Rom Hunter's V17 Old Era ROMs Collection Now Online!

[alex_79]

12 hours ago, alex_79 said:

Maybe the console is based on the NTSC TIA with an external transceiver circuit, like for Brazilian PAL-M 2600s.

I found some clues that suggest this console in fact uses the NTSC palette!

 

I had a look at some "edu juegos 2600" consoles on "Mercadolibre", and this one has some screenshots (taken from a LCD TV in 16:9 aspect ratio).

I compared them with the known roms of these games in both PAL and NTSC versions (and changed the TV format in Stella to see how they'd look when played on different consoles). The color either match the NTSC versions, or the PAL versions if they're played on a NTSC console.

Submarine commander

Original (NTSC only):

 

Auction:

(Matches the NTSC original. Larger black border on top and bottom indicates it's a conversion to 50Hz)

Snail against Squirrel:
PAL:

PAL on NTSC console (NTSC50):

Auction:

 

Mission 3000 A.D. (CCE) NTSC:

Auction:

(Again, increased black border on top and bottom suggests conversion to 50Hz)

Dragonfire NTSC:

Auction:

(converted to 50Hz)

 

Dodge'em PAL:

PAL on NTSC console (NTSC50)

Auction:

This matches the "PAL on NTSC console" version, except for the score, but the original game has a bug (zero page access instead of immediate) that can cause this on certain consoles)

 

The console (note the text "Sistema PAL-N" on the label):

 

Edited April 12, 2022 by alex_79

[Ballblaɀer]

10 hours ago, alex_79 said:

AFAIK Argentina's analog TV system has always been PAL-N, so I guess all consoles sold there used that standard.

E.g. the "Edu Games 2600" clone console is PAL-N.

 

A PAL-N console with a NTSC cartridge will produce a non standard signal (PAL-N color encoding but at 60Hz). I don't know if TV sets sold in Argentina would display that signal or not.

I looked into the Argentina console/TIA/TV thing a bit not too long ago:

Quote

 

The only in-depth discussion that I've ever seen about this subject (i.e. the 2600 in Argentina) is on the Retrogaming.com.ar forums, like in this thread, and this one. It is mentioned that most consoles in Argentina have NTSC TIA chips, and that many contain additional hardware that transcodes the signal to the proper PAL-N format for their televisions. One user states that only a few clones contain PAL TIA chips. It's also stated that some consoles have hardware to manually adjust the console's color output.

 

The reason provided for the existence of cartridges containing ROMs of both formats is that older TV sets in Argentina were 50Hz only, with no vertical/horizontal holds. For consumers with these older sets, cartridges containing PAL ROMs would have been necessary to play with a stable picture.

 

And just to clarify, when I wrote "cartridges containing ROMs of both formats", that was somewhat poorly-worded. I meant to convey that both PAL and NTSC ROMs exist in cartridges made and sold in Argentina.

[Rom Hunter]

2 hours ago, Ballblaɀer said:

I looked into the Argentina console/TIA/TV thing a bit not too long ago:

And just to clarify, when I wrote "cartridges containing ROMs of both formats", that was somewhat poorly-worded. I meant to convey that both PAL and NTSC ROMs exist in cartridges made and sold in Argentina.

True.

 

Some Argentinian companies even released two versions of the same game.

[alex_79]

3 hours ago, Ballblaɀer said:

I looked into the Argentina console/TIA/TV thing a bit not too long ago:

Fantastic info! Thank you!

 

I just went through the first few pages of the Retrogaming.com.ar thread and it also includes pictures of the actual boards, showing a modification almost identical to Brazilian PAL-M consoles: different crystal and added circuitry to generate the PAL "alternate phase".

I will read it with more attention later.

 

I think it would be better to differentiate those roms instead of  identifying them simply as "PAL", as they're meant to be seen with a console using the NTSC TIA color palette. So I'd call them either "PAL-N", or "NTSC50" (NTSC palette, 50Hz).

