On Thu 12 Apr 2018 at 21:40:59 +0200, Johnny Billquist wrote:
> On 2018-04-12 16:06, Paul Koning wrote:
> > I thought it was 15 devices -- 4 bit LUN number with the value 7 reserved 
> > for the controller.
> 
> The LUN in SCSI is for something that looks like subunits or partitions. The
> SCSI ID, which is the primary identifier, is a 3 bit number, giving you a
> max of 8 devices on narrow SCSI, and it's a 4 bit number on wide SCSI. You
> often had three jumpers on the devices, to select the ID, in the old days.

My vague recollection is that one wire of the data bus (either 8 or 16
lines) for each device during bus arbitration, hence the limitation to 8 (or
16 for wide SCSI).

-Olaf.
-- 
___ Olaf 'Rhialto' Seibert  -- Wayland: Those who don't understand X
\X/ rhialto/at/falu.nl      -- are condemned to reinvent it. Poorly.

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