Casio FX-502P series
The FX-501P and FX-502P were programmable calculators, manufactured by Casio from 1978/1979. They were the predecessors of the FX-601P and FX-602P. It is likely that the FX-501P/502P were the first LCD programmable calculators to be produced as up until 1979 (and the introduction of the HP-41C) no manufacturer had introduced such a device. Arithmetic The FX-502P series use algebraic logic as was state-of-the-art at the time. Display The FX-501P and FX-502P featured a single line 7-segment liquid crystal display with 10 digits as main display. An additional 3 digits 7-segment display used to display exponents and program steps when entering or debugging programs and 10 status indicators. The display was covered with a yellow filter, They were the first Casio calculators to implement engineering notation, and the first calculators in general to implement an engineering notation with shift facility (following Hewlett Packard calculators implementing the first engineering notation in general, and some Commodore and Texas Instruments calculators implementing variable scientific notation with exponent shift facility). Programming The programming model employed was key stroke programming by which each key pressed was recorded and later played back. On record multiple key presses were merged into a single programming step. All operations fitted