Sony CDU-541 User manual

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CD-ROM DRIVE
SCSI INTERFACE MANUAL
MODEL CDU-541..
SONY CORPORATION
CD-ROM Drive Division
Mechatronic Products Group

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~DU-541 CO-ROM DRIVE SCSI INTERFACE MANUAL
DOCUMENT REVISION: 1 .00
FIRMWARE VERSION: S-1.0a
First Edition
Copyright 1989, c Sony Corporation
This document is provided as is without warranty of any kind, expressed or
implied, including but not limited to, the implied warranties of
usefulness or fitness for a particular purpose.
This document is subject to change without notice and does not represent a
commitment on
the part of Sony Corporation. This document could have
technical inaccuracies or typographical errors.
SONY is a registered trademark of Sony Corporation.
This document is prepared for use by customers of Sony. It contains
information for writing softw~ for the drive. An operators manual includes
the specifications and use of the CDu-S41 CO-ROM drive is also available.
Revision 1.00 -20 MAR '89
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COU-541 CO-ROM DRIVE SCSI INTERFACE MANUAL
CHANGE LIST
REVISION 1.00 - First release
Revision 1.00 - 20 MAR '89
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
TABLE OF CONTEN"l'S
1. Preface ........................................................................................ 1-1
2• In troduc tion ..................•....................•..•.•••....••..... 2-1
3. Physical Characteristics •••..............••.........•..• '0' •••••••••••• 3-1
4. Logical Characteris tics ..............................................• 4-1
4.1. Conditions ....................................................... 4-1
4 . 1 . 1. Power-on Condi tion ........................................ 4-1
4 . 1 .2. Reset Condi tion •.....•........•..•..•.••...•..••••••.•.•.• 4-1
4.1. 3. Unit Attention Condition .•.......•.•.....••.••..•••.•••••• 4-1
4.1.4. Ready Condition/Not Ready Condition •••..••••••.•.••..••.•• 4-2
4.1.5. ATTENTION Condition ..••.•.•..••••.•...••••••••.•.•••.••.• 4-3
4.2. CODlDl8l'ld Descriptor Block ........................................... 4-4
4.2.1. Operation Code ................................................. 4-4
4.2.2. Relative Address Bit .....•................................ 4-4
4.2.3. Starting Logical Address .••••••••••.•••••••••••••••••••••• 4-4
4.2.4. Transfer Length ...................................................... 4-4
4 .. 2.5. Parameter Length ..................................................... 4-4
4.2.6. Allocation Length •..•••..•.•..•••.......••••....••••.••.•• 4-4
4.2.7. Flag and Link Bits •.•..•..•...••..•....•••••.•.•.••.•••.•• 4-5
4.3. Command Processing ..••..••••...•.•....•....•..••••.••...•••.••.•• 4-5
4.4. Handling of Message Phase ..•.•...••..••••......•••••.••••.•••.•.• 4-6
4•4. 1. MESSAGE IN Phqe................................ ................... 4-6
4.4.2. MESSAGE OtJT Phase .•.••.••••.•.•.••.••.••••••••••••••..•.•• 4-6
4.4.3. Messages ................... I : I •• ol; ~ , " •• ;. .; ;. ~ ••••••••••••••• • 4-7
4.5. Handling of Status Phase ••••••..•..•..••.....••••••.•••••••••••• 4-10
4.5.1. Status Byte Description .•.••••••.••••••••••••••••••.••••• 4-10
4.6. Disconnect/Reconnect ............................................ 4-11
4.1. Disc Compatibility .............................................. 4-11
4.8. TOC Recovery Strategy ........................................... 4-11
4.9. Audio Playback Implementation Rules ••.••.•••••••...••..••••••••• 4-12
5. CD-ROM Devices .......................................•.......•.•...... 5-1
5.1. CD-ROM Model ..................................................... 5-1
5.2. CD-ROM Command Descriptions •.•.•.•....•....••••.•.••.•.•.••.•.••. 5-4
5.2.1. INQUIRY Command •••.........................•.•....•...••.• 5-5
5.2.2. MODE SELECT Command •.....•...•..........•........•...••..• 5-8
