Terminated: 1983
The TI 58, TI 58 C
and the TI 59 are
programmable calculators that can be extended using Solid State Software
Libraries. There is a small slider at the back where these Solid State Software
modules can be inserted. The module shown here is the default MASTER LIBRARY MODULE.
The TI 58 C has non volatile memory (constant memory).
This series of programmable calculators (SR-52, TI SR-56, TI 57, TI 58, TI 58 C, TI 59) really set the tone of most programmable scientific calculators to follow. But they also clearly borrow from the fabulous HP calculators that came before them.
The programming instructions of this calculator include flags (which could be used for a number of hidden functions as well), indirect addressing, subroutines, ...
I actually used this calculator for quite a while during my study, until its battery pack finally gave up.
Succeeded by the TI-66 which uses LCD instead of an LED display.