TidSimplyBuffer in Indy 10

I have some code written using delphi 7 Indy 9 and for some reason I have a
reference to a TidSimplyBuffer that was declared in idTCPConnection -
however this doesnt seem to be in Indy 10.  Here is the code that is using
it...
function StreamToHex(S: TStream): String;
var
  I: Integer;
  B: Byte;
  St: String;
begin
  Result:= '';
  for I:= 0 to S.Size -1 do
  begin
    B:= Ord(PChar(TidSimpleBuffer(S).Memory)[I]);
    St:= Format('%x', [B, 2]);
    while Length(St) < 2 do St:= '0' + St;
    Result:= Result + St;
  end;
end;

Maybe there is another way?
Thanks in advance