In order to use a  monochrome display, one does not need the color boards
SPX or GPX. Duh.
However the composite monochrome output of the MB  is on pin 9 and grd is
on pin 3, if you make your own cable! Or if you use an original  DEC cable
use  type  BC23K-03, single BNC to DB16 Din Pin connector cable.

the DEC type BC23J-03 is a  three BNC to DB16 cable that presumably works
with the colour boards, or framebuffers.
The pinouts there are:

2  => GRD
1  => Red
10 => Green
11 => Blue



I have been fooled into countless hours of bughunting until I found that
out! Someone should put that on the VS3100 hardware page....


Now if only someone would be able to tell me how to setup/install/load  an
xserver or a GUI, even only a monochrome in netBSD 1.5, or wskbd, wscons,
wsmouse on a VS3100/76, or VLC 4000, I'd be all set!

Fred