A PL0 compiler with GUI implemented with C++ MFC. It is capable of translating PL0 Code into an intermediate language "PCode" and interpreting it. It also shows some of the internal structures: the result of lexical analysis, the compiled Pcode and the stack trace during a run.

1. Prepare a input file. The example given computes the factorial of n.

var f, n;
procedure fact;
	var ans1;
	begin
		ans1:=n;
		n:= n-1;
		if n < 0 then f := -1;
		if n = 0 then f := 1
		else call fact;
		f:=f*ans1;
		write(f);
	end;
begin
	read(n);
	call fact;
end.

2. Select file, compile PCode, manually type the input, and then run.