Actually whether you use C or C++ or assembly language to program,the compiler which you are using is responsible for the conversion of you written code to hex form. When you compile/build your written code the compiler converts the written code to hex format which is then loaded to the controller for our application.
The connector you are talking about is Db-25 connector or parallel port connector which is used for connecting printers(you were right.....!!!!!!!).
You can get over the net many compilers for 89C52 where you can write the code & burn the code to the controller.Just have a look on net.
Regards,
Jerin. ;-)