Private Sub ByteVeraendern()
        Dim y As Byte
        Dim W As Byte
        Dim B As Byte
        Dim FileName = "TextDatei.Txt"
        Dim fs As New FileStream(FileName, FileMode.Open, FileAccess.ReadWrite)
        Dim Reader As New BinaryReader(fs)
        Dim Writer As New BinaryWriter(fs)
        For y = 0 To 25
            W = Reader.ReadByte()
            Select Case y
                Case 24
                    B = 101
                    Writer.Write(B)
                Case 25
                    B = 127
                    Writer.Write(B)
                Case Else
                    Writer.Write(W)
            End Select
        Next
        Reader.Close()
        Writer.Close()
    End Sub