5.2.3. MODE SENSE Command ••....••..............•.........•••.... 5-11
5.2.3.1. Current Values .•.......•......•.•••••.•••••.•..• 5-11
5.2.3.2. Changeable Values •..........•..•••.•..•.•••..•.. 5-11
5.2.3.3. Default Values .......•.•..........••.•.••..•.•.. 5-12
5.2.4. PAUSE Command .....•.•...........•..........•.•••.••...••. 5-14
5.2.5. PAUSE/RESUME Command ..................................... 5-15
5.2.6. PLAY AUDIO Command •.•.••.......••.........•••.•.••......• 5-16
5.2.7. PLAY AUDIO(10) Command •..•••....••...••.•••••••...•..•••. 5-17
5.2.8. PLAY AUDIO MSF Command ................................... 5-18
5.2.9. PLAY AUDIO TRACK/INDEX Command ••..•.....•.••..••••••.•••. 5-19
5.2.10. PLAY MSF ComJland .....•...••...••........•.••..•••••....• 5-21
5.2.11. PLAY TRACK Command .•••.••••....••...•..••.••.••••.•••..• 5-22
5.2.12. PLAYBACK CONTROL Command •.....•....•.•....•..........••. 5-23
5.2.13. PLAYBACK STATUS Command •••••..•..•.••...•••••.••••.••••• 5-25
5.2.14. PREVENT/ALLOW MEDIUM REMOVAL Command ....•.••.•..•••.•••• 5-28
5.2. 15. REA.D Com.m8Ild ••••••••••••••••••••••••••••• 4o •••••••••••••• 5~29
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
5.2. 16. READ BUFFER Command •••..•.•••..•...•..........•.•••..••. 5- 30
5.2.17. READ CAPACITY Command •••.•••••••••.....•.....••••..••.•• 5- 31
5.2.18. READ EXTENDED Command •••.•••.••...•........•...••.•..••• 5-33
5.2. 19. READ HEADER Command ••••••••.•••••.......••••...•••.••••• 5- 34
5.2.20. READ HEADER Command ••.•••••.••••••.•..••..••••••••.••••• 5-36
5.2.21. READ SUB-CHANNEL Command ••••••••••.•......••••...•.••••. 5-38
5.2.22. READ SUB-CHANNEL Command ••..•.•..••.........•••••••.•••. 5-41
5.2.23. READ TOe Command ••.••••••.••••••••...•.......••••..••••• 5-44
5.2.24. READ TOC Command ••..•..•....•....•.............••......• 5-46
5.2.25. RECEIVE DIAGNOSTIC RESULTS Command ..............•...•.•• 5-49
5.2.26. RELEASE Command ••••••....••.•................•••.......• 5-50
5.2.27. REQUEST SENSE Command ................................... 5-51
5.2.28. RESERVE Command ••.•••••••••••••••.••.....••••.•.••.•.••• 5-54
5.2.29. REZERO UNIT Command •••••••••••••••••..•.•.....•••••••••• 5-55
5.2.30. SEEK Command •••••••••••••••••••••••••••••••••••••••••••• 5-56
5.2.31. SEEK EXTENDED Command ••••••••••••••.•••.•••••••••••••••• 5-57
5.2.32. SEND DIAGNOSTIC Command ••••••••••••.••••.••••••••••••••• 5-58
5.2.33. START/STOP UNIT Command ••••••••••••••.•••••••••••••••••• 5-60
5.2.34. TEST UNIT READY Command ••••••••••••••.•••••••••••••••••• 5-61
5.2.35. VERIFY Command •••••••••••••••••••••••...•.•.•••••••••••• 5-62
5.2.36. WRITE BUFFER Command •••••••••••••••.•.••••.•••.•..•••••• 5-63
5.3. CD-ROM Page Descriptions ..••••••••••••••••.••••••••.••••••••••• 5-65
5.3.1. MODE SELECT Pages ••••••••••••••••••..••.••••..•••••••.••• 5-65
5.3.1.1. Page Code One •.••••••.•.••••..••.•••.•••.••.•.•• 5-65
5.3.1.2. Page Code Two ••.•••••••••••••.••••••.••••••••••• 5-71
5.3.1.3. Page Code Seven ••••••••.•••....•.••••••••••••••• 5-73
5.3.1. 4. Page Code Eight ................................. 5-73
5.3.1.5. Page Code Nine .................................. 5-75
5.3.2. MODE SENSE Pages •••••••••••••••••••••••••••••••.••••••••• 5-76
5 •4. CD-ROM Addi tional Sense Codes •.•.••••••••••••••••••••••••••••••• 5-77
5.5. CD-ROM Glossary .••••••••••••••••••••••••••••••••••••.•••••.•••• 5-79
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
LIST OF TABLES
4-1: Message Codes •....................................................... 4-7
5-1: Implemented Commands .......................•....................•..• 5-4
5-2:
Inquiry Data .•....••••..............•.....•......................••.• 5-6
5-3: Mode Select Parameter Lis t ................••......•.............••... 5-9
5-4: Block Lengths
for CD-ROM .................•........................•. 5-10
5-5: Page Control Bit Definition ...............•.•....................... 5-11
5-6:
Mode Sense Parameter List ........................................... 5-13
