$NOMOD51
$include (C8051F120.h)
LED BIT P1.6;
CSEG AT 0;
LJMP MAIN;
Reset_Sources_Init:
mov WDTCN, #0DEh ;
mov WDTCN, #0ADh
ret
Port_IO_Init:
mov SFRPAGE, #CONFIG_PAGE ;
mov P1MDOUT, #040h
mov XBR2, #040h
ret
; Initialization function for device,
; Call Init_Device from your main program
Init_Device:
    lcall Reset_Sources_Init
    lcall Port_IO_Init
    ret
MAIN:
    CALL Init_Device;
    CLR LED;

LED = 0;    ?????????? ??????????
mov R5, #00h;
LOOP:
mov R7, #03h; R7, R6, R5 – ???????? ????? ?????????? ????????? ??????
DELAY:
mov R6, #00h; ????????
LOOP1:
djnz R5,$;
djnz R6, LOOP1;
djnz R7, DELAY;

mov C, SW; ??????????? ?????? ? ??????????
cpl c;
mov LED, C;
sjmp LOOP;

End