Intel SOM-4486 ETX Module User Manual page 43

MOV DX,2FH
MOV AL,01H; 01:activate 00:inactivate
OUT DX,AL;
MOV DX,2EH
MOV AL,F5H; Setting counter unit is second
OUT DX,AL
MOV DX,2FH
MOV AL,00H
OUT DX,AL;
MOV DX,2EH
MOV AL,F6H
OUT DX,AL
MOV DX,2FH
MOV AL,05H; Set 5 seconds
OUT DX,AL
;------------------------------------------
; Exit extended function mode |
;------------------------------------------
MOV DX,2EH
MOV AL,AAH
OUT DX,AL
37 Appendix A