Microsoft KB Archive/98737

= Cannot Run MS-DOS Compatibility Box =

Article ID: 98737

Article Last Modified on 10/31/2006



This article was previously published under Q98737



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 &quot;Virtual 8086&quot; 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 KB98737

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