Private Sub Worksheet_Change(ByVal Target As Range)
Const WS_RANGE As String = "A:A"     '<== change to suit

   On Error GoTo ws_exit
   Application.EnableEvents = False

   If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
       With Target
           If Not .HasFormula Then
               .Value = UCase(.Value)
           End If
       End With
   End If

ws_exit:
   Application.EnableEvents = True
End Sub

'This is worksheet event code, which means that it needs to be
'placed in the appropriate worksheet code module, not a standard
'code module. To do this, right-click on the sheet tab, select
'the View Code option from the menu, and paste the code in.

Hi Freddie,

Bob Phillips gave you a VBA approach. You can also format the cells using a
font that only shows uppercase characters, such as;
Felix Titling
Perpetua Titling
Stencil
Showcard Gothic
Goudy Stout

Ed Ferrero
www.edferrero.com