There is disclosed in one example, an encasement for a mobile computer, including: an external casing in a clamshell form factor, the external casing including a base, a secondary display chassis hingedly connected to the base at a secondary hinge, and a primary display chassis hingedly connected to the secondary display chassis at a primary hinge disposed at a removed edge of the secondary display chassis from the secondary hinge, the primary display chassis to substantially overlay the secondary display chassis and the base when the primary hinge is in a closed position; and pivot means disposed to substantially bias the secondary hinge against movement from a selected position in at least one direction in the absence of an electrical input.