If you wanted to host identical devices, for example two VIA's, it's where multiple BSEL come in.

So one VIA would be on BSEL0 and another on BSEL1.

All the SBC's have one expansion slot, so only one BSEL.

But a more advanced board (aka motherboard) would have one bus select for each slot.

So the additional slot would have BSEL1 replacing the BSEL0 on the first one.

Ken Willmott cooked this up so that most of the decode could be shared amongst the add on boards.

A good example of this is the VIA board, which has no decode logic on it at all.

Just a VIA and bypass caps.

Return to SST-6809