compile and run .COM executable in dosbox

dos.ld

OUTPUT_FORMAT("binary")
OUTPUT_ARCH("i386")

ENTRY(_start)
_start = 0x100;

SECTIONS
{
        . = 0x100;
        .text : { *(.text) }
        .data : { *(.data) }
}

hello.S

.data
hello_str: .ascii "hello from binutils$"

.text
.code16
_start: .global _start

main:
mov $hello_str, %dx
movb $0x9, %ah
int $0x21

exit:
movb $0x4c, %ah
int $0x21

.end

Makefile

AS := as
LD := ld
DOSBOX := dosbox

%.o: %.S
        $(AS) --32 -o $@ $<

output.com: hello.o
        $(LD) -T dos.ld -o $@ $<

all: output.com

clean:
        rm *.o *.com

dosbox: output.com
        $(DOSBOX) -C "mount c: ." -C "c:" -C $<