>Think of the on/off board a a "SCSI Terminator for the mother board".
>The serial electronics on the mother board need to "talk" to something
>--- either a modem board, or a (less complicated/less expensive to
>manufacture) on/off board.
This simply isn't true, from two perspectives: first, the on-off board has
nothing whatsoever on it other than the two pushbuttons for reset and power
(I have one sitting on the desk here). Other than the three pins (one of them
ground) that connect to those switches, none of the connectors go anywhere,
not even to ground. Thus there's no electrical difference between the card
existing and not existing, until a switch is depressed. This also implies
that you can run a Duo without the card if you have some way to turn it on
(like an external keyboard and appropriate dock).
Second, serial communications controllers don't need termination or to "talk"
to something. :)
The on-off board seems to exist simply because the modem had to go somewhere,
and the place it had to go was also where the power key has to go (the reset
switch is where it is mostly because it shares a pin with the power key).
I imagine there wasn't a lot of room to maneuver for the Duo designers.
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