Path: utzoo!dciem!array!colin
From: colin@array.UUCP (Colin Plumb)
Newsgroups: comp.periphs.scsi
Subject: Set limits command has no relative bit?
Message-ID: <162@array.UUCP>
Date: 13 Jul 90 20:58:49 GMT
Organization: Array Systems Computing, Inc., Toronto, Ontario, CANADA
Lines: 32

I was reading ANSI X3.131 - 1986 this morning (teaching myself SCSI - it's
a hard slog) and came across command 0x33 - Set Limits.
From my notes, byte 1 (the second byte, after the opcode), has the format
LUNrrrRW
Where LUN is the LUN of the desired target, rrr are reserved bits, and
RW are read-inhibit and write-inhibit bits, respectively.  For the rest
of this series of linked commands, requests to access data out of the specified
(start, length, just like read/write) range, or that violate the conditions
(read if read-inhibit = 1, write if write-inhibit = 1) within the range
will get Check Condition status, sense key = DATA PROTECT.

This is a group 1, 10-byte command.  What I don't understand is why it doesn't
have a Relative Address bit in the lsb of byte 1.  It seems this would be
useful, for example to do a search and then restrict accesses to the blocks
containing the record in question.  It also seems unusual that the group 1
encoding would be violated.

Is this a typo in the standard, or indeed a wierd special case?  Thanks
for any advice.

Oh, BTW, I have a glossy for a WangDAT 1300 which mentions the commands
supported, including:
Locate
Read Block Limits
Read Buffer
Read Position
Seek Block
Write Buffer

Are these SCSI-2 inventions or something?  Thanks for any ideas.
-- 
	-Colin