Date   : Tue, 07 Sep 2004 11:00:06 +0100
From   : Darren Grant <darren.grant@...>
Subject: BBC Master AIV SCSI

Does anyone know any ex acorn engineers ?

In my attempt to build a SCSI interface for the Master I have been studying
reference manuals and the schematic for the SCSI board
http://www.microcomputer.org.uk/documents/schematics/AIV-SCSI_Host_Adaptor.p
ng

The thing that is puzzling me is that on the SCSI interface there is a 16MHz
Oscillator that all it does is feed a 16MHz clock signal to the main board.
I can't figure out why they bother as the Master already has an on board
16MHz Oscillator. By removing the jumper on LK6 and connecting the wire from
the SCSI card to LK6(0) we are literally replacing the inboard 16MHz clock
with the one on the SCSI card. Is the one already on-board not accurate
enough or something. It is not as though the signal is actually used on the
SCSI interface it is a completely isolated circuit.

Any ideas ?