User's Manual

DLT2000 SCSI Interface
8-10 DLT2000/DLT2700 Cartridge Tape Subsystem
When received from an initiator, the tape drive enters the message in phase and return
MESSAGE REJECT.
EXTENDED MESSAGE (01h)
This is sent as the first byte of a multiple-byte message (> 2 bytes) by either initiator or
target. ExtENDED MESSAGE has the following format:
Byte 0
Byte 1
Byte 2
Byte 3
Extended Message Identifier − 01h
Extended Message Length
Extended Message Code
Extended Message additional parameters
Figure 8-1 Extended Message Format
The Extended Message Length specifies the length of the Extended Message plus the
number of additional parameter bytes that are to follow. The length does not include
bytes 0 and 1. A value of zero for the Extended Message Length indicates 256 bytes to
follow.
Possible Extended Message codes are:
00h - MODIFY DATA POINTER (not supported)
01h - SYNCHRONOUS DATA TRANSFER REQUEST
02h - Reserved
03h - WIDE DATA TRANSFER REQUEST (supported on some models)
04h-7Fh - Reserved
80-FFh - Vendor Unique
If the tape drive receives an extended message which it does not support,
it switches to message in phase and returns MESSAGE REJECT after all
the bytes of the message have been transferred.