Program Manager is the shell of Windows 3.x and Windows NT 3.x operating systems. This shell exposed a task-oriented graphical user interface (GUI), consisting of icons (shortcuts for programs) arranged into program groups. It replaced MS-DOS Executive, a file manager, as the default Windows shell.
The program derives from the OS/2 1.2 program PMShell. This had the same icons as the Windows 3.0 program. Unlike the Windows versions, which are meant to illustrate the Multi-Document Interface, one can place groups or icons in a group. The groups in OS/2 were presented in a list. Running the OS/2 version in Presentation Manager for Windows will cause PMShell to read all of Windows groups, via DDE.
The DOSSHELL program in PC-DOS and MS-DOS has a File Manager and a Program Manager, this program being run on the Windows dosx extender. This program also supports nested groups inside groups. It is in part because of this that programs like Norton Commander offer a program launch menu.
In later versions of Microsoft Windows, starting with Windows 95 and Windows NT 4.0, Program Manager was replaced by Windows Explorer as the shell, though Windows 95 gave the user an opportunity to choose which shell they preferred during setup. For backward compatibility with old applications, Program Manager was still included in later versions of Windows. It can be accessed by executing PROGMAN.EXE from the command line or Run dialog. The file is located in the Windows directory in older versions, or the System32 directory in Windows 2000 and Windows XP. On any Windows version, it can be used as the default shell by specifying the Shell value in the registry at either HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon (per machine) or HKCU\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon (per user).
Today, Program Manager has little practical use beyond compatibility with pre-Windows 95 programs. Since Windows XP Service Pack 2, it has been reduced to a stub and a converter for Program Manager shortcuts to Windows Explorer shortcuts. Windows Vista does not
include it at all.
It is still possible to use the Program Manager in Windows XP Service Pack 2 or 3 (and Windows Vista) by replacing (or copying if there was Windows Vista computer) the Progman.exe executable with the executable from Service Pack 1 or the Windows XP original retail release. With the SP1 (or original release) CD, one can expand it by typing expand -r D:\i386\progman.ex_ %Windir% at the command prompt (replacing D: with the CD-ROM drive letter). It is also possible to bypass the Windows File Protection and overwrite the SP2/SP3 version of Program Manager completely. Alternatively, the file can be saved to a different location or using a different filename. If Service Pack 3 has backed up previous files on an RTM or SP1 Windows XP installation, the backed up version can be accessed from: %Windir%\$NtServicePackUninstall$\Progman.exe
The Program manager from Reactos has most of the features of the Microsoft version.