23 May
2020
23 May
'20
7:12 p.m.
On Sat, May 23, 2020 at 10:49 PM Rob Jarratt via cctalk
<cctalk at classiccmp.org> wrote:
video
Err, no. The Pro (and Rainbow, DECmate II, etc) are TV rate. The
horizontal frequency is 15.57kHz or thereabouts. Those machines will
work with TV-rate video capture devices.
[...]
The horizontal sync has a frequency of 26.6KHz, active
low with the
high voltage 3.7V, Vertical sync is 60Hz. I don't believe that
corresponds to any known standard, does it?
I assume it's the same as the Pro video. That might not exactly match
standards. But the intensity output is an acceptable 480i monochrome signal. I've fed mine into a video capture
device and into a TV display,
both
> work. I have wondered about RGB, the I/O board does output
an RGB signal along
with Intensity, Horizontal Sync and Vertical Sync, but I don't know if I
could feed that to a monitor that accepts RGB signals as I don't know what
the voltage levels should be. I have a VR241 which seems to have suitable
inputs but I don't know if I dare send the signals from the I/O board
straight to the VR241. I can't find a manual for it.
Again the VR241 is TV rate. The inputs are, I think, the normal 1V
levels into 75ohms.
My experience is that sensible over-voltages on monitor inputs (e.g.
5V TTL signals into 1V analogue inputs) do no damage. It may not work,
if it does it may look terrible, but it won't let the magic smoke out.
-tony