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I've already been asking around and researching a bit...some of the obstacles I have encountered so far:

GG- 45 pins?
SMS- 50 pins?

GG- larger color palette than SMS? Color mapping is inverted?

I've been interested in doing this for a while now, but even moreso since I've finally gotten my paws on a working SMS...I figured it was possible, because when I used to play my GG a lot, I remembered I was bored and started taking the cartridge out while the GG was on, and when I did that- the resolution changed and I saw much more of the game screen... But sometimes when playing a game like this, all the colors would invert and then the Start button would have no function.
I'm very curious if this can be done (as I would love to play Sonic Triple Trouble full-screen on a tv... Sonic Blast too because I have no idea where to begin searching for a TecToy version for the SMS). If anyone has any info that could help, I would appreciate it if you would get in touch with me...preferrably through email
spilskinanke2097(at)yahoo.com

or on AIM: MuttFox as I am not sure how frequently I will be checking this forum.

My VCL art

Quote

> I've already been asking around and researching a bit...some of the obstacles I have encountered so far:

> GG- 45 pins?
> SMS- 50 pins?

> GG- larger color palette than SMS? Color mapping is inverted?

It's not practically possible to build a converter to play Game Gear games on an SMS, at least not one where games will look corectly and be playable. The Game Gear's features are a superset of the SMS's, so which the GG can run in an SMS compatible mode, the SMS cannot run in a GG compatible mode. What this means is:

-The SMS cannot display the 160x144 pixel display area in full screen - so you'll see about 40 pixels of junk on each side of the screen that you're not supposed to be able to see in a GG game.

-The palette will be mangled. The palette in the GG takes two bytes per entry instead of one, using opne nibble per color gun (with one unused nibble), instead of two bits per gun.

-There is nothing mapped the the start button. While the start button in the GG will act like the SMS pause button when it's running in SMS mode, a GG game running in GG mode reads the start button in an entirely different manner. A GG game running on an SMS would not be able to read the Pause button (or anything else) as a press of the start button, so most games could not be started or paused.

These kinds of problems cannot be solved with a cartridge based adaptor. The only way you could do it would be to design a replacement video chip for the SMS that has a GG compatible mode, and work out a way for the start button (or an externally mounted button) to function as a GG style start button. That is an extreme solution - if you just want to play GG games in fullscreen then you'd be better off trying a console based emulator, or get a TV out card for your PC if it's close enough to your television to be of any use.

As Heliophobe said, there are tow problems: the palette and the start button. Actually, there's a third, the link port, for games that try to check it, and a fourth, the GG stereo port.

Anyway, I *did* run a GG game on my SMS. Unfortunately I don't have the screengrab any more. But here's how it goes:

1. Write GG Sonic to an SMS devcart
2. Run it
3. Notice that it acts as if I'm holding down the Start button (game starts immediately, then pauses).
4. Disassemble the game, find the pause routine and remove it
5. Play!

The palette is DESTROYED, you get 12-bit colours truncated to 6-bit. It looks kind of psychadelic but you wouldn't want to look at it for too long.

If the game happens to want to initialise the link port then it won't even reach the title screen, probably - because I heard you need to emulate it for GG games to run on an emulator. It depends what the SMS returns for that port.

Also, as I found in my VGM player, writing to port $06 (?) for GG stereo will neatly crash an SMS.

So basically: with careful hacking, you can get a game running, but not through any general method and not through hardware. With more hacking, you might be able to get a reasonable palette and maybe even a working pause routine (if you're lucky). But you'll still have on-screen stuff that was off-screen on the GG. For a preview, try playing any TecToy GG to SMS conversion...

Maxim

Well after that stint, I've lost NEARLY all interest...

but a few things remain... like i originally said,the ability to pull a GG game half-out of the system and have it emulate a resolution like that of the master system ON the gg screeen. and nothing beyond where the edges of the gamegear screen would be are jumbled, it's all clear... I have shots of it:

http://geocities.com/muttfox/ggms/ggms.html

and it's not using a SMS-GG converter either, because if you look at the ring/time/lives indicators, they are still within the boundaries of the GG screen.

then what about this:
Is there any way to make the GG output SMS resolution?

Quote

> but a few things remain... like i originally said, the ability to pull a GG game half-out of the system and have it emulate a resolution like that of the master system ON the gg screeen. and nothing beyond where the edges of the gamegear screen would be are jumbled, it's all clear... I have shots of it:

That's quite easy. You need to hack either a cart or your GG to remove the connection to pin 42 and make it possible for you to modify. From here I can read that pin 42 is "GG" with a line over it meaning (as far as my crappy electronics understanding goes) that when it's connected to GND the GG will be in GG mode and when it's at +5V it's in SMS mode.

What you found was that by pulling the cart out you could disconnect the pins at the right end of the connector (most of them are unnecessary for the game to work, they're other stuff) and that leaves pin 42 unconnected, which luckily is far enough from GND to work.

If you can add a switch then you should be able to modify it at will. You probably need to boot the GG in GG mode and put it in GG mode whenever anything GG-specific (Start button, palette changes) happens, so an on-the-fly switch is needed.

Also, the way the GG game works depends ENTIRELY on the game in question. For GG Sonic they were of course working with the same codebase as SMS Sonic, so the scrolling engine is fullscreen. GG-specific games may be a lot uglier.

One thing you can try is to grab an emulator that lets you choose to not crop the GG screen. The only one I know of is FreezeSMS. Turn that option on and see what you get.

