As it has been official & old news that Nokia has surrendered itself to Microsoft. Really unexpected performances are being shown by Microsoft, specially for Lumia devices.
Recently Microsoft twitted that every Lumia phones based on Windows8 will run on upcoming Windows 10 OS from the beginning of 2015. Microsoft is developing it’s new OS & it will make it compatible to support all different Lumia devices.
The old Lumia phones having less RAM will also support the new OS with more smoothness & better activity. After appearance of Windows 8 the demand of Lumia has increased a lot more with its smooth performance with better Graphics support.