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Yurkie

Atari 2600 RGB mod

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Haha! I'm pretty sure it COULD be simpler, but what you describe isn't too tough and fills in some blanks for me. As I understand it, there is no "left" and "right" per-se on the Atari so there is no audio to match up. Just some sounds come on one channel and some on the other. The separation gives a neat effect sometimes. Thanks for the info. I wasn't sure about where to lift the sound from and I knew I needed to do something other than pass it straight. I'll try the cap and if that works.

The audio from the TIA couldn't be any simpler.
Of course this has to be an NTSC TIA chip.

Bend out pins 12 & 13 so they don't go in the socket. You have to learn how to find pin 1.

Solder a wire directly to each pin, or maybe use a piece of socket.
Connect these to the 'not negative' side of a 10uf electrolytic capacitor. I say not negative because the negative pin is marked and the positive pin is not marked.

Then a wire from the capacitor to the Center wire of the White and Red audio RCA cables. The outer wire of the red white RCA cable goes back to the ground in the Atari.

Unless this RGB mod is taking the audio and processing it instead of passing it right out you should have a different sound channel on each of the audio leads.
Search for which pin is left and which is right so sound from games like Combat and Medieval Mayhem match the on screen action.

If the splitting is not acceptable, use the TV menu to change the TV sound to mono. Simple as that.

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... As I understand it, there is no "left" and "right" per-se on the Atari so there is no audio to match up. Just some sounds come on one channel and some on the other. ...

Combat starts the sound of the right joystick player in the right side and the left joystick payer in the left speaker.

Air / Sea may be similar.

Medieval Mayhem, the amazing Warlords update home brew, actually puts hit sounds on the right out the right speaker and left out the left speaker.

So yes it is not stereo, but some games are programmed to use the left and right sensibly. :)

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Skeleton+ uses left and right channels too. They indicate from which direction an enemy is approaching.

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This is an RGB output mod and I'm pretty sure it's the only one. Unless I am mistaken all the other mods are composite video or svideo. Generally speaking, the signal types from best to worst quality are RF (native kind used by the 2600), composite video, svideo, component video, RGB (also called RGBs, RGBHV and VGA[in a sense]), DVI, then HDMI. Check out http://retrorgb.comfor more info on RGB and its use with retro consoles in particular.

 

DVI and HDMI are no different in terms of the raw video signal; they are both digital and use the same encoding scheme (8b/10b). That's why you can get a DVI-to-HDMI adapter (or vice versa) for a couple/few dollars, because all it is doing is "re-pinning" the connector.

 

VGA isn't a type of video signal (it originally had a specific meaning, but it has taken on a far more generic meaning over the years), but the type of video signal it originally used was RGBHV (on the DE-15 connector, AKA: "VGA connector", pins 1, 2, and 3 are R, G, and B respectively; pins 13 and 14 and H- and V-sync, respectively). These days you can have "VGA" over HDMI or DVI if you want to.

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Order completed.

Order received yesterday. Three days, nice!

I think I will install this in my "chrome dome switch" light six for a truly unique Atari VCS.

Hopefully this weekend.

 

Also saying worse RF to best RGB is technically true, but the beautiful, clean, rich RF from a Heavy Sixer is amazing and a great example of "getting it right the first time". For lots of games this RF display is more enjoyable to me than a pixel perfect crisp blocky emulator-like output.

That being said, some games are better with a clear picture.

With this mod, it is nice to have the options of composite, S-Video and RGB to choose from.

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Any word on the Jr adapter board?

 

I will have one eventually, but not in the immediate future. It's different to my usual adapter board. To fit in needs to be made from flexible material and fold around the edge of the motherboard. It's a different process and a bit more expensive.

 

 

The 'stereo' audio was deliberately not included. The vast majority of games were not designed with a thought to sound channel separation. Whether it sounds better or worse with the separation it just a matter of luck. It's also not possible with PAL consoles.

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If you wanted separate audio would it be fine to lift the 2 NTSC TIA pins and wire a 10uf electrolytic capacitor between the pin and the center of the red jack, and the same for the white jack, with ground going to both red and white outer jacks?

