Sync on Green RGB video

Douglas Taylor dj.taylor4 at
Sat Nov 18 21:57:47 CST 2017

On 11/18/2017 6:44 PM, william degnan wrote:
> On Nov 18, 2017 4:09 PM, "Douglas Taylor via cctech" 
> <cctech at <mailto:cctech at>> wrote:
> >
> > I have a couple of vaxes that output 'unique' video, Alpha 3000 300, 
> Alpha 3000 400, Vax 4000 VLC, and Vax Station 3100 M76.
> >
> > The Alpha and VLC each have a 3W3 type of connector and the 3100 has 
> a 15 pin DEC designed connector.
> >
> > What does it take to connect these to inexpensive, modern VGA light 
> weight monitors?
> >
> > Doug
> >
> I have played around with that problem.  If you have a converter to 
> get into a VGA port a newer high-end vga display will be able to 
> adjust, but not a cheap one.  Because I use my vice vga/digital 
> display for mode stuff, I use a huge SGI color display for all of my 
> 3w3 outputting systems and I just switch the cable around.  If you 
> could imagine 5 or 6 systems clustered around the one display.
> I am sure someone here has a technical explanation, but in a nutshell 
> the 3W3 world signal isn't the same as a standard vga and cheap vga 
> displays can't handle the refresh rate.  Someone will prob. refine my 
> answer but that's why you can't just stick an adapter on there.
> Bill Degnan
> twitter: billdeg
> <>
I ran into a similar comment somewhere on the internet somewhere (it's a 
big place) that you had to make sure that the LCD monitor supported the 
H,V rates put out by the DEC video frame buffer.

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