DOCUMENT:Q98737 30-JUL-2001 [lanman] TITLE :Cannot Run MS-DOS Compatibility Box PRODUCT :Microsoft LAN Manager PROD/VER: OPER/SYS: KEYWORDS:kbnetwork ====================================================================== 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 ====================================================================== Keywords : kbnetwork ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.