MD Port Swap - Utility

• physical : no
• rom : yes
• licensing : unlicensed
• code : mdportswaputility
• Date(s) : 2026
• By(s) : YoSoyNacho

MD Port Swap — Genesis/Mega Drive Controller Port Swapper

Win32 GUI tool for Sega Genesis / Mega Drive ROMs that:

Swaps all Controller Port 1 <-> Port 2 I/O register references in ROM code.
Recomputes and fixes the ROM header checksum afterward.

Originally intended for using an external controller as Port 1 on the Sega Nomad, but you can use it however you want

The tool scans the whole ROM for these sequences and flips the last byte (03<->05, 09<->0B), which makes the game read/write the pad through the opposite port everywhere in the code, with no game-logic changes.

This won't help games that use indirect/computed I/O addressing (rare).

Data retrieved from romhackplaza.org

MD Port Swap - Utility

• title : MD Port Swap - Utility
• language : English
• last updated : 2026
• by : YoSoyNacho
• version : 1.0.0
• download : 2
• platform : SEGA Genesis
• code : mdportswaputility

• ↪ https://romhackplaza.org/utilities/md-port-swap-utility

Screenshots