MS-DOS Executive

MS-DOS Executive is a primitive file manager used as the default shell in Windows 1.0 and Windows 2.x. The application was deprecated by Windows 3.0, which replaced it with the Program and File Manager, and finally removed in Windows 3.1.

In Windows 1.0 and 2.x, the application receives special treatment as it doesn't have a standalone executable file but is rather stored in the fast boot blob ( or , respectively) created during installation. The file  under fast boot is a one-byte stub, which allows another instance of the program to be launched at will. In Windows 3.0 or with slow boot enabled under older versions, the file is a regular executable.

History
The MS-DOS Executive is arguably one of the first applications to be written for Microsoft Windows, as a window titled "MS-DOS" was already featured in the photos of the 11/1/83 build, however, it is questionable to what degree the environment was actually functional. Unlike later revisions, the early version roughly simulates a MS-DOS command line with a  prompt. The window features a command bar on top listing all the supported commands. The window originally used proper MS-DOS command names, although they were soon changed to names that didn't match up with their DOS equivalents.

The application was rewritten in early 1984 to its nearly final design, as seen in the screenshots of the Tandy 2000 builds showing the now-renamed "DOS Window". The window now has a proper menu bar, with drive icons and the current directory path directly under it. The rest of the window is filled by a listing of the directory contents. As of Development Release #4, the program was renamed to "MS-DOS Executive". The list item flow direction was changed from horizontal to vertical by Beta Release. The last change was made during the development of Windows 3.0, which changed the upper-case file names to lower-case.