assume cs:code

a segment
  db 1,2,3,4,5,6,7,8
a ends

b segment
  db 1,2,3,4,5,6,7,8
b ends

c segment
  db 0,0,0,0,0,0,0,0
c ends

code segment
start:
  mov bx,0
  mov dx,0

  mov cx,8

s:  
  mov ax,a
  mov ds,ax
  mov dx,ds:[bx]

  mov ax,b
  mov ds,ax
  add dx,ds:[bx]

  mov ax,c
  mov ds,ax
  mov ds:[bx],dx

  add bx,2

  loop s

  mov ax,4c00h
  int 21h
        
code ends

end start

assume cs:code

a segment
  dw 1,2,3,4,5,6,7,8,9,0ah,0bh,0ch,0dh,0eh,0fh,0ffh
a ends

b segment
  dw 0,0,0,0,0,0,0,0
b ends

code segment
start:
  mov ax,b
  mov ss,ax
  mov sp,16

  mov ax,a
  mov ds,ax
  mov bx,0
  mov cx,8

s:  
  push ds:[bx]
  add bx,2
  loop s

  mov ax,4c00h
  int 21h
        
code ends

end start