Message format, One-byte messages | Seagate Ultra 320, Ultra 160

Table 24: Message format

Message code	Message format


00h	One-byte message (TASK COMPLETE)
01h	Extended messages
02h–0Ah	One-byte messages

0Bh	Obsolete one-byte messages

0Ch–0Eh	One-byte messages
0Fh–10h	Reserved one-byte messages

11h–13h	Obsolete one-byte messages

14h–15h	Reserved one-byte messages
16h–17h	One-byte messages

20h–24h	Two-byte messages

25h–2Fh	Reserved two-byte messages
30h–54h	Reserved

55h	One-byte message

56–7Fh	Reserved
80h–FFh	One-byte message (IDENTIFY)

4.2.1One-byte messages

One-byte messages consist of a single byte transferred during a MESSAGE phase. The byte’s message code determines the message to be performed as defined in Tables 27, 40, and 45. The IDENTIFY message is a one-byte code, but its format is different.

4.2.2Two-byte messages

Two-byte messages consist of two consecutive bytes transferred during a MESSAGE IN phase or a MES- SAGE OUT phase. The value of the first byte determines the message to be performed as defined in Tables 27, 40, and 45. The second byte is a parameter byte used as defined in the message descriptions.

4.2.3Extended messages

A value of 01h in the first byte of a message indicates the beginning of a multiple-byte extended message. The minimum number of bytes sent for an extended message is three. All of the extended message bytes shall be transferred in consecutive MESSAGE IN phases or consecutive MESSAGE OUT phases. See sections refer- enced in Table 26 for details of the extended messages.

Table 25: Extended message format

Bit	7	6	5		4	3		2	1	0
Byte


0				EXTENDED MESSAGE (01h)

1			EXTENDED MESSAGE LENGTH (n–1) [1]

2				EXTENDED MESSAGE CODE [2]

3-n			EXTENDED MESSAGE ARGUMENTS [3]

1.The EXTENDED MESSAGE LENGTH field specifies the length in bytes of the Extended Message Code plus the extended message arguments to follow. The total length of the message is equal to the EXTENDED MESSAGE LENGTH plus two. A value of zero in the EXTENDED MESSAGE LENGTH field indicates 256 bytes follow.

2.The extended message codes are listed in Table 26.

84	Parallel SCSI Interface Product Manual, Rev. A

Image 98

Seagate Ultra 320 manual Message format, One-byte messages, Two-byte messages, Extended messages, Extended message format

