On most laptops, the is handled by the Embedded Controller (EC) and the BIOS, but special functions (brightness, volume, Wi-Fi toggle, external display switching) require a software layer — a driver and utility — to communicate with Windows. Sony VAIOs use a proprietary Sony Notebook Utilities and Sony Shared Library (sometimes called Sony Firmware Extension Parser or VAIO Event Service ). Without these, the FN key may do nothing or only partially work.