Apple is set to unveil a portable tablet-sized computer that can surf the web and may also serve as an electronic book reader in time for the Christmas shopping season. The device will be able to connect to the internet and, like the iPod Touch, will have the ability to play movies. But it will not have phone capability. Apple is believed to be sharing details of the tablet device with book publishers, in a bid to rival Amazon’s Kindle. The screen will measure up to 10 inches (25 centimetres) diagonally.