Even though early specifications of the limitations of low-end devices (256 MB) stated that Fast App Switching (FAS) would not be available – it actually is! It’s just so much less likely to happen because of the memory limitations. The updated MSDN documentation explains it as: Fast Application Switching is supported on 256-MB devices. However, because keeping applications in a dormant state for Fast Application Switching is dependent on the phone’s available memory, an application running on 256-MB devices will be terminated and tombstoned more often and more quickly than the same application running on a phone with more memory.

I first came on to this when holding the back key in the 256 MB emulator – it gave me the regular FAS view where I could flip between apps. After a moment of confusion I came to the conclusion that they must’ve kept the app switch view but are just letting apps always tombstone. Then, in a twitter conversation with Ginny Caughey, she told me that FAS does exist on 256 MB phones, but is less likely to occur since the phone will run out of memory. I had to try it out…

First I created two small apps that just display if their Activated-event had IsApplicationInstancePreserved, and holding the back key confirmed the obvious; none of them has their instance preserved on startup.

But, when resuming app number 1 the FAS was confirmed.

Nicely done Microsoft! The ability to be able to jump back and forth between apps is a great improvement over the pre-Mango behavior of having to back into an app to be able to resume it. This way of handling FAS on low-end devices is a very nice compromise, especially the apps have been written to handle tombstone nicely, and they all have right?…