Editing TI-BASIC (section)

=== Functions ===
==== TI-83/84 (Z80) ====
The Z80 version of TI-BASIC makes explicit "functions" like those in 68k impossible. However, all variables are global so functions can be emulated by setting variables, similar to arguments, before calling another program. Return values do not exist; the <code>Return</code> statement stops the current program and continues where the program was called.

==== TI-89 (68k) ====
The 68k version of TI-BASIC allows creating user-defined functions.  Functions have the same syntax as programs except that they use the <code>Func</code>...<code>EndFunc</code> keywords instead of <code>Prgm</code>...<code>EndPrgm</code>, and that they are not allowed to use instructions that perform I/O, modify non-local variables, nor call programs.  However, functions can still be non-[[pure function|pure]] because they can call built-in functions such as <code>getTime()</code>, <code>getKey()</code>, or [[pseudorandom number generator|<code>rand()</code>]]. All functions have a return value, which in the absence of an explicit <code>Return</code> statement is the last expression evaluated.