yacc and pointless violence

[Walter E. Pohl]

	I'm trying to learn the program yacc, and I decided the best way
would be to type in hoc1 from Kernighan and Pike's "The Unix Programming
Enviroment."  So, it compiles and all fine.  So, I run it, and it gives
me "illegal instruction - core dumped".
	Has anyone else tried using yacc on this particular piece of code?
(pg. 237-240 from K&P)  Can anyone tell me what may be going wrong?  I'm
running under System V on a 3b2.
	If no one can help me with this, I'm going to take red hot knitting
needles and plunging them into my eyes.