dos_alloc:              mov     ah, 48h
                        mov     bx, 2000h
                        int     21h
                        jc      __exit
                        mov     dosalloc_seg, ax
                        mov     dir_ptr.o, 0
                        mov     dir_ptr.s, ax
                        add     ax, 1000h
                        mov     buf_ptr.o, 0
                        mov     buf_ptr.s, ax
__exit:                 ret

dos_dealloc:            mov     ah, 49h
                        mov     es, dosalloc_seg
                        int     21h
                        push    cs
                        pop     es
                        ret