Excerpts from internet.computing.netbsd.port-pmax: 23-Oct-100 Re:
VR290??  by Simon Burge@wasabisystem 
> I'll admit to knowing almost zero about VGA - do it have separate
> horizontal- and vertical-sync?  It certainly looks like a completely
> passive device.  Unfortunately my multimeter probe doesn't fit into
> the VGA socket holes so I can't tell you what goes to which pin...

I have my PMAG-B hooked up to an ancient multisync SVGA monitor with BNC
3/5 BNC inputs, however the cable that I'm using only has 3 BNC wires,
which indicates that it's probably a sync-on-green signal.  That means
that the sync is sent in the green cable, in addition to the normal
green signal. 

Fortunately, the green signal is the middle connector, so when I
accidently plugged in my video cable to the DEC backwards the image was
stable with very strange colors, indeed. :) 

Only certain SVGA monitors support this (it's not terribly uncommon, but
the cheaper ones do not).  What do the other two BNC connectors do? 
Well, for signals that are not sync on green, the H/V syncs are sent on
those pins.  You can find HD-15 devices that will do either
sync-on-green or separate sync cables.  Most PC video cards will output
separate syncs signals, and a few of the more fancy ones can be told to
do otherwise.

Cheers,

JCSmolens

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