IBM DCAS-32160 - Ultrastar 2.1 GB Hard Drive, Specifications

Page: 179 / 232

9.0 SCSI MESSAGE SYSTEM
This chapter details how the message system is implemented on the file. Included is a functional description
of the supported messages.
9.1 Supported Messages
The message supported by the file is shows in Figure 122.
MESSAGE CODE Direction Negate ATN
(hex) Before last ACK
COMMAND COMPLETE 00 IN
ÄÄÄ
SYNCHRONOUS DATA TRANSFER REQUEST 010301 IN OUT Yes
WIDE DATA TRANSFER REQUEST* 010203 IN OUT Yes
SAVE DATA POINTER 02 IN
ÄÄÄ
RESTORE POINTERS 03 IN
ÄÄÄ
DISCONNECT 04 IN
ÄÄÄ
INITIATOR DETECTED ERROR 05 OUT Yes
ABORT 06 OUT Yes
MESSAGE REJECT 07 IN OUT Yes
NO OPERATION 08 OUT Yes
MESSAGE PARITY ERROR 09 OUT Yes
LINKED COMMAND COMPLETE 0A IN
ÄÄÄ
LINKED COMMAND COMPLETE (w/FLAG) 0B IN
ÄÄÄ
BUS DEVICE RESET 0C OUT Yes
ABORT TAG 0D OUT Yes
CLEAR QUEUE TAG 0E OUT Yes
SIMPLE QUEUE TAG 20XX IN OUT No
HEAD OF QUEUE TAG 21XX OUT No
ORDERED QUEUE TAG 22XX OUT No
IGNORE WIDE RESIDUE* 2301 IN
ÄÄÄ
IDENTIFY 80
Ä
FF IN
ÄÄÄ
IDENTIFY 80
Ä
FF OUT No
Key: IN = Target to Initiator, OUT = Initiator to target.
YES = Initiator shall negate ATN before last ACK of message.
NO
= Initiator may or may not negate ATN before last ACK
of message.
ÄÄÄ
= Not applicable
XX = Queue Tag
* = Wide SCSI Only
Figure 122. Supported Messages
If an unsupported message is received, the file will send the M E S S A G E REJECT message to the initiator. If
at the time the unsupported message is received a valid NEXUS exists then the file will continue with the
command. If no valid NEXUS exists then the file will go to Bus Free.

Copyright IBM Corp. 1996
165