x42_ee_toolbox

About

This is my collection of x42 (HP-42S, SwissMicros DM42, Free42) programs. These programs are little helpers for my daily work as an electrical engineer, researcher and teacher and I preferably use them on a DM42. I admit that sometimes the programs may not be written optimally: I'm a kid of the 80s, my calculators during school were a TI-30 and a TI-Voyage-200 (which I never programmed) - my first programming language was C. I started using RPN calculaters in my 30s just for fun (thanks to a colleague). However I really like the programmability of the x42. I think there is no modern tool/software that gives the possibility to write such little everyday helpers in such a simple and clean way.

Program documentation

Information on program usage is written in the according program files.

functions (use with SOLVER)

• CCOAX: Coaxial/zylinder capacitor
• CPLATE: Plate capacitor
• FPBW: Full power bandwidth of an op-amp
• LC: Resonant frequency of an LC resonant cirucit
• RC: Cut-off frequency of a passive RC low pass filter
• RPAR: Parallel resistance of two resistors
• RTD: Resistance-temperature relation of Platinum type RTDs (e.g. Pt100)
• VREG: Voltage regulator (e.g. LM317)
• XC: Reactance of capacitor
• XL: Reactance of inductor

programs (use with XEQ)

• C→Z, L→Z: Impedance of an element, [HP42-EE]
• CONJ: Complex conjugate of x stack
• DY: Delta-wye conversion, [HP42-EE]
• I÷: Current divider, [HP42-EE]
• NIST: Physical constants
• QUAD: Roots of quadratic equation
• RFIT, RVIEW, ESER: Find a combination of two standard resistors for a desired value
  • Timing tests with fitting 1234 Ohm with E12 series, solving for 10 results:
  • Result without delay on Free42 computer app
  • 8 s on USB powered DM42
  • 21 s on battery powered DM42
• V÷: Voltage divider, [HP42-EE]
• X||Y: Parallel impedance of x and y stack

convert

Unit conversion program. The program was released by Werner on the hpmuseum.org forum [Werner-Convert42]; .txt files are the original files from the froum, .hp42s files may contain changes.

• CONV: Main conversion program
• DMENU: Helper program to build a menu based on matrices
• CRMATS: Helper program to create the menu matrices; this program must be executed once before using the the conversion program

non-engineering

• TVM: Time value of money (solver function), [HP42-OM]
• TVM2: Time value of money, [HP42-PE]

Toolchain

All programs are human readable text files with UTF8 encoding, so any editor should work fine to read the code. Files with the ending .hp42s are limited to the original HP-42S commands, while files ending with .free42 may contain some commands only available on Free42.

There are different ways to get the programs onto your platform/device:

• Of course you can simply transcode the files on your device (if you are fortunate enough to have an HP-42S, this is also the only option).
• To use the programs on the desktop version of Free42 you can simply put the calculator application into programming mode and copy and paste the program code into the application. You may further export raw or state files to export them for the use on a Free42 mobile app or a DM42.
• Directly generating raw files is supported by the txt2raw program, provided on the Free42 homepage. This repository contains a make_raw.py python file that batch converts all source files to a raw file.

Links and resources

• [HP42-QR]: HP-42S Quick Reference Guide
• [HP42-OM]: HP-42S Owner's Manual
• [HP42-PE]: HP-42S Programming Examples and Techniques
• [HP42-EE]: HP-42S Electrical Engineering
• [Werner-Convert42]: Forum post '(42) Conversions' on hpmuseum.org of Werner