HAVING AN EXTERNAL USB cd-writer or hard disk works wonders as long as your operating system is in good shape. But if someday the system stops booting, you are lost. Booting from good old MS-DOS or Windows boot diskettes - even fitted with the needed third party NTFSDOS or EXTFS drivers - gives you access to your fixed hard disk only, but none of the USB peripherals can be accessed from the DOS command line.
Imagine that you want to use Paragon Drive Backup, Powerquest's Drive Image, or Norton Ghost, to backup your hard disk partitions to that nice 120gb external USB 2.0 hard disk you just bought. You can't do it. Or if your wife/husband has managed to mess up her/his system so badly that it can't boot anymore, yet she/he wants you to have a copy of those nice digital pictures stored on a compactflash card plugged into the compactflash reader?. No way, Jose. Not from DOS, used to be the phrase.
Well, now you CAN.
The minor miracle here is using a driver file called "USBASPI.SYS" ("Panasonic v2.06 ASPI Manager for USB mass storage"). Given the right parameter incantations, this 16-bit Panasonic-developed DOS driver will let your system boot good-old DOS -any flavour, maybe even Caldera's OpenDOS and recognize all USB devices connected to the respective controllers. So this USB device identification is also useful for debugging/troubleshooting purposes.
The Panasonic DOS drivers seem to work on most USB chipset implementations, including Intel and NEC, as well as NVidia, VIA, and SIS. It seems Panasonic engineers didn't want to have to write a driver every time for every different chipset, so they wrote this "universal" driver to work with all possible USB controllers.