RE: CPCI: Question on Definition of V(I/O) pin

[Ivor Bowden <ivor@peritek.com>]

At 01:36 PM 3/22/2002 -0500, Andrew.Ingraham@compaq.com wrote:

<clip>
"You shouldn't leave any of the pins unconnected.  At bare minimum, bus them
and bypass them.  And as noted, the V(I/O) pins, if kept separate, must be
used by something."
<end of clip>

They don't need to be bussed in all cases, yes? Say you used one bypassed
VIO pin to control the buffer characteristics, and just bypassed the rest.

And they don't need to be used for something if separate, yes? Say you had a
single voltage card but wanted to be sure that in the case of someone
changing the key (not so hard to do with PMC or CPCI) that your card does
not short system 3.3V & 5V together via VIO, you could use your single
voltage for the buffers and leave VIO unconnected and unbussed (except each
pin must be bypassed of course).

In either of these cases, not bussing the pins could save significant
routing resources..

-Ivor