Boser HS-4705 Manual page 26

The following sample programs show how to Enable, Disable and
Refresh the Watchdog Timer:
;----------------------------------------------------------------------------------
; Enter the WDT function mode, interruptible double-write
;----------------------------------------------------------------------------------
MOV DX, 2EH
MOV AL, 87H
OUT DX, AL
OUT DX, AL
MOV DX, 2EH
MOV AL, 07H
OUT DX, AL
MOV DX, 2FH
MOV AL, 08H
OUT DX, AL
MOV DX, 2EH
MOV AL, F5H
OUT DX, AL
MOV DX, 2FH
MOV AL, 80H
OUT DX, AL
MOV DX, 2EH
MOV AL, F7H
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, 00H
OUT DX, AL
;---------------------------------------------------------------------------------
; Exit extended function mode
;------------- -------------------------------------------------------------------
MOV DX, 2EH
MOV AL, AAH
OUT DX, AL
* User can also use AL, 00H's defined time for reset purposes, e.g.00H
for Disable, 01H = 1sec, 02H = 2sec.....FFH = 255sec.
20
; select CRF0
; * 00H=Disabled