Adaptec 3940UW User's Guide download pdf (Page 72)

B-2

AHA-3940U/3940UW/3940UWD User’s Guide

Stock Number: 511041-00, Rev. B Page: B-2

Print Spec Number: 494569-00

Current Date: 2/14/97 ECN Date: 2/17/97

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.

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Adaptec 3940UW User's Guide Page 72