ToToTEK.COM

rbudrick · Joined: 26 Mar 2004 Posts: 373

Yes, I know many say this is not possible, but it obviously is:

http://geocities.com/vjkemp/sega/ggtv.htm

I worked on this with Victor for quite a while and this is as far as we got. Without a dev unit to reverse engineer, we didn't get so far.

I think it would be an incredible product.

-Rob

timofonic · Posted: Fri Apr 23, 2004 9:45 pm Post subject:

It's a nice idea! I like the possibility of 1:1 aspect ratio and PAL/NTSC! Smile

rbudrick · Joined: 26 Mar 2004 Posts: 373

IMO, it's probably the most asked for item for GG developers...though most attempts fail. I'veonly met a couple guys with that Dev GG. If anyone has one or know someone who has one, PM me. I'll pay a LOT of money for one.

-Rob

Suppafly · Joined: 23 Jul 2003 Posts: 191 Location: Mexico

I once saw this adapter in an EGM article back in the early 90`s. The article said that sega used that modded game gear to display game gear games on a tv screen. The image only filled half of the screen, and they showed a pic of ax battler.....i think it included a pic of the mod too

rbudrick · Joined: 26 Mar 2004 Posts: 373

Yep,

It's on that link I posted.

-Rob

kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

Very impressive, I hope some day the project will be comparable to Sega's original unit. I knew someone would attempt this project some day :)

rbudrick · Joined: 26 Mar 2004 Posts: 373

Hi Folks,

I will pick this project up again if someone can find me one of those dev units...I've only met a couple people out there with them and they are reluctant to part with them. I will pay quite well for one.

However, there is enough material there to reverse engineer it based on the info on that link. If one can get a hold of that chip in the dev unit, which is found in some Sega System 24 arcade boards, then it would be (I imagine) not too hard to figure out. I had no luck there, but if we pool some resources...

-Rob

Tongueman · Joined: 12 Dec 2003 Posts: 39 Location: Japan

Hi, folks. I've also done the video mod (http://www.spini2k.com/chrisc/segahacking/gamegearvideo.html) and the video output is very nice on a TV, albeit in B&W.

I think it would not be too difficult for someone experienced in engineering to make up a converter for the GG's video signal to produce RGB video, even without knowing how that SEGA decoder worked. The encoding seems quite simple, but it would still need some circuitry to convert it to RGB or a nice colour composite signal.

The 4 video pins (plus composite sync) output a greyscale video image with RGB video encoded. For each "pixel" of the GG image, there are actually 3 pixels (but since this is an analogue video output, 3 levels) of information being passed through the video output. These 3 levels correspond to red, green, and blue values for the pixel if it were in colour. Imagine, if you will, that the GG's horizontal resolution is 256 lines (but only 160 are within the active display area for GG games). The video output of the GG is thus about 768 lines, with R,G, and B values interleaved. (This is just my guess.)

I can use the game Mappy as an example. In the game, there are doors which flash very quickly between bright red, green, and blue colours. When this game is displayed on a TV, the door doesn't flash but move horizontally, very minutely.

Surely, some circuitry that is timed to the horizontal clock (Hsync) can be made to take each of these lines, and combine the triplets into a colour composite signal, or output them as RGB levels? I have no EE experience, but with the above information it can be done. I'd love to have a colour output for my GG as much as everyone. Smile

rbudrick · Joined: 26 Mar 2004 Posts: 373

For anyone who attempts this, please note that in Master System mode, the screen is in color, only it is a bit messed up, sometimes crossing the red, green and blue colors...I dunno, I couldn't figure it out...

-Rob

g8crapachino · Guest

How about a Sega Game-Gear to Sega Genesis/Mega adaptor?

rbudrick · Joined: 26 Mar 2004 Posts: 373

g8crapachino, you should really post a new topic on that in order to keep on subject. Very Happy

-Rob

g8crapachino · Guest

It really isn't that far off topic. Follow the logic...You want to play GG games on a TV --> The GG is basically an upgraded and portable version of the Master System --> The Genesis plugs into a TV --> There is already an adaptor to play Master System games on a Genesis.

Therefore, rather then hacking up a Game Gear just to output to a Television, why not an adaptor to play Game Gear games on a Genesis?