Public Class Form1
    Public Declare Function Inp Lib "inpout32.dll" Alias "Inp32" (ByVal _
      PortAddress As Integer) As Integer
    Public Declare Sub Out Lib "inpout32.dll" Alias "Out32" (ByVal PortAddress _
    As Integer, ByVal Value As Integer)
    Dim Btn(7) As Button                      '8 Button für PortBit D0-D7
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Me.Size = New Size(330, 85)
        Out(888, 0)
        For i As Int32 = 0 To 7
            Btn(i) = New Button
            Controls.Add(Btn(i))
            Btn(i).Text = "D" & Chr(55 - i)
            Btn(i).BackColor = Color.Gray
            Btn(i).Location = (New Point(10 + 38 * i, 10))
            Btn(i).Size = (New Size(35, 30))
            AddHandler Btn(i).MouseDown, AddressOf BtnDown
        Next
    End Sub
    Private Sub BtnDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs)
        Dim s As String = CType(sender, Button).Text
        Out(888, Inp(888) Xor 1 << CInt(AscW(s.Chars(1))) - 48)    'Bitauswahl ( 
        ' D0-D7)umschalten
        Dim status As Int32 = Inp(888)                             'LPT1 
        ' abfragen
        For i As Int32 = 0 To 7                                    'D0 - D7
            If CBool(status And 128 >> i) Then                     'Wert abfragen
                Btn(i).BackColor = Color.YellowGreen               'Bit = 1
            Else
                Btn(i).BackColor = Color.Gray                      'Bit = 0
            End If
        Next
    End Sub
End Class