[Open-graphics] hardware feature suggestion for the PCI analyzer

[Dieter]

It would be useful if the OGD could generate a pulse suitable
for triggering an oscilloscope.  This would be useful if the
user suspects analog problems such as a line floating, or two
drivers enabled at the same time and 'fighting', or a glitch.

There could be a scope trigger delay time after the logic analyser
trigger.  The user could easily get the number of samples
from the display.  This would be easier than futzing around
with the delayed sweep, and would work with scopes that don't have
a delayed sweep feature.

To trigger the scope before the LA triggered, the user could find
a way to trigger the LA sooner, find a time machine :-) , or obtain
a delay line for the signal (aka the plugin full of coax).  Those
newfangled digital scopes probably provide this feature.