I got a handheld emulator console as a Christmas gift. Configuring shaders that emulate crt TVs, I realized I had no mental model of how those TVs worked at all.

I’m used to “pixels are three little lights combining rgb colors”, which doesn’t work here, so I went on a rabbit hole and let me tell you, analog TVs are extremely impressive tech.

Getting an electron beam to hit a glass, making the chemicals on it spark, covering it in a “reading motion” for hundreds of lines, and doing that 60 times a second! And the beam is oriented by just careful usage of magnets. It sounds super sci-fi for an already dead, 130 years old technology.

I also learned that my childhood was a lie. Turns out that the logic in consoles of the time was tied to the speed of the beam, which in turn used alternating current’s frequency as a clock. This means that since European current changes 50 times per second rather than 60, our games played in slowmo (about 0.8x). American sonic was so much faster! And the music was so much more upbeat!

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techiferous 7 hours ago | parent | next [-]

Don't forget how they found a way to squish closed caption information into analog broadcast. The electron beam traces a path on the CRT display by drawing the odd lines from top to bottom (which draws half the image) and then the even lines (the rest of the owl) from top to bottom. While the electron beam is repositioning itself from the bottom of the screen to the top of the screen, there is a brief period of time where other data can be transmitted. That's where closed caption data was shoehorned in.

	▲	Findecanor 4 hours ago \| parent \| next [-]
		Teletext used the vertical blanking interval too. It consisted of numbered pages of text, each number input on the numpad on the remote control as a form of hypertext. Page after page was transmitted after one-another, repeatedly. It was sometimes used for subtitles, with some pages with a transparent background. Better receivers cached pages so you wouldn't have to wait for its next transmission when going to another page... Digital television formats adopted the framing from analogue formats and sends the same data in digital form within the vertical blanking interval. Many channels have stopped offering teletext. One network here in Sweden still uses it to deliver news, and I often prefer that format because the articles are concise and distraction-free. BTW. I was once asked to hack together a system for using data in the vblank period to control relays at a remote site.
	▲	butlike 4 hours ago \| parent \| prev [-]
		Technology Connections does a really good video on this on YouTube

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schnitzelstoat 8 hours ago | parent | prev | next [-]

> Turns out that the logic in consoles of the time was tied to the speed of the beam, which in turn used alternating current’s frequency as a clock. This means that since European current changes 50 times per second rather than 60, our games played in slowmo (about 0.8x). American sonic was so much faster! And the music was so much more upbeat!

Wasn't this the reason behind different versions of the game for PAL and NTSC etc.? So I imagine the games would play quite similarly, just with a lower refresh rate in Europe?

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kace91 7 hours ago | parent | next [-]

>So I imagine the games would play quite similarly, just with a lower refresh rate in Europe?

That was my assumption as well! But nope, gameplay was coupled to framerate for a surprising range of years.

You can see comparisons on YouTube, check the music of the pal/ntsc version of sonic for the genesis/megadrive.

Apparently it was still happening to some extent during the PSX era. I remember the turn meter bars in FF7 filled very slow, and this explains it.

	▲	butlike 4 hours ago \| parent [-]
		If you have an original copy of Grim Fandango, the elevator-and-forklift puzzle is impossible without a patch, since the scene moves at (iirc) the processors clock speed, so modern CPUs ran too quickly to make the action possible to solve the puzzle. This is obviously fixed in the remastered version, though

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CTDOCodebases 7 hours ago | parent | prev | next [-]

> Wasn't this the reason behind different versions of the game for PAL and NTSC etc.? So I imagine the games would play quite similarly, just with a lower refresh rate in Europe?

Yes and no. Some games play at a similar speed but some (most if I recall correctly) weren't modified for the PAL market so they play slow and the image is squashed down. Street Fighter II on the SNES (PAL) is a classic example of this.

	▲	schnitzelstoat 6 hours ago \| parent [-]
		Damn, Street Fighter 2 on the SNES is literally the first game I remember ever playing. I never knew I was playing an inferior version!

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Findecanor 4 hours ago | parent | prev [-]

The vertical resolution was also different. Some games developed for NTSC got black bars, or a silly banner in the PAL version. Many PAL games were not ported for NTSC regions at all.

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2 hours ago | parent | prev | next [-]

[deleted]

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whycome 8 hours ago | parent | prev | next [-]

What other sci fi technology is being lost on us now? I always that the complexity of the local-battery-powered copper-cable telephone exchange system was bonkers. It was the backbone for all our landline calls.

	▲	Findecanor 4 hours ago \| parent [-]
		The telephone system also powered the phone, and often worked when the power grid did not.

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mghackerlady 4 hours ago | parent | prev [-]

well, not quite with the 50hz thing. They slowed them down to run at 50hz, but they could've rewritten them to work at full speed by dropping frames