I am investigating the Philips PCF8584 chip. It ties a CPU to the I2C serial bus. This chip does all of the data sending and receiving, kinda like a uart. The chip uses two addresses and could be put on a floppy disk board and set to addresses $FF4E and $FF4F for instance. I have hand-wired this chip to a plug-in board to try it out.

It should act like a RBF driver, with data packets. Am currently thinking about how the software should flow. Right now I am collecting ideas as how to use the XMODE parameters to specify the sub-address of the target device and the command to send along with the data packet. Ultimately this I2C serial bus could be tied to a Real Time Clock, for instance the Dallas 1307.