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Comment by mikepurvis | Hacker News Reader

Can’t you still just use a real CRT? Or is it then just back to the latency question?

CRTs wear out with use, so they're only getting rarer by the day. The electronics can mostly be fixed, but the tubes can't. You can extent their lives a bit, but you're only delaying the inevitable. When it's gone (too low brightness, burn-in, bad focus), there's nothing that can be done about it to get it back to the way it was when it was new.

That's almost true, but just almost. Behold: https://colorvac.de/service/

There was some repair available. At very least, the neck could be cut off, and the electron gun bits replaced with new.

According to the Vintage Television Museum near Columbus, Ohio, the last company in the US to be able to do this closed in 2010, and the last one remaining in Europe closed in France in 2013. (I myself don't know if there are any in some other corner of the world.)

The museum did succeed in getting a bunch of the repair equipment from the shop in France, and one person involved was even trained there, but it's been a very long process.

Currently, the equipment seems to be in Maryland in the care of a person named Nick Williams. The last update I can find from him[2] is a few years old, and expressed concern about the war that had recently begun in Ukraine affecting the supply of electron guns.

tl;dr, it may still be possible to repair some aspects of some CRTs, and doing so is apparently not a completely-lost art -- yet.

[1] https://www.earlytelevision.org/crt_project.html

[2] https://www.earlytelevision.org/nick_report_5-1-2022.html

Colorvac.de is in Germany

Every small city used to have a repair shop that could fix them.

Were there really companies repairing the phospher wearing out?

Repairing the tvs, sure, but i find it hard to believe there were repair shops for the issue parent was mentioning.

No. Repairing phosphors require complete removal of phosphor layers and re-application using basic multi step deposition for RGB strips, on the inner surface of the tube. That's not a shop repair.

Re-adjust, not fix.

For me they are weirdly hard to obtain. Don't show up in second hand shops. Ebay shipping is prohibitively expensive.

Interesting. I still have a bunch showing on my local Facebook Marketplace, but who knows what shape they’re in plus it probably varies a lot from city to city.

I can well imagine that it’s gotten expensive finding a quality one (eg trinitron) of reasonable size.

They are truly dying out. Wish I'd kept my color c64 monitor -- it would probably be worth a lot now (or at least would be awesome to use for retro purposes).

They don't show up in second hand shops because their value is essentially negative. If it doesn't sell, you have to pay to dispose it.

Who's spreading that CRT latency thing? Latencies for CRTs are in nanoseconds.

Right but you still have the latency of frame buffers inside the emulator, plus more again when that’s converted out to analog, especially if an HDMI connector is still in the mix— ideally you’d do this on original hardware or at least a PC with a graphics card that has native s-video or VGA outputs.

You only need one pixel worth of RAM to display HDMI input into a CRT. You don't need to buffer the whole thing, at all. Especially if you were driving the tube with your own driving circuit.

Most monitors and TVs do buffer at least a whole frame because of the processing, scaling, etc that they're doing: https://www.rtings.com/monitor/tests/inputs/input-lag

That said, yeah, in the special case of an HDMI-driven CRT that was specifically designed with ultra low latency in mind, you could buffer way less than a frame— though I imagine you'd probably want to buffer at least a line at a time just for sanity with the timing of driving the electron gun. And obviously this would depend on the HDMI picture resolution exactly matching that of the CRT.

HDMI is RGB plus clock in 4 differential pairs. Fundamentally you just need 3 shift registers with reset tied to clock. Out comes the signal and you wire that to RGB electron guns through an E24 resistors assortment pack.

LLMs probably don't know enough about them to be useful in this discussion. Classic Google Search would be better. Yours fixating on pixels shows that.

I think the difference here is more that I'm talking about the practical reality of today's display interfaces (both sides have a full frame in memory, typical overall latency is 5-50ms), whereas you're discussing what could be theoretically possible with dedicated emulation hardware that streams out an unbuffered HDMI signal and an HDMI-supporting CRT that operates similar to a modern VRR gaming display.

There have been some low-latency demos using bare metal development on the raspberry pi. But DOSbian ain't it, which is the topic at hand.

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