DB9 joystick to USB adapter acting weird on C64 : r/c64
USBJoy2.0 - adapter. Connect your Atari Amiga C64 joystick to PC! Develop your own usb device! - Polish electronics for 3D printers, CNC, robotics, retro computers
USB Joystick Adapters – breadbox64.com
9 Pin Joystick to USB Adapter
Retronics USB Joystick Adapter and Other Coolness with V-USB | Code and Life