HP-IL Video converter 80columns; what usual/standard screen to connect?

[floppy]

Hello,
in order to make a video of the magic "snake" game in HP71B Forth (some persons could see it working in Stuttgart 2024 in VIDEO80 application on a notebook), I found a HP-IL Video converter 80columns around stuttgart, unfortunately no screen till now. So now,
- has anybody a screen, around Stuttgart-Germany, for lending few days/weeks which can be connected to such HP-IL 80column video converter device?
- if not, what kind of usual screen device should work connected to such a device? (they I will ask my friends/colleagues.. or eBay/Kleinanzeigen)
Any recommendation is welcomed for screens to be lend or bought.

[toml_12953]

(10-27-2024 05:00 PM)floppy Wrote:  Hello,
in order to make a video of the magic "snake" game in HP71B Forth (some persons could see it working in Stuttgart 2024 in VIDEO80 application on a notebook), I found a HP-IL Video converter 80columns around stuttgart, unfortunately no screen till now. So now,
- has anybody a screen, around Stuttgart-Germany, for lending few days/weeks which can be connected to such HP-IL 80column video converter device?
- if not, what kind of usual screen device should work connected to such a device? (they I will ask my friends/colleagues.. or eBay/Kleinanzeigen)
Any recommendation is welcomed for screens to be lend or bought.

Any monitor or TV that accepts standard composite connections (usually using an RCA jack) will work.

[Dave Frederickson]

(10-27-2024 05:31 PM)toml_12953 Wrote:  Any monitor or TV that accepts standard composite connections (usually using an RCA jack) will work.

The vintage HP video interfaces seem to exhibit a lot of jitter on modern monitors. I suspect that noise is filtered out by the older monitors with lower bandwidth. There was quite a discussion on this topic at HPSeries80 on groups.io.
https://groups.io/g/hpseries80/topic/76321012#msg4986

I acquired an Extron DVS 304 (RGB) from eBay and it cleared up the jitter nicely on all of my video interfaces, except the Mountain Computer HP92198, which displays fine on my vintage HP 82912A.

I suggest a vintage monitor.

[brouhaha]

(10-27-2024 05:00 PM)floppy Wrote:  - if not, what kind of usual screen device should work connected to such a device?

These work best with a monochrome (b&w, green, or amber) CRT monitor that takes composite video input at standard analog television scan rates. These were commonly used for closed-circuit TV in security systems, and of course for old personal computers. Any analog monochrome CRT that was used with 8-bit microcomputers such as the Apple II, Atari 400 or 800, or Commodore 64 would be fine, though most users of those microcomputers preferred color monitors.

Color CRT monitors are not recommended unless they are special high-resolution monitors, but still use the standard analog television scan rate. Those are quite uncommon, though high resolution broadcast and industrial studio monitors did exist, such as the Sony PVM-8045Q.

The video scan frequencies generated by the HP-IL video interfaces do not match up exactly with the broadcast standards, so using them with LCD monitors often doesn't work as well.

[brouhaha]

(10-28-2024 01:32 AM)Dave Frederickson Wrote:  

(10-27-2024 05:31 PM)toml_12953 Wrote:  Any monitor or TV that accepts standard composite connections (usually using an RCA jack) will work.

The vintage HP video interfaces seem to exhibit a lot of jitter on modern monitors. I suspect that noise is filtered out by the older monitors with lower bandwidth.

I don't think it's noise. The video output is digitally driven and crystal-locked, so it is actually quite stable and noise-free. I think the generated video timing just deviates enough from what modern LCD televisions and monitors expect that they can't sync as well.

LCD monitors and televisions expect full compliance with the actual broadcast standard timing (e.g., RS-170A in the NTSC world) that they don't deal gracefully with deviations. Broadcast and cable channels, DVD output, etc. is generally in near perfect compliance with the standards.

VCR output can have some timebase variation for electromechanical reasons, though they generally servo the motors to a crystal requency reference, and any instantaneous timing is still fairly close and proportionate.

Microcomputers and their accessories usually were only designed to satisfy analong monitors, which were much more tolerant of signal variations. They were not required to meet broadcast standards, and when they were used as broadcast sources, expensive piece(s) of studio equipment (proc amp and gen lock) were used to clean up the signal and correct timing errors.

[MeindertKuipers]

I do not have the video interface anymore, but when I did I used a TV capture/tuner for USB. These usually allow you to tweak the timing a bit and I had good results, and mine had a composite video input.

[Sylvain Cote]

(10-28-2024 10:04 AM)MeindertKuipers Wrote:  ... I used a TV capture/tuner for USB ...

I use HP composite monitors (82912A & 82913A) but I also use this Amtake RCA to HDMI converter.

