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  • Joined: 28 Sep 1999
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GG to SMS adapter
Post Posted: Sat Jul 11, 2015 3:38 am
I recently developed a Game Gear to SMS cartridge adapter to facilitate dumping GG games with the SMS Reader. You can use it play GG games that run in SMS mode on the SMS as well.

It has a power LED and a "Game Gear mode" LED that lights if the cartridge won't work on the SMS. Some of the GG specific signals are broken out to a pin header which isn't populated in the picture below.

It can be mounted in a SMS cartridge shell if you cut up the top of the shell quite a bit to make room for the cartridge connector. The connector was salvaged from a Game Gear Game Genie. It was pretty hard to remove, but that's a better option than scrapping a GG console for one!
gg-adapter.jpg (236.57 KB)
gg-adapter.jpg

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  • Joined: 03 May 2014
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congrats
Post Posted: Tue Jul 14, 2015 4:23 pm
looks great, do you have any video to share?
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  • Joined: 28 Sep 1999
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Post Posted: Tue Jul 14, 2015 9:52 pm
tatsui wrote
looks great, do you have any video to share?


Nah, but it looks just like a regular SMS game playing in the end. :)
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  • Joined: 13 Jul 2006
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  • Location: Rio de Janeiro - Brazil
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Post Posted: Fri Jul 17, 2015 12:40 pm
You know what I would love to see? A "smart" GG to SMS adapter, that would watch the address and data buses and patch instructions in real time to bypass the incompatibilities between the 2 systems, such as palettes.

I wonder if this is even possible... Are the signals necessary for this available to the cartridge at all? And I know that automatic palette conversions wouldn't always look good, and lots of GG games have garbage in the video outside the GG viewport, but still, many games would at least be playable.
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Post Posted: Fri Jul 17, 2015 11:48 pm
Quote
I wonder if this is even possible... Are the signals necessary for this available to the cartridge at all? And I know that automatic palette conversions wouldn't always look good, and lots of GG games have garbage in the video outside the GG viewport, but still, many games would at least be playable.


Good question. The main thing that makes GG games not work are the writes to the serial I/O which conflicts with the SMS slot control, so you could add a circuit that detected those writes and prevented them from being passed to the rest of the system. That would at least get games running, though perhaps not playable.

The palette problem is difficult though, you'd need some logic to monitor accesses to the VDP and snoop palette writes, and there's all kinds of subtle ways a game can access the VDP that would break that since access to VRAM and CRAM re-use the same internal elements.

I think it's possible, but maybe not practical.
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  • Joined: 13 Jul 2006
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  • Location: Rio de Janeiro - Brazil
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Post Posted: Sat Jul 18, 2015 4:38 am
Looking at the cartridge connector pinout, it appears that the cartridge could use the address and data lines along with the /IORQ signal to see what data is written to which IO port, making it possible to detect CRAM writes.

However, I don't think there's anything that can be done to intercept those writes, so that manipulated color values could be sent to the VDP instead.

The only thing I can think of is that the cartridge could buffer the 16-bit colors that were written and write them again later after converting them to 8-bit, whenever it can steal some time to do this. This could possibly screw up the timing in some games, and not work well in games that modify the palette mid-frame...

Oh well, I'm not a hardware person, so it's not like I could make something like this anyway. =)
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  • Joined: 22 Dec 2004
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  • Location: UK
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Post Posted: Mon Jul 27, 2015 10:10 am
Hey Charlie,

Nice job on the adapter, Looks nice. I can see why you'd pick Taito Chase HQ, being that the SMS release is not 60hz compatible.

I have a couple of questions for you, if that's alright? ;)

Do you know if it is possible to source a Game Gear cartridge connector rather than using one from a Game Gear itself?

Will you be posting the Gerber files on a site like https://oshpark.com so people can get the PCB printed for themselves? I'm assuming you aren't planning a production run yourself. ;)

This question goes out to everyone, Has anyone posted Gerber files to make an SMS Gender Adapter for JP to EU/US?

It has been mentioned here: http://www.smspower.org/forums/15591-SegaMasterSystemGenderAdapterFORPALCONSOLE
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  • Joined: 28 Sep 1999
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Post Posted: Sat Aug 01, 2015 10:45 pm
Hiya Whitesnake,

Quote
Do you know if it is possible to source a Game Gear cartridge connector rather than using one from a Game Gear itself?


