What is Dos Operating System :: MS-Dos Stands for Microsoft Disk Operating System & It is developed by Microsoft Corporation.Dos Operating system was developed in 1981 and its first version was named as Dos 1.00.In Dos work are performed by managing disk And disk files. It Provides a interface between computer hardware and Software programs. Dos is a 16 bit operating system that means it can save and process 16 bit of data at single time. It is a single user and single tasking Operating system. It is NON-GUI(Graphical User Interface) It Works on CUI(Character User Interface)environment.