phatIO is a new way of controlling external hardware by manipulating a file stored on an SD card. This means there is no need to install an IDE, and because each computer views the phatIO as a mass storage device, it can be used with any operating system. See the phatIO controlling an Adafruit LED Matrix in the video above.
When plugged into a computer’s USB port, phatIO (pronounced “fat-eye-oh”) appears as a USB filesystem/memory stick. You can control devices connected to phatIO by writing to files on that filesystem. Any computer that can write to a USB memory stick and any program/language that can write to a file can talk to phatIO and control things.
phatIO significantly reduces the effort needed to control things with a computer – no drivers have to be installed or low level libraries used. Each of the 20 general purpose IO pins can be controlled by saving a “0” or “1” to their control file.