org 0x1000000 use32 [map symbols] begin: _begin: jmp entry align 4 multiboot_header: MULTIBOOT_HEADER_MAGIC dd 0x1BADB002 MULTIBOOT_HEADER_FLAGS dd 0x00010003 Checksum dd -(0x1BADB002 + 0x00010003) header_addr dd multiboot_header load_addr dd _begin load_end dd _end bss_end dd _end entry_val dd entry entry: mov byte [0xB8000], 65 _loop: jmp _loop _end: