List of SCSI message codes

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A SCSI message code is a computer term which defines how SCSI devices send interface management information. The message code comprises one or more bytes.

List of message formats[edit]

The first byte of the message determines the format:

Value Message format
00h One-byte message (COMMAND COMPLETE)
01h Extended messages
02h-1Fh One-byte messages
20h-2Fh Two-byte messages
30h-7Fh Reserved
80h-FFh One-byte message (IDENTIFY)

List of message codes[edit]

Value Message name Format
00h COMMAND COMPLETE
01h EXTENDED MESSAGE 01nnyy... - nn is the length, yy is the extended message code
02h SAVE DATA POINTER
03h RESTORE POINTERS
04h DISCONNECT
05h INITIATOR DETECTED ERROR
06h ABORT
07h MESSAGE REJECT
08h NO OPERATION
09h MESSAGE PARITY ERROR
0Ah LINKED COMMAND COMPLETE
0Bh LINKED COMMAND COMPLETE (WITH FLAG)
0Ch BUS DEVICE RESET
0Dh ABORT TAG
0Eh CLEAR QUEUE
0Fh INITIATE RECOVERY
10h RELEASE RECOVERY
11h TERMINATE I/O PROCESS
12h-1Fh Reserved
20h SIMPLE QUEUE TAG 20nn - where nn is the queue tag
21h HEAD OF QUEUE TAG 21nn - where nn is the queue tag
22h ORDERED QUEUE TAG 22nn - where nn is the queue tag
23h IGNORE WIDE RESIDUE 230i - where i is the number of bytes to ignore (can be 1, 2 or 3)
24h-2Fh Reserved for two-byte messages
30h-7Fh Reserved
80h-FFh IDENTIFY

List of extended message codes[edit]

Value Length Message name Format
00h 05h MODIFY DATA POINTER 010500aaaa - where aaaa is added to the current data pointer
01h 03h SYNCHRONOUS DATA TRANSFER REQUEST 010301pprr - where pp is the period and rr is the REQ/ACK offset
02h nn Reserved - was formerly used for the EXTENDED IDENTIFY message in SCSI-1 01nn02...
03h 02h WIDE DATA TRANSFER REQUEST 010203ee - where ee is the transfer width exponent
04h-7Fh Reserved
80h-FFh Vendor-specific

References[edit]