Dave,
I was thinking of a second and third active bay for a 500 series scope. I think it would be easier to do with a 7000 series scope, in terms of having interface support for extra bays, but I¡¯m sure that bandwidth would kill you over the longer backplane wire runs. It seems like it should be easier to do this at the lower bandwidth of the 500 series (I¡¯m looking at the 15 MHz 533A, but even 33 or 50 MHz shouldn¡¯t be too challenging).
I¡¯ve been cleaning and repairing a 500/53A scope-mobile rack and there¡¯s lots of open space in there, as well as a number of cut outs that suggest there were plans to do other things with the space. I¡¯d be willing accept an arrangement where all three plug-ins were powered up, but only one was active at a time, but I¡¯d prefer to be able to use multiple plug-ins simultaneously (hence the question about how a multichannel plug-in like the CA decides when to put which channel on the signal lines of the plug-in interface).
¡ªJeff Dutky