5-7: Audio Control Data Format ........................................... 5-24
5-8: Channel Output Selection ..............•.......••....•...........•.•. 5-25
5-9: Audio Status Data Format •.......•....•.•.•.••••.•.••......•.•....••• 5-26
5-10: Audio Status •.•.•••.•••••••.....•.•.•.•........•.................•• 5-27
5-11: Read
Buffer Header ••.••••.....•••••.••..••••••••••.•.••..........•• 5- 31
5-12: Read Capacity Data ................................................. 5-32
5-13:
Header Data Format ................................................. 5-35
5-14: Header Data Format .......................................•........• 5-37
5-15: Logical Block Data Mode Format .•••••.••.•••••••.•••...•.•.••..•..•• 5-37
5-16: Sub-Channel Q Data
MSF Format •..•••••••••••.•.•..••..•.........••. 5-39
5-17: Sub-Channel Q Data
LBA Format ..•••.•.•••••.•.••••.........•.....•• 5-40
5-18: MC, TC and Returning Data ........•.•••.•••••.•••••.........•....•.• 5-42
5-19: The Format
of Time Data (MC=O, TC=O) •....••...•.••...............•• 5-42
5-20: Audio Status ....................................................... 5-43
5-21: The Format of Media Catalog Number (MC=O, TC=1) ........•...•.....•. 5-43
5-22: The Format
of Track In~rnational Standard Recording Code (MC=1,
TC=O) •••••.••..••...•.••....•••••••••.••••.••••••..•.•......•....•• 5-44
5-23:
Toe Data Format .................................................... 5-45
5-24: Definition of Control Field Bits ••••.•••••••••..•••.••••.•••.•••••• 5-46
5-25: TOC Data Format ......................•..••......................... 5-47
5-26: Definition Of Control Field Bit ••.•••••••••••.••...••...•.••.•.•••• 5-48
5-27: Receive
Diagnostic Data •••..••.•.••.••••.••••••..••.••....•••••••.• 5-49
5-28:
Error Code 70h Sense Data Format ••••.••.•••••.•••••••.....••.•..••. 5-52
5-29: Sense
Key Descriptions ...•.....•.••••...•••••.•.••..••.........•••• 5-53
5-30: Send Diagnostic Data ........•....•..••..•.••.••......•....••..•.••• 5-59
5-31:
Write Buffer Header .............•••.•.•.•.••.•.•......•........•••. 5-64
5-22: Page Codes ......................................................... 5-65
5-23: Page Code One: Read Error Recovery Parameters ••..••••....•.....•.• 5-65
5-24:
Error Recovery Byte Bit Settings •.•..••.••..•..•••.•............•.. 5-66
5-25:
Error Recovery Procedures - CD-ROM Mode One Data ..........•........ 5-67
5-26:
Error Recovery Procedures - CD-ROM Mode One Data ••..........•...... 5-68
5-27:
Error Recovery Procedures - CD-ROM Mode One or Two Data ..........• ·5-69
5-28: Error Recovery Procedures - CD-ROM Mode One or Two Data .•........ ·.5-70
5-39: Page Code Two: Disconnect-Reconnect Parameters •..•........••.••..• 5-71
5-40: Buffer Full Ratios ...•...........•••.•..••••.••.•••..••.•.......••• 5-72
5-41: Page Code Seven:
Verify Error Recovery Parameters .•.•..••.......•• 5-73
5-42: Page Code
Eight: CD-ROM Parameters •..•...•.....•.........•...•..•. 5-73
5-43:
Logical Block Address Format ....••••••••..•....•••.....•..•......•• 5-74
5-44: Minute Second Frame Format
.....••....••.•••.••.•.•................• 5-74
5-45:
Inactivity Times .•..•.•......••.•••.•••..•.•••..............•...•.. 5-64
5-46: Page Code Nine:
CD-ROM Audio Control Parameters ..•••.•..........••. 5-75
5-47: Page Codes ......................................................... 5-76
5-48: Additional Sense Code Descriptions .•.•..•••.•............•......•.. 5-77
5-49:
Additional Sense Code Descriptions •..•••••.•.•..••..............•.. 5-78
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1.00 -20 MAR '89
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
1. Preface
This document details the implementation of a SCSI command set for a Read-
Only device type (i.e. CD-ROM). This implementation complies with the ANSI
X3.131-1986 standard. In addition several of the concepts proposed in the
common command set document for direct-access devices have been incorporated.
