Dim Shared As Byte grid(8, 8), r, c

Sub placeKings()
    Dim As Byte r1, r2, c1, c2

    Do
        r1 = Int(Rnd*8)
        c1 = Int(Rnd*8)
        r2 = Int(Rnd*8)
        c2 = Int(Rnd*8)
        If (r1 <> r2 And Abs(r1 - r2) > 1 And Abs(c1 - c2) > 1) Then
            grid(r1, c1) = Asc("K")
            grid(r2, c2) = Asc("k")
            Return
        End If
    Loop
End Sub

Sub placePieces(pieces As String, isPawn As Byte)
    Dim numToPlace As Byte = Int(Rnd*(Len(pieces)))

    For n As Byte = 0 To numToPlace-1
        Do
            r = Int(Rnd*8)
            c = Int(Rnd*8)
        Loop Until(Not(grid(r, c) Or (isPawn And (r = 7 Or r = 0))))
        grid(r, c) = Asc(Mid(pieces, n, 1))
    Next n
End Sub

Sub toFen()
    Dim As Byte ch, countEmpty = 0
    Dim As String fen

    For r = 0 To 8-1
        For c = 0 To 8-1
            ch = grid(r, c)
            If ch <> 0 Then
                Print " " & Chr(ch);
            Else
                Print " .";
            End If
            If ch = 0 Then
                countEmpty += 1
            Else
                If countEmpty > 0 Then
                    fen += Chr(countEmpty + 48)
                    countEmpty = 0
                End If
                fen += Chr(ch)
            End If
        Next c
        If countEmpty > 0 Then
            fen += Chr(countEmpty + 48)
            countEmpty = 0
        End If
        fen += "/"
        Print
    Next r
    fen += " w - - 0 1"
    Print fen
End Sub

Randomize Timer
placeKings()
placePieces("PPPPPPPP", True)
placePieces("pppppppp", True)
placePieces("RNBQBNR", False)
placePieces("rnbqbnr", False)
toFen()
Sleep