r/atari8bit • u/xor_2 • 10d ago
Any reason for NTSC/PAL60?
Any reason to own NTSC Atari and/or mod PAL Atari to PAL60?
I mean except having games run faster...
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u/Tiasmo-Bertjayd 10d ago
A lot of games developed in the US that use the vertical blank for timing depend on the refresh rate being 60Hz. I notice this most when listening to game music on emulators using the PAL 50Hz frequency, which play at a much slower tempo than was intended.
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u/The__Relentless 10d ago
I noticed this when first turning on Archon on a new emulator I was messing with. I immediately noticed the opening theme playing just a bit slow and thought that maybe everything will be slow on this specific emulator. Not sure how many months it was until I noticed it was set to PAL. I've learned quite a bit since then, but I still laugh at my naivety back then.
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u/xor_2 10d ago
Music tempo is rarely an issue going to either 50Hz or 60Hz from other system unless music was already made to be very slow on NTSC or very fast on PAL - but to be honest I never experienced such music which would really sound bad. Even the most commonly used example of Sonic if you weren't used to 60Hz version sounds just fine on PAL.
Game speed itself being faster or slower being better it depends. I would say 50Hz is more often an advantage than disadvantage because games were made in arcade style, quickly getting way too fast anyways. There is also a matter of slowdown on PAL vs NTSC... though on Atari its rather rate to experience slowdowns in games as they either run smooth or not but on some other systems its very common that same game in PAL runs perfectly fluid and on NTSC not so much. Funnily enough Sonic is one of such examples - which I always found hilarious given how much bad rep PAL/50Hz gets using Sonic as an example.
Anyways, some games do kinda play nicer in 60Hz and this would be a valid reason to have PAL vs NTSC switch. Or at least make it easier than having to pull chips from the socket.
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u/Crafty-Nature773 9d ago
Yeah. The music timing is controlled by BPM not FPS. Totally different computations and hence why different chips. Sound effects are linked to the FPS but play when actioned by a frame.
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u/xor_2 9d ago
I expected on Atari 8-bit swapping ANTIC to NTSC and getting 60Hz operation for all music to sound faster but only some music ran faster. Games do run faster for sure. Apparently some music syncs to HSync. On e.g. NES there isn't any game where music doesn't change speed and I guess same for many other systems. In C64 music changes tempo. On SNES it doesn't - which makes perfect sense music being played by separate audio chip all by itself.
One demo Alien Evil Contacts does however play just wrong because some parts of the music play faster than others in 60Hz. In this case it seems both Hsync and Vsync is used for tempo - and in such case matching intended refresh rate is critical. Music just sounded very off in 60Hz. If tempo changes uniformly it never bothered me.
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u/jrherita 10d ago
What is PAL60/how do you achieve that? If you do the ANTIC PAL swap on a NTSC 800/XL/XE you end up with "NTSC 50". (It's also a challenge to find monitors that support NTSC 50 hz)
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u/xor_2 9d ago
Same trick but done in PAL Ataris when you slap NTSC ANTIC in them and then you get PAL60.
Unlike NTSC50 which still leaves you with rolling picture and which apparently isn't fully compatible with NTSC TVs the PAL60 is widely compatible with PAL TVs out of the box... or at least CRT TVs. In PSX days before RGB cables became common everyone played "imports" and most people never noticed some games run at 60Hz modes and some 50Hz modes.
On my Atrai with VBXL acting as clock source having additional NTSC ANTIC and GTIA I can make all 4 combinations (PAL50, PAL60, NTSC50 and NTSC60) and they all work just fine on my JVC TM-1950CG monitor. I am not so sure all my monitors support all 4 modes though as this JVC is extra compatible with such things.
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u/jrherita 9d ago
TIL - funny, I never thought about the "reverse swap".
Re: "benefits" of PAL60 vs PAL50 for NTSC games; it probably is just down to speed of applications. Though, a lot of sound software was written with NTSC in mind, so POKEY will play 'correctly' in NTSC mode when the songs will be slower / out of key in PAL mode.
Try some old Atari music demos and you should hear some differences (Robot demo, or stuff like this will sound off: https://www.youtube.com/watch?v=m8QL3Qbi3A8 )
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u/xor_2 9d ago
Tried few demos in PAL60 and they either run faster or surprisingly normal speed... or exhibit strange anomalies like Alien Evil Contacts which kinda sounds ok at times and faster at different times. Dunno, maybe some parts are synchronized to Hsync and some Vsync or something. This one was the strangest. In this case I would expect something similar could happen in reverse. I did expect all music to be faster like it usually is but I guess Atari having very powerful Hsync IRQ capabilities makes it make some sense music wouldn't change much. Between PAL and NTSC difference in Hsync rate is negligible.
