Good Afternoon I have some inexplicables troubles about the memory IDL use for my application. I have an application which load an display 4 images with the following dimensions, 7000x5000, the theorical memory uses is supposed to take 3 RGB Band X 4 images X 7000 X 5000 = 420 Mbytes. When i run my apllication on 64 bits vista, the task managers indicates exactly 420 Mbytes memory for the idl application that make sense. But when i run exactly the same application on a 32 bits XP, i get 840 Mbytes (The double of theorical memory). Is Xp And Vista manage memory differently ??? I was thinking the problem comes from 32 bits vs 64 bits, but a 64 bits XP give the same trouble (840 Mbytes). The vitrtual machine version installed on all computers are the same (IDL 7.0 that is the version used for compile the .sav) Is anybody have got an explication of this? Thanks very much for your help   Aurélien Boulben XEOS Imaging