The goal of this project is to use the GPIO pins of a Raspberry Pi along with a DB25 breakout board to implement the IEEE-1284 parallel port protocol. Specfically I am attempting to get communciations with the Rio PMP300 MP3 player to work with modern operating systems. This particular device uses the nibble mode to return data in 4bits via the status register.
Research / Links Paralell Port Protocol http://electrosofts.com/parallel/ https://wiki.osdev.org/Parallel_port https://en.wikipedia.org/wiki/Parallel_port