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Atari 7800 NTSC and PAL models diferences


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I wonder what was the differences between 7800 models. As what i've read recently i assume that (correct me if I'm wrong):


1. Only early NTSC models have expansion port.

2. NTSC models has "thin rainbow" design, and PAL models "thick rainbow" design

3. Only PAL models have Asteroids game built in

4. NTSC models comes bundled with joystick-like controlers similar in shape and design to 5200 controlers, whilst PAL models comes with nes-like pads


Are there any other differences between various models?

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  • 4 months later...

[quote name=Sub(Function(:))' date='Thu Jul 22, 2010 6:21 PM' timestamp='1279822863' post='2056427]

As discussed her recently there is also a PAL version that supports RGB video output. It appears to have only be sold in France. The video output socket was a 13 pin DIN, similar to the Atari ST range. It was supplied with a 13 Pin DIN to SCART cable.


it is exactly the same connector as the ST, I recently purchased an ST RGB cable and it works perfectly with my French 7800

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  • 11 years later...

Hey, i own the ntsc 7800 model with expansion port but if i try atari 2600 sky skipper those controls don’t respond,but if i try atari 2600 popeye on it,it just runs fine on the 7800,so i wonder am i missing something or do i something wrong???

yeah i hit all controller switches,i hit pause,select,reset i hit all the buttons but the game just don’t respond,nothing moves,now i don’t know if i own the pal or ntsc version of sky skipper,but till now i can only speculate,


BTW all ntsc 7800 games just work fine on my ntsc 7800 i just get response out of my controllers with it,so why not with sky skipper(yet) is beyond me.

Edited by johannesmutlu
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  • 2 weeks later...

Electronically speaking they are vastly different, the PAL (and French RGB) variants being the poor cousins of the NTSC machines.


The MARIA is a lot of the problem with both machines as it has some quirks. On the NTSC machine that manifests mainly in the colour drift gets as it warms up. The colour is linked to the temperature of the MARIA and after about 15-20mins it settles. But the colour at start up might be quite different. On the PAL machine it doesn't drift, it rolls... Which is much more annoying. Very visible on darker colours (the front screen of Commando looks particularly bad). The amount of roll varies from MARIA to MARIA.


The next problem comes from how the colour burst clock is generated. On the NTSC machine it's nice and goes to the MARIA that then passes it on to the TIA. On the PAL machine however the clock is split and feeds both directly. This results in a diagonal rolling interference. Combined with the colour rolling, it starts to make the picture bad... Which is compounded by the way the two chroma signals are combined on the PAL machine as they effect each other. Meaning you can usually get a nice chroma setting out of one side of the machine to the detriment of the other. Again this is far less of an issue on the NTSC machine.


The next problem effects both machines, though is less noticable on PAL due to it's multitude of other issues. There is often a fairly significant chroma timing issue with them. In that the Luma signal is slightly out of sync with the chroma. This can result in colour fringing (easily seen with Frenzy running in Berzerk mode as a 'shadow' down the sides of the mazes).


The French RGB machine is a PAL machine that feeds into a simple S-Video to RGB encoder internally. It's not very good to say the least and tends to mangle the PAL machine's already poor signal into one that's barely better than RF. It's terrible. S-Video to RGB encoders can be good, but they tend to be the size of a 7800 to do the job properly, not the size of a modulator. Hence the bodged in Atari one is particularly rudimentary.


Now most of these issues can be solved, but the PAL machine is pretty much hobbled in picture terms vs the NTSC one when it comes to simple mods. Just adding a UAV doesn't fix any of it's issues and still looks pretty bad. Adding a UAV to an NTSC machine however well get a very acceptable picture to just about anyone. One that can be tweaked further with a chroma shift board that @-^CrossBow^- has to reduce/eliminate the colour fringing. The French RGB machine is a bit of a lost cause unfortunately, to get a good picture out of it, you have to pull out what makes it special and just run it as S-Video or Composite. Both of which are better than RGB...


Now picture quality aside, there are PAL machines out there that came equipped with a region free bios (always an EPROM, though not all EPROMS are the region free bios. It'll usually say on the sticker if it is. If it's a standard ROM it's not the region free bios). Which is nice as it'll have a go at playing NTSC games and a few glitches aside, generally it has a good poke at it. You can put the bios into an NTSC machine and it'll have a go with PAL releases but it's less successful. It does however get you a copy of Asteroids if you switch it on without a cartridge in.


Compatability-wise, both machines can be a bit variable and there's no real way of seeing which is which. Some have no problems at all, whereas other's can have odd problems with some games and the Dragonfly cart with certain ROM images (Ballblazer seems to be a good one for triggering it as it crashes). Telling these apart is a complete crapshoot as they're so variable componet-wise. But there are other little issues with associated bodges that might get around some of them if you have them.

Edited by juansolo
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1 hour ago, Mitch said:

As far as I am aware, all PAL 7800s have the universal bios with built in Asteroids. I have yet to see a confirmed case where a PAL 7800 has a different bios.

They all have Asteroids, didn't know they were all universal. I sit corrected on that one ;)

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  • 4 weeks later...
On 7/22/2010 at 3:51 PM, Rastignac said:

NTSC roms are encrypted. PAL roms are not encrypted. So, NTSC 7800 console can't run PAL 7800 roms. PAL 7800 console can't run NTSC 7800 roms.

NO! These aren't encrypted. They just have a header, allowing the game to run. Without this header, the game won't run. Here's a documentary on it:

A78 Header Specification - 8BitDev.org - Atari 7800 Development Wiki

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On 5/22/2022 at 9:49 PM, Ecernosoft said:

NO! These aren't encrypted. They just have a header, allowing the game to run. Without this header, the game won't run. Here's a documentary on it:

A78 Header Specification - 8BitDev.org - Atari 7800 Development Wiki

Actually the code needs to be in memory when the NTSC unit starts running. So the data is like a hash of the top memory blocks and it is not in the header. You actually need to reserve some area on the ROM for the hash.

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