How to keep running DOS 16 bit applications when Windows 11 drops NTVDM

Question

I have a business client who runs an old DOS 16-bit accounting and point-of-sale system in his industrial supply warehouse. He does not want to switch from the legacy DOS application since all of his sales and back-office staff are very comfortable with the old style ‘terminal’ interface.

The client asked me:

"With Windows 11 64-bit on the way, I’m thinking that moving to 32-bit Linux may be the way to go."

He is concerned about this (from the Internet):

Windows 11 does not support NTVDM, which eliminates support for 16-bit application supportability.

Windows 11 is 64-bit only and will likely not run DOS programs well. Note that if you use a 32-bit operating system, you have to make sure you are using the 32-bit versions of any Windows programs you're using (not the 64-bit versions). Only the 32-bit versions of W7 & W8 & W10 work correctly with DOS programs!

Key Requirements:

• 16 staff Windows workstations on a Windows network
• which share 4 networked printers
• each printer is attached to a local workstation
• there is a Windows server that hosts the main accounting stock item files for the POS lookups
• there are some Python applications which
  • send invoice as PDF to Outlook email
  • send invoice as PDF to shared network printer

We need a 16-bit DOS emulator which will satisfy the key requirements above. What do you recommend? And should we look at a DOS emulator running on Linux, or Windows?

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Also, this I think is useful information to add. Not so much an answer to the problem, but a mitigation of how critical it actually is in practice.

I read that the Windows 11 64-bit deadline is for OEMs – Original Equipment Manufacturers. Hardware suppliers will not be able to buy 32-bit Windows 10 to pre-install for sale on a new PC. Existing 32-bit Windows users however can carry on as they were, and individual users should be able to buy a legal 32-bit Windows.

So, down the line, the client may buy new workstations which come pre-installed with 64-bit Windows 11 – but nothing would prevent him from installing 32-bit Windows 10 himself.

Answer 1

In absolute terms yes, migrating to a current accounting system would be better. However, that will not be easy.

Migrating away from a Windows NTVDM-based solution won’t be easy either, but there are a few options. First, note that support for 32-bit isn’t as much of a concern as one might think. On Windows, DOS-based programs are only supported directly on 32-bit versions of Windows because NTVDM is only available there. But that’s not the only way to run a DOS program, and various emulation environments can be used on Windows and Linux.

One option available on modern 64-bit PCs in both Windows and Linux is to run DOS inside a full-blown hypervisor or PC emulator. That might not be appropriate in your case, in particular because providing access to host directories and host printers isn’t well-supported for DOS-style guest operating systems.

DOSBox-style environments would provide a better solution: they make host directories directly available in the DOS environment. (They also provide more conventional memory for DOS programs, and don’t require a licensed version of DOS since they emulate it entirely.) The original DOSBox is intended for running games, so it probably won’t be a great fit; in particular, networking and printing support might not be good enough for your purposes. A couple of DOSBox descendants would fit the bill on Windows, including 64-bit Windows:

• DOSBox-X — this is actively developed, with frequent releases, and much better support of applications; it includes networking and printing support, and DOS programs running inside it can start commands on the host, which would allow you to implement your PDF handling workflow.
• vDos — this is also supposed to be a good DOS environment for Windows, with printing and networking support, but I’ve never used it.

There is also a proof-of-concept 64-bit NTVDM, NTVDMx64, but its legal status seems to be somewhat sketchy.

If you were to migrate to Linux, DOSBox-X would still be a possibility; it isn’t widely available in distributions yet (it will hopefully be available in Debian 12 and Ubuntu 23.04) but it’s easy to install anyway, and it’s the most usable option for your scenario in my opinion. There would be a couple other options:

• DOSEMU — this runs well, has good networking and printing support, but is unmaintained and is no longer available in most distributions. (It was removed from Debian two years ago and didn’t ship in Debian 10 or 11.)
• Dosemu2 — this is still in development, but its aim is to provide a modern replacement for DOSEMU, with networking and printing support.

Unlike DOSBox, these require a DOS installation, so you’d need either FreeDOS (or fdpp in Dosemu2) or some way of getting licenses for MS-DOS, PC DOS or some other DOS variant.

Answer 2

I know you already have accepted an answer, but maybe consider 86Box instead, running a full copy of MS-DOS (or FreeDOS) and your application.

It supports networking and can print to a PostScript file, which then could be consumed by a Python script (e.g. this) to turn it into a PDF.

I made a quick test:

1. Create a new 86Box machine and point the parallel port to PostScript.

2. Under Windows on that machine, add a printer that outputs PostScript (I used "HP LaserJet 4P/4MP PostScript").
3. When I print, under the printer directory where my disk image is, I get a PostScript file that I can view with e.g. Okular.

Answer 3

There is another software solution not mentioned in the existing answers: winevdm. It's supposed to be a drop-in replacement for the old NTVDM that works on x64 Windows. It hooks itself in the native mechanism for handling legacy EXE files, and uses a Windows port of Wine to run the incompatible applications.

Having tested it, it works quite well, and I haven't encountered any serious bug despite its pre-release status. It handles printers and local filesystem access, in addition to GUI interaction.

Answer 4

Why even bother upgrading to Windows 11 (or 10). Why not buy a new PC (with Windows Licence), and downgrade to Windows XP or 7 or even just stick with 10. You obviously don't need the latest version of Windows (heck you could probably just run W95 if pushed).