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From: ASTVKBPA@UIAMVS.BITNET (Val Bluestein)
Newsgroups: comp.sys.apple
Subject: Re: Expansion Box
Message-ID: <8712021731.aa12058@SMOKE.BRL.ARPA>
Date: Wed, 2-Dec-87 22:11:11 EST
Article-I.D.: SMOKE.8712021731.aa12058
Posted: Wed Dec  2 22:11:11 1987
Date-Received: Sun, 6-Dec-87 08:23:25 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 34

Ray,
 I've never done anything like the slot switcher but...
What I would try is switching the I/O select, Device Select, and
I/O Strobe (1,41,20).  These are the signals that tell the cards
if it is being accessed,  If these are kept low (I think, take a look
at them with a scope or look in a manual to see if they are active high
or low), the card will never respond.  The power lines probibly don't
need to be switched (unless you are haveing power problems). You might
want to filter them through a AND gate (OR gate if they are active low)
                    |
                    <
                    >   pull down resistor
                    <
                    >
                    |
                    |   +-
                    +---| \
                    |   |  |-----   IOSTB
       IOSTB------- | --| /
                    |   +-
                    |
                    |   +-
                    +---| \
                    |   |  |---- DEVSEL
       DEVSEL------ | --| /
                    |   +-
                   etc

This will keep the lines low unless you pull the control input high
Hope you have luck, keep us posted.
                             Val Bluestein

Disclaimer: I think this is right, but if your machine goes poof!
            you never heard of me!