HP-42S
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.
![]() The HP-42S | |
Type | Programmable scientific |
---|---|
Manufacturer | Hewlett-Packard |
Introduced | 1988 |
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 (Lewis) |
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 |
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.[2] As this calculator is regarded amongst the best ever made in terms of quality, key stroke feel, ease of programming, and daily usability for engineers,[3] in the HP calculator community the 42S has become famous for its high prices in online auctions, up to several times its introduction price, which has created a scarcity for utility end users.
Specifications
![](../I/Hp42s_battery_compartment.jpeg.webp)
![](../I/HP42S_Calculator_Internal_Teardown.jpg.webp)
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.
Step | Instruction | Comment |
---|---|---|
01 | LBLFAC | Start of program "FAC" |
02 | 1 | 1 is put into X, hence the value to be calculated upon (which was initially in X) is lifted (pushed) into stack register Y |
03 | LBL00 | Define label 00 |
04 | RCL×STY | Recall stack register Y and multiply with X |
05 | DSESTY | Decrement stack register Y and if not zero ... |
06 | GTO00 | ... go back to label 00 |
07 | END or RTN | Returns control (and result in X) to either the user or to a calling program. |
Legacy
In May 2017, SwissMicros released pre-production samples of an RPN calculator closely resembling the HP-42S, the DM42. The final product was released on the 9 December 2017. 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 (configurable), ca. 75 KB usable RAM, a beeper, a callable real-time clock as well as an infrared port for HP 82240A/HP 82240B printer support and a USB interface (with Micro-B connector) 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 matte black physical vapor deposition (PVD) 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 QSPI 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. The DM42 is also the hardware basis for the community-developed WP 43S calculator,[5][6] a successor to the WP 34S.
See also
References
- HP-42S RPN Scientific Calculator - Owner's Manual (PDF) (1 ed.). Corvallis, OR, USA: Hewlett-Packard Co. June 1988. p. 3. 00042-90001. Archived (PDF) from the original on 2017-09-17. Retrieved 2017-09-17.
- "HP-42S". Museum of HP Calculators. Retrieved 2016-10-27.
- http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv020.cgi?read=177373
- Hosoda, Takayuki (2007-10-10). "Upgrading the memory of the HP 42S to 32KB". Archived from the original on 2017-09-17. Retrieved 2011-08-12.
- Bonin, Walter (2019) [2015]. WP 43S Owner's Manual (PDF). 0.13 (draft ed.). ISBN 978-1-72950098-9. ISBN 1-72950098-6. Retrieved 2019-10-31. (314 pages)
- Bonin, Walter (2019) [2015]. WP 43S Reference Manual (PDF). 0.13 (draft ed.). ISBN 978-1-72950106-1. ISBN 1-72950106-0. Retrieved 2019-10-31. (271 pages)
Further reading
- HP-42S RPN Scientific Calculator - Owner's Manual (PDF) (1 ed.). Corvallis, OR, USA: Hewlett-Packard Co. June 1988. 00042-90001. Archived (PDF) from the original on 2017-09-17. Retrieved 2017-09-17.
- HP-42S RPN Scientific Calculator - Programming Examples and Techniques (PDF) (1 ed.). Hewlett-Packard. July 1988. 00042-90020, 00042-90019. Archived (PDF) from the original on 2017-12-19. Retrieved 2017-12-19.
- Strapasson, José Lauro; Jones, Russ (January 2010). An Alternative HP-42S/Free42 Manual (PDF). 0.7. Archived (PDF) from the original on 2017-09-17. Retrieved 2017-09-17.
- Horn, Joseph K. (2017-08-23) [1988-11-09]. "HP-42S Owner's Manual Addendum: Hidden Matrix Functions". Archived from the original on 2017-09-17. Retrieved 2017-09-17.
- "DM42 User Manual". 3.17. SwissMicros GmbH. 2020-10-21 [2016]. Archived from the original on 2020-10-21. Retrieved 2020-10-21.
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.
- Okken, Thomas (2011-04-20). "Free42, A HP-42S Calculator Simulator". Retrieved 2011-08-12.