Also the screenshots for the database should be taken with Stella set to NTSC-50 (e.g. by cycling through the modes with ALT-F after loading the rom), as that's how they appear on a real Argentinian console. (According to that thread the PAL-N clone console using a PAL TIA are a small minority)

[Thomas Jentzsch]

1 hour ago, alex_79 said:

I think it would be better to differentiate those roms instead of  identifying them simply as "PAL", as they're meant to be seen with a console using the NTSC TIA color palette. So I'd call them either "PAL-N", or "NTSC50" (NTSC palette, 50Hz).

Also the screenshots for the database should be taken with Stella set to NTSC-50 (e.g. by cycling through the modes with ALT-F after loading the rom), as that's how they appear on a real Argentinian console. (According to that thread the PAL-N clone console using a PAL TIA are a small minority)

Naming them "NTSC50" or "NTSC-50" would make Stella autodetect the correct TV format. I wonder if we should also support "PAL-N" as alternative name.

[alex_79]

23 minutes ago, Thomas Jentzsch said:

I wonder if we should also support "PAL-N" as alternative name.

I think that's a good idea.

[Rom Hunter]

3 hours ago, alex_79 said:

I think that's a good idea.

How do you sort them out?

313 scanlines and PAL palette off?

Is there a way to create a list of PAL-N ROMs?

Edited April 13, 2022 by Rom Hunter

[Thomas Jentzsch]

The scanlines can be 312 as well. But you are on the right track.

 

I don't think this can be created automatically (without coding and some assumptions). But you only have to work with the known PAL ROMs.

Edited April 13, 2022 by Thomas Jentzsch

[alex_79]

1 hour ago, Rom Hunter said:

Is there a way to create a list of PAL-N ROMs?

Unfortunately there isn't.

There's no technical difference that can be used to automatically sort them based on the rom alone (in the same way that you can't automatically tell apart SECAM form PAL, or PAL60 from NTSC). You need to know which country they were sold in, and so the target console they were intended to be used on.

2600 roms are actually neither NTSC nor PAL nor any other TV format, the consoles are. The only info you can get from the rom is the framerate at which the game will run (typically 50Hz or 60Hz, with some Taiwanese pirate games somewhere in the middle at ~55Hz!).

 

I read the 2 threads on the Retrogaming.com.ar forum linked above. It seems that almost all 2600 PAL-N consoles sold (and typically manufactured) there were based on the NTSC TIA¹, with a different crystal and an additional circuit to make them output PAL-N color signal. (very similar to PAL-M consoles in Brazil)
To output a true PAL-N signal, the roms should be 50Hz.

 

It is also said that you can tell if a game is PAL or NTSC by looking if the colors looks "right" on a PAL-N console.

This is not correct, as the "Edu Juegos" roms and the screenshots of the console for sale on Mercadolibre are proof that some games were converted to 50Hz from the NTSC version, without changing the colors.

 

"Enduro","River Raid","International Soccer" form the "Edu Juegos" dumps and "Submarine Commander", "Mission 3000 A.D.", "Dragonfire" from the "Mercadolibre" auction show "correct" colors on a PAL-N console, but they're definitely *not* NTSC games. (They'll likely roll on a NTSC console, as they're 50Hz).

 

My opinion is that Argentinian carts which displays at 50Hz should be labeled PAL-N (e.g. the 8 "Edu Juegos" roms), to specify that you need to play them with NTSC palette, if you want to reproduce how they looked when used with Argentinian consoles (And I just noticed that @Thomas Jentzsch updated Stella so that it will automatically recognize "PAL-N" or similar in the filename and switch to the proper mode).

 

60Hz ones (like "Lily Adventure") can be just labeled as NTSC, as they use the same framerate and palette of NTSC games (The same is true for Brazilian "PAL-M" ones). On a PAL-N console they look the same as if they are played on a NTSC console, although they are not 100% compatible with every PAL-N TV set.

 

I realize that this entire TV format subject is quite confusing when dealing with the 2600, and my bad english doesn't help I'm sure. (I usually refrain from typing such long posts for this reason)?

 

 

-----------------------------------------------

(¹) The only known exception from those thread is a console called "Froggy Junior", which is a Taiwanese 2600 Jr clone based on the PAL TIA (and modified for PAL-N output).

 

[Rom Hunter]

Would you consider Air Raid a PAL-N ROM?

[alex_79]

I consider it a (buggy, as it outputs too many scanlines) NTSC release.