There are extensions to the SCSI interface included for audio control.
This implementation represents the best information available to Sony
Engineering at the time. There is continuing work in the X3T9.2 committee to
develop an SCSI-2 standard that will incorporate CD-ROM commands as well as
extensions to the original SCSI standard. It is Sony Engineering's intention
to comply with the proposed.SCSI-2 document at the earliest feasible date. At
this time it is expected that most of the current implementation will comply
with SCSI-2. However the commands used for audio control are still
controversial and most likely will change in a future firmware release.
\,
Information about the current status of the audio commands and the proposed
SCSI-2 interface for CD-ROM can be obtained from Sony CD-ROM Engineering.
2. Introduction
This document covers the Sony CDU-541 CD-ROM drives. The CDU-541 is a half-
height CD-ROM drive which embeds a drive, a SCSI controller and a
audio/headphone
circuit. Not only SCSI commands but also SCSI-2 commands
which relate to the audio function are supported in this model. All commands
supported are described in alphabetic order in this document.
3. Physical Characteristics
The Sony SCSI controller uses a single-ended asynchronous SCSI interface
that complies with the physical characteristics of ANSI X3.131-1986 Section
4.0. Please refer to that standard for detailed information.
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
4. Logical Characteristics
The logical characteristics of the controller comply with ANSI X3.131-1986
for a single-ended asynchronous implementation. The controller supports
disconnect/reselect. Several additional logical characteristics are discussed
here to aid in understanding the operation of the drive and controller.
4. 1. Condi tions
TQis section describes certain conditions as they relate to the operation of
the drive and the interface.
4.1.1. Power-on Condition
The power-on condition occurs when power is first applied to the unit. The
controller performs power-on diagnostics. If a caddy is inserted the drive
loads the caddy and attempts to read the table of contents. For the duration
of the power-on condition the controller will return BUSY status. If a
failure in power-on diagnostics occurs the controller will return CHECK
CONDITION STATUS. If after the caddy is inserted it does not seat properly,
or the drive is unable to focus, or the drive is unable to achieve spindle
lock-up or the table of contents is not recovered the controller will return
a CHECK CONDITION STATUS.
4.1.2. Reset Condition
The reset condition occurs whenever the RST signal is asserted, or a BUS
DEVICE RESET message is received.
4.1.3. Unit Attention Condition
The unit attention condition occurs following a power-on condition, a reset
condition, the insertion of a caddy with the successful recovery of the table
of contents or the receipt of a MODE SELECT command from another initiator.
The unit attention condition will persist for each initiator until that
initiator issues a command to the logical unit for which the controller
returns a CHECK CONDITION status. If the next command from that initiator to
the logical unit (following the CHECK CONDITION status) is REQUEST SENSE, then
the UNIT ATTENTION sense key is returned. If any command other than REQUEST
SENSE is received, the unit attention condition is lost.
If more than one unit attention condition occurs the unit attention
condition with the highest priority will be reported. The priority is
1) Power on / reset
2) Not ready to ready transi~~en (medium change)
3)
MODE SELECT command istnea-trom another initiator
If an INQUIRY command is received from an initiator with a pending unit
attention condition the controller will perform th~ INQUIRY command and will
not clear the unit attention condition.
If a REQUEST SENSE command is received from an initiator with a pending unit
attention condition then the controller will discard any pending sense data,
report UNIT ATTENTION sense key, and clear the unit attention condition for
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
that initiator. The additional sense code will be set to the appropriate
value.
If an STOP UNIT command (with LoEj set) is received from an initiator with a '-_---
pending unit attention condition the controller will perform the command and
will not clear the unit attention condition.
If an initiator issues a command other than INQUIRY, REQUEST SENSE, or STOP
UNIT (with LoEj set) while a unit attention condition exists for that
initiator, the controller will terminate the command with a CHECK CONDITION
status.
4.1.4. Ready Condition/Not Ready Condition
The ready condition occurs after a caddy is inserted and the table of
contents has been recovered from the disc.
