@Blue Ink: A processor takes the next byte of data in its stream and interprets what to do with it.
Notepad does the same with a text stream (the next character determines whether to display it or move to a new line, and which glyph to display).
The only data that cannot be a form of code is data that is never processed in any form.
That's a very loose definition of "data", but even that doesn't suffice. There's plenty of dataflow architectures out there; think of an FPGA, for instance, or any hardware FSM machine.