Atari PAT Station?

Im looking into buying Gaymond's Atari PAT 900 that he put up on the NG
this morning. But.. Im not entirely sure what it is exactly. I know it
is a power supply and lots of input variations (joy, track etc) and from
what I have heard, they are very heavy. Are there different variations
of the PAT stations?
  thanks
     jess

-- 
Jess M. Askey            *** Coming Soon - The Game Archive ***
Game Spot/Audio Analyst  *  Pinball, Video, Parts, Collecting *   
509 S. 2nd Street Unit B *    http://www.gamearchive.com      *
Laramie WY 82070         **************************************