| HP-42S | |
| Type: | Programmable scientific |
| Entry: | RPN |
| Manufacturer: | Hewlett-Packard |
| Introduced: | 1988 |
| Discontinued: | 1995 |
| Processor: | Saturn (Lewis) |
| Precision: | 12 display digits (15 digits internally), exponent ±499 |
| Display Type: | LCD dot-matrix |
| Display Size: | 2 lines, 22 characters, 131×16 pixels |
| Prog Lang: | RPN key stroke (fully merged) |
| Memory Step: | 7200 |
| Memory Rom: | 64 KB of ROM |
| Ports: | IR (Infrared) printing |
| Supply: | 3×1.5 V button cell batteries (Panasonic LR44, Duracell PX76A/675A or Energizer 357/303) |
| Weight: | 6oz |
| Dimensions: | 148×80×15 mm |
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.
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.
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 key.Subroutines are enclosed in /Label (name of subroutine) and /Return (halts execution unless it is in a subroutine in which case it returns to the caller). Keystrokes (of functions) are enclosed between and or .
In a running program, a label 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.
is used in much the same way with one important difference: after an 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 label (Execute) key.Important Difference is that executes the label and returns to previous subroutine and continues execution from the line following,whereas branches to the label specificied and doesn't return back.
packs the current subroutines and moves to new program space.nnnn can be used to reach a particular line of program.
A simple program to calculate circumference of circle
| Step | Instruction | Comment |
|---|---|---|
| 00 | ||
| 01 | Start of program "CIR" | |
| 02 | Puts π on the stack | |
| 03 | Prompts for Value of R and stores it in R | |
| 04 | Squares the value in X register | |
| 05 | Multiplies values in X and Y register | |
| or | Returns control (and result in X) to either the user or to a calling program. |
Program instructions like,, halt the program execution,which can be continued by pressing .
is used to view contents of a register,For example R in the above example.
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
Here is a sample program to solve the equation °F = (9/5×°C) + 32
| Step | Instruction | Comment |
|---|---|---|
| 00 | ||
| 01 | Start of program "TEMP" | |
| 02 | Declares F as a variable for solver | |
| 03 | Declares C as a variable for solver | |
| 04 | Recall F | |
| 05 | ||
| 06 | ||
| 07 | ||
| 08 | Recall C | |
| 09 | ||
| 10 | ||
| 11 | ||
| 12 | ||
| or | Returns control (and result in X) to either the user or to a calling program. |
In a similar way,expressions can be integrated.After selecting the variable of integration,enter the lower limit and then press on, similarly input (upper limit) and (accuracy).
HP 42s can be accessed through Android Emulators like Emu42 and Free42.
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.[1]
Functionality
Programmability