Write and Flush

I am wondering whether or not a call to the Flush() procedure is 
required after a call to Write(Output) (assuming Output is tied to the 
screen)?

Example:
 
begin
  Write(Output, 'Enter a string: ');
  Flush(Output);     { do we need this here? }
  ReadLn(Input, s);
end.

In languages like C, this is the standard practice, but I can't find 
any mention about needing to do this in Pascal. I'm assuming we do 
because Output is still a text file...