I'm currently trying to use the nj32disk.sys driver to use my USB stick as a virtual hard drive. The problem is that the driver acts like a floppy disk. My question is: Is there a documentation about nj32disk.sys?

1 Answer 1


There’s a short text file describing NJ32DISK.SYS, but it doesn’t say much:

NJ32DISK.SYS is the ASPI disk driver for USB mass-storage devices (it assigns a DOS drive letter). Run the USB hardware driver (such as USBASPI.SYS) before NJ32DISK (similar to the way you first run the cd-rom ASPI driver before running MSCDEX). If USBASPI does not find any USB mass-storage devices on bootup, NJ32DISK will not load or assign any drive letters. Drive letters assigned will come after the internal Floppy drive, Hard drive, and other bios established storage devices have been assigned drive letters.

This driver will assign its USB drive letters before the CD/DVD gets assigned their drive letters (due to NJ32DISK being loaded in Config.sys wheras the CD/DVD MSCDEX driver is loaded in Autoexec.bat).
Therefore to keep your CD/DVD drive letters consistant, it is suggested that you always boot with the USB mass-storage devices connected, or that you assign a "starting" drive letter to your CD/DVD unit that appears lower in the alphabet than the USB assigned drive letter.

After a drive letter has been assigned, you can remove and replace the
mass-storage media (of the same formatted Mb size) in a similar fashion as you can remove and replace floppy diskettes (the cache may have to be refreshed to recognize the media change though, just as you must often do with floppy diskettes).

You might be better off looking at Bret Johnson’s USB drivers, they’re documented and quite configurable.


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