A not
1)
2)
3)
4)
ready condition occurs for the following reasons:
There is no caddy inserted.
The drive is unable to load or unload the caddy.
The drive is unable to recover the table of contents.
The controller cannot select drive. (This can only occur
controller was previously able to select the drive).
if the
A check condition status will be returned for the drive not ready condition
only for commands that require or imply a disc access. The following commands
will not return a check condition status for the not ready condition. The
value in parentatheses is the command code.
1)
INQUIRY (12h) 6) STOP UNIT with LoEj bit set to one (lBh)
2)
MODE SELECT (15h) 7) ALLOW MEDIUM REMOVAL (lEh)
3)
RESERVE (16h) 8)
READ BUFFER (3Ch)
4) RELEASE (17h) 9)
WRITE BUFFER ( 3Bh)
5) MODE SENSE (lA)
The following commands will return a check condition status for the not
ready condition. The value in parentatheses is the command code.
1)
TEST UNIT READY ( OOh )
lS) READ HEADER (44h)
2)
REZERO UNIT (Olh) 16)
PLAY AUDIO (10){4Sh)
3) READ (08h) 17)
PLAY AUDIO MSF (47h)
4)
SEEK (OBh)
18) PLAY AUDIO TRACK/INDEX (48h)
5)
START UNIT with Start bit set (lBh) 19)
PAUSE/RESUME (4Bh)
6) RECEIVE DIAGNOSTIC RESULTS (lCh) 20)
READ TOC (C1h)
7) SEND DIAGNOSTIC (lDh) 21)
READ SUB-CHANNEL (C2h)
8) PREVENT MEDIUM REMOVAL (lEh) 22)
READ HEADER (C3h)
9) READ CAPACITY (2Sh) 23)
PLAYBACK STATUS (C4h)
10) READ EXTENDED (28h) 24)
PAUSE (CSh)
11) SEEK EXTENDED ( 2Bh)
25) PLAY TRACK (C6h)
12) VERIFY (2Fh) 26)
PLAY MSF (C7h)
13) READ SUB-CHANNEL (42h) 27)
PLAY AUDIO (C8h)
14) READ TOC (43h) 28)
PLAYBACK CONTROL (C9h)
4-2
--.----

CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
4.1.5. ATTENTION Condition
The ATTENTION condition allows an initiator to inform the controller that
the initiator has a message ready. The controller may get this message by
performing a MESSAGE OUT phase.
The initiator creates the ATTENTION condition by asserting ATN at any time
except during the ARBITRATION or BUS FREE phases.
The initiator will assert the ATN signal before releasing ACK for the last
byte transferred in a bus phase for the ATTENTION condition to be honored
before transition to a new bus phase. An ATN asserted later might not be
honored
until a later bus phase and then may not result in the expected
action. A controller will respond with MESSAGE OUT phase as follows:
1. If ATN occurs during a COMMAND phase, MESSAGE OUT will occur after the
transfer of all command descriptor block bytes has been completed.
2. If ATN occurs during a DATA phase, MESSAGE OUT will occur at the
controller's convenience on a logical block boundary. The initiator must
continue REQ/ACK handshakes until it detects the phase change.
3. If ATN occurs during a STATUS phase, MESSAGE OUT will occur after the
status byte has been acknowledged by the initiator.
4. If ATN occurs during a MESS~GE IN phase, MESSAGE OUT phase will occur after
the current MESSAGE 1M byte has been acknowledged by the initiator.
5. If ATN occurs during a SELECTION phase and before the initiator releases
the BSY signal, MESSAGE OUT will occur immediately after that SELECTION phase.
6. If ATN occurs during a RESELECTION phase, MESSAGE OUT will occur after the
controller has successfully sent its IDENTIFY message for that RESELECTION
phase.
The initiator shall keep ATN asserted if more than one byte is to be
transferred. The initiator may negate the ATN signal at any time except it
shall not negate the ATN signal while the ACK signal is asserted during a
MESSAGE OUT phase. Normally, the initiator negates ATN while REQ is true and
ACK is false during the last REQ/ACK handshake of the MESSAGE OUT phase.
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COU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
4 .2. CollUlland Descriptor Block
The Command Descriptor Block (COB) is a packet of six or ten bytes sent
from the host computer during a command phase that requests the controller to __ --
perform some operation. The common parts of the COB are described here.
4.2.1. Operation Code
The operation code is the first byte of the COB and indicates whether a six
or ten byte is being sent. Each command has a unique operation code.
