I've only seen this work with a really new BIOS and one that could boot Linux from a USB Flash drive.
http://openfacts.berlios.de/index-en.phtml?title=Linux_bootable_USB_keydrive_HOWTO
I have yet to see DOS access to such.
Bob
I am tring to see my Usb flash drive after booting to dos.I can use the duse utility to see my USB hd, but cannt see my usb flash. Need help fast

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