THE HP
Programmable Calculator
HP 35S
This calculator can do many things, and can be bought
for about $60.

It can be programmed. It cannot link to a PC.

However, here are
some notes, with a sample elementary program for the
h-dial. Also, an EOT calculation (described in the notes) but using an
EQUation as opposed to a program

The notes cover how to enter a program, and tips to avoid frustration.

My personal wish is that they revert to what was done 25 years ago, namely
use BASIC and not the convoluted method of programming now used. The
current method is comparable to BASIC but entering formula and so on is
very convoluted, hence why I added
these notes.
PERSONAL PREFERENCE

In spite of the HP35s, my
personal preference is the
Casio fx9860, in particular,
the spreadsheet, and its
cost.