  Spatial and kinematical correlations between HI and CO (2-1) emission of the
southern spiral galaxy NGC4945 are studied with a common angular (23 arcsec)
and velocity resolution (7 km/s). The 21cm continuum emission is also observed.
The HI kinematics yield a galaxy mass of 1.4x10^{11} Mo within a radius of 380
arcsec, with molecular and neutral atomic gas each contributing 2%. Nuclear HI
absorption at velocities 80 km/s higher than systemic indicates gas flowing
towards the centre. HI features at each end of the major axis (R ~ 600 arcsec)
are interpreted as spiral arms that are viewed tangentially and that also cause
prominent emission features in the radio continuum, HI, and CO further inside
the galaxy. A central elongated region showing non-circular motions is
interpreted as a bar which fuels the nuclear starburst. HI and CO
position-velocity data have been analysed using linear resonance theory and
possible locations of resonances are identified.
