Optical Drive and Library SCSI-2 Command Reference

SCSI Command Overview
Drive Control Commands
Chapter 11-6
Command Complete 00H
This message is sent from the target to the initiator to indicate that the
execution of a command has terminated and that valid status has been
sent to the initiator. After successfully sending this message, the target
goes to the Bus Free Phase by releasing BSY (Busy).
Extended Message 01H
This message is sent from either the initiator or the drive to indicate that
the message is an extended message. The drive supports only the
synchronous data transfer request (SDTR) message.
An SDTR message exchange will be initiated by a SCSI device when an
arranged data transfer agreement becomes invalid. The agreement
becomes invalid after an intermediate status such as:
• Hard reset condition
• BUS DEVICE RESET message
• Wide data transfer message
•Power cycle
The initiator may also initiate a SDTR message exchange when
appropriate to negotiate a new data transfer agreement (synchronous or
asynchronous).
Table 1-2 Extended Message Format
Byte 7 6 5 4 3 2 1 0
0 Extended Message (01H)
1 Extended Message Length (03H)
2 Synchronous Data Transfer Request Code (01H)
3 Transfer Period Factor (m times 4 nanoseconds)
4 REQ/ACK Offset (x)