Microsoft has detailed the next update in line for Windows Phone 8 ahead of Nokia's Lumia press event on October 22. As expected, this will be an evolutionary update for the mobile OS rather than a significant refresh, which focuses on three main engineering goals: enable a new generation of Windows Phone 8 devices, enhance the platform with new capabilities for current users and partners, and improve overall quality.

Among the update's highlights is support for screens between 5 and 7 inches and resolutions up to a maximum of 1080p; features that Nokia is widely expected to take advantage of with the rumored Lumia 1520 phablet. This will enable "jumbo-sized" Start screens with up to six Live Tiles on each row, rather than the four that's currently available, and Microsoft has already scaled built-in apps and hubs to take advantage of the extra space.

In addition to larger screens, the update introduces quad core processing to Windows Phone 8 for the first time ever by adding support for Qualcomm's top-of-the-line Snapdragon 800 SoC.

There's also a new feature called Driving Mode that's automatically triggered when pairing the handset to a user-defined Bluetooth device – a Bluetooth headset, for example – to limit notifications including texts, calls, and quick status alerts on the lock screen until you're safely parked. Microsoft says you can configure Driving Mode to send automatic replies to people who call or text while you're driving.

Other notable improvements include easier data tethering to Windows 8.1 via Bluetooth, a suite of apps called Mobile Accessibility to make the OS easier to use for blind and visually impaired users, better storage management, rotation lock, custom ringtones for more things, manually closing apps, and more.

Microsoft says the update will begin to rollout in the coming weeks and will continue over several months. Specific timing depends on a number of factors including carrier and phone model.

If you just can't wait or happen to be a developer wanting to test your apps against the latest release, Microsoft is also launching the Windows Phone Preview for Developers program, which anyone early access to updates for $19 a year. To participate you need to meet one of three conditions: having a "developer-unlocked" phone, being a registered Windows Phone Store developer, or a registered Windows Phone App Studio developer.