  The beam-beam effects of the PEP-II as an asymmetric collider are studied
with strong-strong simulations using a newly developed particle-in-cell (PIC)
code. The simulated luminosity agrees with the measured one within 10% in a
large range of the beam currents. The spectra of coherent dipole oscillation
are simulated with and without the transparency symmetry. The simulated tune
shift of the coherent $\pi$ mode agrees with the linearized Vlasov theory even
at large beam-beam parameters. The Poicare map of coherent dipole is used to
identify the beam-beam resonances.