I like the option of separation for games that use it, and games that play and sound wrong I find it simple to use the display remote and press menu, audio, mono.

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If you wanted separate audio would it be fine to lift the 2 NTSC TIA pins and wire a 10uf electrolytic capacitor between the pin and the center of the red jack, and the same for the white jack, with ground going to both red and white outer jacks?

I like the option of separation for games that use it, and games that play and sound wrong I find it simple to use the display remote and press menu, audio, mono.

 

The pins are open collector outputs so a pull up resistor to the +5V supply is required to get any output. I don't recommend connecting the pin straight to the outside world like this. It's too easy to damage the TIA because there's no protection from ESD and other environmental dangers.

 

Ideally, you should use a buffer-amplifier between the two audio signals and the outside world. It can be simple, a pair of transistors or dual op-amp would do.

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I'm so glad you finally responded and that I hadn't done any mods yet. I understand your reasons for not including the dual channel option but I have experienced it and enjoy it. I'm glad you cautioned about lifting directly from the chip before I did it. I've never done any designing of circuits and where as I understand what they do when explained, I don't possess the knowledge to design them on my own and wouldn't have known what was needed. I still have some questions on how to apply what you suggest and what part I actually need so I'll go do some research.

 

The pins are open collector outputs so a pull up resistor to the +5V supply is required to get any output. I don't recommend connecting the pin straight to the outside world like this. It's too easy to damage the TIA because there's no protection from ESD and other environmental dangers.

 

Ideally, you should use a buffer-amplifier between the two audio signals and the outside world. It can be simple, a pair of transistors or dual op-amp would do.

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The pins are open collector outputs so a pull up resistor to the +5V supply is required to get any output. I don't recommend connecting the pin straight to the outside world like this. It's too easy to damage the TIA because there's no protection from ESD and other environmental dangers.

 

Ideally, you should use a buffer-amplifier between the two audio signals and the outside world. It can be simple, a pair of transistors or dual op-amp would do.

Thank you, Tim, for your reply! I only follow directions and assemble things. I don't know circuit design.

I found the longhornengineer schematic, I'd forgotten about the resistors.

This is how the stereo mod has been done to date.

post-29575-0-42045800-1444407286_thumb.jpg

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I will have one eventually, but not in the immediate future. It's different to my usual adapter board. To fit in needs to be made from flexible material and fold around the edge of the motherboard. It's a different process and a bit more expensive.

 

Damn that's unfortunate. I'm assuming you would be using something similar to Kevtris NES HD mod, with an interposer board and ribbon?

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I found a problem with the "extra button" used to switch the video modes. It is activated by pressing left and right simultaneously. If someone connects paddles to the joystick port (paddles use left and right for fire buttons) and presses both fire buttons, it will activate the "extra button" pallet switch.

 

No, you misunderstand. Pressing the extra button on the controller is the equivalent of pressing both left and right on the joystick at once. It doesn't do anything at all by itself, only in combination with one of the three other signals. For example, to change the palette press extra + fire (equivalent to left + right + fire). The 2600RGB doesn't interfere with any 2600 controllers that I could find documented.

 

 

Thank you, Tim, for your reply! I only follow directions and assemble things. I don't know circuit design.

I found the longhornengineer schematic, I'd forgotten about the resistors.

This is how the stereo mod has been done to date.

 

I've attached an audio buffer circuit you can build. It's made from a cheap dual op-amp and some passive components.

 

 

 

Damn that's unfortunate. I'm assuming you would be using something similar to Kevtris NES HD mod, with an interposer board and ribbon?

 

It's not so simple. There's very little space in the Jr model so the TIA must remain attached to the PCB.

post-2716-0-82519100-1445336646_thumb.png

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For example, to change the palette press extra + fire (equivalent to left + right + fire). The 2600RGB doesn't interfere with any 2600 controllers that I could find documented.

 

The Starplex:

post-3056-0-54510400-1445349954_thumb.jpg

 

I'm pretty sure driving controllers and trackballs (in trackball mode) will cause a problem, they don't use the directions the same way a joystick does.

