BIOS 10h error

this program is working fine

#include
int main()
{
union REGS regs;

regs.h.ah = 0x00;
regs.h.al = 0x13;
int86(0x10,&regs,&regs);
regs.h.ah = 0x0c;
regs.h.al = 8;
regs.x.cx = 50;
regs.x.dx = 50;
int86(0x10,&regs,&regs);

}

but this program is not working why anyone can please tell me ?

and explain the reason also.



org 0x100

mov ah,0
mov al,0x13
int 0x10
mov ah,0x0c
mov al,9
mov cx,50
mov dx,50
int 0x10

ret

the above program compiled as : nasm -o s.com s.asm


advanc thanx