Maxim

Author	Message
AG-Wolf Guest	GG -> SMS Converter (no NOT the other way around) Posted: Mon Dec 30, 2002 9:41 pm
AG-Wolf Guest	I've already been asking around and researching a bit...some of the obstacles I have encountered so far: GG- 45 pins? SMS- 50 pins? GG- larger color palette than SMS? Color mapping is inverted? I've been interested in doing this for a while now, but even moreso since I've finally gotten my paws on a working SMS...I figured it was possible, because when I used to play my GG a lot, I remembered I was bored and started taking the cartridge out while the GG was on, and when I did that- the resolution changed and I saw much more of the game screen... But sometimes when playing a game like this, all the colors would invert and then the Start button would have no function. I'm very curious if this can be done (as I would love to play Sonic Triple Trouble full-screen on a tv... Sonic Blast too because I have no idea where to begin searching for a TecToy version for the SMS). If anyone has any info that could help, I would appreciate it if you would get in touch with me...preferrably through email spilskinanke2097(at)yahoo.com or on AIM: MuttFox as I am not sure how frequently I will be checking this forum. My VCL art

Heliophobe Site Admin Joined: 25 Oct 1999 Posts: 2029 Location: Monterey, California	Posted: Mon Dec 30, 2002 10:16 pm
	Quote > I've already been asking around and researching a bit...some of the obstacles I have encountered so far: > GG- 45 pins? > SMS- 50 pins? > GG- larger color palette than SMS? Color mapping is inverted? It's not practically possible to build a converter to play Game Gear games on an SMS, at least not one where games will look corectly and be playable. The Game Gear's features are a superset of the SMS's, so which the GG can run in an SMS compatible mode, the SMS cannot run in a GG compatible mode. What this means is: -The SMS cannot display the 160x144 pixel display area in full screen - so you'll see about 40 pixels of junk on each side of the screen that you're not supposed to be able to see in a GG game. -The palette will be mangled. The palette in the GG takes two bytes per entry instead of one, using opne nibble per color gun (with one unused nibble), instead of two bits per gun. -There is nothing mapped the the start button. While the start button in the GG will act like the SMS pause button when it's running in SMS mode, a GG game running in GG mode reads the start button in an entirely different manner. A GG game running on an SMS would not be able to read the Pause button (or anything else) as a press of the start button, so most games could not be started or paused. These kinds of problems cannot be solved with a cartridge based adaptor. The only way you could do it would be to design a replacement video chip for the SMS that has a GG compatible mode, and work out a way for the start button (or an externally mounted button) to function as a GG style start button. That is an extreme solution - if you just want to play GG games in fullscreen then you'd be better off trying a console based emulator, or get a TV out card for your PC if it's close enough to your television to be of any use.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Tue Dec 31, 2002 11:35 am
	As Heliophobe said, there are tow problems: the palette and the start button. Actually, there's a third, the link port, for games that try to check it, and a fourth, the GG stereo port. Anyway, I did run a GG game on my SMS. Unfortunately I don't have the screengrab any more. But here's how it goes: 1. Write GG Sonic to an SMS devcart 2. Run it 3. Notice that it acts as if I'm holding down the Start button (game starts immediately, then pauses). 4. Disassemble the game, find the pause routine and remove it 5. Play! The palette is DESTROYED, you get 12-bit colours truncated to 6-bit. It looks kind of psychadelic but you wouldn't want to look at it for too long. If the game happens to want to initialise the link port then it won't even reach the title screen, probably - because I heard you need to emulate it for GG games to run on an emulator. It depends what the SMS returns for that port. Also, as I found in my VGM player, writing to port $06 (?) for GG stereo will neatly crash an SMS. So basically: with careful hacking, you can get a game running, but not through any general method and not through hardware. With more hacking, you might be able to get a reasonable palette and maybe even a working pause routine (if you're lucky). But you'll still have on-screen stuff that was off-screen on the GG. For a preview, try playing any TecToy GG to SMS conversion... Maxim

AG-Wolf Guest	Posted: Fri Jan 03, 2003 1:11 am
AG-Wolf Guest	Well after that stint, I've lost NEARLY all interest... but a few things remain... like i originally said,the ability to pull a GG game half-out of the system and have it emulate a resolution like that of the master system ON the gg screeen. and nothing beyond where the edges of the gamegear screen would be are jumbled, it's all clear... I have shots of it: http://geocities.com/muttfox/ggms/ggms.html and it's not using a SMS-GG converter either, because if you look at the ring/time/lives indicators, they are still within the boundaries of the GG screen. then what about this: Is there any way to make the GG output SMS resolution?

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Making the GG use SMS resolution Posted: Fri Jan 03, 2003 8:47 am
	Quote > but a few things remain... like i originally said, the ability to pull a GG game half-out of the system and have it emulate a resolution like that of the master system ON the gg screeen. and nothing beyond where the edges of the gamegear screen would be are jumbled, it's all clear... I have shots of it: That's quite easy. You need to hack either a cart or your GG to remove the connection to pin 42 and make it possible for you to modify. From here I can read that pin 42 is "GG" with a line over it meaning (as far as my crappy electronics understanding goes) that when it's connected to GND the GG will be in GG mode and when it's at +5V it's in SMS mode. What you found was that by pulling the cart out you could disconnect the pins at the right end of the connector (most of them are unnecessary for the game to work, they're other stuff) and that leaves pin 42 unconnected, which luckily is far enough from GND to work. If you can add a switch then you should be able to modify it at will. You probably need to boot the GG in GG mode and put it in GG mode whenever anything GG-specific (Start button, palette changes) happens, so an on-the-fly switch is needed. Also, the way the GG game works depends ENTIRELY on the game in question. For GG Sonic they were of course working with the same codebase as SMS Sonic, so the scrolling engine is fullscreen. GG-specific games may be a lot uglier. One thing you can try is to grab an emulator that lets you choose to not crop the GG screen. The only one I know of is FreezeSMS. Turn that option on and see what you get. Maxim

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