CRC XModem/ZModem solution

Function calcrc(ByVal data() As Byte, ByVal count As Integer) As Integer
    Dim crc As Integer = 0
    Dim i, j As Integer
    Dim d As Integer

    For i = 0 To count - 1
        d = data(i)
        crc = crc Xor (d << 8)
        For j = 0 To 7
            If ((crc And &H8000) <> 0) Then
                crc = (crc << 1) Xor &H1021
            Else
                crc = (crc << 1)
            End If
        Next
    Next
    calcrc = crc And &HFFFF
End Function

Sub Main()
    'Please note data(6) declare 7 items (OK, that's VB madness)
    Dim data(6) As Byte
    Dim crc As Integer
    data(0) = &H38
    data(1) = &H51
    data(2) = &H4D
    data(3) = &H4E
    data(4) = &H30
    data(5) = &H30
    data(6) = &H23
    crc = calcrc(data, 7)
End Sub