Check out
http://www.everymac.com/systems/apple/mac_mini/index-macmini.html.
It gives info and specs for all Mac Mini's from the M9686LL/A introduced January 11, 2005 to the Apple Mac mini "Core i7" 3.0 introduced Late 2014.
Remember another product's buy line that taunted "Progress is our most important product"?
Rgds,
Ed