Re: PATCH: Different SCSI ordering for WIDE SCSI chains.

Paul Slootman (
Wed, 2 Dec 1998 08:54:11 +0100

On Tue 01 Dec 1998, Brandon S. Allbery KF8NH wrote:
> In message <>, Paul Slootman writes:
> +-----
> | In article <> wrote:
> | >When mixing narrow and wide devices you must only use the first eight
> | >scsi ids. If you don't, scsi arbitration will not work correctly. The
> | >scsi bus uses the data bits to arbitrate for the bus. A narrow device
> |
> | This is not true. Your narrow devices will simply see that they are not
> | selected when one of the wide devices on address 8 and up is selected,
> | and ignore it. As long as you keep your adapter on a low address, all
> +--->8
> IIRC, if the host adapter is issuing commands and then disconnecting, a
> narrow device can send a response while a wide device is already talking on
> the bus because it won't see the wide device, resulting in a collision.

This won't happen, because the bus phase will show the narrow device
that it is not free. Using the data bits for selecting a device is only
a very small part in the entire arbitration sequence.

Paul Slootman

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