I have the main unit and Casio FA-1 interface.
type programmable calculator
country Japan
year 1978
graphic LCD seven-segment, 10 x 3 digits
The Casio FX-502P — Programmable Scientific Calculator
The Casio FX-502P, released in 1979, was one of Casio’s pioneering programmable scientific calculators — capable of storing and executing programs of up to 128 steps. The FX-502P brought genuine programming capability to a pocket calculator format, allowing scientists, engineers, and students to automate complex repetitive calculations. Casio’s competitive pricing made programmable calculators accessible to students who could not afford Hewlett-Packard’s more expensive RPN alternatives, and the FX-502P was widely used in universities and technical colleges throughout the early 1980s.