Some of us might have read about Mozilla foundation coming up with a new mobile operating system which will be developed in HTML5, called Firefox OS. And we all thought that it will be one big HTML5 web page when booted up! Well its much more than that. Its a complete mobile operating system now. Mozilla now have a working emulator of the OS called r2d2b2g. The OS can be previewed on Firefox browser as an add on. Its a 61.2 Mb download and once done you can test it by selecting Tools > B2G Desktop. BTW b3g stands for ‘Boot to Gecko’.