Memory usage in Windows Mobile 5.0 is quite different than what it was in previous versions. Not only do devices now support permanent storage but the way RAM is used is also different. Fortunately for us, the Windows Mobile Team Blog has written a good article that looks at RAM in Windows Mobile 5.0.
One thing that many WM5.0 users have noticed is that a 64MB RAM device will show only about 50MB RAM free. So, where is the missing RAM? The primary source of this confusion stems from the fact that the control panel which shows your RAM usage only counts RAM that you have any control over. That is to say, it only shows running applications. There are other uses for RAM, and such things are hidden from you. The article looks at some of the functions that use up some of the missing 14MB of RAM.
Not everyone will agree with Microsoft about hiding that RAM but at least the case of the missing RAM has been solved.