Boot phase 1 occurs after the localization subsystem has been initialized, but before the full registry is ready. Typically, an external bootable read/write file systems (like FATFS) is loaded during boot phase 1. The first bootable file system mounted during boot phase 0 or 1 will contain the working registry hive files. Registry keys for any storage devices started during boot phase 1 must be in the boot registry (boot.hv). See "Configuring the boot file system" below for details on bootable file systems. In the following example, the auto-load file system or block driver "SampleDriver" will load during boot phase 1: