By Category of Calculator Graphing Standard Programmable Financial By Curriculum General Math Pre-Algebra Algebra Trigonometry   Calculus Geometry   Statistics Finance By Field General Science Physics Biology Chemistry By Unique Feature for Graphing Models Equation Editor (Ability to Display Equation as Written) Split Display (Graph & Table) Equation Display (as Written) Slide Show   Shift Graph, Change Graph Rapid Graph/Window/Zoom   Pen-Touch Operation Reversible Keyboard By Unique Feature for Standard Models Constant Calculation Chain Calculation (+, -, x,) Chain Calculation (, log) Last Answer Memory   D.A.L. (Direct Algebraic Logic) Ability to Display Equations   Playback Function Multi-Line Playback Function   Formula Memory Function   By Other Conditions Twin Power (Solar Cell & Battery) Includes Hard Case Optional See-through Version for OHP Available Optional PC-Link Kit Available   Set-to-Set Communication Cable Available Optional Data Collection System Available