Codex was designed for the TI-83+ (?) and higher calculators. It's one of the many programming libraries available that lets BASIC programmers access many useful Assembly functions, and can spice up any already made program.
Routines (some of the many)
- Scroll the graph screen in any direction
- Type lowercase text
- Turn Alpha-lock on (for Input statements)
- Hide the Run indicator
- Create/erase/inverse windows on the screen quickly
- Delete programs with a single command