SIO2Arduino is an open-source implementation of the Atari SIO device protocol that runs on Arduino hardware. Arduino hardware is open-source and can be assembled by hand or purchased preassembled.
This fork does not require any additional libraries. It should work delightfully well with the base SD library included with current Arduino SDKs. This change may also fix some issues with certain SD card hats that may not have worked under the older libraries.
For more information on SIO2Arduino, see the website at:
http://www.whizzosoftware.com/sio2arduino
For more information on the Arduino platform, go to:
http://www.arduino.cc
Also note that this fork is licensed under the GPL version 3 license.