DOS stands for disk operating system. The most prevalent from of DOS was manufactured by Microsoft. The last version of DOS to be marketed separately was 6.22 and was used in conjunction with windows 3.11 windows 95 includes DOS. The main difference between windows and DOS is the ability to “multitask” or use two or more programs or data files simultaneously. In these programmes we have directories or folders that work like a filling cabinet. They help keep our hard disk organized by keeping system files together or program files together and separate from data files. Some types of files include executable or from data files. Some types of files include executable or program files (file names end in .exe) dynamic link libraries (.dll) which are called upon by programs to do routines, and initialization files (.ini) which are used by certain programs to store startup settings.

The earliest avtar of Microsoft Windows was Interface Manager, which was being developed in September 1981. The first ever version of Windows operating system was announced on November 10, 1983. It was an extension of MS DOS, and sported a graphic user interface. Windows 1.0 was finally released into market in November, 1985.