Contents

Parallel Scsi Interface Page Parallel Scsi Interface Page Revision status summary sheet Revision Date Writer/Engineer Parallel Scsi Interface Product Manual, Rev. a Table of Contents Parallel Scsi Interface Product Manual, Rev. a Logical characteristics Wide transfer Message system specification SPI information units Miscellaneous Scsi bus characteristicsScsi commands Drive features List of Figures Xii Parallel Scsi Interface Product Manual, Rev. a How to use this interface manual Interface requirements Scope of Scsi standards General interface description Applicable standards Glossary Scsi client-server modelPage Page Page Page Page Page Keywords Message Name Hex Code Number Physical interface characteristicsSummary of Scsi messages Scsi bus Scsi IDs and associated Scsi bus arbitration priorities Priority Scsi bus signals overview Pcrc signal usage requirements Scsi target usage of Pcrca SE signals Signal statesSignal values LVD signals OR-tied signals Voltage and current definitions Data bit P cable Data bit a cable I/O DB15-8 Scsi bus phase Signal sourcesSignal sources DB7-0 Timing Scsi bus timingScsi bus control timing values in nanoseconds Reference Type Value ns Unless Timing description Nanoseconds unless otherwise noted Scsi bus data and information phase ST timing valuesTiming values for negotiated transfer rate Timing values for negotiated transfer rate in nanosecondsPage ATN transmit setup time Min Receive Scsi bus data and information phase DT timing values Interconnect and system margin Total transmitter error budget Receiver errorsFast-160 Fast-320 Comments Crosstalk time shift ATN transmit setup timeATN receive setup time ISI of data Bus set delay Bus clear delayBus free delay Bus settle delay PCRC receive setup time Flow control receive setup timeFlow control transmit setup time PCRC transmit setup time Power on to selection Data release delayPhysical disconnection delay QAS arbitration delay Receive internal hold time Receive internal setup timeReceive setup time Receive negation period Reset to selection Reset delayReset hold time Residual skew error Strobe offset tolerance System deskew delaySkew correction range System noise at launch Measurement points Clocking methods for data transfers LVD measurement points ST latching data vs. DT latching data Paced transfer on a Scsi bus DT synchronous transfer example Synchronous transfers Data transfer modesAsynchronous transfers Paced transfers Data group transfers ST Data phase parallel transfersDT Data phase parallel transfers Information unit transfers Negotiation Negotiation algorithm Negotiable fields and effects of successful negotiation When to negotiateNegotiable fields Negotiation message pair Field name Field Name Message Numerically Responding message requirementsResponse shall be Transfer agreements Value Description Message Transfer rate Transfer period factorTransfer period factor relationships Synchronous 12.6 REQ/ACK offset Transfer width exponent Iureq Protocol optionsProtocol options bits PPR negotiation setting Iureq to zero Bus phases resulting from Iureq changesSdtr negotiation PPR negotiation setting Iureq to one PPR negotiation keeping Iureq set to zero RTI Retain Training Information WrflowRdstrm Pcompen Transfer Period Negotiable field combinationsTransfer Message restrictions Negotiation message sequences Parallel Scsi Interface Product Manual, Rev. a Unexpected and expected bus free phases Scsi bus phases overviewBUS Free phase Expected bus free phases Arbitration and QAS overview Normal Arbitration phase QAS phase overview QAS protocol Selection phase Selection overview Information unit transfers disabledInformation unit transfers enabled Selection using attention condition timeout procedure Physical reconnection Reselection phaseReselection phase overview Physical reconnection timeout procedure Scsi bus fairness Signal Phase Direction of transfer Comment Information transfer phasesInformation transfer phases ST synchronous data transfer Asynchronous transferSynchronous transfer DT synchronous transfer Information unit transferPage Data group data field transfer Page Page Page Paced transfer Paced transfer training pattern Start of section B DT Data in phase training patternStart of section a DT Data OUT phase training pattern Start of section C 3.2 P1 data valid/invalid state transitions Starting pacing transfers at end of training pattern Starting pacing transfers with no training pattern Ending pacing transfers Paced information unit transfer Deskewing Wide transfer Command phase Data phase Status phase Message phase Message OUT phase Signal restrictions between phasesMessage in phase exception condition handling Message OUT phase exception condition handling Scsi bus phase sequences Scsi bus phase sequences overview Hard reset or protocol error Reselection Selection Arbitration DT Data Message OUT Data bus protection ST data bus protection using parityParity checking rules for Selection and Reselection phases Data bus protection overview Error detection capabilities Order of bytes in the CRC field General message protocols and formats Message formats Two-byte messages Message formatOne-byte messages Extended messages Link Control Messages Link Control message codes Message categoriesExtended Message Codes Key Identify message format DisconnectIdentify Bit Byte Ignore field definition Ignore Wide ResidueIgnore Wide Residue message format Invalid data bits Message Parity Error Initiator Detected ErrorLinked Command Complete Message Reject Modify Data Pointer message format Modify Bidirectional Data Pointer Modify Bidirectional Data Pointer message format No Operation Parallel Protocol Request Parallel Protocol Request message format Value 00h 01h-FEh FFh Description Timing values Use QAS for arbitration Use ST Data in and ST Data OUT phases to transfer dataValid protocol options bit combinations Parallel Protocol Request messages implied agreement Save Data Pointers Restore PointersQAS Request Synchronous Data Transfer Request Synchronous Data Transfer Request message format Sdtr messages implied agreements Task Complete Target initiated Sdtr negotiationInitiator initiated Sdtr negotiation Wide Data Transfer Request Wide Data Transfer Request message format Responding Scsi device Wdtr response Implied agreement Wdtr message implied agreementTarget initiated Wdtr negotiation Task attribute messages Task attribute message overview and codes ACA message format Task attribute message codesACA Auto Contingent Allegiance Head of Queue Ordered Abort Task Task management messagesTask management message codes Task management message codes 0Eh Abort Task SET Logical Unit ResetTarget Reset Clear ACA Miscellaneous Scsi bus characteristics Bus reset condition Hard reset Reset events Asynchronous condition recovery Active pointers Saved pointers Incorrect initiator connection Command processing considerations and exception conditionsAsynchronous event notification Unexpected Reselection phase SPI information units Information unit transfer logical operationsPage Parallel Scsi Interface Product Manual, Rev. a 115 116 Parallel Scsi Interface Product Manual, Rev. a Parallel Scsi Interface Product Manual, Rev. a 117 SPI command information unit SPI information units SPI command information unit Bit Byte Task Attribute Codes Description Task Management flags Codes Description SPI LQ information unit SPI LQ information unit Bit Byte Bidi Direction F0H SPI LQ information unit typeCodes Type Description FFh AllPage SPI data information unit Bit Byte SPI data information unitSPI data stream information unit SPI status data stream information unit Bit Byte Reserved Reserved for FCP SPI status information unitSPI status information unit Bit Byte Packetized Failures code Codes Description SPI command information unit fields invalidPacketized Failures field Bit Byte Task management function not supportedPage 130 Parallel Scsi Interface Product Manual, Rev. a Reserved Command implementation requirementsCommand Descriptor Block CDB Page Fixed and variable length Command Descriptor Block formats Additional CDB Data if required Typical CDB for 12-byte commands Bit ByteTypical CDB for 16-byte commands Bit Byte Typical variable length CDB Bit Byte Operation Code 7Fh Additional CDB Length n-7Page Link b Control field Bit Byte LastNaca a Status Status precedence Command examples Single command example Disconnect example Disconnect example Timing examples Auto Contingent Allegiance or Contingent Allegiance Overlapped commands Clearing an Auto Contingent Allegiance condition Asynchronous Event Reporting Incorrect logical unit selectionSense data Autosense Unit Attention condition Queued tasks formerly queued I/O processes Target hard resetLogical unit reset Untagged task queuing Tagged task queuing Parameter rounding Programmable operating definition Incorrect initiator connection Self-test operations Default self-testS.M.A.R.T. system Short and extended self-tests Self-test modes Foreground modeBackground mode Exception commands for background self-tests Device type a Command Reference All device types Protection code Self-test mode summaryError detection for asynchronous information phases Covered signals Word Location Signal MeaningPage Protection code usage Error detection propertiesCode description Enabling protection code checking Error handlingProtection code transmission Disabling protection code checking Case 1-Power off during removal or insertion SPI-3 equivalent term SCSI-2 term SPI-3 to SCSI-2 terminology mappingSPI-3 to SCSI-2 terminology mapping Index Code value reserved Disconnect privilege 148 domain 5, 9 dormant Initiator 3, 6, 14, 131, 140 faulted Multidrop 7 multimode Page Scsi Page Wdtr 40 170 Parallel Scsi Interface Product Manual, Rev. a Page Seagate Technology LLC