Actually, you may not _need_ an extender. I've worked on plenty of devices for which I don't have the extender boards, and what I do is pull the board of interest and tack-solder short wires onto the ppoints I am interested in. Put the board back in place and monitor the free ends of the wires with 'scope or logic analyser. Then pull the board again and move the wires to new points, based on the resutls fo the first measurements. Normally it only takes me 2 or 3 'goes' to find the faulty IC. Obviously this doesn;t work for very high-speed stuff where the extra capacitance of the test wires would be an issue. But I think it might well be OK for most Multibus 1 stuff. I've not followeed that link, but if that;'s a product that's still available, why not buy it? -tony