  We investigate the question of computational resources (such as stacks and
counters) necessary to perform radix conversions. To this end it is shown that
no PDA can compute the significand of the best $n$-digit floating point
approximation of a power of an incommensurable radix. This extends the results
of W.~Clinger. We also prove that a two counter machine with input is capable
of such conversions. On the other hand we note a curious asymmetry with respect
to the order in which the digits are input by showing that a two counter
machine can decode its input online if the digits are presented in the
most-to-least significant order while no such machine can decode its input in
this manner if the digits are presented in the least-to-most significant order.
Some structural results about two counter machines (with input) are also
established.
