It appears that if the FAT filesystem is enabled, but there's no SD card (or for some reason it cannot be mounted), the 'autorun' facility does not work. I suspect it is waiting indefinitely for a console connection in order to output the 'Failed to mount SD card' message, before running 'autorun.bbc'.
It appears that if the FAT filesystem is enabled, but there's no SD card (or for some reason it cannot be mounted), the 'autorun' facility does not work. I suspect it is waiting indefinitely for a console connection in order to output the 'Failed to mount SD card' message, before running 'autorun.bbc'.