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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.

HP-42S
HP-42S
TypeProgrammable scientific
ManufacturerHewlett-Packard
Introduced1988
Discontinued1995
Calculator
Entry modeRPN
Precision12 display digits (15 digits internally), exponent ±499
Display typeLCD dot-matrix
Display size2 lines, 22 characters, 131×16 pixels
CPU
ProcessorSaturn (Lewis)
Programming
Programming language(s)RPN key stroke (fully merged)
Firmware memory64 KB of ROM
Program steps7200
Interfaces
PortsIR (Infrared) printing
Other
Power supply3×1.5 V button cell batteries (Panasonic LR44, Duracell PX76A/675A or Energizer 357/303)
Weight6 oz (170 g)
Dimensions148×80×15 mm

Overview

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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.[1]

Specifications

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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[2] and over-clocking hardware[3] hacks are possible)
  • Peripherals: HP 82240A infrared printer

Features

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Programming

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Main article: Focal (HP-41)

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 PRGM key. Subroutines are enclosed in LBL/Label (name of subroutine) and RTN/Return ( halts execution unless it is in a subroutine in which case it returns to the caller). Keystrokes (of functions) are enclosed between LBL and RTN or .END.

In a running program, a GTOlabel 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.

XEQ is used in much the same way with one important difference: after an XEQ 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 XEQlabel (Execute) key. Important Difference is that XEQ executes the label and returns to previous subroutine and continues execution from the line following XEQ,whereas GOTO branches to the label specificied and doesn't return back.

GTO.. packs the current subroutines and moves to new program space.GTO.nnnn can be used to reach a particular line of program.

Programming examples

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A simple program to calculate circumference of circle

Step Instruction Comment
00 { 6-Byte Prgm }
01 LBLCIR Start of program "CIR"
02 PI Puts π on the stack
03 INPUTR Prompts for Value of R and stores it in R
04 X↑2 Squares the value in X register
05 × Multiplies values in X and Y register
END or RTN Returns control (and result in X) to either the user or to a calling program.

Program instructions like STOP, PROMPT, INPUT halt the program execution,which can be continued by pressing R/S.

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

Using Integral and Equation Solver

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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 MVAR

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

Step Instruction Comment
00 { 31-Byte Prgm }
01 LBLTEMP Start of program "TEMP"
02 MVARF Declares F as a variable for solver
03 MVARC Declares C as a variable for solver
04 RCLF Recall F
05 9
06 5
07 ÷
08 RCLC Recall C
09 ×
10 -
11 32
12 -
END or RTN Returns control (and result in X) to either the user or to a calling program.

After, accessing the solver using Shift 7 (SOLVER ), select program TEMP.

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

Emulators

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Emu 42

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

 
WP 34s

WP 34s

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WP 34S project uses a modern HP financial calculator HP 30b as the starting point to create an advanced scientific RPN calculator. It is a more powerful scientific (non-graphing) calculator compared to the original HP 42s.[4]

Functionality

  • Euler's Beta and Riemann's Zeta functions, Bernoulli and Fibonacci numbers, Lambert's W, the error function as well as Chebyshev's, Hermite's, Laguerre's and Legendre's orthogonal polynomials, and testing for primality,
  • Many statistical distributions and their inverses like Poisson, Binomial, Geometric as well as Cauchy-Lorentz, Exponential, Logistic, Weibull for reliability analysis, Lognormal and Gaussian with arbitrary means and standard deviations,
  • Programmable sums and products, first and second derivatives

Programmability

  • RPN keystroke programmable à la HP-41 - up to 925 steps in RAM - numeric and/or alpha labels, thousands of steps burnable into flash banks.
  • Externally programmable by developers via JTAG interface

See also

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References

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  1. ^ "HP-42S". Museum of HP Calculators. Retrieved 2016-10-27.
  2. ^ 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.
  3. ^ HP 42S Easy Double Speed / Turbo Mode for Calculator and Programs, retrieved 2022-08-05
  4. ^ https://commerce.hpcalc.org/34s.php

Further reading

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