format mz
entry main_segment:start

segment main_segment
    start:
    mov ax, data_segment
    mov ds, ax

    call far proc_segment:sayHi

    ;terminate
    mov ah, 4Ch
    int 21h

segment proc_segment
    sayHi:
        mov ah, 09h
        mov dx, hello
        int 21h

        retf

segment data_segment
    hello db "Hello$"