CASIO PB-700 (1983)
It maybe looks like a calculator, but it is a fully-featured ultra-mobile computer from the early 80s. Weighing just 315 grams, It has a custom 8-bit CPU, up to 16kB of RAM, built-in BASIC and display with a resolution of 160×32 pixels (20×4 characters). The machine can be expanded with some sort of a docking station that adds a four-color plotter and tape storage.
