[R] Translate twobin in S-plus to R?

[Ulf Emanuelson]

Hi all,

I'm new to R, but have got the task to translate a short program written 
for S-plus. I am now stuck on a command twobin which does not seem to be 
available in R. Anyone know a replacement for this? The syntax used for 
this command in my code is:

zobs<-twobin(obstab[1,1],obstab[1,2],obstab[2,1],obstab[2,2],0.05)

where obstab is a two by two contingency table and the command produces an 
object (?) with, among other things, a chi2-value.

Any and all help would be appreciated!

Ulf