Aaeon PCM-4335 Manual page 86

;; Setting I/O Chip Program Configuration Register Value
;; Input : al = register number
;; ah = setting value
W977Write PROC
push dx
call EnterConfig
call SelectDevice
mov
out
mov
mov
out
call ExitConfig
pop
ret
W977Write ENDP
end
78 PCM-4335 User's Manual
;; Enter Config Mode
;; Select Logical Device
dx,cs:CONFIG_PORT ;; Write value(al) to Config Port
dx,al ;; to select register number
al,ah
dx,cs:DATA_PORT
dx,al ;; to setting register value
dx
;; Write data(ah) to Data Port
;; Exit Config Mode