Gerry Houlder Gerry_Houlder at
Mon Aug 15 16:32:00 PDT 1994

This is the change proposed by Giles:
>"The first message sent by the initiator after the SELECTION phase
>shall be an IDENTIFY, ABORT, or BUS DEVICE RESET message. If a target
>receives any other message it shall issue a BUS FREE request."
>All that is needed is to reword the last sentence as follows:
> "If -ATN IS NOT ACTIVATED OR IF the target receives any other
> message..."    (CAPS indicate the change.)
This change means that SCSI-3 targets cannot function in SCSI-1 or SCSI-2
systems that use selection without ATN. This will absolutely require initiators
to put the drive in "SCSI-2 mode" or "SCSI-3 mode" before installing it in the
system. Or it could require target manufacturers to support even more different
and unique code versions than we have to now. I don't think this is a good
idea. The target manufacturer's problem of selling a SCSI drive to a
distributor and having that drive work in a wide variety of SCSI-1, SCSI-2, or
SCSI-3 systems and have it be able to plug and play (not necessarily a
reference to the Plug and Play SCSI proposal) will become impossible.
Distributors don't like to stock more than one version of a drive. It seems
like every time they do, their customer invariably orders the wrong one
(Murphy's law reigns supreme) and the distributor gets lots of "no trouble
found" returns. This results in trouble for lots and lots of perfectly good
drives. This is too high a price to pay for protection against a much rarer
hardware fault.
Gerry Houlder -- Gerry_Houlder at
Seagate Technology   -   920 Disc Drive   -   Scotts Valley, CA 95066 USA
Main Phone 408-438-6550   -   Email Problems postmaster at
Technical Support: BBS 408-438-8771  Fax 408-438-8137  Voice 408-438-8222  

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