Date   : Tue, 17 Apr 2007 10:31:59 -0500
From   : julesrichardsonuk@... (Jules Richardson)
Subject: Acorn SCSI board arbitration

Phil Blundell wrote:
> On Tue, 2007-04-17 at 15:17 +0100, Richard Gellman wrote:
>>> In the Master AIV version? In the Winchester flavour there seems to be no
>>> way
>>> for a host to just assert just one of the 8 data lines (corresponding to
>>> the
>>> ID of that host) and leave the other lines in a high-impedance state where
>>> another host on the bus is free to assert them.
>> Hmm. Certainly writing to the data bus is possible, but two hosts arguing
>> over zero-state bits might cause a "heated" discussion....
> 
> I thought SCSI used open-collector signals thoughout for that reason.

I think you may well be right there... and if I'm understanding correctly then 
multiple OC outputs can be tied together without anything exploding - and I 
think the 7438 gates that are used in the Winchester controller have OC outputs...

hmmmm... <scratches head>