Standard command on most TI Calcalators, commonly used in TI-Basic programs. (Note: The Program I/O screen doesn't exist on all TI Calculators (like the TI-83 for example), in which case it just prints on the main screen)

The Texas Instruments TI-89 User's Guide defines the command as follows:

Output

Displays exprOrString (an expression or
character string) on the Program I/O screen
at the next coordinates (row,column).

An expression can include conversion
operations such as ->DD and ->Rect. You can
also use the > operation to perform unit and
number base conversions.

If Pretty Print = ON, exprOrString is "pretty
printed."

From the Program I/O screen, you can press
F5 to display the Home screen, or a program
can use DispHome.