I cannot find the comma key on my TI-89 Titanium graphing calculator. When I searched google for more information, the only hints I got were that it was above the [ key (mine is a semicolon there) or below the cosine key (mine is a } there). Anyone actually have one of these who knows where the comma key is? I can’t do derivaties or graphs without it. 
Hah thanks I found it, looking at the keymap the little icon had been rubbed off. Good grief.
Above the 9, to the right of the ).
Next time you lose track of a character or command, you can always get it in the catalog (above the Z, and under APPS)