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.
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. Additionally, it features a two-line dot matrix display, which made stack manipulation easier to understand.
Production of the 42S ended in 1995. 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, 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
- 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
- Peripherals: HP 82240A infrared printer
Features
- All basic scientific functions
- Statistics
- Probability
- Equation solver that can solve for any variable in an equation
- Numerical integration for calculating definite integrals
- Matrix operations
- Complex numbers
- Vector functions
- Named variables, registers and binary flags
- Graphic display with graphics functions and adjustable contrast
- Menus with submenus and mode settings that use the bottom line of the display to label the top row of keys
- Sound
- 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
- The ability to run programs written for the HP-41C series of calculators
Programming
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. The program consumes 18 bytes. No memory registers are used.| Step | Instruction | Comment |
| 01 | Start of program "FAC" | |
| 02 | 1 is put into X, hence the value to be calculated upon is lifted into stack register Y | |
| 03 | Define label 00 | |
| 04 | Recall stack register Y and multiply with X | |
| 05 | Decrement stack register Y and if not zero... | |
| 06 | ... go back to label 00 | |
| 07 | or | Returns control to either the user or to a calling program. |