Microsoft has announced an update to its Windows Phone 8 operating system it says will support higher resolution display screens. The ability of so-called \"phablet\" phones with 5-inch and 6-inch screens to run Windows Phone 8 at 1080p HD will create new opportunities for Microsoft\'s hardware partners looking to compete with other increasingly popular giant-screen devices in the in the smartphone arena. The update will also allow Windows Phone 8 to take advantage of faster quad-core processors, Microsoft said. It will allow more \"Live Tiles\" -- the signature interface style of Windows phones -- by adding a third column of tiles on larger phones. The upgrade -- the third since Windows Phone 8 was released a year ago -- also includes a Driving Mode, which will automatically silence incoming calls and texts so that users can concentrate on safe driving. The feature can automatically respond to incoming calls with a text message to alert the caller to the fact the user in on the road. The feature can activate activated automatically when the phone is linked wirelessly with a Bluetooth device in the car, such as a hand-free headset.