[OS X TeX] pushdown automata?

[Art Werschulz]

Hi.

Any suggestions for drawing pushdown automata using TiKZ (or some  
other LaTeX-friendly package)?  Something like the following (which  
will only look good in a monospaced font):

+---------+
| State   |-------+
| control |       |
+---------+       V
     |	       +---------------+
     |          | a | a | b | b |
     |          +---------------+
     V
   +---+
   | x |
   +---+
   | y |
   +---+
   | z |
   +---+

Thanks.

Art Werschulz
207 Stoughton Avenue, Cranford  NJ 07016-2838
(908) 272-1146