Specifications

Appendix A Programming the Watchdog Timer 103
;; Enter to I/O Chip Program Configuration Register Mode Enterv
Config proc
push ax
push dx
mov al,87h ;; Specific value to enter Config
;; Mode
mov dx,cs:CONFIG_PORT
out dx,al ;; Write to Config Port twice!
out dx,al
jmp $+2 ;; Delay
jmp $+2 ;;
pop dx
pop ax
ret
EnterConfig endp
;; Exit to I/O Chip Program Configuration Register Mode
ExitConfig proc
push ax
push dx
mov al,0aah ;; Specific value to exit Config
;; Mode
mov dx,cs:CONFIG_PORT
out dx,al
pop dx
pop ax
ret