Vintage Hewlett Packard HP 28S Advanced Scientific Calculator featuring a unique clamshell folding design. This classic piece of computing history includes a dual-keyboard layout with alpha and numeric keys, a multi-line LCD screen, and extensive mathematical functions. The unit is currently non-functional and is being offered for parts, repair, or as a collector's display piece. Notable corrosion residue is present on the battery terminals, and the unit has not been tested with batteries. Made in the USA, this model is a staple for vintage tech enthusiasts and HP calculator collectors.