[R] xyplot with par

[Afshartous, David]

All,
Is there are a simple way to plot multiple xyplots on the same page
in the code below (it currently overwrites the first plot w/ the
second).
I searched the archives and saw a similar question but the answer didn't
seem to work.
thanks
dave

x1 = rnorm(10)
x2 = rnorm (10)
y1 = rnorm(10)
y2 = rnorm (10)
op = par(mfrow = c(2,1))
xyplot(y1 ~ x1)
xyplot(y2 ~ x2)