MS-DOS Executive

MS-DOS Executive is the shell and first app launched upon boot from Windows 1.0 until its removal in Windows 3.1.

It was first used in Windows 1.x as a simple file manager and primitive shell. In Windows 3.x, it was replaced by File Manager and a new shell called Program Manager was introduced;  was not removed until Windows 3.1, however.

MS-DOS Executive was only available in the x86 16-bit architecture.