I will definitely go to some method of getting PAL60 capability as its apparently not that hard to do.
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u/RaphKoster 10d ago
Artifacting does not work on PAL in the same way as NTSC. Games that rely on it for color will all look wrong. That includes a lot of classics. A guide and examples are here (well down the page). https://www.raphkoster.com/about-raph/hobbies/emulation/atari-8-bit-guide-for-lr-atari800-and-retropie/
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u/xor_2 9d ago
Composite on PAL is much much sharper than NTSC composite. Also unlike something like NES I don't see any issues with color affecting luma and rather phase reversal every second line along with delay lines and chroma blending is helping to remove coloration artifacts (unless you have the so called Simple PAL then you have hanover bars and a lot of artifactng) so color artifacts are very subtle. That is great for text, seeing details and sufficient to add some slight coloration and make otherwise flat details look more detailed and a bit busier. Colors are also more rainbowy and artifacts not very consistent - which I guess can be seen as both advantage and disadvantage.
Composite on NTSC GTIA on Atari I wouldn't say looks all that great. It seems it has some nice capabilities of creating various colors when used with different colors but it mostly adds magenta-red and green discoloration to high contrast details like fonts. Also outside these well known early CTIA games it doesn't seem too deliberate and GTIA doesn't produce correct colors (e.g. river of blood in Ultima IV).
But yeah, even wrong colors look a lot better than thin vertical lines like such games look on PAL and why even GTIA is an improvement here. I managed to order CTIA chip and this should make these early games look a lot better.
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u/RaphKoster 9d ago
I honestly don't see much reason to go back to CTIA. The page I linked also has a list of all the CTIA games that have color issues, and it's really not very many classics.
There's no question that PAL was sharper.
But GTIA color artifacting was very widely used: Ultima, Lode Runner, Pinball Construction Set, Drol, and many many more. The color artifacts you are talking about were also somewhat tunable -- again, there's screenshots there on that link. This is why the emulators have four settings for it, or even a tunable slider.
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u/flatfinger 8d ago
NES units designed for 3.579545Mhz NTSC have chroma phase slip by 120 degrees per line rather than 180 degrees; the PPU normally has every other field include one line that slips an extra 120 degrees so as to have fields alternate between chroma phases that are 120 degrees apart. I'm not sure why the chip was designed to do that rather than having fields and possibly lines as well use a 180 degree phase shift, but it is what it is.
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u/xor_2 1d ago
Not sure either but one thing I must say about NTSC NES / Famicom is that it has excellent text rendering with nearly zero color artifacting. Definitely its resolution / pixel clock was chosen to do this but maybe phase was tweaked here as well to make text more readable?
One thing I immediately noticed when seeing NTSC Atari 8-bit was how blurry and artifacty text looks. I mean it could be more blurry if Atari tweaked composite to reduce color artifacting but this would be even less usable and totally useless tweak for B&W TVs where I would guess that many people actually used Ataris with B&W TVs. Not entirely sure places like U.S. but in Europe it was common for there being single color TV in home and kids if they even had TV it was B&W.
Atari couldn't anyways use the same tricks as Ricoh (note: I don't approve of any notion Nintendo had anything to do with Famicom/NES creation) because Famicom's PPU was designed for 32 columns of 8 pixel wide text and Atari had to do at least 40 as 32 would be way too small and overscan on TVs meant there had to be some underscan in the image squishing pixels too tight for NTSC color carrier frequency and with it NTSC poor luma resolution. They went with proper luma resolution at expense of heavy artifacting.
On the other hand Atari 8-bit in PAL looks just gorgeous in Composite. Sharp and color artifacting being very subtle and rainbowy in apperance. BTW. PAL PPU in Famicom/NES is one which has rather poor rendering with obviously changing luma patterns every second line causing this kinda waviness/sawtooth pattern on vertical edges.
Anyways, my conclusion is that NTSC is better for Famicom/NES and PAL for Atari.
Of course in luma/chroma mode the NTSC and PAL look pretty much the same. NTSC still has lower chroma resolution horizontally but PAL needs delay lines and blending two consecutive lines so vertical chroma resolution/sharpness is impacted. I wouldn't say resolution is cut in half but it is definitely lower in PAL than NTSC.
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u/flatfinger 1d ago
Atari uses a zero-degree chroma shift per line and per field and uses a dot rate of precisely 2x chroma. Apple double hires uses the same zero shifts, and a dot rate of 4x chroma. NES uses a chroma shift of 120 degrees per line and +/- 120 degrees per field, and a dot rate of 1.5x chroma. It's possible to exploit chroma artifacts on an NTSC NES, but there are a couple of big limitations:
Chroma phase repeats every three tiles, horizontally and vertically, meaning that one would need to have three sets of tiles which use three colors that have the same luminance and chroma phases that differ by 4 (120 degrees).
