HP 42S

Updated on Dec 13, 2024

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Manufacturer Hewlett-Packard Discontinued 1995		Introduced 1988 Entry mode RPN

Type Programmable scientific Precision 12 display digits (15 digits internally), exponent ±499

The HP-42S is a programmable RPN Scientific hand held calculator introduced by Hewlett Packard in 1988. It has advanced functions suitable for applications in mathematics, linear algebra, statistical analysis, computer science and others.

HP-41 replacement

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. Additionally, it features a two-line dot matrix display, which made stack manipulation easier to understand.

Production of the 42S ended in 1995. In the HP calculator community, the 42S is famous for its high prices in online auctions, with good condition calculators typically selling at around US$400 (2016) This is nearly a four-fold increase in price over its introduction cost and has created a scarcity for utility end users. Yet, this calculator is regarded amongst the best ever made in terms of quality, key stroke feel, ease of programming, and daily usability for engineers.

HP-42S specifications

Series: Pioneer

Code Name: Davinci

Introduction: 1988-10-31

64 KB of ROM

8 KB of RAM

Functions: Over 600

Expandability: Officially no other than IR printing (32 KB memory upgrade and over-clocking hardware hacks are possible)

Peripherals: HP 82240B infrared printer

HP-42S 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 (unrelated to the DEC FOCAL programming language).

The HP-42S supports indirect addressing with which it is possible to implement a Universal Turing machine and therefore the programming model of the HP-42S can be considered Turing-complete.

Sample program

This is a sample program which computes the factorial of an input integer number (ignoring the calculator's built-in factorial function). The program consumes 18 bytes. No memory registers are used.

References

HP-42S Wikipedia

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