I have the main unit.
type calculator
The Texas Instruments TI-57 — Programmable Calculator Pioneer
The Texas Instruments TI-57, released in 1977, was one of TI’s early programmable calculators — an affordable entry point into programmable calculation that made the concept accessible to students and professionals who could not afford the more expensive TI-58 and TI-59. With 50 programming steps and algebraic entry, the TI-57 allowed users to automate repetitive calculations and store programs for repeated use. TI’s programmable calculator range of the late 1970s introduced programming concepts to a generation of users who had never touched a computer, and many engineers and scientists trace their first programming experience to devices like the TI-57.