sdb@shark.UUCP (Steven Den Beste) (10/14/83)
The select (either switch or software) on the expansion interface is used to choose which slot gets the two predefined select lines that the COCO provides to the cartridge. All of the slots are actually on the bus at all times, but it is assumed that, just as all good hardware should be, that they are all tristated when not being used. However, if you want to do your on address decoding, you can access the bus from any slot anytime you want. This is what the X-pad does. Steve Den Beste