Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
What's the best DB9 (Atari 2600, 7800, ColecoVision, Sega Master System, Genesis, Odyssey2, C64, etc.) original controller to USB adapter in 2021? : r/RetroPie
USB Adapter for DB9 Joysticks (Amiga, Commodore, Atari) | eBay
USB DB9 Joystick adapter
Creating a 9 Pin Joystick Cable End - 3D Printing DIY - PCBurn
Resurrect your DB9 joystick, Mayflash USB Adapter Review – Vintage is The New Old