[Thomas Jentzsch]

58 minutes ago, alex_79 said:

I consider it a (buggy, as it outputs too many scanlines) NTSC release.

Since it originates from LA, I agree. 

 

Probably it is still in some prototype state, which frequently used a value between PAL and NTSC.

[Rom Hunter]

I think it's quite difficult to determine what is a PAL-N ROM.

For example, Sancho's Words-Attack shows the correct colours when set on NTSC-50, but is by no means a ROM from Argentina.

Same goes for a lot of Quelle ROMs and even Atari's 32 in 1 Cartridge.

Generally speaking, you can set a PAL ROM that looks 'purple-ish' on screen on NTSC-50 to get the correct colours, but that doesn't tell me anything about whether or not that ROM is originally from Argentina.

 

Edited April 13, 2022 by Rom Hunter

[alex_79]

21 minutes ago, Rom Hunter said:

Generally speaking, you can set a PAL ROM that looks 'purple-ish' on screen on NTSC-50 to get the correct colours, but that doesn't tell me anything about whether or not that ROM is originally from Argentina.

Correct, you cannot get that info by looking at the rom. You either know where the rom has been dumped from, or you don't. If you know that a certain rom came from a cart from Argentina, then you can label it "PAL-N".

[Ballblaɀer]

Here's a new ROM for everyone's enjoyment curiosity about the Argentina NTSC50 thing. Custer's Revenge from Artkaris, shown and discussed in my Twitter thread:

 

 

custers-artkaris.bin

[Thomas Jentzsch]

11 hours ago, alex_79 said:

Correct, you cannot get that info by looking at the rom. 

I wonder if a semi-automatic emulator guess based on the color codes used would work. E.g. colors $1x, $ex and $fx should be rarely used in PAL games. And other colors might have a different distribution between PAL and NTSC too. So by analyzing the color codes used at runtime, it would be possible to calculate a probability. 

 

I have no idea how well this might work, if the calculation results provide good enough data. First one would have to collect data from NTSC and PAL ROMs and check, if the color codes used provide usable data.

[alex_79]

With pirate games, which often were converted from one format to another by only adjusting the framerate, the result would reflect the palette of the original version, not necessarily how those games looked like when people played them back in the day on their consoles.

The "good" colors aren't always the historically correct ones.

On the other hand, it could be a way to automatically detect PAL60 homebrews and hacks...

[Thomas Jentzsch]

Well, if e.g. a PAL conversion misses the colors, wouldn't it technically be a NTSC-50 game?  

Edited April 14, 2022 by Thomas Jentzsch

[alex_79]

2 minutes ago, Thomas Jentzsch said:

Well, if e.g. a PAL conversion misses the colors, wouldn't it technically be a NTSC-50 game?  

...or a bad PAL game. It depends on the point of view.?

[alex_79]

More to the point, the TV format depends (also) on the console.

A NTSC game converted to 50 Hz can be

• a PAL game with bad colors if played on a PAL console.
• a PAL-N game with good colors if played on a PAL-N console.
• A NTSC-50 game with good colors if played on a NTSC console.
• a PAL-M-50 (does this exist?) with good colors if played on a PAL-M console.
• a SECAM game (all SECAM games have bad colors!) if played on a SECAM console.

So I think it makes sense to consider where the cart was sold to choose how to label the rom and what palette to use when emulating it.

Edited April 14, 2022 by alex_79

[Thomas Jentzsch]

Sure. The analysis result would only give a hint if the color codes used are likely from the PAL or NTSC palette. If that idea works at all.

[+Andrew Davie]

7 hours ago, alex_79 said:

 

• a SECAM game (all SECAM games have bad colors!) if played on a SECAM console.

I beg to differ!  Not quite all! 

 

[Thomas Jentzsch]

I took 12 common games (PAL and NTSC versions), measured how frequently which color was used and made some pretty basic calculations. 

 

22 of the 24 ROMs would have been detected correctly and most hits were pretty clear. Of course the result would look different (worse) if more games would be tested. But there seems to be some pattern.

[dukdukgoos]

Maybe this has been asked and answered already, but is there a DAT available for this collection?

[Rom Hunter]

You mean this?

compare-v16-v17.htm