Description

RPN83P is an RPN calculator app for the TI-83 Plus series and the TI-84 Plus series calculators. The app is inspired mostly by the HP-42S calculator, with some significant features borrowed from the HP-12C, the HP-16C, the HP-19BII, and the TI-85 calculators. RPN83P hopes to be the easiest and cheapest gateway app that introduces new users to the beauty and power of RPN calculators.

Features:
* traditional RPN stack (X, Y, Z, T, configurable from 4 to 8 levels), with LASTX register
* input edit line with scrollable cursor using arrow
* 8-line display showing 4 stack registers
* hierarchical menu system similar to HP-42S
* auto-start capability using the Start-Up app
* storage registers (resizable 25-100) and variables (A-Z,Theta)
* all math functions with dedicated buttons on the TI-83 Plus and TI-84 Plus
* STAT statistics and CFIT curve fitting, inspired by HP-42S
* BASE conversion and bitwise operations, inspired by HP-16C and HP-42S
* TVM time value of money, inspired by HP-12C, HP-17B, and HP-30b
* CPLX complex numbers, inspired by HP-42S and HP-35s
* UNIT conversions of ~170 units, inspired by HP-19BII and TI-85
* DATE: date, time, datetime, timezone, hardware clock, proleptic Gregorian calendar from 0001 to 9999

Installation:

* Install the rpn83p.8xk flash app file.

Starting:

* Press APPS.
* Scroll down to the RPN83P entry.
* Press ENTER.

Exiting:

* Quit app: 2ND QUIT
* Turn off device: 2ND OFF

Version: 1.1.0 (2025-10-07)

Major Changes from 1.0.0:

* WARNING: upgrading from v1.0 to v1.1 will cause MODE settings to be reset to factory values; but preserves RPN stack (X-T,A-D), storage registers (R00-R99), storage variables (A-Z,Theta), STAT registers (SigmaX-SigmaYLX), TVM registers
* reorganize BASE menu, no functional change
* reorganize DATE menu, new entry methods
* reimplement UNIT conversions, now similar to TI-85 and HP-19BII, expand supported units from 30 to ~170
* fix RPN stack and LASTX edge cases
* reorganize USER_GUIDE into 21 chapters, merged into a single PDF for release
* now consumes 4 flash pages (64 kiB), increase from 3 flash pages

Screenshots