Appendix A Programming the Watchdog Timer 99
;; 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
