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.