HP-42S

The HP-42S RPN Scientific is a programmable RPN Scientific hand held calculator introduced by Hewlett-Packard in 1988. It is a popular calculator designed for science and engineering students.

Overview

Perhaps the HP-42S was to be released as a replacement for the aging HP-41 series as it is designed to be compatible with all programs written for the HP-41. Since it lacked expandability, and lacked any real I/O ability, both key features of the HP-41 series, it was marketed as an HP-15C replacement.

The 42S, however, has a much smaller form factor than the 41, and features many more built-in functions, such as a matrix editor, complex number support, an equation solver, user-defined menus, and basic graphing capabilities (the 42S can draw graphs only by programs). Additionally, it features a two-line dot matrix display, which made stack manipulation easier to understand.

Production of the 42S ended in 1995.<ref name="HPM_HP42S"/>

Specifications

HP-42S battery compartment and the IR diode

HP-42S calculator internal teardown

• Series: Pioneer
• Code Name: Davinci
• Introduction: 1988-10-31
• 64 KB of ROM
• 8 KB of RAM
• Functions: Over 350
• Expandability: Officially no other than IR printing (32 KB memory upgrade<ref name="Hosoda_2007"/> and over-clocking hardware<ref>Template:Citation</ref> hacks are possible)
• Peripherals: HP 82240A infrared printer

Features

• All basic scientific functions (including hyperbolic functions)
• Statistics (including curve fitting and forecasting)
• Probability (including factorial, random numbers and Gamma function)
• Equation solver (root finder) that can solve for any variable in an equation
• Numerical integration for calculating definite integrals
• Matrix operations (including a matrix editor, dot product, cross product and solver for simultaneous linear equations)
• Complex numbers (including polar coordinates representation)
• Vector functions
• Named variables, registers and binary flags
• Graphic display with graphics functions and adjustable contrast
• Menus with submenus and mode settings (also custom programmable) that use the bottom line of the display to label the top row of keys
• Sound (piezoelectric beeper)
• Base conversion, integer arithmetic and binary and logic manipulation of numbers in binary, octal, decimal and hexadecimal systems
• Catalogs for reviewing and using items stored in memory
• Programmability (keystroke programming with branching, loops, tests and flags)
• The ability to run programs written for the HP-41C series of calculators

Programming

The HP-42S is keystroke-programmable, meaning that it can remember and later execute sequences of keystrokes to solve particular problems of interest to the user. The HP-42S uses a superset of the HP-41CX FOCAL language.

All programs are stored in one continuous program space, and may be created and edited by switching to programming mode, using the Template:Keypress key. Subroutines are enclosed in Template:Keypress/Label (name of subroutine) and Template:Keypress/Return (halts execution unless it is in a subroutine in which case it returns to the caller). Keystrokes (of functions) are enclosed between Template:Keypress and Template:Keypress or Template:Keypress.

In a running program, a Template:Keypress label causes program execution to branch to the specified label and continue running at that line. Executing a GTO instruction from the keyboard moves the program pointer to the corresponding label. No program lines are executed.

Template:Keypress is used in much the same way with one important difference: after an Template:Keypress instruction has transferred execution to the specified label, the next RTN (return) or END instruction causes the program to branch back to the instruction that immediately follows the XEQ instruction. Programs/Subroutines can also be executed with the help Template:Keypress label (Execute) key. The important difference between the Template:Keypress and Template:Keypress is that Template:Keypress executes the label and returns to previous subroutine and continues execution from the line following Template:Keypress,whereas Template:Keypress branches to the label specified and doesn't return.

Template:KeypressTemplate:KeypressTemplate:Keypress packs the current subroutines and moves to new program space.Template:KeypressTemplate:Keypressnnnn can be used to reach a particular line of program.

Programming examples

A simple program to calculate area of circle

Step	Instruction	Comment
00	{ 6-Byte Prgm }
01	Template:KeypressTemplate:KeypressTemplate:KeypressTemplate:KeypressTemplate:Keypress	Start of program "AREA"
02	Template:KeypressTemplate:Keypress	Prompts for Value of R and stores it in R
03	Template:Keypress	Squares the value in X register
04	Template:Keypress	Puts π on the stack
05	Template:Keypress	Multiplies values in X and Y register
Template:Keypress or Template:Keypress	Returns control (and result in X) to either the user or to a calling program.

