The windows executable format contains two entry points, one pointing to the actual windows program, and one pointing to a DOS program, which are both included in the executable file. In most cases the DOS entry point refers to a short procedure (stub) that outputs a short message like "This program must be run under Win32" and exits.
However, a few programs might include both fully functional DOS and Windows programs in the same executable. That isn't necessarily very user-friendly because it makes the exefile twice as large as required. And when started in a DOS box (ie. with windows loaded) it'll automatically execute the windows version of the program, even though the user might have desired to run the (possibly superior) DOS version.
In most cases it'll only display the stub-message (which might be eventually useful for programmers whom want to test their stubs) and in a few cases it might unlock access to a fully featured DOS program. The only program that I know about would be MFT.EXE (quarterdecks fine diagnostics tool that is included in the QEMM package).
|Download EXEC (ca. 2 KBytes)|