  We report on a simulation in progress of an SU(2) X U(1) fermion-Higgs model
with two *non-degenerate* fermion doublets. The Zaragoza proposal for chiral
lattice fermions is used; naive fermions are studied for comparison. The aims
of this simulation are a non-perturbative study of the decoupling of species
doublers, of triviality bounds on the Higgs and fermion masses and of the
phenomenological quantity Delta-rho.
