The purpose at the time was to look at how RAM was used for the system file cache. But it turned out to be great at showing what Superfetch was doing as well. Thanks to a hint in a blog by Alex Ionescu (the new guy on the Windows Internals 5th Edition book) I figured out how to get information on all 7 levels of Standby Cache and have updated the tool, which is now posted on my site at this link: www.tmurgent.com/Tool_ATM.aspx . Here is a snapshot: ATM Screenshot Simply put, the green colors represent RAM that is actively in use, and the other colors represent “available memory”. Only the darkest blue color at the top is the zero and free memory pools. All those other colors represent the standby lists. Vista and above use a seven layer standby list, as opposed to the single standby list in Windows XP, 2003, and before. Standby Lists are where memory goes that isn't (completely) in use right now, but contains contents that could be used under the right circumstances.

Source: http://www.brianmadden.com/blogs/timmangan/archive/2009/08/18/updated-atm-tool.aspx