Date   : Sun, 11 Jan 2004 21:02:18 +0000
From   : Philip Blundell <pb@...>
Subject: Re: Host adapter Issue D

On Sun, 2004-01-11 at 20:43, Mark Usher wrote:
> Just been looking at my non-reponsive Issue D Acorn Winchester Host
> adapter.
> On the reverse of the board is a single "mod" - ie. Wire link from one
> point to another and the original track link has been broken. 
> The original layout takes IC7 (74LS138N) PIN 5 to IC6 (74LS138N) PIN 15
> - modified to go to IC6 PIN 13.
> 
> Does anyone else have this mod on their board? Ie was it a factory mod.
> Can't see anything about it in the service manual.

My issue D board does not have that change.  It sounds like this
modification is probably altering the address that the board will
respond at on the bus.  The '138 is a 3-to-8 line decoder; pin 15 is the
Y0 output, and pin 13 is the Y2 output.

p.