The Installable File System driver is the 32-bit file system required for
Windows to run. It is not required to boot into DOS. In can only be installed
manually in config.sys using a Device/DeviceHigh
statement, but an entry in config.sys is usually not required
because ifshlp.sys is loaded automatically (with the standard default
configuration) just before Windows starts.
Ifshlp.sys can only be loaded manually (see above) in Config.sys using a Device or DeviceHigh statement