At the end of 2007, I got three Western Digital MyBook World 500 GB Network Attached Storage units. As it turns out, these contain a 200 MHz ARM9 with 32 MB RAM, and connections to network and USB connection as well as a 2.4 GB partition off a large disk, in a convenient small package. They are designed to go on the network and operate as file servers. Later, in the summer of 2008, I bought a few more of them. These are slightly different, and need some additional attention before they can work right.
As it turns out, these devices run Linux on the inside, and it is possible to gain access to the internals, and make an ssh server, or connect hardware, such as a serial port, or, as I've found out, an I2C bus as well. This opens up quite a number of possibilities.
The following pages show some details and notes I have made about these devices. I have also had great use of the forum and information at the Hacking WD MyBook World Ed site, and some of the information here has also been posted on that site.
I have divided this document into several parts: