DLT1/VS80 SCSI Interface Guide
81-81276-01 Rev A01
July 2004
3-9
Figure 3-4
shows the format for this extended message.
Figure 3-4.
WDTR Message Format
A SCSI tape drive initiates a WDTR message exchange whenever a previously arranged transfer width
agreement may have become invalid. The agreement becomes invalid after any condition that leaves
the data transfer agreement in an indeterminate state:
•
After a hard reset condition
•
After a BUS DEVICE RESET message
•
After a power cycle.
The tape drive implements both the wide and synchronous data transfer options. It negotiates the wide
data transfer agreement before negotiating the synchronous data transfer agreement. If a synchronous
data transfer agreement is in effect, the tape drive resets the synchronous agreement to asynchronous
mode after accepting a WDTR message.
The transfer width is expressed as 2
n
where
n
is the transfer width in bytes. The established transfer
width applies to all logical units. Valid transfer widths for the tape drive are 8 bits (m = 00h) and 16
bits (m = 01h). Values of
m
greater than (01h) are reserved.
Bit
Byte
7
6
5
4
3
2
1
0
0
Extended Message Identifier (01h)
1
Extended Message Length (02h)
2
WIDE DATA TRANSFER REQUEST (03h)
3
Transfer Width Exponent
Содержание DLT1/VS80 SCSI
Страница 1: ...DLT1 VS80 SCSI Interface Guide...
Страница 5: ...DLT1 VS80 SCSI Interface Guide 81 81276 01 Rev A01 July 2004 v Taiwan Statement Japanese Notice...
Страница 6: ...DLT1 VS80 SCSI Interface Guide vi July 2004 81 81276 01 Rev A01 Notes...
Страница 12: ...Table of Contents xii July 2004 81 81276 01 Rev A01 Notes...
Страница 16: ...List of Figures xiv July 2004 81 81276 01 Rev A01 Notes...
Страница 20: ...List of Tables xviii July 2004 81 81276 01 Rev A01 Notes...
Страница 24: ...Chapter 1 Introduction 1 4 July 2004 81 81276 01 Rev A01 Notes...
Страница 32: ...Chapter 2 General SCSI Bus Operation 2 8 July 2004 81 81276 01 Rev A01 Notes...
Страница 42: ...Chapter 3 SCSI Messages 3 10 July 2004 81 81276 01 Rev A01 Notes...
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