The 1972 Casio-mini was the first handheld calculator. Over 2 million units were sold. This calculator helped launch the PC revolution - how? The inexpensive mini and other early handheld calculators forced other manufacturers, like MITS, out of the market (see MITS 1440)..looking for a new business MITS went on to produce the Altair 8800 computer and the rest was history. Click on image for larger view.