Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I need to run a 16-bit diagnostic tool in real mode under Windows XP, Vista, or 7. How can I accomplish this?

share|improve this question

migrated from Aug 7 '10 at 2:39

This question came from our site for professional and enthusiast programmers.

Windows XP and later (Vista, 7) are based on the Windows NT kernel and don't rely on DOS, unlike Windows 3.1, 3.11, 95, 98, and ME. Windows Me dropped real-mode DOS support.

Windows NT includes a NTVDM (NT Virtual DOS Machine) that emulates a 16-bit DOS mode for 32-bit but not 64-bit versions.

If you really need to run tools that rely upon low level BIOS and hardware interface calls in 16-bit mode, you need to boot into a DOS environment completely outside of Windows.

FreeDOS an example of a separate 16-bit real mode DOS environment. You can install it into a separate partition, run it off of a live CD, or from a USB stick.

share|improve this answer
Or use a virtual machine? (Depending on what you are using the diagnostic tools for) – MrStatic Aug 7 '10 at 3:26
@MrStatic, the whole point is that the program needs access to the REAL hardware, not virtual. If it were happy with virtual hardware it would run fine under Windows. – psusi Jul 19 '12 at 14:58
@psusi, where did you get that from? It doesn’t specifically say it’s a hardware diagnostic program. – Synetech Sep 1 '12 at 22:42
@Synetech, because if it was happy running under a virtual machine, it would be happy running under the normal built in dos vm that windows has and uses to run dos programs, hence, the question would be moot. Also a 16 bit software diagnostic tool would be utterly useless when you aren't running a 16 bit os. – psusi Oct 5 '12 at 15:35
> It would be happy running under the normal built in dos vm that windows has and uses to run dos programs @psusi, unfortunately that’s not true. There are plenty of DOS software that won’t run correctly or at all in even XP’s NTVDM for one reason or another (vis 3D games). – Synetech Oct 5 '12 at 17:36

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.