TI58C, the programmable calculator!

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"Fibonacci" test

The objective of this test was to find the most elementary programming problem possible allowing to write an almost identical program on all Texas Instruments programmable calculators.
This problem :

should not include trigonometric functions, to be able to concern calculators "The MBA", BA-55 and BA-54,

should not include conditional branching instructions, to be able to apply to calculators having only RST as unconditional branching instruction. (TI-55, TI-53 and also "The MBA", BA-55 and BA-54),

had to be able to be expressed in mathematical formula, to be able to relate to the calculators "not really" programmable TI-68 and TI-60X (*).

The program had to be able to deliver a result for a given value :

either iteratively up to n (loop with GOTO or RST),

either directly: result alone for n only.
Finally, this program had to be as short and as simple as possible to know if the most complex and powerful calculators could solve a problem as easily as the most rudimentary machines.

The object of this rudimentary programming test was a continuation of Fibonacci which can be reduced to a loop :
+ RCL 01 = R/S EXC 01 RST
the launch is done by entering the value 1 then R/S (after RST). then R/S for each subsequent value.

(*) as the TI-68 and TI-60X calculators only used formulas, it was not possible to program a recursive sequence, so it is Binet's formula which was used to solve the problem posed.
On the other hand, for the other calculators, Binet's formula was not necessarily the best choice: 47 programming steps for the TI-58C for example.