On Sun, Jan 20, 2019, 4:11 PM Warner Losh <i...@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 <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 >> >
