Hey, I need to draw a cirlce in a TI-89 Voyage 200, which I can, but it needs to be moveable. When I try to move it, it just flickers.

:pp(a)
:-Prgm
:ClrDraw
:2 -> x
:2 -> y
:0.0 -> d
:Circle x,y,2
:For n,1,a,1
:0 -> k
:While k=0
:getkey() -> k
:EndWhile
:If k=338 Then :y+d -> y