The Keypad Joypad - Amiga, Atari, C64... | Hackaday.io
Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
Reading C64 Joysticks and Analog Signals (Programming Electronics with the Commodore 64 Part 3) - Retro Game Coders
Joystick information and circuits
Vectrex Controller to Atari 2600 Adapter - CNK
Connectors Commodore VIC 20 – My old computer
DIY) USER PORT DONGLE for C64 586220 DIAGNOSTIC CARTRIDGE - Share Project - PCBWay
Arduino Project: Commodore 64/Amiga, Atari 2600/XL/ST, ZX Spectrum Joystick to Windows/Linux (RetroPie) USB | jfrmilner's Tech Blog
Problems Connecting an Arduino Uno to a Commodore 64 Joystick Port - Retrocomputing Stack Exchange
Reading C64 Joysticks and Analog Signals (Programming Electronics with the Commodore 64 Part 3) - Retro Game Coders
Technical corner
Joystick – C64-Wiki
Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
Joystick - DenialWIKI
Mingos Commodorepage
C-64 Workshop / Pin Connections
commodore 64 - Would a multi button controller have been possible on the C64? - Retrocomputing Stack Exchange
Obsolescence Guaranteed: Converting the 'Commodore 64' DTV
Connectors Commodore 64 – My old computer
Tube Time on Twitter: "the left one is a Commodore 1351 mouse designed for a C64/C128, while the right one is meant for an Amiga. the pinouts are very close and neither