I realize this is an old thread, but it's dear to my heart so I have to put in my two cents worth.
The one in Ken's photo with separate attachment points for each disc is what I know as a disc plow, just like Ken said. The ones with a single axle through several disc are what I call a disc tiller. The photo Egon posted is a good example of the disc tiller. The ones I've used were branded J.D. and Athens. I preferred the Athens possibly because mine had less wear than the J.D. that I used, it also seemed heavier . The guy who bought my Athens wanted to use it to turn under straw behind a combine. The Athens came in both a rubber tired and steel wheeled models. Wrestling with the weighted rear wheel to install a tire was a bear, so, if I ever get another one l'd like to try one with all steel wheels.
Somewhere on the internet I ran across an article describing how after using the disc tiller for enough years so much dirt is eventually thrown toward the edge of the field that the field comes to be shaped like a bowl. That's probably why the offset gang disk became more popular.
Now somebody please get busy and help bteny10 find a oneway. See previous 4 posts. Sorry I stepped on your posts btenny.