Quick arbitration questions

Bill Galloway BillG at breatech.com
Mon Feb 1 18:08:52 PST 1999

* From the T10 Reflector (t10 at symbios.com), posted by:
* "Bill Galloway" <BillG at breatech.com>

You are looking at the correct version of SPI-3. You have found a few of the
many problems with QAS.


Section "QUICK ARBITRATION phase" has lots of problems. The
section as worded violates most asynchronous information transfer rules.
The initiator does not assert ATN until it gets ready to negate ACK, so the
target (and snoopers) cannot look at ATN on the assertion on ACK. The phase
lines are required to remain stable until after the REQ/ACK handshake is
complete, I hope QAS does not intend to violate this as well. The wording
should be (IMHO), the target shall negate the phase lines within one system
deskew delay after detecting the negation of ACK.

I know most of you have heard me harp on this before but I still do not see
how a device with a 32ns Async REQ/ACK filter is going to snoop an 8ns

2) first paragraph e) happens in parallel with first paragraph c)
and d)

3) Since e) is really in parallel with earlier steps the target would still
be driving BSY.

4) See answer to 1)

5) true

6) true

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at breatech.com

-----Original Message-----
From: owner-t10 at Symbios.COM [mailto:owner-t10 at Symbios.COM]On Behalf Of
Andrew Roy x2180
Sent: Monday, February 01, 1999 6:35 PM
To: T10 Reflector
Subject: Quick arbitration questions

* From the T10 Reflector (t10 at symbios.com), posted by:
* Andrew Roy x2180 <andrewr at eng.adaptec.com>
Greetings, all!

These questions are based on SPI-3 revision 2 (16 Nov 1998).  If I
should be looking at a later revision, please let me know what revision
and how to get it.  Thanks very much.

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