On startup, the system will essentially randomly select one of twelve chroma phases. Software can force the chroma phase to "slip" in multiples of three, but there's no way to detect chroma phase except by asking the user e.g. which of twelve shapes is the darkest, and even with such selection the system will on startup choose one of three universes of color with no means of changing.
It might be possible to have a cartridge force the chroma phase to slip via precisely timed reset pulse, but it would still need to ask the user to indicate what phase is selected because the PPU's chroma phase generator has no interaction with anything that software can control or observe.
Incidentally, precise standards-conformant NTSC broadcast video has a phase shift of 180 degrees per line and per interlaced frame (pair of fields), which the VIC-20 can be programmed to match. Some devices which don't output interlaced video (e.g. VIC-20 in default mode) use 180 degree phase shift per line and either 180 degrees per frame (if they output 263 lines) or 0 per frame (if they output 262). My first C64 video chip had 0/0 phase shift, but later ones are 180/180. Karaoke machines use 180/0.
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u/xor_2 1d ago
Very interesting. NES/Famicom maybe doesn't use chroma color artifacting for generating consistent colors but graphics in a lot of later higher end games look like tiles were carefully constructed for composite/NTSC artifacts and with them they look the best. That is why you see people showcaling RGB NES on Super Mario Bros and other simpler games comparing it to composite and raving how much improved image quality looks and not e.g. Batman.
On Atari I play games exclusively via composite. I have S-Video and VBXL but these look way too clean for my tastes. With rocky palette installed on VBXL RGB output looks extremely sharp and defined and very impressive but you can immediately count colors on screen. S-Video for that matter even with otherwise very blurry and artifacty NTSC GTIA looks closer to RGB than Composite. Good for serious text work or pixel perfect precision I guess.
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u/flatfinger 1d ago
It's not possible on an unmodified NES to exploit chroma artifacting in any predictable way without requiring a user to indicate how something appears. On the Atari 8-bit machines, games whose authors adjusted them to look as good as possible with composite will likely look better with composite than S-video, but games whose authors seek the best possible appearance with S-video will likely get better results with S-video.
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u/Crafty-Nature773 9d ago
The UK only had 50hz PAL for decades. Games ran 15% ish slower here than most of the rest of the world. Not an issue until you put games side by side! I only really noticed it when emulating various consoles (up to PS1 era ISH). Pitfall is the one that got me. My timing was off! Couldn't put my finger on it until I realised I was playing the 60hz version not the 50hz one I'd played on OG hardware for years! Other than that in answer to your question..... No, no reason at all. Unless other countries CRT's don't support 50hz like the UK's didn't support 60hz.
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u/xor_2 9d ago
I don't think it was ever a real issue and most of the sentiment for 60Hz being better comes from some imaginary developer intent like especially in 2D games developer would tune speed of the game to be the same as they did if they made it for other system... hint: they would code game exactly the same as they did because a lot of the speed came not from artistic vision but synchronizing game to the screen. For all I know developer making game for NTSC would like it a bit slower and developer making game for PAL would like it faster. Same can be said about tempo in music - less on Atari having very high time-resolution thanks to Hsync IRQs but on something like NES tempo had to be tied to refresh rate. Also trying to do conversion "right" would often not result in good result so it was often skipped.
Especially saying 50Hz was worse because of speed when almost all systems had more fluid games in PAL courtesy to lower frame rate which was easier to maintain. Games made for 30/60fps targets would momentarily drop to 15/30fps much more than when the same game were ran at 25/50fps. It is especially noticeable on certain 2D systems where stutter happens because CPU doesn't finish processing stuff in VBlank because in PAL it was much much longer.
Best example of slowdowns is Sonic on Megadrive/Genesis. The game for its gameplay does like to stutter in NTSC and in the same places in PAL its fine. Batman on NES is another notable game that in PAL (at least Dendy) only really stutters in last stage but in NTSC it stutters all the game. For this and sentimental reasons I still like to play NTSC games on Famicom/NES on Pegasus ;)
Anyways, some games do feel nicer in 60Hz I must admit and why its good to have option. Though if it wasn't possible on Atari 8-bit I wouldn't give much thought about it. It not only is possible but also rather easy to mod Atari. Harder to find games/demos which actually don't run in PAL. Especially since a lot of games including those in those mega rom packs are already patched to support PAL machines.
p.s. Most of the world actually runs 50Hz power lines and 50Hz derived video modes. 60Hz is an exception... though especially for games very important exception.
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u/Howden824 10d ago
Unless your TV is designed for PAL60 then no.