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Atari 2600 - Stereo Mod?


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#1 82-T/A OFFLINE  

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Posted Thu Jun 21, 2012 2:21 PM

What? Why did no one tell me?

I found this random book on clearance called "Hardware Hacking" and there was a section in there entirely on the Atari 2600. Apparently, the Atari 2600 is in stereo, but they never bothered to actually implement it on the hardware level. Since the stuff all ports through the RF box... it apparently loses it's stereo and just turns to Mono. Anyway, the guy in this book actually discusses how the Atari 2600 had originally been designed to house two small speakers in the case, and that it would have been in stereo. I'd always wondered about the fact that there were these two speaker indentations in the woodgrain / vader console... and now it makes sense.

Anyway... you guys probably ALLL know this already, but this is totally new to me... and I'm totally going to do it. I might as well also use that opportunity to do the S-Video hook-up too while I'm at it.

Anyway, did anyone else here NOT know that the Atari 2600 was actually in stereo? There's apparently a whole host of games that support it too... like Combat (for example) which will have the shooting sound effect come from whatever side of the screen it's shot from...

#2 FujiSkunk ONLINE  

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Posted Thu Jun 21, 2012 2:38 PM

Anyway, did anyone else here NOT know that the Atari 2600 was actually in stereo? There's apparently a whole host of games that support it too... like Combat (for example) which will have the shooting sound effect come from whatever side of the screen it's shot from...


The 2600 has two sound channels, and it is possible to tap into each sound channel discretely on the motherboard. That by itself wouldn't necessarily mean the 2600 was meant to be in stereo, except that ability is in fact by design.

Lots of dedicated game systems released in the '70s didn't bother sending audio to the TV and instead had beepers or other such bits in the console itself. The 2600 was going to take that a step further, with two built-in speakers, one for each sound channel. You can see a leftover artifact of this design in the earliest 2600 cases, which have speaker "vents" built into the case in front of the cartridge port.

Early games like Combat were programmed to take advantage of this by dedicating a sound channel to each player. So it's not that the sound is programmed to come from the "correct" side of the screen, but that the sound on a given side would always represent the same player's movements, shots and explosions. Atari eventually scrapped the speaker idea, I believe to keep the costs down, and went with mixing the audio into the TV signal instead. So only those earliest games were programmed with stereo effects in mind.

Edited by FujiSkunk, Thu Jun 21, 2012 2:41 PM.


#3 SpiceWare ONLINE  

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Posted Thu Jun 21, 2012 2:57 PM

So only those earliest games were programmed with stereo effects in mind.

some later games too :D


Skeleton+ and A-VCS-tec Challenge feature stereo as well.

#4 82-T/A OFFLINE  

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Posted Thu Jun 21, 2012 3:56 PM

Anyway, did anyone else here NOT know that the Atari 2600 was actually in stereo? There's apparently a whole host of games that support it too... like Combat (for example) which will have the shooting sound effect come from whatever side of the screen it's shot from...


The 2600 has two sound channels, and it is possible to tap into each sound channel discretely on the motherboard. That by itself wouldn't necessarily mean the 2600 was meant to be in stereo, except that ability is in fact by design.

Lots of dedicated game systems released in the '70s didn't bother sending audio to the TV and instead had beepers or other such bits in the console itself. The 2600 was going to take that a step further, with two built-in speakers, one for each sound channel. You can see a leftover artifact of this design in the earliest 2600 cases, which have speaker "vents" built into the case in front of the cartridge port.

Early games like Combat were programmed to take advantage of this by dedicating a sound channel to each player. So it's not that the sound is programmed to come from the "correct" side of the screen, but that the sound on a given side would always represent the same player's movements, shots and explosions. Atari eventually scrapped the speaker idea, I believe to keep the costs down, and went with mixing the audio into the TV signal instead. So only those earliest games were programmed with stereo effects in mind.


Oh ok... so like 2 voice polyphony? Sort of like how the Tandy has a 3-voice speaker (vs the PC's 1 "voice" if you will... heh).

Ok, I guess the guy mis-interpreted it... but I can see how he would have assumed it was stereo.

#5 FujiSkunk ONLINE  

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Posted Thu Jun 21, 2012 4:05 PM

Oh ok... so like 2 voice polyphony?


