You might want to take a look at our MicroUSB Project at
http://www.microusb.org/. We have developed an USB Host Adapter for 6502 based Homecomputers, including Atari XL/XE, Commodore C=64 and Apple II.
The hardware schematics can be found in the SoureceForge Projects File area:
http://prdownloads.sourceforge.net/micr ... art_11.PDF
THe SL811HS should work with an 1541, and we are currently working on FAT and VFAT code. We can currenty read and write sectors and decode the FAT Table, listing the drives directory.
Goal is to have a full USB Flashstick / Harddrive Driver.
Assembled USb Carts can be ordered from Steve Tucker at
http://www.atarimax.com. You can open the Cartridge Cover and connect the USB Cart Board with your computer for prototyping. Glenn Jones had done similar for the Apple II:
http://www.strotmann.de/twiki/bin/view/ ... SBAppleTwo
It seems to me that we are all working on similar projects. Lets work together!
Best regards
Carsten Strotmann