%define MULTIBOOT_HEADER_MAGIC 0x1BADB002 %define MULTIBOOT_HEADER_FLAGS 0x3 [global start] [global _start] start: _start: jmp multiboot_entry align 4 multiboot_header: ; magic dd MULTIBOOT_HEADER_MAGIC ; flags dd MULTIBOOT_HEADER_FLAGS ; checksum dd -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS) multiboot_entry: mov byte [0xB8000+160*10+2*2], 'J' mov byte [0xB8001+160*10+2*2+1], 0x07 looplbl: hlt jmp looplbl