Exactly.

Ok, I guess the guy mis-interpreted it... but I can see how he would have assumed it was stereo.


He may have been writing about how the 2600 was going to be in stereo, and/or how it can be hacked to offer stereo output. Either way, the system "officially" supports only mono sound.

So only those earliest games were programmed with stereo effects in mind.

some later games too :D


I stand corrected! :)

#6 atari2atari OFFLINE  

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Posted Thu Jun 21, 2012 4:59 PM

... like Combat (for example) which will have the shooting sound effect come from whatever side of the screen it's shot from...


COMBAT actually always sounds from the same side of the speakers that the PLAYER represents - - PLAYER 1 on the left, PLAYER 2 on the right. Even if PLAYER 1 is on the right side of the screen, the shot still comes from the left!

Cool mod though, eh? :)

PITFALL II is fun to play on a modded system - - the melody comes out of one speaker, and the beat out of the other!


I just modded several units with stereo sound (see signature), and put switches on them, too, so I can turn it on and off as needed. It's definitely a nice mod!

The "Console Game Hacking" book is what I used (I attached the relevant pages), but what they DON'T tell you is exactly what pin is LEFT and what pin is RIGHT!

PIN 12 on the TIA is the RIGHT channel

PIN 13 is the TIA is the LEFT channel


Have fun - - post some pictures of your "work log" and finished mod, if you don't mind! It's always nice to see other's work!

-a2a

Attached File  Stereo 2600 section from Chapter 8 - Game Console Hacking - Having Fun While Voiding Your Warranty.pdf   254.96KB   1136 downloads

#7 82-T/A OFFLINE  

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Posted Thu Jun 21, 2012 5:15 PM

Thanks Atari (for the PDF too). I'm definitely going to do that. I'm not that awesome with a soldering iron... I've re-wired a VW Bus, an 81 TransAm, and an 87 Fiero... but never done anything with electronics, so I may have to take my time with this.

I'll post pictures and log the whole process like I do with my car stuff...

Should be pretty cool. I think I'll do a switch like you did too.

#8 flammingcowz OFFLINE  

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Posted Fri Jun 22, 2012 8:17 AM

My atari has been modded and has stereo out, and I've noticed a lot of games that play through one speaker or the other because of it. I thought it would be cool at first, but it is actually kind of annoying.

Kaboom! only comes out of the left speaker
The music to Ms. Pac-Man plays through both
Jr. Pac-Man sounds comes out of one
etc.

#9 Syntaxerror999 OFFLINE  

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Posted Sat Jun 23, 2012 8:55 PM

You could mod it where both audio channels get merged then split into left and right. You wouldnt get the cool audio effect like in combat or pitfall 2, but games like kaboom would sound normal.

#10 retrofixes OFFLINE  

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Posted Tue Apr 21, 2015 5:06 PM

Forgive me for digging up such and old thread but google brought this up during some research.

 

I was viewing that PDF posted above and the Atari stereo mod.

 

 

I do not understand why they used resistors and soldered them back to the motherboard? 

Why not simply solder to the pins 12 /13  (without pulling them) and go straight to the RCA jacks with a 1uf cap.

 

Perhaps this has to do with keeping RF intact.

 

I would composite mod if going through the trouble of stereo.

 

Am I missing something here?

 

Thanks,


Edited by retrofixes, Tue Apr 21, 2015 5:28 PM.


#11 atari2atari OFFLINE  

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Posted Tue Apr 21, 2015 5:55 PM

I think the resistors are required because the output from the TIA is too "bright" and maybe would be distorted and loud without them?

 

You should try what you suggest, though, maybe by just using alligator clips instead of soldering, and then report back on how it does or does not work.

 

That definitely would be a great addition to the conversation!  I'd be interested to hear if it works.

 

-a2a



#12 retrofixes OFFLINE  

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Posted Tue Apr 21, 2015 6:43 PM

I've used that connection before without issue. The output is what you would expect from a 5v chip. The audio is actually quiter when tapping the chip directly. This bypasses the audio amp but also gives a clean near perfect audio signal.

This stereo mod is very similar to what is performed on NES consoles. 

 

I have a few prototyped Atari PCB kits with the composite + stereo option or mono option.

Though I never realized some games were designed for stereo, that is exciting and justifies the mod in my opinion

 

Looking at the old PDF made me question the install.


Edited by retrofixes, Tue Apr 21, 2015 6:48 PM.


#13 Turbo-Torch OFFLINE  

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Posted Wed Apr 22, 2015 7:44 AM

I never knew this until a read a description of Medieval Mayhem the other day.  I always suspected the round cut-outs on my old six switcher were for speakers.  Back in usenet days, many seemed to think it was for venting.

 

That by itself wouldn't necessarily mean the 2600 was meant to be in stereo, except that ability is in fact by design.

 

 

I know this is a revived thread from years ago, but can someone explain this to me?  Isn't that like saying the 2600 wasn't necessarily meant to be in color but it was designed to be in color?

 

 

Oh ok... so like 2 voice polyphony? Sort of like how the Tandy has a 3-voice speaker (vs the PC's 1 "voice" if you will... heh).

Ok, I guess the guy mis-interpreted it... but I can see how he would have assumed it was stereo.

 

 

What does how many sounds something can play simultaneously have to do with stereo?  If you have separate sounds coming from a left channel and right channel, it's stereo.



#14 SpiceWare ONLINE  

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Posted Wed Apr 22, 2015 7:53 AM

I know this is a revived thread from years ago, but can someone explain this to me?  Isn't that like saying the 2600 wasn't necessarily meant to be in color but it was designed to be in color?

 

For stereo sound, the sound comes out the appropriate side of the screen for the action that occurred.

 

Based on the earlier games, any sound effect for the left player came out the left speaker even if the event happened on the right side of the screen.

 

In other words, as originally used, each player had a mono speaker that was dedicated for just their sound effects.

 

It's likely that if it had shipped with two speakers then some games would have utilized them as stereo speakers, just like some homebrews have.


Edited by SpiceWare, Wed Apr 22, 2015 7:55 AM.


#15 Turbo-Torch OFFLINE  

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Posted Wed Apr 22, 2015 8:03 AM

For stereo sound, the sound comes out the appropriate side of the screen for the action that occurred.

 

 

Wouldn't that would be a game feature and not the definition of stereo? 



#16 SpiceWare ONLINE  

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Posted Wed Apr 22, 2015 9:23 AM

Wouldn't that would be a game feature and not the definition of stereo?


Stereophonic sound

Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of directionality and audible perspective.


So having two speakers is not the same as stereo if the two speakers are not being used to indicate where (the directionality) the onscreen action took place.

#17 Turbo-Torch OFFLINE  

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Posted Wed Apr 22, 2015 10:04 AM

So you're implying that Combat is stereo as long as each player stays on their side of the playfield...once they cross that center point and it's no longer accurate to the image on a TV screen, it becomes two channels of mono?

Seriously, what does "onscreen" or video have to do with the true definition of stereo?  If I listen to a Beatles album, it's still stereo with no video reference attached to it.  Stereo was around long before it became a feature on TVs in the early 80s.



#18 SpiceWare ONLINE  

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Posted Wed Apr 22, 2015 10:34 AM

Not implying that at all - Combat was not designed for audio directionality, therefore it's not a stereo game.  Games like Medieval Mayhem and Skeleton+ were designed with directionality, therefor they are stereo games.

 

 

Anyway you're now coming across as being intentionally obtuse, so I don't plan to make any more responses.

 



#19 macdlsa OFFLINE  

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Posted Fri Apr 24, 2015 2:42 AM

... Combat was not designed for audio directionality, therefore it's not a stereo game...

 

'course by definition, a stereophonic system, intended as "devices+software", should be able to re-build an appropriately recorded sound scene.
 
Obviously this can be true for "messages" coming from a theater, a stage, an auditorium... while, we all know, post-production sound engineers "falsify" this scene by introducing effects, modifying the original position of the instruments and whatsoever...
 
Darrell, the sound of your game(s) is outstanding and amazing, and it fully respects the definition of "stereoscopic sound" !
What you're talking about Medieval Mayhem is called "panning effect", which is really "sensible" in "our" video game matter as it is in the Cinema and almost all audiovisual productions.
 
Then, the sound of Combat is not "hooked" to the corresponding image on the screen ?
Yep, but do not misrepresent : simply, it's not a "well-intended" stereoscopic-sound game, but not definitely non-stereo as it definitely isn't monaural...
 
We all know that a particular system, intended as a set of devices only, could be be called "stereophonic" simply if it's able to produce sound on two separate channels, regardless of the message being played.
Thus, a modded VCS with proper separate audio outputs IS stereophonic :thumbsup: ! 
Listen to some games' music is somewhat "regarding", considered that the VCS was marketed in 1977 (but designed since 1973...) : I think about Gremlins' tunes, Track&Field...
Try to listen to Thrust+ score !!! It's really, really amazing !
 
In conclusion, I'm pretty sure it's correct this could (and should) be called "stereo sound".
 
 
That's all  ;)
 
20141026_172517.jpg

Edited by macdlsa, Fri Apr 24, 2015 2:45 AM.


#20 Thomas Jentzsch OFFLINE  

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Posted Fri Apr 24, 2015 3:33 AM

 

Thus, a modded VCS with proper separate audio outputs IS stereophonic :thumbsup: ! 

...
Try to listen to Thrust+ score !!! It's really, really amazing !

Thrust may sound stereophonic, but that's mainly because of the music player code design and how it is used. In this tune, channel 0 and 1 both have their own pattern set. So e.g. the "drum" pattern are always played on the same channel. However, both channels could share the pattern set, and the "drums" could move back and forth between the channels. If you are e.g. playing three different instruments with just two channels, you have prioritize*. And then the instruments change channels permanently.

 

Effectively this may (I have no modded 2600) result into a nice stereo effect in Thrust, but IIRC it was not designed that way. 

 

* The same is true for sound effects, usually you have priorities there too.



#21 macdlsa OFFLINE  

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Posted Fri Apr 24, 2015 8:05 AM

That priority matter is very interesting ! Although I'm not a programmer, I could understand how it works, and I mean it : Thrust+ score is NOT designed to have such a (nice !) stereo effect.

 

But that's not my "point", Tom : it actually HAS a stereo sound, if you use an audio-out modded console ! You used both sound generators in Thrust+ code, then, what I want to say is :

 

-Almost all VCS' games, with some exception (for example, Defender and Jungle Hunt audio runs on left channel only...), use both sound generators

-On modded VCS every single generator is directly connected (yep, with the appropriate components such as the capacitor to avoid any undesidered ***and pernicious*** continue voltage) to its "proper" output thru RCA PinJack connector.

-Finally, we have two separate audio outputs, and that's enough to identify this device as stereo, even if almost all its software collection is NOT intended to be "stereoscopic sounding" !

 

Believe me : use a stereo-mod VCS, "treat" Thrust+ music score with a tube-preamplifer, as I did in that retrocomputing/gaming "expo" shown in my previous picture, and you won't go back to a monaural output VCS  ;) .



#22 macdlsa OFFLINE  

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Posted Fri Apr 24, 2015 8:46 AM

... forgot...

 

@ 82-T/A : http://atariage.com/...vy#entry3071622

 

@Tom : http://atariage.com/...vy#entry3100836



#23 Thomas Jentzsch OFFLINE  

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Posted Fri Apr 24, 2015 8:59 AM

I just tried Thrust+ for the first time ever in Stella with "Sound" set to "Stereo" and now I know what you mean.

Drums and bass are always on the left, melody and hi-hats are on the right.

BTW: You should give Star Fire a try. That sounds cool in stereo too.

#24 macdlsa OFFLINE  

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Posted Fri Apr 24, 2015 9:25 AM

Yep, and also Boulder Dash sounds pretty cool !
... seems you have had a kind of "regard" in doing the score of your games, Tom  ;)   :thumbsup:  :thumbsup: !



#25 Thomas Jentzsch OFFLINE  

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Posted Fri Apr 24, 2015 9:47 AM

I didn't do the music. Thrust+ Platinum and Star Fire music are both done by Paul Slocum, he is a pure music genius.

Boulder Dash is based on the original music, the idea and data where provided by Freq Quimby (batari).

http://atariage.com/...c/#entry2340226




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