Avago Technologies LSI53C1000R - Manual (Page 52)

2-22 Functional Description
Version 2.2 Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
completed a selection or when it has successfully responded to a
selection or reselection. The CON bit is also set when the LSI53C1000R
wins arbitration in low level mode.
2.2.5 Designing an Ultra160 SCSI System
Software modifications are needed to take advantage of the Ultra160
speed in the LSI53C1000R. Because Ultra160 SCSI is based on existing
SCSI standards, it can use existing drivers if they are able to negotiate
for Ultra160 synchronous transfer rates. Also, the target device must be
able to communicate at Ultra160 speed. The LSI53C1000R uses Domain
Validation to determine whether or not the system is capable of
Ultra160 SCSI before activating DT clocking. Refer to
Section 2.2.5.1, “Ultra160 Features,” for more information on DT clocking.
LVD SCSI fulfills the hardware requirements for Ultra160 SCSI transfer
rates, increased cable lengths, and additional devices on the bus. All
devices on the bus must have LVD SCSI capabilities to guarantee
Ultra160 SCSI transfer rates. For additional information on
Ultra160 SCSI, refer to the SCSI Parallel Interface-3 (SPI-3) working
document that is available on the world wide web at the T10 Home Page,
http://www.t10.org . Also, check the SCSI Trade Association web site
at http://www.scsita.org/ . Chapter 6, “Specifications,” contains
Ultra160 SCSI timing information. In addition to the guidelines in the draft
standard, make the following software adjustments to accommodate
Ultra160 SCSI transfers.
2.2.5.1 Ultra160 Features
Domain Validation – Domain Validation is a procedure in which a host
queries a device to determine its ability to communicate at the negotiated
Ultra160 data rate. In software, the following steps are performed to
ensure the selected device can successfully transfer data at the
negotiated speed.
Step 1. Select a device.
Step 2. Issue Inquiry command.
Step 3. Issue Parallel Protocol Request (PPR) message.
Step 4. Issue Write Buffer command.
Step 5. Issue Read Buffer command.
Step 6. Examine the data pattern to ensure validity.