Obtaining Yacc

My Linux (Mandrake 7.2) supposedly has yacc installed, but I can't
make it do anything.  I would like to reinstall it with a current
version.

Meanwhile, I'm using bison, which is working fine thus far and has an
info file good for newbies like me.

But I'd still like to try obtaining and installing yacc per se.

Where is it available for download?

Thank you.