HP-42S

HP-42S

The HP-42S
Type	Programmable scientific
Manufacturer	Hewlett-Packard
Introduced	1987
Discontinued	1995
Calculator
Entry mode	RPN
Precision	12 display digits (15 digits internally),[1] exponent ±499
Display type	LCD dot-matrix
Display size	2 lines, 22 characters, 131×16 pixels
CPU
Processor	Saturn
Programming
Programming language(s)	RPN key stroke (fully merged)
Firmware memory	64 KB of ROM
Program steps	7200
Interfaces
Ports	IR (Infrared) printing
Other
Power supply	3×1.5V button cell batteries (Panasonic LR44, Duracell PX76A/675A or Energizer 357/303)
Weight	6 oz (170 g)
Dimensions	148×80×15mm

The HP-42S RPN Scientific 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.^[2] 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)^[3] 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.^[4]

HP-42S specifications

HP-42S battery compartment and the IR diode

• 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 82240A 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.

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.

Legacy

In May 2017, SwissMicros released pre-production samples of an RPN calculator closely resembling the HP-42S, the DM42. Even though slightly smaller (144×77×13 mm, 170 g) than the original HP-42S (148×80×15 mm, 170 g), the calculator comes with an additional top row of keys for soft menus, a keyboard layout supporting direct alpha character input, a much larger high-contrast display (Sharp low power transflective memory LCD with a resolution of 400×240, protected by Gorilla Glass) showing all four stack levels at once, ca. 77 KB usable RAM, a beeper, a callable real-time clock as well as an infrared port for HP 82240A/HP 82240B printer support and an USB interface (with Micro-USB plug) emulating a FAT16-formatted USB mass storage device for easy program transfer and state backup / transfer as well as for firmware updates. The calculator, which comes in a stainless steel case with black PVD (Physical vapor deposition) coating, supports keyboard overlays and is based on a modified version of Thomas Okken's GPLed Free42 simulator with Intel's decimal floating-point math library for higher precision (decimal128) running on an STM32L476RG processor (ARM Cortex-M4 core, 128 KB RAM, 1 MB internal flash) with another 8 MB of external flash (of which ca. 6 MB are available to users). It is powered by a CR2032 coin cell or via USB and clocked dynamically at 24-80 MHz.

References

External links

• HP-42S Owner's Manual on HP41.net
• 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.
• Okken, Thomas (2011-04-20). "Free42, A HP-42S Calculator Simulator". Retrieved 2011-08-12. 
• An Alternative HP-42S/Free42 Manual
• Hosoda, Takayuki (2007-10-10). "HP-42S memory upgrade and overclock". Retrieved 2011-08-12.