  Westerbork Radio Synthesis Telescope observations of the redshifted 21cm line
absorber against the z_em = 0.871 double lobed quasar 3C196 show that the
intervening absorber is an L approximately equal L* spiral galaxy (3C196-G1)
and that the absorbing layer of cold gas extends to radii of at least 30
h_50^-1 kpc. The new data solve several long standing puzzles about this system
by (1) discovering a second 21cm absorption feature, corresponding to
absorption against the NE lobe of the background radio source and (2) spatially
``resolving'' the two absorption features to isolate the absorption along the
two lines of sight to the opposing radio lobes. These findings resolve the
disagreement in redshift between the UV metal and 21cm lines, and as well as
demonstrating that the neutral layer does absorb both lobes of the background
radio source. Simple kinematic models with an inclined, rotating gas disk match
the observed 21cm profile and are also compatible with both the redshift and
velocity spread of the absorption measured in UV resonance lines along a third,
independent line of sight to the quasar nucleus and with the lack of 21cm
absorption in as earlier VLBI experiment that was sensitive to opacity against
the hot spot in the northern lobe. The inferred rotation speed and luminosity
for the galaxy are compatible with the z approximately 0 Tully-Fisher Relation.
  This system illustrates well how 21cm absorption against extended background
radio sources is a powerful tool in determining the nature of the damped
Lyman-alpha class of QSO absorption line system.
