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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