In general we can say that if you keep your program code close to ANSI Pascal, you will have no problems porting from Turbo Pascal, or even Delphi, to Free Pascal. To a large extent, the constructs de ned by Turbo Pascal are supported. This is even more so if you use the -So or -S2 switches.
In the following sections we will list the Turbo Pascal and Delphi constructs which are not supported in Free Pascal, and we will list in what ways Free Pascal extends the Turbo Pascal.