As I have mentioned before, most of my duties involve financial calculations in an industrial environment.
The calculator I prefer among all, because of its simplicity (no menus) and its portability (fits in my jacket and occupies very limited space in a crowded desk, is the HP15.
Here is a dump of the program memory:
Let's start with an oldie, in the version that appears in the Advanced Functions handbook - no change needed. It uses the A to E keys in User mode, following the standard n -i- PV- PMT-FV. One key for entering the data and placing the program pointer in the right place; then R/S to execute:
I will continue in the next few blogs with the rest of the memory. For the sake of engineer futility, I have left space enough for a 3x3 + 3 equation system if some time was needed - and it has not been the case so far !!