[Dave Frederickson]

(10-28-2024 05:20 PM)Sylvain Cote Wrote:  

(10-28-2024 10:04 AM)MeindertKuipers Wrote:  ... I used a TV capture/tuner for USB ...

I use HP composite monitors (82912A & 82913A) but I also use this Amtake RCA to HDMI converter.

From personal experience and from listening to the guys on HPSeries80 I gather the little USB converters don't do a very good job which is why I ended up with a Extron unit.

Edit: I agree with Eric, it's probably a timing issue which the USB converters won't do much about. The Extron DVS 304 is a video scaler so I'm guessing it generates the proper timing pulse for the selected resolution. And there's one on eBay for $21 + shipping from New York.

[Sylvain Cote]

(10-28-2024 06:51 PM)Dave Frederickson Wrote:  

(10-28-2024 05:20 PM)Sylvain Cote Wrote:  I use HP composite monitors (82912A & 82913A) but I also use this Amtake RCA to HDMI converter.

From personal experience and from listening to the guys on HPSeries80 I gather the little USB converters don't do a very good job which is why I ended up with a Extron unit.

FWIW, I have just successfully tried my converter between a DELL U3223QE 32-inch 4K monitor (HDMI) and a MC00701A unit connected to a HP-71B.
For sure, the quality of the signal is composite not 4K progressive, but it is at least as good, if not better, compared to the rendering on the original HP composite monitor.

[Mark Power]

I don't have experience of the 80 column interface, but with HP 82163A 40 column interface I also use the Amtake RCA to HDMI interface suggested by Sylvain. £9 in the UK from Amazon.

Taking the HDMI into my Dell 4K monitor the picture is rock solid. However, when I tried the composite output from a BBC Micro into the Amtake it kept losing sync, a known issue apparently, due to very poor timing circuitry and poor crystal in the BBC. It is possible that you might have this problem with different HP-IL Video Interfaces.

To record the output of the HP-IL video interface I take the HDMI from the Amtake into a Guermok HMDI to USB-C Video Capture Card (it is more of a dongle really) - £19 from Amazon in the UK. This goes into my MacBook Pro and appears as a camera, so you just record it with QuickTime or any other suitable recording tool.

[Maximilian Hohmann]

Hello,

after some searching I finally found my video interface. Unfortunately it is not the 80 column version, but the HP-82163B with 32 columns and 16 lines, the "B" stands for European TV format (PAL / 50Hz).

In the garage I also found a long forgotten HP-35731B green monitor which had been sitting in the same place since the year 2000 when we moved in. I had bought it in the late 1980ies in a long gone computer surplus store close to the venue of our Stuttgart meeting last weekend, in the hope to connect it to my HP-150 whose built-in monitor was a little too small for my taste, but there was no way to connect it.

It was very dusty and dirty from the dormice who must have built a nest on top of it during those years. I made the mistake of only cleaning it from the outside. When I turned it on, there was instant fire and smoke inside from burning dust and cobwebs... After taking it apart and cleaning it inside, it seems to work. I connected it to an HP-75C via the video interface and got only garbage on the screen initially, but adjusting the "HHOLD" trim pot on the PCB resulted in a legible (but still garbled) display. Whilst adjusting the HHOLD, a capacitor exploded in another part of the PCB, probably unrelated to the adjustment. Lucily I was wearing my reading glasses when that happened. Obviously that capacitor is not really required because nothing changed on the display when it went up :-)

So if 32x16 is enough to play "Snake" I now have the hardware to go with it.

Regards
Max

[floppy]

I will have a look (next.. days/weeks/years..) if the current HP71B SNAKE Forth program (for 80 columns) can be modified for 32 columns and how funny it is.
https://github.com/f4iteightiz/HP71B_for.../SNAKE.SRC

[Maximilian Hohmann]

Hello!

(10-30-2024 06:33 PM)floppy Wrote:  I will have a look (next.. days/weeks/years..) ...

There is no hurry, but I guess, the monitor is not really useable. While I was writing the above post I kept the monitor running (all in all maybe 15 minuters) and another component went up in smoke. Don't know what it was but it smells awful. Before I set the house on fire I will bring the unit to the recycling collection.
When I find the time I will try to connect the video interface to the TV. Last time I tried, the TV didn't synchronise to the signal, but that was over 10 years ago and a different screen.

Regards
Max

[Maximilian Hohmann]

Hello,

in the meantime I was successful connecting the old HP-IL video interface to our modern (well, sort of) TV screen. It was easier that I thought because our "integrated network receiver", i.e. the amplifier that connects the various sources like satellite receiver and DVD player to the TV and handles the audio processing and output, has an "AUX" connector under a lid on it's front panel. This is compatible with the HP interface and produces a good picture on the screen. Internally it must have an analog video to digital HDMI converter.

Regards
Max