-To build the firmware with WinAVR, change into the "firmware" directory,
-check whether you need to edit the "Makefile" (e.g. change device settings,
-programmer hardware, clock rate etc.) or bootloaderconfig.h and type "make"
-to compile the source code. After you upload the code to the device with
-"make flash", you should set the fuses with "make fuse".
+To build the firmware with WinAVR, change into the "USBaspLoader" directory,
+check whether you need to edit the files mentioned above (e.g. change device
+settings, programmer hardware, clock rate etc.) and type "make" to compile
+the complete source code.
+After you upload the code to the device with "make flash", you should set
+the fuses with "make fuse".
+
+If you already have some working USBaspLoader on your controller, you can
+use "make update" to flash the "updater"-firmware to it.
+After starting this firmware on the microcontroller it will replace the
+old bootloader with the new one just compiled.
+The update-feature can be used on boards, where HVPP or ISP is not possible
+after production anymore. (Or you just want to save trouble laying out ISP.)
+Therefore you also could implement the "HAVE_SPMINTEREFACE_MAGICVALUE"-
+feature, protecting your board from wrong updates for other boards.
+