The Codex is a dual-screen tablet computer, about the size of a 4"x6" day planner, with a self-supporting binding and embedded sensors. The device can be oriented in a variety of postures to support different nuances of individual work, ambient display, or collaboration with another user. In the context of a pen-operated note taking application, we demonstrate interaction techniques that support a fluid division of labor for tasks and information across the two displays while minimizing disruption to the primary experience of authoring notes. Author Keywords dual screen, sensors, pen, tablet, mobility, collaboration ACM Classification Keywords H.5.2 Information Interfaces and Presentation: Input