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I just got an HDMI capture card.

This is super tempting.

The most expensive part will be the framemeister, however. I'd love to stream RGB Atari 2600.

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Hi Tim -

 

Your site states that "Palettes may be modified by the user (requires a serial EEPROM programmer)." Are you planning to release any more information on the ROM format so we can try custom palettes?

 

Thanks.

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I just got an HDMI capture card.

This is super tempting.

The most expensive part will be the framemeister, however. I'd love to stream RGB Atari 2600.

 

Here's my first capture - with 2600 RGB mod, and stereo mixed in Atarivox, + 60 FPS...with a couple of recent pick-up games at the Portland Retro Game Expo...The Wall Jump Ninja is pretty fun

 

Link:

 

Took awhile to edit this surprisingly, I had more but couldn't figure out how to edit 60FPS outside of youtube's built in editor...

 

Lastly, don't fault the RGB for the green color dim on top portion of the screen on Frogger - looked fine on my LCD. Something to do with the capture card possibly...

 

cheers

Edited by funkwad

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Here's my first capture - with 2600 RGB mod, and stereo mixed in Atarivox, + 60 FPS...with a couple of recent pick-up games at the Portland Retro Game Expo...The Wall Jump Ninja is pretty fun

 

Link:

 

Took awhile to edit this surprisingly, I had more but couldn't figure out how to edit 60FPS outside of youtube's built in editor...

 

Lastly, don't fault the RGB for the green color dim on top portion of the screen on Frogger - looked fine on my LCD. Something to do with the capture card possibly...

 

cheers

 

That looks absolutely perfect :)

 

I'm live streaming Frankenstein's Monster this weekend, on my current setup.

 

S-Video mod > S-video to HDMI upscaler > Avermedia HD-DVR.

 

I wish I had an Elgato. I seen a stream with the direct s-video input of a supergun, and it looked crisper than my Dreamcast test I did on the setup.

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Your site states that "Palettes may be modified by the user (requires a serial EEPROM programmer)." Are you planning to release any more information on the ROM format so we can try custom palettes?

 

The first 128 bytes is the header. It's not used so just set all values to zero.

 

Then just append palette files as needed. A palette file is almost the same format as the Stella emulator uses. The only difference is there is no SECAM palette information.

 

For reference,

  • The palette file must be 768 bytes long. Colours are stored in 24-bit RGB, with the first byte for red, the second for green, the third for blue, for a total of 3 bytes per colour.
  • The first 384 bytes of the file (128 * 3) will be used for the NTSC palette. The next 384 bytes (128 * 3) will be for the PAL palette.

 

Minimum 1 file, maximum 6 files. If the next palette it tries to load is set all to 0xFF then it assumes it's at the end and wraps around. Current user selected PAL and NTSC palettes are remembered separately.

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The Starplex:

 

I'm pretty sure driving controllers and trackballs (in trackball mode) will cause a problem, they don't use the directions the same way a joystick does.

 

 

Driving controllers are fine, they don't connect to left/right at all. From brief research, it appears a 2600 trackball or supporting games don't actually exist (???).

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Minimum 1 file, maximum 6 files. If the next palette it tries to load is set all to 0xFF then it assumes it's at the end and wraps around. Current user selected PAL and NTSC palettes are remembered separately.

 

Could you elaborate on how the palette switch work? I don't have your board yet and I'm not sure I understand what happens when you press the switch.

 

Say if you have PAL/NTSC autodetect, a 60Hz game and press the switch, does it roll through all three NTSC palettes or all six NTSC and PAL palettes? In what order? Same behaviour if the region autodected mode is off?

 

What could be interesting for a v1.1 board is some space to attach an LED, which would briefly flash one to n times when the palette is changed, so we know where we are in the cycle.

 

(and maybe, just throwing it out there, separate switches: one for the PAL / NTSC colour scheme, and one for the Original / Custom1 / Custom 2 palette switch? I'm just thinking out loud here, don't mind me too much)

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