Al Williams writes about the surprising continued availability of Reverse Polish Notation calculators in 2026, despite RPN losing the mass market to algebraic entry decades ago. RPN uses a stack-based system where operators follow their operands, eliminating the need for parentheses or an equals key. Today's options range from the still-sold HP-12C to SwissMicros' modern enthusiast machines, DIY builds on ATmega and ESP32 hardware, and a thriving ecosystem of phone and desktop apps.
- The first RPN calculator was the Friden EC-130 (1964), a 44-pound desktop unit at $2,150 whose CRT displayed all four stack levels simultaneously
- SwissMicros' R47, at ~$300, features an 8-level stack, built-in electrical engineering functions, and firmware still officially in beta
- HP released a native Linux build of HP Prime as a 2019 AppImage, but it predates the Python programming addition; the only way to get Python on Linux is running an older Windows version under Wine with Soda 9 in Bottles, and you must not let it update
- Alex Garza's PAXER kits reproduce HP-15C/16C/41C on ATmega328 for under $100, adding continuous memory, backlight, and real-time clock
- The 10LC turns a ~$50 ESP32-based M5Stack Cardputer into a pocket RPN calculator
- Free42, a clean-room HP-42S implementation by Thomas Okken, runs on Android, iOS, Windows, macOS, and Linux
- The first RPN calculator was the Friden EC-130 (1964), a 44-pound desktop unit at $2,150 whose CRT displayed all four stack levels simultaneously
- SwissMicros' R47, at ~$300, features an 8-level stack, built-in electrical engineering functions, and firmware still officially in beta
- HP released a native Linux build of HP Prime as a 2019 AppImage, but it predates the Python programming addition; the only way to get Python on Linux is running an older Windows version under Wine with Soda 9 in Bottles, and you must not let it update
- Alex Garza's PAXER kits reproduce HP-15C/16C/41C on ATmega328 for under $100, adding continuous memory, backlight, and real-time clock
- The 10LC turns a ~$50 ESP32-based M5Stack Cardputer into a pocket RPN calculator
- Free42, a clean-room HP-42S implementation by Thomas Okken, runs on Android, iOS, Windows, macOS, and Linux
This article walks through building a minimalist VisiCalc clone in C, covering the core data model (cells, grid), a recursive‑descent parser for formulas, dependency handling via repeated recalculation, and a text‑based UI using ncurses. It explains how to parse cell references, evaluate expressions, and implement a simple modal interface with commands, editing, and navigation. The post culminates in a working terminal spreadsheet that supports basic functions like @SUM, @ABS, @INT, and @SQRT, and demonstrates how to render the grid, status bar, and edit line. It also discusses limitations and possible extensions, linking to the full implementation on GitHub.
Calc is an interactive calculator providing large numeric calculations and programmable functionality. It supports various operators, functions, variable assignments, and complex numbers.
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