KiCAD schematics for the adapter.
The compact pcb (suggested) uses a detachable ribbon cable to connect to to the computer and features an optional jumper to switch the adapter to C64 mode.
The full adapter has an ICSP header for programming the PIC in-circuit, and through-hole D-sub connectors for both the computer and controller side of the adapter. Using an extension cable or soldering a joystick cable pigtail directly to the computer side of the adapter is recommended; the adapter will not fit directly in most joystick ports.
The tiny pcb (untested; not recommended) has edge connectors for solder cup D-sub connectors and uses a simple solder bridge jumper to convert it to C64 mode.
The schematics for this project are licensed under the Creative Commons Attribution 4.0 International licence. See LICENSE for details.