As I continue futzing around with the new 7.1.1 SDK for Windows Phone Technology Preview, I stumbled upon an interesting feature. Key to 7.1.1 Tech Preview are the dual emulators in 256mb and 512mb flavors.
The emulator in the 7.1 SDK can ONLY be run as as a 512 megabyte emulator, and ONLY one emulator at a time.
The 256 megabyte emulator in 7.1.1 SDK is a great environment for devs to use to test their apps in the 256mb memory environments. There is also a 512mb emulator as well. Both of them show up in the Device Launch dialog.
With the 7.1.1 Technology Preview of the Windows Phone SDK, you can have TWO emulators running at once. Launch two Visual Studios and open a Windows Phone project in each one. Deploy one to the 256mb emulator, and deploy the second project to the 512mb emulator. Voila, two emulators at once.
Where could this be useful? I know several folks working on multiplayer games. Using this approach you could debug the two windows back and forth, simulating a multiuser environment on one machine. Sweet.
With released 7.1 SDK, you could, however, run one app in the emulator, and run another instance of Visual Studio connected to a physical device for two simultaneous app debugging sessions. Of course, you could do the physical plus two emulators approach for three debugging connections. More debugging joy for all.
I tried a number of different ways to get two emulators up in the released 7.1 SDK. Command line launching, command line with a Visual Studio instance, two Visual Studio instances, two VS instance under different privileges, and whatever else I hit. Note the different privilege attempt yielded the following message - "Error: An instance of Windows Phone Emulator is launched with different User Access Privileges. Please close the current running instance and relaunch the Emulator". No luck at all!
See also - Windows Phone 7.1.1 SDK Technology Preview and Emulator Options, 7.1.1 SDK notes in dfwiki .