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This web page is about official development cartridges, produced and distributed by Nintendo.
DMG-256K-EPROM
No photos are available.DMG-MBC1-512K-EPROM
No photos are available. I dunno, pretty standard cart I suppose.I can tell you that a demo port of the game Elite by Hybrid Technology ran on it.
See: http://www.iancgbell.clara.net/elite/demos/index.htm
DMG-MBC1-1M-EPROM
No photos are available.DMG-MBC1-2M-EPROM
No photos are available.DMG-MBC1-1M-EPROM+64K
No photos are available.DMG-MBC1-2M-EPROM+64K
No photos are available.DMG-MBC1-Multichecker
This is known lol, I just need to write more.DMG-MBC1-4M-EPROM+64K
No photos are available.DMG-MBC1-8M-EPROM+64K
No photos are available.DMG-MBC1-16M-EPROM+64K
No photos are available.DMG-MBC1-1M-EPROM+256K
No photos are available.DMG-MBC1-2M-EPROM+256K
No photos are available.DMG-MBC1-4M-EPROM+256K
No photos are available.DMG-MBC2-1M-EPROM
No photos are available.DMG-MBC2-2M-EPROM
No photos are available.DMG-MBC3-4M-ROM2-256K
No photos are available.DMG-MBC5-32M-FLASH
This one is also known. I need to write more.DMG-MBC5-32M-R-FLASH
Images from 2Far 2Quit. https://www.youtube.com/watch?v=q9nd86vbgTU
Images from Tim Hentenaar. http://hentenaar.com/gb-dev-cart
Year: 1999(?)
This cartridge is easily identifiable by its unique shell and colors.
Related to the "R" in the name, this cartridge has Rumble functionality (used in a few games with special cartridges like Pokemon Pinball).
The color seems to derive from the Japanese release of Pokemon Pinball. I believe it was the first Rumble Game Boy game released, April 14, 1999.
Image from Mokuzai Studio. https://mokuzai.studio/product/pokemon-pinball-japanese-game-boy-color/
DMG-MBC3-16M-FLASH
Image sources located at https://chainswordcs.com/pokemon-prototype-cartridges.html
Year: 2000
This cartridge is also very easily identifiable by its unique shell.
I have only ever known of Pokemon games being flashed on these carts.
Lots more info at https://chainswordcs.com/pokemon-prototype-cartridges.html
The shell seems to derive from some Hudson releases with special hardware inside, like Robopon Sun Version and Pocket Family GB.
Those two had black colored shells, but Pocket Family GB 2 had a clear translucent shell like the dev cart.