Exact results for the BPS index are known for a class of BPS dyons in type
II string theory compactified on a six dimensional torus. In this talk we
set up the problem of counting the same BPS states in a duality frame in
which the states carry only RR charges. We explicitly count the number of
states carrying the lowest possible charges and find agreement with the
result obtained in other duality frames. Furthermore we find one to one
correspondence with black hole microstates. We will also report some
recent developments for higher charges.
