Sega Genesis & Mega Drive Emulator for iPhone | Retropa

Genesis and Mega Drive are the same system

The console left Japan as Mega Drive and reached North America as Genesis; Europe and most of Asia kept the Mega Drive name. Same chips inside, so a game file cares about none of this. Retropa lists both names, and the extensions you see vary a little by region.

• Mega Drive dumps usually carry .md or .smd.
• North American rips often use .gen.
• The extension is a label, not a hardware switch.

The JGenesis core

JGenesis is the one core behind Genesis and Mega Drive here, and it also drives Master System, Game Gear and a few other Sega handhelds. That breadth is handy, but it makes the detected system per game important: import a Master System title with the system still set to Genesis and the result is confusing at best.

• JGenesis covers MD, GEN, SMS and GG.
• Check the detected system before you file a bug report.
• Both the core and the system stick to the game they were set for.

Import a Mega Drive game

Store the ROM locally; a cloud placeholder will look right in the browser and then fail at import. Choose it from the library's import entry, start the game once, and check picture, sound and the stock touch layout before adding a skin or a filter.

Mapping a six-button pad

Sega shipped three-button and six-button pads, and a few games quietly change how they play depending on which one they think is attached. In the touch layout, make sure A, B, C and, where the game offers them, X, Y, Z and Mode are all within reach. Then try a button pair the game actually asks for.

• Set up both the three-button and six-button layouts.
• Start doubles as pause in many titles, so keep it reachable.
• A paired controller removes most mis-press trouble.

Display treatment for a 16-bit console

Mega Drive output was built for a CRT, so scanlines or an aperture grille usually read truer than a raw pixel grid, especially on the dithering that a TV would have smoothed into a new shade. Advanced filters here work from the actual output area rather than a fixed integer multiple.

• Compare each preset against the plain picture.
• Heavy dithering is a good stress test for any preset.
• The advanced filter set needs Retropa Plus.

When a Genesis game will not start

Work through the extension, the system shown for that game and then the error text itself. Region and system mix-ups happen more often on this core than on single-platform setups, precisely because it serves several consoles. Leave the original file alone and fix the detected system before changing anything deeper.

• Jot down the app version, detected system, core and error.
• Support does not need your ROMs or any BIOS file attached.
• Back up saves separately before you move them across cores.