What's new

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
It's been a dream of mine since childhood, being able to play Game Gear games on the Master System.

Outside of the different cartridge form factor and pinout, there are a few software incompatibilities. It's possible to patch Game Gear ROMs to make them playable on the Master System, I had a go a few years back and it's actually pretty simple. That's how I though, why not designing a device that would do those software patches on the fly?

That's exactly what the Gear Master Converter does:
- defeats ROM header BIOS check
- reduces palette (from 4096 colours on the GG to only 64 on the MS)
- handles the start button
- disables writes to ports $00~06 since they are within the range of the memory and I/O control registers (unexpected writes to the memory control registers can cause to deactivate ROM or RAM access, resulting in a crash indeed)

You can see a video of it running an unmodified GG ROM here:
https://vimeo.com/560494780

Unfortunately the last hurdle is finding GG cartridge slots. If anyone has a lead please contact me.

[EDIT]
I've tested the adapter on PAL and SECAM MS, in 50 and 60Hz, both model 1 and 2.
It doen't work on a MD/Genesis with a Power base converter since not all signals are available through the cartridge port.

My initial goal was to design a device Sega could have sold BITD. That means with no extra hardware required:
- PAUSE button on the MS is START
- not compatible with the START button on MD/Genesis pads
- not remapping the START button on the second controller
Sega wouldn't have released a product that would have needed a second controller and map the START button to it.
In the same way they wouldn't have required users to play with a MD/Genesis pad.
Thats said there's no technical difficulty in adding that kind of support. Maybe I'll push the design further in the future with a menu letting players choose how START button should be handled, or give them the choice between different palette modes (as suggested by Bob from RetroRGB https://www.retrorgb.com/).

[EDIT 2]
Supports region change (cause yes, the GG has a region bit which differs between Japanese and overseas units, hence the game with Japanese text in the video since the bit wasn't handled and left to 0 = JAP).
Also supports GG games using MS ROMs (e.g. Castle Of Illusion).

[EDIT 3]
Why the name Gear Master Converter? Because it does the opposite of the Master Gear Converter:

1623676895266.png


https://segaretro.org/Master_Gear_Converter
 
Last edited:

nem

Enlightened
Joined
May 29, 2016
Messages
4,149
Reaction score
3,326
Location
Finland
This is really neat! I have tons of GameGear games that get no love from me, because I can't be bothered to play handhelds anymore. It's big CRTs or nothing for me.
 

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
The video link seems to be your admin link, this one worked for me: https://vimeo.com/559623208

Someone made a set of PC-Engine hucard slots specifically for dumping, maybe they've got an idea where to get GG slots?

Can't seem to find the shop again, only a tweet: https://twitter.com/db_himself/status/824378977653506053?s=20
Thanks, link is fixed now.
Honestly I tried to contact many companies regarding those GG cartridge slots, they're manufactured somewhere for sure, Tototek used to have them listed in their parts section, Analog has an adapter for GG games so does RetroN. But I either got no answer or hit a big wall.
 

Fluffy

Grand Master
Joined
Dec 15, 2018
Messages
590
Reaction score
1,042
Location
UK
I guess if you're happy to buy a few thousand you can get custom tooling made, like the guys who got new Amiga DB23 connectors made.
 

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
@Fluffy I really don't know who to contact. Also I reckon that's probably a 5k investment.
 

Fluffy

Grand Master
Joined
Dec 15, 2018
Messages
590
Reaction score
1,042
Location
UK
I did contact a few companies through Alibaba when I was looking for transparent PAL/JPN SNES cartridge shells. One offer was a minimum custom run of 700, though I guess they had the moulds already. He didn't get back to me when I asked for an actual quote, though.

One starting point would be someone like that:
https://dgyuliang.en.alibaba.com/company_profile.html
https://terminal-blocks.en.alibaba.com/company_profile.html

I would probably as a start make some photos of the connector from all sides with a ruler as reference, and from the PCB with the required pin spacing, and query if they have a similar connector already.
 
Last edited:
  • Like
Reactions: nem

Hammy

Champion
Joined
Feb 3, 2018
Messages
1,115
Reaction score
2,118
Location
U.K
Very cool device! Another thing sega stupidly did not do BITD.
The SNES / gameboy one must of sold tons as it was very common to get them in "carboot lots" BITD.

Silly question maybe, but will it run on the MD via an SMS adapter?
I know the GG modes are not available on the MD either but the "usual" SMS stuff is....
 

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
Very cool device! Another thing sega stupidly did not do BITD.
The SNES / gameboy one must of sold tons as it was very common to get them in "carboot lots" BITD.

Silly question maybe, but will it run on the MD via an SMS adapter?
I know the GG modes are not available on the MD either but the "usual" SMS stuff is....
I see at least two reasons for Sega not to release it:
- drastic palette reduction (from 4096 base colours on the GG to 64 on the MS, that's 64 times less!)
- visible areas that are normally outside of the GG screen

I really doubt it will work on the MD since it needs vital signals that I'm afraid aren't available (or undocumented?) on a MD in MS mode. Also Sega loves to make silent changes between two hardware revisions.
 

djsheep

Multi Boyz Overlord
Legendary
Multi Boyz
Joined
May 20, 2016
Messages
5,234
Reaction score
6,822
Location
Brisbane, Australia
Will this be able to use the GG Everdrive?
 

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
I have updated first post with a better video.

@djsheep I don't know I don't have an Everdrive.
 

donluca

Enthusiast
Joined
Sep 23, 2015
Messages
252
Reaction score
157
Location
Italy
Unbelievable, this is really the stuff of dreams, well done Apocalypse!

I wonder if maybe a Mega Drive could have been a better candidate as a "host" system? IIRC it still has direct access to the Z80 and you could take advantage of the Mega Drive VDP's larger palette (512 colours, don't quote me on that, going from memory).
 

Apocalypse

Staff member
Legendary
Joined
Dec 6, 2017
Messages
3,719
Reaction score
6,401
Location
New-Zealand
Unbelievable, this is really the stuff of dreams, well done Apocalypse!

I wonder if maybe a Mega Drive could have been a better candidate as a "host" system? IIRC it still has direct access to the Z80 and you could take advantage of the Mega Drive VDP's larger palette (512 colours, don't quote me on that, going from memory).
Unfortunately not, it has NOT direct access to the Z80 and not all Z80 signals are available.
 
Top