' FB 1.05.0 Win64

Dim As Integer n

Do
  Input "Enter size of matrix "; n
Loop Until n > 0

Dim identity(1 To n, 1 To n) As Integer '' all zero by default

' enter 1s in diagonal elements
For i As Integer =  1 To n
  identity(i, i) = 1
Next

' print identity matrix if n < 40
Print

If n < 40 Then
  For i As Integer = 1 To n
    For j As Integer = 1 To n
      Print identity(i, j);
    Next j
    Print
  Next i
Else
  Print "Matrix is too big to display on 80 column console"
End If

Print
Print "Press any key to quit"
Sleep