20 Jan
2019
20 Jan
'19
3:24 p.m.
On Sun, Jan 20, 2019, 4:11 PM Warner Losh <imp at bsdimp.com wrote:
As a PS, I connected the real vr201 with a keyboard
and got the attached
photo. It looks like there is a one line error about missing keyboard in
the first line when there is no keyboard. Counting out the rows on the boot
screen confirms. So this is much closer than I thought.
The attached photo is actually the video on through the converter. Looks
like I left out that sentence, which was kinda important.
Warner
On Sun, Jan 20, 2019, 3:16 PM Warner Losh <imp at bsdimp.com wrote:
On Sun, Jan 20, 2019 at 12:57 PM Marvin Johnston via cctalk <
cctalk at classiccmp.org> wrote:
Yea. I'm going to order one or two others to see if I can get them to
work... The TRB says:
4.4.8.14 Composite Video Signal Characteristics
The composite video output provides a compatible EIA RS-170 output
generated by combining the video signal with a composite sync signal.
NOTE The use of dc coupling is not in strict agreement with the EIA
RS-170 standard. To agree with RS170, the video generator output load would
require a 10 microfarad capacitor in series with the output. Without the
capacitor, the RS-170 2 milliamp dc short circuit requirement is violated.
The composite video output has the following nominal characteristics:
I. Output impedance = 75 ohms, dc coupled to 0.0 V
2. Sync level = 0.0 V
3. Reference black level = approximately 0.3 V with a 75 ohm load
4. Reference white level = approximately 1.0 V with a 75 ohm load
5. The composite sync waveform conforms to EIA RS-170 standards.
The vertical interval is composed of six equalizing pulses, six vertical
sync pulses, and six more equalizing pulses.
The timing is as follows:
Equalizing pulse width = 2.33us +/- 50ns
Vertical pulse width = 27.28us +/- 200ns
Horizontal pulse width = 4.71us +/- 50ns
Horizontal blank width = 11.84us +/- 50ns (80-column mode)
= 12.34us +/- 50ns (132-column mode)
Front porch 1.54us +/- 50ns
This differs a little from what I've found online for RS-170 timings:
Reference Black = 0.075V
White = 1.00V
Sync = -0.40V
in some places but seems to correspond to the pics at
https://en.wikipedia.org/wiki/Composite_video almost exactly. So I'm
confused.
But I've seen other numbers as well. And the timings are roughly
consistent with the envelops suggested in an old terribly scanned doc from
the 80's that talks about video formats...
Anyway, video formats always proliferate into a cluster of almost the
same standards and it's hard to know what, exactly, to call them...
I'm not sure if this helped, or not :(
Warner
I'm trying to find a way to get my DEC
Rainbow's monochrome output
onto a
newer monitor than my aging VR201 (especially
since I zapped something
in
it and my diagnostic efforts to date haven't
fixed it).
I can't remember the video output on the Rainbow, but I wanted to do
something similar to have one setup for the S-100 machines. After
looking on eBay (before I banned them from my use), I found a device
that basically had RCA audio/video inputs with a VGA output. It also had
the advantage of having an analog TV tuner built in so I could also use
things like the old video games that had the Channel 3/4 output.
The device is buried somewhere so I can't tell you the brand.