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CHAPTER 3
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MANAGING THE WINDOWS DESKTOP
If you want to run MS-DOS applications on Windows XP, your course of
action is a little trickier. You can run applications in the standard command-
line virtual machine, cmd.exe. Or you can run your application in a DOS
emulation environment, command.com. Both are managed by NTVDM, or
NT Virtual DOS Machine, which sets environment variables needed by DOS
programs when you run them.
Environment variables can be set by modifying or creating custom
AUTOEXEC.NT and CONFIG.NT files that are run when the virtual
machine starts. The AUTOEXEC.NT and CONFIG.NT files can be found in
the Windows\system32 directory. If you were comfortable modifying their
analogues in DOS, you can do the same in Windows XP.
Very old MS-DOS applications relied on the CPU clock speed to deter-
mine how fast the application ran. Even if you configure the environment
correctly, there’s no easy way under Windows XP to slow down the emulation
environment. Your best bet is to download a third-party “slowdown” applet
that you can run prior to launching your older application. This can provide
some relief for impossibly fast applications. However, this is not guaranteed,
and the environment may not be stable, so use slowdown applications at
your own risk. Mo’slo is a popular slowdown utility available in several differ-
ent versions at www.hpaa.com/moslo.
Application Compatibility Toolkit
If you don’t want to spend your time adjusting settings repeatedly
in order to find what works, there may be an easier way to create a com-
patible environment for your older applications.
Microsoft offers an advanced set of tools, intended for system admin-
istrators, called the Application Compatibility Toolkit. Its core applica-
tion, the Compatibility Administrator, contains a number of settings
and fixes for many applications. They are settings that have worked in
other environments and may in yours. You can download the toolkit
at http://msdn.microsoft.com/library/default.asp?url=/downloads/list/
appcomp.asp.
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