9 pin to USB Dual Atari Joystick and Paddle Adapter by iCode, DB9 Ports, Pro Edition… : Electronics - Amazon.com
THAT @REM SHOW on Twitter: "This is my full gamut of joysticks, all of which are DB9 ports (not usb). In order: QuickShot (crap), megadrive pad (pretty good), custom nes-type pad (cheap),
Amazon.com: 9 pin to USB Dual Atari Joystick and Paddle Adapter by iCode, DB9 Ports, Pro Edition… : Electronics
Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
Build a USB Adapter for Retro Joysticks - Hackster.io
DB9 joystick to USB adapter acting weird on C64 : r/c64
Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
Ultimate Arcader Joystick DB9 Black – Ultimate Mister FPGA
Retro 9 Pin Joystick to USB Converter : 4 Steps (with Pictures) - Instructables
General Purpose port - MSX Wiki
ArcadeR 9 pin retro joystick - Amiga Shop
Retro 9 Pin Joystick to USB Converter : 4 Steps (with Pictures) - Instructables