Aaeon PCM-4335 Manual page 85

;; Select The I/O Chip Program Configuration Register Logical Device
;; Input : bl = logical device number
SelectDevice proc
push ax
push dx
mov al,07h
mov dx,cs:CONFIG_PORT ;;
out dx,al
jmp $+2
mov al,bl
mov dx,cs:DATA_PORT
out dx,al
pop dx
pop ax
ret
SelectDevice endp
;; Select Control Register 7 (CR07)
;; Write to Config Port
;; Write Logical Device Number
;; to Data Port
Appendix A Watchdog Timer 77