page 3-8 explains how to
change this setting in SCSISelect. Read the device documentation to
learn how to enable parity checking on SCSI devices.
You should disable SCSI Parity Checking on the channel only if any
of your SCSI devices does not support it.
Setting Enable Disconnection
In the DOS environment you can increase performance slightly if
you set Enable Disconnection to no when there is only one device on
the SCSI bus. You should set this option to yes, however, if you have
more devices on the SCSI bus. See Enable Disconnection on page 3-13
to learn more about this option.
B-2
AHA-3940U/3940UW/3940UWD User's Guide
Stock Number: 511041-00, Rev. B
Print Spec Number: 494569-00
Current Date: 2/14/97
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Page: B-2
ECN Date: 2/17/97
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