Getting the most out of DOS and Win-OS/2 sessions

Wikis > ArcaOS > Compatibility Subsystems > Getting the most out of DOS and Win-OS/2 sessions

ArcaOS includes a robust Virtual DOS Machine (VDM) capable of running DOS and 16-bit Windows applications without the need of an additional hypervisor such as VirtualBox or VirtualPC. This page should help you customize your DOS and Win-OS/2 sessions for each of your applications.

High CPU utilization

Some DOS applications continuously poll for keyboard (and possibly) mouse input. This polling, while unnoticed on a system booted directly into DOS, tends to manifest itself in a multitasking system like ArcaOS as a CPU hog, demanding almost constant processor attention.

The best way we’ve found to combat this is using a third-party utility called TAME, available from the developer’s page. If you find that you have one or more DOS applications which seem to exhibit this behavior, you might want to try TAME. (Note that Arca Noae does not endorse, sell, or in any other way profit from the sale of TAME licenses, nor are we affiliated with the developer of TAME in any way. Arca Noae likewise does not provide support for TAME.)

Speed issues (too fast)

Timing is another frequent issue observed with applications originally written to run on a 4.77MHz Intel 8088 processor, and utilize the CPU for timing of events. Today’s processors run at such frequencies that these applications may be barely controllable as a result.

For these issues, we recommend another third party utility, Mo’Slo, available from the developer’s page. Mo’Slo provides other control capabilities, as well. (Note that Arca Noae does not endorse, sell, or in any other way profit from the sale of Mo’Slo licenses, nor are we affiliated with the developer of Mo’Slo in any way. Arca Noae likewise does not provide support for Mo’Slo.)


Simply put, Win32s is a subset of the 32-bit Windows API which provides some 32-bit Windows applications services required to run under 16-bit Windows, namely, Windows 3.11, running in Enhanced Mode. Microsoft produced a series of releases of Win32s, culminating in release 1.30c, in January, 1996.

The latest release of Win32s supported by Win-OS/2 is release 1.25a, available from the Hobbes archive (when downloading, be sure to get the zip dated 1998-04-23). The package includes the Freecell card game as an optional install, and which is itself a Win32s application, allowing you to ensure that Win32s is working correctly on the system.

Installing Win32s 1.25a

Installation is fairly straightforward: download the package, extract, extract the two zips contained in it, start a Win-OS/2 full screen Enhanced Mode session, and run setup.exe. Specific directions follow:

  1. Unzip the downloaded archive to an isolated directory in a DOS-compatible path (i.e., all directories must conform to the DOS 8.3 naming and path length conventions – no long directory or names or extra-deep paths).
  2. Create two subdirectories, disk1 and disk2.
  3. Extract W32S125A.ZIP to the disk1 subdirectory.
  4. Extract W32S125B.ZIP to the disk2 subdirectory.
  5. Start a Win-OS/2 full screen session. Ensure the session is configured for Enhanced Mode.
  6. Either from the Run option on Program Manager’s File menu or from File Manager, browse to the location of disk1, locate setup.exe and start it.
  7. Follow the prompts to install Win32s. Installing Freecell is recommended.
  8. After install, the disk1 and disk2 directories may be removed from the system, as these files are no longer necessary.

Uninstalling Win32s

Microsoft did not provide an automated method to remove Win32s. Instead, the directions were contained in Microsoft Knowledgebase article Q120486, currently still available from MIT’s archived pages, here, and abstracted for reference, below:

  1. Important: Ensure that all Win-OS/2 sessions have been closed.
  2. Open X:\OS2\MDOS\WINOS2\SYSTEM.INI in your favorite text editor (where X: is the ArcaOS boot volume).
  3. Remove the following line from the [386Enh] section:
  4. Modify the following line from the [BOOT] section:
    drivers=mmsystem.dll winmm16.dll

    to read (remove winmm16.dll):

  5. Delete the following files from X:\OS2\MDOS\WINOS2\SYSTEM:

    Note: All Win-OS/2 sessions must be shut down in order to delete some of these files.

  6. Delete all files under X:\OS2\MDOS\WINOS2\SYSTEM\WIN32S and remove the WIN32S subdirectory itself.
  7. Restart Win-OS/2.

The system should now run without Win32s. (Freecell may be removed by deleting the Freecell program item from the Win32 Programs group in Program Manager, deleting all files in the FREECELL program directory (usually X:\WIN32APP\FREECELL), and removing the empty FREECELL subdirectory.

Troubleshooting Win32s installation issues

Some information relating to common errors may be found in MIT’s archive of Microsoft Knowledgebase article Q106715.

Further Win32s notes and information

Do not attempt to install a Win32s version higher than 1.25a in Win-OS/2, as these are known not to work. Follow the removal procedures above to remove any later version before installing version 1.25a.

Links for more information:

Fandom’s Microsoft wiki article on Win32s
RGB Classic Games Utilities for Playing Win9x Games
The Win32s compatibility list


This entry last updated: by Lewis Rosenthal