Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!ucbcad!ucbvax!UIAMVS.BITNET!ASTVKBPA 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!