PC Guard for Dos PRO - Version 3.05 PC Guard for DOS PRO v3.05 is a professional software protection system without hardware keys. With PC Guard PRO you can easily protect unlimited number of executable files and create protected installation disks for your software with no additional investments. There are two protection methods (envelope and loader) and three protection modes (noic, auto and code). With PC Guard you can also create demo versions of your programs with time, date and execution limitations. PC Guard PRO is heavily tested, highly compatible, fully transparent and easy to use.