SDK

Software Development Kits (SDK) are available for many TI Graphing Calculators.
  
TI-83 Plus / TI-84 Plus / TI-73 Explorer ™ SDK
Tools for developing applications for the TI-83 Plus Family, TI-84 Plus Family and TI-73 Explorer ™.
   Details
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TI-89 / TI-92 Plus SDK
Tools for developing applications for the TI-89, TI-89 Titanium, Voyage™ 200 and TI-92 Plus
   Details
   Download