  Berlekamp and Zigangirov completely determined the capacity error function
for binary error correcting codes with noiseless feedback. It is still an
unsolved problem if the upper bound for the capacity error function in the
non-binary case of Ahlswede, Lebedev, and Deppe is sharp. We consider
wraparound channels with limited magnitude and noiseless feedback. We
completely determine the capacity error function for all $q$-ary wraparound
channels with a magnitude of level $r$. All of our algorithms use partial
noiseless feedback. Furthermore, a special case of the problem is equivalent to
Shannon's zero-error problem.
