HP-42S

HP-42S
Company type	Product
Industry	Electronics, Calculators
Predecessor	HP-41 series
Founded	October 31, 1988; 38 years ago
Fate	Discontinued in 1995
Products	Programmable scientific calculators
Parent	Hewlett-Packard

The HP-42S RPN Scientific calculator is a programmable handheld device utilizing RPN, launched by Hewlett-Packard in 1988. It gained significant popularity among science and engineering students due to its sophisticated capabilities.

Overview

The HP-42S was most likely developed as a successor to the older HP-41 series, with full compatibility for HP-41 software. Nevertheless, it did not offer the same level of expandability or extensive I/O features as the HP-41, leading it to be positioned more as an alternative to the HP-15C model.

In contrast to the HP-41, the 42S was more compact and incorporated a greater number of built-in functions. These included a matrix editor, support for complex number calculations, an equation solver, customizable user menus, and basic graphing capabilities through programming. Its two-line dot matrix screen enhanced stack visibility.

Manufacturing of the HP-42S ceased in 1995.

Specifications

Product line: Pioneer
Internal code name: Davinci
Release date: October 31, 1988
ROM capacity: 64 KB
RAM capacity: 8 KB
Functions count: Over 350
Official expandability limited to IR printing; however, unofficial upgrades include 32 KB memory expansions and hardware modifications for overclocking
Supported peripheral: HP 82240A infrared printer

Features

Comprehensive set of fundamental scientific functions, including hyperbolic functions
Advanced Statistics capabilities such as curve fitting and forecasting methods
Extensive Probability functions encompassing factorials, random numbers, and the Gamma function
An Equation solver capable of finding roots for any variable within an equation
Numerical integration tools for calculating definite integrals
Matrix manipulation with an integrated editor, including operations like the dot product, cross product, and simultaneous resolution of linear equations
Full support for calculations involving Complex numbers, including representations in polar coordinates
Vector-related functions for mathematical and physical applications
Utilization of named variables, dedicated hardware registers, and binary flags for advanced data handling
Graphic display calculator offering graphical functions along with adjustable contrast settings
User-customizable menus that leverage the bottom line of the display to label keys dynamically
Audio output through a piezoelectric beeper
Base conversion and integer arithmetic capabilities across binary, octal, decimal, and hexadecimal systems, including binary logic operations
Memory catalog system enabling review and management of stored data items
Programmability through keystroke sequences supporting control structures such as branching, loops, conditional tests, and flag manipulation
Backward compatibility allowing execution of programs designed for the HP-41C series

Programming

The HP-42S supports keystroke programming, allowing users to record and run custom sequences of keystrokes. Its programming language extends the capabilities of the HP-41CX's FOCAL language.

Programs are stored in a contiguous memory area accessible via the key. Subroutines are defined between label declarations () and return commands (), which either terminate program execution or return from a subroutine. Instructions inside subroutines are enclosed by and or .

During program flow control, invoking label jumps directly to that label without returning control after execution. Conversely, label calls a subroutine at that label and resumes execution at the following instruction upon return. Programs or individual subroutines can also be initiated using the key.

Additional programming commands include , which compacts existing subroutines and allocates new program memory space, as well as nnnn, which performs a direct jump to a specified program line number.

Programming Examples

Below is a straightforward program designed to compute the area of a circle:

Step	Instruction	Explanation
00	{ 6-Byte Prgm }
01	Template:Keypress Template:Keypress Template:Keypress Template:Keypress Template:Keypress	Initiate program named "AREA"
02	Template:Keypress Template:Keypress	Request radius R input and save it
03	Template:Keypress	Raise the value in the X register to the power of two
04	Template:Keypress	Insert π onto the stack
05	Template:Keypress	Multiply the contents of X and Y registers
Template:Keypress or Template:Keypress	Deliver the computed result in X back to user or calling routine

Commands such as , , and halt execution until resumed with . Use to examine the contents of registers.

Employing Integral and Equation Solver

To perform solving or integration, programs must compute f(x) for the target function. Variables are defined using .

Example: Convert °C to °F using °F = (9/5 × °C) + 32

Template:Keypress or Template:Keypress

Step	Instruction	Explanation
00	{ 31-Byte Prgm }
01	Template:Keypress Template:Keypress Template:Keypress Template:Keypress Template:Keypress	Launch program labeled "TEMP"
02	Template:Keypress Template:Keypress	Define F as a solver variable
03	Template:Keypress Template:Keypress	Define C as a solver variable
04–12	Template:Keypress Template:Keypress, 9, 5, ÷, Template:Keypress Template:Keypress, ×, -, 32, -	Construct equation for solver input
Output result to user or calling program

Access the solver by pressing + (), then choose the desired program. Integration is performed similarly by specifying the variable, integration bounds (, ), and desired precision ().

Emulators

HP 42S calculators can be emulated on Android devices through applications such as Emu42 and Free42, allowing users to utilize HP 42S features on mobile platforms.

Reference Books

Program Guides and Keystroke Collections

HP-42S Owner's Manual
HP-42S Programming Examples & Techniques
Step-by-Step Solutions: Electrical & Mechanical Engineering
Advanced Circuit Analysis with the HP-42S
An Easy Course in Using the HP-42S

Instructional Books on RPN Calculators

Algorithms for RPN Calculators
Scientific Analysis on the Pocket Calculator
Engineering Statistics with a Programmable Calculator
Applied Mathematical Physics with Programmable Calculators
Mathematical Astronomy with a Pocket Calculator
Handbook of Electronic Design and Analysis Procedures
Calculator Programs for Chemical Engineers (Volumes 1 & 2)

Algorithm and Keystroke Program Collections for HP 41/HP 42S

Comprehensive Physics and Mathematics Programs
Software Library of HP 41 Programs (Compatible with HP 42S)

External links