Declare Function ReadPort Lib "io.dll" (ByVal Address As Long) As Byte
Declare Sub WritePort Lib "io.dll" (ByVal Address As Long, ByVal Value As Byte)

Dim PortAdr As Long   ' Portadresse
Dim PortWert As Byte  ' Ausgelesener Wert oder Übergebender Wert
 
' Port lesen
PortAdr = 255 'als Beispiel
 
PortWert = ReadPort (PortAdr)
 
' Port ausgeben
PortWert = 128
 
Sub WritePort ( PortAdr, PortWert)