GN Twin, Genesis portable

Includes but not limited to: SNES, Genesis, Sega CD, PlayStation 1, Nintendo 64, Dreamcast, Game Gear and I guess the Virtual Boy.

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Sparkfist
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GN Twin, Genesis portable

Post by Sparkfist » Thu Nov 26, 2009 9:35 pm

Hey guys. I'm sure there are some of you out there that have a GN Twin, like the one used for this portable. I'm looking to get a quick project made while the weather is getting colder.

I know there are people that have figured out the pin out for removing the NES and the SNES in the FC Twin. Has anyone done the same for the GN Twin? I want to keep the NES in working order, so I need to remove the controller, and such. So if anyone can help I'd really love the help.

Thanks for the input guys.

-Sparkfist
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Ace_1
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Re: GN Twin, Genesis portable

Post by Ace_1 » Fri Nov 27, 2009 10:55 pm

The controller signals can be tapped from the 2 glop-top boards on the GN Twin's Genesis board. The GN Twin uses NES controller signals interfaced via conversion chips(the glop-top boards) to convert the NES controller signals into signals that the Genesis side understands, since the signals are different. This did cause some issues, however:

-Some games suffer from ENORMOUS control lag
-Any Master System game played via a Power Base Converter would not register any input from the D-pad.

My GN Twin's Genesis board is a mess, so I'd need you to take a high-res picture of the GN Twin's Genesis board so I can give you the pinouts of the 2 glop-top boards so you can wire a real Genesis 3-button or 6-button(you're best off using this) controller to your portable and still keep your NES board functional.

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Re: GN Twin, Genesis portable

Post by Sparkfist » Sat Nov 28, 2009 8:25 pm

I'm going to try and get some good clear pictures out of my camera and post them. Haven't had much luck today. If there is any thing else you'd like to know I'm willing to post it.

-Sparkfist
vskid wrote:Nerd = likes school, does all their homework, dies if they don't get 100% on every assignment
Geek = likes technology, dies if the power goes out and his UPS dies too

I am a geek.

Ace_1
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Re: GN Twin, Genesis portable

Post by Ace_1 » Sat Nov 28, 2009 11:16 pm

What I would really like would be a closeup of the sound circuitry used on the GN Twin, and, if possible, the source of the sound outputs(there are 3: FM left, FM right, PSG). I will be fitting a new sound circuit on mine to clean up the sound. That's actually the reason why the GN Twin sounds so bad: not because the system has the sound chips(Yamaha YM2612, Texas Instruments SN76489) reverse-engineered incorrectly, but rather because the sound is amplified very poorly, resulting in severe distortion. Sega screwed up the exact same way with the Genesis 2 and a very late revision of the Genesis 1, causing not just distortion, but a horrible hissing noise whenever sound would come out of the Genesis.

Also, I'd like to know which pins of the TecToy-580G GOAC are not connected anywhere so that I can find the RGB outputs(that GOAC outputs both Composite and RGB) for full 32X compatibility(this may be surprising, but the GN Twin is compatible with the 32X, although to get it working right, you need to tap the RGB/Composite Sync signals off the TecToy-580G and either replace the old sound circuit that sucks or add 2 resistors in parallel with the Genesis side's sound output from the 2 pins on the cartridge slot where the 32X's audio outputs come from, more precisely B1 and B3, located on the bottom left of the cartridge slot when facing the system).

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Re: GN Twin, Genesis portable

Post by Sparkfist » Tue Dec 01, 2009 5:58 pm

Here are a couple quick shots. I'll have time tomorrow to take the boards out and get clearer and if you want more specific shots.

http://img.photobucket.com/albums/v446/ ... 140053.jpg" onclick="window.open(this.href);return false;

http://img.photobucket.com/albums/v446/ ... 140054.jpg" onclick="window.open(this.href);return false;

-Sparkfist
vskid wrote:Nerd = likes school, does all their homework, dies if they don't get 100% on every assignment
Geek = likes technology, dies if the power goes out and his UPS dies too

I am a geek.

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Re: GN Twin, Genesis portable

Post by Ace_1 » Sat Dec 05, 2009 10:26 am

Thanks SparkFist!

Now, I don't exactly remember the pinouts of the glop-top boards, but I have a sheet where I wrote down which pins carry Genesis controller signals, so I'll go pull that out and modify your image of the entire GN Twin Genesis board to give you the pinouts according to a Genesis controller port.

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Re: GN Twin, Genesis portable

Post by aadz93 » Sat Feb 12, 2011 2:14 pm

Ace_1 wrote:Thanks SparkFist!

Now, I don't exactly remember the pinouts of the glop-top boards, but I have a sheet where I wrote down which pins carry Genesis controller signals, so I'll go pull that out and modify your image of the entire GN Twin Genesis board to give you the pinouts according to a Genesis controller port.

hey can you give me the pinouts because I am trying to build a portable genesis and I ripped off the nes board by accident
There are no stupid questions, just stupid people.

Ace_1
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Re: GN Twin, Genesis portable

Post by Ace_1 » Wed Mar 09, 2011 4:16 pm

Hang tight for a few minutes. I'll get those pinouts for you.

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