Anyone tried to hack the TV tuner for the sega Game Gear??

[mkg]

Anyone tried to hack or reverse-engine the TV tuner for the sega Game Gear??
How it does work??
Because is seen that the TV tuner produces hi-color graphics and amazing audio.
If we reverse-engine it, we can get special chips run on GG, even a 32X add-on for the GG.

[GiGaBiTe]

You mean this thing?

www.retrocollect.com/Articles/the-rise-and-fall-of-the-sega-game-gear-tv-tuner-accessory.html

It's what it says it is, a TV tuner. It takes an NTSC/PAL signal and digitizes it and blasts it to the Game Gear.

The TV tuner pulls pin 43 low on the cartridge port and uses pin 44 and 45 for left and right channel audio from the tuner, which goes through the internal audio amplifier and to the speakers.

As to how it digitizes the NTSC/PAL signal to show up on the screen, it probably works in similar fashion to virtua racing on the Genesis. An array of tiles/sprites are created on the GG side and the TV tuner just keeps DMAing data to update said tiles/sprites continually.

You can try some hacking on the Game Gear by pulling pin 43 low and then writing data to the VDP in various ways to see what happens on the screen.

www.smspower.org/maxim/Documents/Pinouts
www.smspower.org/uploads/Development/msvdp-20021112.txt

I don't get why you think it has "amazing colors" because the TV tuner still has to conform to the limitations of the Game Gear, which is a 160x144 screen with 32 out of 4096 colors available at any given time on the screen.

Also, making a "32x like addon" for the Game Gear would be a terrible idea. You'd essentially be making a self contained console in a cartridge that does what the TV tuner does to get an image on a tiny and color limited screen. Trying to interface directly with the game Gear hardware doesn't make any sense, you have an 8 bit Z80 with a 64 kB memory map, there's no room to put anything without massive amounts of bank switching.

[mkg]

I tough that interfaced directly with the screen and the audio.

So it must go through the z80 and the VDP?

And also i don´t have a Game Gear, i saw the "amazing colors" in a youtube video showing the tv tuner

[GiGaBiTe]

The audio is directly passed through to the amp, but the picture is digitized, converted to tiles and sent to the VDP.

The tile conversion is probably done inside the tuner cart because the Z80 doesn't have near enough power to do that.

[mkg]

Ummm... at lest we can put soundchips into GG carts (Like Konami done with some FamiCom games)

[mkg]

www.sega-16.com/forum/showthread.php?30846-Which-consoles-have-audio-and-or-video-in-on-the-cart-slot-(Or-expansion-slot-)

Well, the video isn't converted to tiles (that would be too slow since there's some limit on how much data you can send the VDP each frame) but instead is passed trough the cart bus so the Z80 isn't turned ON. (As the third post says)