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Take the NES, the Super NES and say, the PlayStation, they all have something in common : games on PAL regions were about 16.7% slower than their NTSC counterpart.

Now if on you play an arcade game, let's say Pang 3, the ROM for Europe region runs at the exact same speed than the ROM for Japan region.

So why did arcade cabinets designated to run in 50Hz regions didn't exhibit the same slower speed as it was the case for consoles running also in 50Hz regions ?

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    There is no direct relation between the frequency of the mains / TV system and the speed of a computing device. The only reason some (certainly not all) systems were slower in their PAL varieties is because the internals of these systems were closely tied to the video output system and it was easier and/or cheaper to just slow the entire system down by 1/6. For the manufacturers of arcade systems this was probably much less of an issue because they were integrated systems with their own video displays (not some third party television).
    – StarCat
    Dec 28 '20 at 11:06
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    I'm not sure your premise is correct: Games weren't "16.7% slower" on PAL systems. Processor clock speeds were roughly the same; the PAL version of a given game would run about as fast as the NTSC version. Only if you ran NTSC code on a PAL device you'd experience a slowdown, because code whose execution was tied to the frame rate (e.g., executed once per frame) was called less frequently. Dec 28 '20 at 11:16
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    There were also other ways for manufacturers to make their systems work with different video standards. For example, the Atari 8-bit systems ran a little under 1% slower on PAL systems (1.78MHz vs 1.79), but due to the lower frame rate, a PAL system had about 6.000 machine cycles more available per frame.
    – StarCat
    Dec 28 '20 at 11:35
  • @StarCat that makes sense
    – aybe
    Dec 28 '20 at 11:37
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    @SolomonSlow -- Yes, and in converting from 60Hz to 50Hz, this code would have to be rewritten to ensure that whatever gameplay happens in 6 frames in one version happens in 5 frames in the other. Here's a side-by-side of Super Mario Bros on the NES, showing that this is indeed doable: youtube.com/watch?v=mUI5xFEW_tg Dec 28 '20 at 15:16
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Arcade cabinets are closed systems that you simply plug into the wall; the only thing that needs to change between regions is the PSU. The internal hardware will run at the same frequencies and therefore output graphics at the same rates and sizes regardless of the region.

Conversely, consoles and home computers of the era mostly expect the user to supply their own display, which may be a television. Therefore they’re adapted for each country’s television standards.

Market realities of the era plus the way that relevant hardware usually varies between 50Hz and 60Hz regions tends to lead to letterboxing and slower games; it’s not unavoidable but is common. Arcade games don’t have that hardware variation.

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    Re, "only thing that needs to change between regions is the PSU." I know I'm straying away from "retro" with this comment, but these days, even the PSU probably doesn't need to change. Coin acceptor, on the other hand... Dec 28 '20 at 15:07
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    Is it really true that arcade machines "output graphics at the same rates and sizes regardless of the region"? With CRTs, there are good EMI reasons to match the frame rate to the mains frequency, as this reduces visible artefacts due to nearby motors, transformers, etc. Do arcade machines have other means to eliminate such interference? Dec 28 '20 at 15:13
  • @TobySpeight that’s my understanding. Also, I had plenty of NTSC/PAL region modified consoles — i.e. flip a switch to change region and output at 60Hz rather than 50 — and had no problems with even consumer CRTs, albeit all will have been ‘90s vintage or newer. I think it’s about then that some VCRs started offering NTSC compatibility too, to watch grey imports. I also remember the Super Famicom being a hot grey-import item before the SNES eventually materialised. So I’m an analogue simpleton but empirically any such issues seem to have been resolved at some point.
    – Tommy
    Dec 28 '20 at 16:21
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    @TobySpeight: Just the way they were built made it already practical to add more shielding, better netfilters and better power converters. Also, frame rates and video frequencies in these machines don't have to be standard too. I always have the impression that somehow this must have been the case, those games had a real steady picture.
    – chthon
    Dec 28 '20 at 17:03
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    The frequency of video frame rate is irrelevant to the mains frequency, and has been since color TV was invented. The video output of any computer system is not in lock with mains frequency anyway. The point of TV connected device is to simply output a signal that is compatible enough with local TV system to get stable picture and color. Sometimes the game is just stupidly ported to advance game time once per frame, so if an object moves one pixel per one frame then it will move slower on a 50Hz system. Good design and porting of multistandard game should make the frame rate irrelevant.
    – Justme
    Dec 29 '20 at 9:57
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Take the NES, the Super NES and say, the PlayStation, they all have something in common : games on PAL regions were about 16.7% slower than their NTSC counterpart.

Sure? Any proof for that? They did display maybe 16% less pictures per second, but so does every US TV show aired in Europe. To me no of the actors seam like pumped with tranquillizers.

Now if on you play an arcade game, let's say Pang 3, the ROM for Europe region runs at the exact same speed than the ROM for Japan region.

Well, it isn't a ROM, but a game board that does the display. And most important here, they use the same board in Europe than in the US or Japan. The software (ROM - but more often than not EPROM) differs only for on screen language - if at all, as some games can be switched between languages.

So why did arcade cabinets designated to run in 50Hz regions didn't exhibit the same slower speed as it was the case for consoles running also in 50Hz regions ?

As these, unlike game consoles, do not differ between regions - at least not in game related parts. What differs are transformators and PSUs as they need to cope with the different frequencies and, more important, different voltages. Another part that usually differs are the coin slots/money detectors, as different countries happen to have different coins.

Arcade cabinets are closed system, not intended to be interoperable with other devices, like local TV. Consoles in contrast have to do exactly that, work with a local TV at default setting.

A comparable situation with computer would be the Commodore PET. An all in one solution, much like a game cabinet. Id did not have to bother with 50 half frame per second TV. Again, it was the power supply that had to be changed to work with the various voltages available in Europe at the time.

The equivalent in game consoles would be the Vectrex. Here again it was an all in one unit containing the CRT as well. So when MB sold it in Germany, all they did was replace the 115V transformer with a 220V unit. Nothing else ... well, ofc, warranty sticker and packaging had to be changed as well :))

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  • My understanding is that most (although perhaps not all) TV shows are converted by careful frame-dropping (or frame-blending). Quick check is to see if the run-time of an episode for a "one-hour show", with all advertising excluded, is closer to to 42 minutes (no slow-down) or 50 minutes (slow-down). It did use to be that "films on TV" in Europe were slightly sped up, as the 24 frames per second (usually double or triple flashed) of the film and the 25 frames (well, 50 half-frames) of the PAL format was close enough that it was mostly not converted.
    – Vatine
    Dec 31 '20 at 7:32
  • @Vatine: I would expect that most PAL to NTSC conversions probably also produced six frames of NTSC for every five frames of PAL, despite the fact that this would cause each hour (3600 seconds) of PAL video to become about 3603.6 seconds of NTSC video.
    – supercat
    Jul 30 at 23:02
  • @supercat Entirely possible. I mostly have not looked at the NTSC side of things.
    – Vatine
    Jul 31 at 5:54

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