4.2.2. Relative Address Bit
The relative address bit is applicable to some ten byte commands. This
version of the controller does not implement relative addressing.
4.2.3. Starting Logical Address
The starting logical address specifies the logical block at which the
requested read, verify or play operation is to begin. Not all COB's have
starting logical addresses.
4.2.4. Transfer Length
The transfer length specifies the number of logical blocks to be
transferred. A transfer lengt~ value of zero has special meaning in some
commands. The size of the logical blocks can be set using the MODE SELECT
command.
4.2.5. Parameter Length
The parameter length specifies the exact number of bytes of sense data that
the host will transfer to the controller.
4.2.6. Allocation Length
The allocation length specifies the maximum number of bytes that the
initiator has allocated for returned sense data. An allocation length of zero
indicates that no sense data will be transferred. This condition will not be
considered as an error. The controller will terminate the DATA IN phase when
allocation length bytes have been transferred or when all available sense data
have been transferred to the initiator, whichever is less.
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
4. 2. 7. Flag and Link Bi ts
The link bit set to one indicates that the initiator requests a link to the
next command upon successful completion of the current command. If the link
bit is one, the controller will return INTERMEDIATE status upon successful
termination of the command. The message sent depends on the flag bit.
The link bit set to zero indicates that the initiator does not want the
commands linked. If the link bit is set to zero, the flag bit shall be set to
zero .
If the link bit is set to one and the flag bit is set to zero, the
controller will send LINKED COMMAND COMPLETE message if the current command
completes successfully.
If the link bit is set to one and the flag bit is set to one, the controller
will send LINKED COMMAND COMPLETE(WITH FLAG) message if the current command
completes successfully.
4.3. Command Processing
Upon normal command completion (successful or unsuccessful), the controller
returns a status byte to the initiator. Since most error and exception
conditions cannot be adequately described with a single status byte, one
status code, CHECK CONDITION, ~dicates that additional information is
available. The initiator may issue a REQUEST SENSE command to retrieve this
additional information.
An initiator should never send a second command to a logical unit until the
command in progress is terminated. The command is normally terminated with a
COMMAND COMPLETE message, but termination may result because of other events·
such as the RESET condition.
If the controller receives a selection from an initiator that has a command
in progress (i.e. the controller has disconnected) the controller will abort
the first command and not perform the second command. A CHECK CONDITION
status is returned. The sense key is set to ABORTED COMMAND, and the
additional sense code is set to OVERLAPPED COMMANDS ATTEMPTED.
The occurrence of an initiator sending a second command to a logical unit
with a command in progress by the same initiator is considered a catastrophic
failure from the controller's viewpoint.
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
4.4. Handling of Message Phase
The message phase is a term that references either a MESSAGE IN, or a
MESSAGE OUT phase. Multiple messages may be sent during either phase. The
first byte transferred in either of these phases shall. be either a single-byte
message or the first byte of a multiple-byte message. Multiple-byte messages
shall be wholly contained within a single message phase.
4.4. 1. MESSAGE IN Phase
The MESSAGE IN phase allows the target to request that message(s) be sent to
the initiator from the controller.
The controller will assert C/O, I/O, and MSG during the REQ/ACK handshake(s)
of this phase.
4.4.2. MESSAGE OUT Phase
The MESSAGE OUT phase allows the controller to request that message(s) be
sent from the initiator to the controller. The controller may invoke this
phase at its convenience in response to the ATTENTION condition created by the
initiator.
The controller will assert C/O and MSG and negate I/O during the REQ/ACK
handshake(s) of this phase. The controller will handshake byte(s) in this
phase until ATN goes false, unless an error occurs.
If the controller detects one or more parity error(s) on the message byte(s)
received, it may indicate its desire to retry the message(s) by asserting REQ
after detecting ATN has gone false and prior to changing to any other phase. -~-
The initiator, upon detecting this condition, shall re-send all of the
previous message byte(s) in the same order as previously sent during this
phase. When re-sending more than one message byte, the initiator shall assert
ATN prior to asserting ACK on the first byte and shall maintain ATN asserted
until the last byte is sent.
The controller will act on messages as received as long as no parity error
is detected and will ignore all remaining messages sent under one ATN
condition after a parity error is detected. When a sequence of messages is
re-sent by an initiator because of a target detected parity error, the target
will not act on any message which it acted on the first time received.
