Why AutoCAD 386 Doesn't Work with Windows NT
ID: Q101813
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The information in this article applies to:
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Microsoft Windows NT operating system version 3.1
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Microsoft Windows NT Advanced Server version 3.1
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Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0
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Microsoft Windows NT Server versions 3.5, 3.51, 4.0
SUMMARY
AutoCAD 386 release 11 and 12 do not run with Windows NT because AutoCAD
386 requires DPMI version 1.0 and Windows NT supports version 0.9. When you
try to run AutoCAD 386 in a virtual machine, you receive the following
Pharlap error message:
The 386 chip is currently executing in virtual 8086 mode under the
control of another program. You must turn off this other program in
order to use 386 DOS-Extender to run in protected mode.
MORE INFORMATION
The AutoCAD memory model requires the ability to map a block of a virtual
machine's conventional memory (below 640K) into one or more of its
protected mode segments.
NOTE: The same conventional memory block is mapped by AutoCAD into multiple
protected mode segments; therefore, any extensions must not assume a 1-to-1
mapping between a particular conventional memory block and a particular
segment.
For AutoCAD to run from the Windows NT MS-DOS command prompt:
- Microsoft would have to implement DPMI 1.0 call 0509 (Map
Conventional Memory) in the NT DPMI server. 386|DOS-Extender detects
this functionality by making DPMI call 0401 (Get DPMI Capabilities)
and checking if bit 3 is set in AX. This is how AutoCAD runs under
OS/2 2.0.
-or-
- An NT driver would need to be written with the same functionality
that the PHARLAP.386 device driver provides when it is loaded under
Windows 3.1. This functionality allows 386|DOS-Extender to remap
arbitrary linear regions be reading and writing PTEs for pages that
are locked in memory. It also requires that DPMI calls 0600 and
0601 actually lock pages into memory so they don't move after they
are remapped. 386|DOS-Extender detects this capability by making
DPMI call 0A00 with DS:ESI pointing to the string
"PHARLAP.LINEAR_REMAP." If the capability is present, it returns an
entry point that 386|DOS-Extender can call to remap linear regions.
AutoCAD 386 is manufactured by Autodesk, Inc., a vendor independent of
Microsoft; we make no warranty, implied or otherwise, regarding this
product's performance or reliability.
Additional query words:
prodnt ACAD vdm session
Keywords : kb3rdparty ntdosap NTSrvWkst
Version : 3.1 3.5 3.51 4.0
Platform : winnt
Issue type :