i don't have a ti-83 plus, just a ti-83.
i was messing around with a weird behavior i found. so if i were to type
on the home screen when none of the string variables are defined and pressed ENTER, then i get a random-looking string of commands and stuff. i discovered that i could add other undefined variables, and that would result in the random string being longer. so a bit later i put a bunch of undefined variables in the string, then i scrolled through the mess, and sometime after the thing looped, i pressed ENTER. what happened was odd. the calculator froze, then the screen went blank with the words "RAM FAIL" displayed.
on a side note: i later found out that pressing the "Y=" button instead of ENTER seems to have a different result. that and where in the mess of commands i press ENTER or "Y=" affects what happens, and if i scroll left after the loop, i can sometimes crash the calculator. twice i got a screen full of charecters i didn't know were in the ti-83, like greek letters, a hash symbol(#), and letters from other languages. too bad it always comes before a freeze