If the target receives all of the message byte(s) successfully (i.e., no·
parity errors), it will indicate that it does not wish to retry by changing to
any information transfer phase other than the MESSAGE OUT phase and transfer
at least one byte. The target may also indicate that it has successfully
received the message byte(s) by changing to the BUS FREE phase
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'-
~~
CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
Table 4-1: Message Codes
==============================================================================
Code Description
Direction
OOh
COMMAND COMPLETE In
02h
SAVE DATA POINTER In
03h
RESTORE POINTERS
In
04h
DISCONNECT
In
04h
DISCONNECT
Out
05h
INITIATOR DETECTED ERROR Out
06h
ABORT
Out
07h
MESSAGE REJECT
In
Out
08h
NO OPERATION Out
09h
MESSAGE PARITY' ERROR Out
OAh
LINKED COMMAND COMPLETE In
OBh
LINKED COMMAND COMPLETE
(WITII FLAG) In
0Ch
BUS DEVICE RESET Out
80h -
FFh IDENTIFY Out
==============================================================================
Key: In = Target to initiator. Out = Initiator to target.
4.4.3. Messages
The
single byte messages (Tabie 4-1) are listed below along with their code
values and their definitions.
COMMAND COMPLETE OOh. This message is sent from the controller to an
initiator to indicate that the execution of a command (or series of linked
commands) has terminated and that valid status has been sent to the initiator.
After successfully sending this message, the controller will go to the BUS
FREE phase by releasing BSY. The controller will consider the message
transmission to be successful when it detects the negation of ACK for the
COMMAND COMPLETE message with the ATN signal false.
SAVE DATA POINTER 02h. This message is sent from the controller to direct
the initiator to save a copy of the present active data pointer for the
currently attached logical unit.
RESTORE POINTERS 03h. This message is sent from the controller to direct
the initiator to restore the most recently saved pointers (for the currently
attached logical unit) to the active state. Pointers to the command, data;
and status locations for the logical unit shall be restored to the active
pointers. Command and status pointers shall be restored to the beginning of
the present command and status areas. The data pointer shall be restored to
the value at the beginning of the data area in the absence of a SAVE DATA
POINTER message or to the value at the point at which the last SAVE DATA
POINTER message occurred for that logical unit.
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CDU~541 CD-ROM DRIVE SCSI INTERFACE MANUAL
DISCONNECT O4H. This message is sent from the controller to inform an
initiator that the present physical path is going to be broken (the target
plans to disconnect by releasing BSY) , but that a later reconnect will be
required in order to complete the current operation. This message shall not
cause the initiator to save the data pointer. After successfully sending this
message in, the controller will go to the BUS FREE phase by releasing BSY. The
controller will consider the message transmission to be successful when it
detects the negation of ACK for the DISCONNECT message with the ATN signal
false. If DISCONNECT messages are used to break a long data transfer
into two or more shorter transfers, then a SAVE DATA POINTER will be issued
before each DISCONNECT message.
This message may also be sent from an initiator to the controller to
instruct the controller to disconnect from the SCSI bus. After the DISCONNECT
message is received, the controller will switch to MESSAGE IN phase, send the
DISCONNECT message to the initiator preceded by SAVE DATA POINTER message, and
then disconnect by releasing BSY. After releasing BSY, the controller will
not partiCipate in another ARBITRATION phase for at least a disconnection
delay. If the controller cannot disconnect at the time when it receives the
DISCONNECT message from the initiator, it will respond by sending MESSAGE
REJECT message to the initiator.
INITIATOR DETECTED ERROR OSh. This message is sent from an initiator to
inform the controller that an error (e.g., parity error) has occurred that
does not preclude the controll~r from retrying the operation. Although
present pointer integrity is not assured, a RESTORE POINTERS message or a
disconnect followed by a reconnect, shall cause the pointers to be restored to
their defined prior state.
ABORT 06h. This message is sent from the initiator to the controller to
clear the present operation. If a logical unit has been identified, all
pending data and status for the issuing initiator from the affected logical
unit will be cleared, and the controller will go to the BUS FREE phase.
Pending data and status for other initiators is not cleared. If a logical
unit has not been identified, the controller will go to the BUS FREE phase.
No status or ending message will be sent for the operation. It is not an
error to issue this message to an logical unit that is not currently
performing an operation for the initiator.
MESSAGE REJECT 07b. This message is sent from either the initiator or
controller to indicate that the last message it received was inappropriate or
has not been implemented.
