The present invention provides a personal information system unit detachable case. This case has a top cover assembly, a bottom cover assembly, both of which are pivotable around a longitudinal axis forming a hinge assembly. The top and bottom cover assemblies are similar in shape and function to allow a personal information management electronic system unit to be mounted within the case either facing to the right or to the left at the user's preference. Mounted on the hinge assembly is a mounting rail, which is pivotally mounted on the hinge assembly of the detachable case. This mounting rail extends most of the internal vertical dimension of the case. The mounting rail provides a means for removably attaching a personal management unit within the detachable case. Indents and other openings are provided in the top and/or bottom cover assemblies to accommodate a specific personal system unit or other type of electronic instrument whether it faces toward the top assembly or bottom assembly.