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.
Warner On Sun, Jan 20, 2019, 3:16 PM Warner Losh <i...@bsdimp.com wrote: > > > On Sun, Jan 20, 2019 at 12:57 PM Marvin Johnston via cctalk < > cctalk@classiccmp.org> wrote: > >> >> > 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. >> > > 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 >