In order to indicate its intentions of sending this message, the initiator
shall assert the ATN signal prior to its release of ACK for the REQ/ACK
handshake of the message that is to be rejected. If the target receives this
message under any other circumstance, it shall reject this message.
When the controller sends this message, it will change to MESSAGE IN phase
and
send this message prior to requesting additional message bytes from the
initiator. This provides an interlock so that the initiator can determine
which message is rejected.
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
NO OPERATION 08h. This message is sent from an initiator in response to a
the controller's request for a message when the initiator does not currently
have any other valid message to send.
MESSAGE PARITY ERROR 09h. This message is sent from the initiator to the
controller to indicate that one or more bytes in the last message it received
had a parity error.
In order to indicate its intentions of sending this message, the initiator
shall assert the ATN signal prior to its release of ACK for the REQ/ACK
handshake of the message that has the pari ty error. This provides an
interlock so that the controller can determine which message has the parity
error. If the controller receives this message under any other circumstance,
it will signal a catastrophic error condition by releasing the BSY signal
without any further information transfer attempt.
LINKED COMMAND COMPLETE OAb.
the initiator to indicate that
and that status has been sent.
the initial state for the next
This message is sent from the controller to an
the execution of a linked command has completed
The
initiator shall then set the pointers to
linked command.
LINKED COMMAND COMPLETE (WITH FLAG) OBh. This message is sent from the
controller to an initiator to indicate that the execution of a linked command
(with the flag bit set to one) has completed and that status has been sent.
The initiator shall then set the pointers to the initial state of the next
linked command. Typically this message would be used to cause an interrupt in
the initiator between two linked commands.
BUS DEVICE RESET 0Ch. This message is sent from an initiator to direct the
controller to clear all current commands on that SCSI device. This message
forces the SCSI device to an initial state with no operations pending for any
initiator. Upon recognizing this message, the controller will go to the BUS
FREE phase.
IDENTIFY BOh to FFh. These messages are sent by either the initiator or the
controller to establish the physical path connection between an initiator and
controller for a particular logical unit. The logical unit number addresses
one physical drive attached to the controller.
Bit 7. This bit shall be set to one to distinguish these messages from
the other messages.
Bit 6. This bit is only set to one by the initiator to grant the the
privilege of disconnecting. If this bit is zero, the controller will not
disconnect. This bit is set to zero when the identify message is sent by the
controller.
Bits 5-3. Reserved.
Bits 2-0. These bits specify the logical unit number in the controller.
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CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
Only one logical unit number shall be identified for anyone selection
sequence; a second IDENTIFY message with a new logical unit number shall not
be issued before the bus has been released (BUS FREE phase). The initiator
may send one or more IDENTIFY messages during a selection sequence. However, '~
the logical unit number in any additional IDENTIFY messages shall be the same
as the logical unit number specified in the first IDENTIFY message sent by the
initiator.
When sent from the controller to an initiator during reconnection, an
implied RESTORE POINTERS message shall be performed by the initiator prior to
completion of this message.
4.5. Handling of Status Phase
The controller will always follow the selection phase with a command phase.
If exception handling requires a status phase it will occur after the command
phase. (Example: A reservation conflict or busy status.)
A status byte will be sent from the controller to the initiator during the
STATUS phase at the termination of each command unless the command is cleared
by an ABORT message, by a BUS DEVICE RESET message, an assertion of the RST
signal, or by an unexpected BUS FREE condition.
4.5.1. Status Byte Description
GOOD (OOh). This status indicates that the controller has successfully
completed the command.
CHECK CONDITION (02h). This status indicates that an error, exception, or
abnormal condition has caused the sense key or additional sense code to be
set. The REQUEST SENSE command should be issued following a CHECK CONDITION
status, to determine the nature of the condition.
BUSY (oBh). This status indicates that the controller is busy. The
controller is unable to perform a command from an otherwise acceptable
initiator. The normal initiator recovery action is to issue the command again
at a later time.
INTERMEDIATE (lOh). This status indicates that a command in a series of
linked commands has completed successfully. This status is returned for every
linked command in a series of linked commands except the last command, unless
an error, exception, or abnormal condition causes a CHECK CONDITION status·or
a RESERVATION CONFLICT status to be returned. If the intermediate status is
not returned, the chain of linked commands is broken; no further commands in
the series are executed.
RESERVATION CONFLICT (18h)~ This status indicates that the initiator
attempted to access a logical unit that is reserved for to another SCSI ID.
The normal
initiator recovery action is to issue the command again at a later
time.
4-10