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

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migrated from Aug 7 '10 at 2:39

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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.

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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

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