Well, I suppose if the TI-55 can be called a programmable calculator, the same is true for this Sharp unit. It is a very decent little multifunction calculator, quite a pleasure to use; unfortunately, its programming model is rather limited. The calculator has enough memory to record two keystroke sequences, the combined length of which must not exceed 40 keystrokes. A very simple branch capability is provided, which allows a program to be restarted if the selected condition is true.

Unfortunately, this branch capability makes it difficult (or rather, impossible) to set initial values for variables programmatically, because these initial values would be reapplied every time the calculation restarts. It is also not possible to store initial values in any of the "temporary" variables A-F, because when the program is run, the calculator would prompt for these variable's values anyway.

This programming model is demonstrated by the following factorial program:

0⇒M
AB⇒B
A-1⇒A
x>M
B

When the program is run, the calculator prompts for the values of A and B, and calculates B×A!. It is not possible to set B initially to 1 in the program.

The 40-step program memory is too limited for even attempting to implement something as complex as the Gamma function. However, Stirling's formula can be implemented as follows (this implementation calculates the logarithm of the extended factorial, typically to a precision of 4 digits):

ln2Aπ÷2+AlnA-A+ln(1+1÷12A)