Mine

procedure TForm1.BitBtn1Click(Sender: TObject);
var text:string;
    i:integer;
    counter:array[65..90] of integer;
begin
  for i:= 65 to 90 do
    counter[i]:=0;

  text:=uppercase(memo1.Text);

  for i:= 1 to length(text) do
    counter[ord(text[i])]:=counter[ord(text[i])]+1;

  for i:= 0 to 25 do begin
    stringgrid1.Cells[i,0]:=chr(i+65);
    stringgrid1.cells[i,1]:=inttostr(counter[i+65]);
  end;
end;

end.