Intermediate Store Method For TI-60X Programs

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The TI-60X is an early EOS advanced scientific calculator from the 1990s. It was the successor to the TI-60, a programmable calculator with limited memory, lacking label or conditional instructions. Despite this, some nice programs were possible. The TI-60X replaced the programming capabilities with "formulas", stored expressions which would prompt for the variables used and give a result, similar to the expr-eval function on the TI-36X Pro.

Running a program on the TI-60 simply required a single press of the R/S key, recalling and storing from the memory, using a number on the display, and ending with the final result on the display, being stored in the corresponding variable to the formula name. Executing a formula on the TI-60X requires pressing 2nd FMLA, then the corresponding ALPHA letter of the desired formula. After this, the user is prompted for each variable used, which will automatically have their previous values, which can be entered and reviewed with ENTER or confirmed with SOLVE, moving on to find the result of the formula.

Luckily, I have found a very useful method for TI-60X programming, intermediate storage of results in variables unrelated to the formula being executed. The STO command can be used at any point within a formula to store a value calculated halfway through it, and continue afterwards. This allows for many programming possibilities, such as initializing variables, incrementing values to be used in the next formula, or saving multiple results to be recalled. Even multiplication by zero within parentheses can be used to alter a variable without changing the outcome of the main formula.

You may ask, why use the TI-60X with limited memory and functionality when the TI-68 is available? Unfortunately, the TI-68 gives an error when STO is used in a formula.

I have written an example program which uses this method:
Enter formula Y=X²+1 STO +X*0
Press ENTER
Enter a starting value for X, perhaps -3
Press SOLVE
The corresponding Y value for (-3)² will be displayed and stored
Continue to press SOLVE to see the automatically incremented X value and each corresponding Y value

I hope to use this in some interesting programs soon. If you do not have a TI-60X, it is a nice machine and not too expensive on eBay.