Program instructions like Template:Keypress, Template:Keypress, Template:Keypress halt the program execution,which can be continued by pressing Template:Keypress.

Template:Keypress is used to view contents of a register,For example R in the above example.

Using Integral and Equation Solver

It is necessary to write a program or subroutine that evaluates f(x) for the function which needs to be solved or integrated. Variables used in program should be declared using Template:Keypress

Here is a sample program to solve the equation °F = (9/5×°C) + 32

Step	Instruction	Comment
00	{ 31-Byte Prgm }
01	Template:KeypressTemplate:KeypressTemplate:KeypressTemplate:KeypressTemplate:Keypress	Start of program "TEMP"
02	Template:KeypressTemplate:Keypress	Declares F as a variable for solver
03	Template:KeypressTemplate:Keypress	Declares C as a variable for solver
04	Template:KeypressTemplate:Keypress	Recall F
05	Template:Keypress
06	Template:Keypress
07	Template:Keypress
08	Template:KeypressTemplate:Keypress	Recall C
09	Template:Keypress
10	Template:Keypress
11	Template:KeypressTemplate:Keypress
12	Template:Keypress
Template:Keypress or Template:Keypress	Returns control (and result in X) to either the user or to a calling program.

After, accessing the solver using Template:Button Template:Keypress (Template:Keypress ), select program Template:Keypress.

In a similar way, expressions can be integrated. After selecting the variable of integration, enter the lower limit and then press on Template:Keypress, similarly input Template:Keypress (upper limit) and Template:Keypress (accuracy).

Emulators

Emu 42

HP 42s can be accessed through Android Emulators like Emu42 and Free42.

WP 34s

Reference Books

File:RPN Books.png

Reference Books

Guides and Collections of Keystroke Programs

Documentation for the HP 42S calculator at hpcalc.org<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

• HP-42S Owner's Manual <ref>Template:Cite web</ref>
• HP-42S Programming Examples & Techniques<ref>Template:Cite web</ref>
• Step-by-Step Solutions: Electrical Engineering (42S)<ref>Template:Cite web</ref>
• Step-by-Step Solutions: Mechanical Engineering (42S)<ref>Template:Cite web</ref>
• Advanced Circuit Analysis with the HP-42S<ref>Template:Cite web</ref>
• An Easy Course in Using the HP-42S<ref>Template:Cite web</ref>

Educational Texts on RPN calculators

• Algorithms for RPN Calculators<ref>Template:Cite web</ref>
• Scientific Analysis on the Pocket Calculator<ref>Template:Cite web</ref>
• Engineering Statistics with a Programmable Calculator<ref>Template:Cite web</ref>
• Applied Mathematical Physics with Programmable Pocket Calculators<ref>Template:Cite web</ref>
• Mathematical Astronomy with a Pocket Calculator<ref>Template:Cite web</ref>
• Handbook of Electronic Design and Analysis Procedures using Programmable Calculators<ref>Template:Cite web</ref>
• Calculator Programs for Chemical Engineers(Vol 1 & 2)<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

Collection of Algorithms/Keystroke Programs for HP 41/HP 42S

• Software Library for HP 41 Programs(Compatible with HP 42S)<ref>Template:Cite web</ref>

See also

• FOCAL character set
• Comparison of HP graphing calculators
• HP calculators
• List of Hewlett-Packard pocket calculators
• NOMAS (support)

Further reading

• Template:Cite book
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• HP-42S Quick Reference Guide (1 ed.). Corvallis, OR, USA, Dex Smith. October 1988. 00042-92222E.
• Template:Cite web
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External links

• SwissMicros DM42
• HP-42S intro on hpcc.org
• HP-42S page on hpmuseum.org
• HP-42S resources on hp42s.com (defunct as of July 2017)
• HP-42S description on rskey.org
• HP-42S description on thimet.de
• Free42 for Android by Thomas Okken, an Open Source project.
• Template:Cite web