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Q98737: Cannot Run MS-DOS Compatibility Box

Article: Q98737
Product(s): Microsoft LAN Manager
Version(s): 
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 30-JUL-2001

SUMMARY
=======

You cannot run an MS-DOS compatibility box with LAN Manager 2.0, 2.1, 2.1a or
2.2 when using HPFS386.

It is not anticipated that this will change, because running the MS-DOS box on a
server is a bad idea for three reasons:

- The MS-DOS program runs in real mode, so if it were to crash, the machine
  probably would not recover.

- Interrupt switching between real and protected modes in the 80286 model used
  by OS/2 1.x takes a great deal of time, degrading performance noticeably on
  an HPFS386 server.

- An MS-DOS program runs in real mode, so it can defeat any and all OS/2
  security measures. Because HPFS386 supports local security, it cannot allow
  the MS-DOS box.

The amount of available memory in the MS-DOS 3.x emulation is considerably less
on the LADDR device driver versions of OS/2 1.x than in previous versions using
monolithic disk drivers. On OS/2 versions shipped with LAN Manager 2.1 and
later, the available memory in the MS-DOS box is no larger than about 320K.

Windows NT runs MS-DOS programs in a more secure manner using "Virtual 8086" mode
on Intel x86 architecture processors and software emulation on other processors.
This allows you to run MS-DOS programs with minimum risk on the servers. OS/2
versions 2.x use much of the same approach to crash-resistance.

Additional query words: 2.00 2.10 2.10a 2.20

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Keywords          : kbnetwork 

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