Private Sub Form_Load()
    'Place this code in the Form_Load routine of your application's startup form.
    'Search for the "USBSIMM1" hardware.
    If OpenUSBdevice("USBSIMM1v1.0") Then
        'If the hardware is found, pass control to the application's main form
        Form1.Show (1)
    End If
End Sub

Private Sub SetPortAToInput()
    'Set all of the lines of Port A to input.
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 73   ' Port A direction command
    OutBuffer(1) = &H0  ' 0 is input
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Private Sub SetPortAToOutput()
    'Set all of the lines of Port A to output.
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 73   ' Port A direction command
    OutBuffer(1) = &HFF ' 1 is output
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Private Sub SetPortBToInput()
    'Set all of the lines of Port B to input.
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 74   ' Port B direction command
    OutBuffer(1) = &H0  ' 0 is input
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Private Sub SetPortBToOutput()
    'Set all of the lines of Port B to output.
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 74   ' Port B direction command
    OutBuffer(1) = &HFF ' 1 is output
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Private Function ReadPortA() As Byte
    Dim OutBuffer(10) As Byte
    Dim InBuffer(10) As Byte
    OutBuffer(0) = 69   ' Read Port A command
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
    Call ReadUSBdevice(AddressFor(InBuffer(0)), 6)
    ReadPortA = InBuffer(1)
End Function

Private Function ReadPortB() As Byte
    Dim OutBuffer(10) As Byte
    Dim InBuffer(10) As Byte
    OutBuffer(0) = 70   ' Read Port B command
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
    Call ReadUSBdevice(AddressFor(InBuffer(0)), 6)
    ReadPortB = InBuffer(1)
End Function

Private Sub WriteToPortA(ByteToWrite As Byte)
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 65   ' Write Port A command
    OutBuffer(1) = ByteToWrite
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Private Sub WriteToPortB(ByteToWrite As Byte)
    Dim OutBuffer(10) As Byte
    OutBuffer(0) = 66   ' Write Port B command
    OutBuffer(1) = ByteToWrite
    Call WriteUSBdevice(AddressFor(OutBuffer(0)), 6)
End Sub

Listing 1. Use these routines with the provided support files to detect the USBSimm and read and write to its ports.