Query About Passing values

Hi..can anybody tel me that how the output would be changed for same input depending upon the method of passing values/reference/name etc.to a function?For example consider the folloing code

procedure exchange(A:integer,B:integer)
temp:integer;
begin
temp:=A;
A:=B;
B:=A;
end
begin
M:=2;X[M]=4;
exchange(M,X[M]);
write(M,X[2]);
end

what is the output for the above code when
1)If the parameters are passed by value
2)If the parameters are passed by reference
3)If the parameters are passed by name

Please help me to find out this...