As far as I know there aren't any commercially available connectors that are compatible with GG games. You have to either take apart a GG console for one, or take apart a GG Game Genie.

Quote
Will you be posting the Gerber files on a site like https://oshpark.com so people can get the PCB printed for themselves? I'm assuming you aren't planning a production run yourself. ;)


Absolutely. I want to make a few tweaks to the PCB layout first (no change in functionality) and I'll make it available through OSH Park. I have some other SMS projects that I'll distribute through that route too.
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  • Joined: 22 Dec 2004
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Post Posted: Tue Aug 04, 2015 12:53 pm
Charles MacDonald wrote
Hiya Whitesnake,

Quote
Do you know if it is possible to source a Game Gear cartridge connector rather than using one from a Game Gear itself?


As far as I know there aren't any commercially available connectors that are compatible with GG games. You have to either take apart a GG console for one, or take apart a GG Game Genie.

Quote
Will you be posting the Gerber files on a site like https://oshpark.com so people can get the PCB printed for themselves? I'm assuming you aren't planning a production run yourself. ;)


Absolutely. I want to make a few tweaks to the PCB layout first (no change in functionality) and I'll make it available through OSH Park. I have some other SMS projects that I'll distribute through that route too.


Awesome, I look forward to it. :)
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Post Posted: Mon Jul 11, 2016 3:30 am
I've published the PCB layout for the SMS to GG adapter:

https://oshpark.com/shared_projects/ozcIRkhg

Some time later I'll put up proper documentation for it at my website.

For assembly, you need two 330 ohm resistors in an 0805 package, two LEDs in an 0805 package (your choice of colors) for the "Power" and "GG Mode" indicators, and a Game Gear cartridge connector taken from the Game Gear Game Genie.

I don't know if you can use a cartridge connector from a Game Gear console itself. If somebody tries it, let me know how that works.

To be clear the adapter is really intended for dumping GG games, but you can play GG games that run in SMS mode this way too, such as Chase H.Q.

The adapter isn't intended to be used with a cartridge shell, but you can try it anyway. :D
1549f50557a0e510b97bc517db6d6702.brd.zip (14.7 KB)
Attachment fairy

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  • Joined: 05 Nov 2014
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  • Location: Auckland - NZ
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Post Posted: Thu Jul 28, 2016 9:11 am
Hay! This is pretty neat. I started doing the same thing last year and got most of the way there. My wife randomly decided she wanted a divorce, and well.. life sort of fell apart from there. All the projects i had going on at the time have sit in my draw at work since then. 10 months down the line im sort of starting to pick things up again. Anyway.. Ive got a cart connector i pulled off a dead game gear at work, what a bitch that was to get off. I might cheat and just use your board layout and build this from there. I got keen and designed some bits that replicate the cart slot on the back of a game gear, so the cart stays put in the socket better. Ill add that to the one i build and post some pics when its done.
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Post Posted: Sun May 19, 2019 8:43 pm
Charles MacDonald wrote
I've published the PCB layout for the SMS to GG adapter:

https://oshpark.com/shared_projects/ozcIRkhg

Some time later I'll put up proper documentation for it at my website.

For assembly, you need two 330 ohm resistors in an 0805 package, two LEDs in an 0805 package (your choice of colors) for the "Power" and "GG Mode" indicators, and a Game Gear cartridge connector taken from the Game Gear Game Genie.

I don't know if you can use a cartridge connector from a Game Gear console itself. If somebody tries it, let me know how that works.

To be clear the adapter is really intended for dumping GG games, but you can play GG games that run in SMS mode this way too, such as Chase H.Q.

The adapter isn't intended to be used with a cartridge shell, but you can try it anyway. :D


Amazing man !

I will try to build one using a GG console connector ! I will let you know :)

THANK YOU !

If you can, are you able to tell me if the pinout of your PCB is the same as this one: https://i.imgur.com/UTnWuVY.png

(*MOD* Attachment fairy. Please don't link to imgur)


EDIT:
It works: http://www.smspower.org/forums/17490-ADapterToUseEverdriveGGOnMasterSystem#10622...

:)
UTnWuVY.png (54.54 KB)
UTnWuVY.png

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