Cupertino (US), Dec 5 (DPA) The newest version of the operating system that powers iPhones, iPads and the iPod touch - iOS 4.2 - is ready for installation.

IPad users will notice the biggest changes, since this is the first ever update for that machine's operating system. It will allow multitasking on the tablet computer, so multiple applications can run at once with the possibility of transferring data between them.

IPad users have also missed out on the themed folders for sorting apps that iPhone users have been able to enjoy for a while.

The new Mail software can aggregate several accounts into one inbox, while a Game Center offers a sampling of simple online games.

But there is something new for the iPhone - AirPrint, which allows printing via a wireless connection. Initially, the function will be supported by multiple HP printers. To download and install the system updates, the devices have to be hooked up to a computer running the iTunes programme.