USB flash drives are NAND-type flash memory data storage devices integrated
with a USB (universal serial bus) interface.  They are typically small,
lightweight, removable and rewritable.

==> SIO2USB, by ABBUC Regional Group Frankfurt / Main

The SIO2USB Interface is a peripheral device that can be attached to an ATARI
8-bit computer using the SIO-Bus.  It emulates one or more ATARI Floppy-
Drive(s) and does not require any special drivers or Operating-Systems, it is
fully compatible with all ATARI DOS Systems and extensions.  Because the
device is connected to the SIO-Bus, it is not necessary to open or modify the
ATARI.  The device is powered by the SIO-Bus and does not need an external
Power Adapter.  The data are stored on standard USB Mass Storage Devices (USB
FLASH Drives) as ATARI-Imagefiles (ATR or XFD) on a standard FAT filesystem.

SIO2USB features:

 o Can boot an ATARI 8-bit Computer without physical Floppy Drive
 o Emulation of up to 3 (virtual) Disk drives simultaneously
 o Simple device, attached to SIO-Port, no modification of computer necessary
 o Mixed operation of real Floppy and SIO2USB possible
 o Fully compatible with all ATARI DOS and OS and all ATARI compatible
   extensions
 o Storage of ATARI-Imagefiles on standard USB FLASH Drives
 o Configuration of the device by built-in keys and LC-Display or
   configuration program on the ATARI
 o Built-in Real Time Clock (RTC)
 o Power supply for the device and USB FLASH Drive from SIO-Bus
 o Updated SIO2USB Firmware can be applied from within the ATARI (no
   additional device or computer required)
 o Updates available via Internet (USB FLASH Drive) or direct from the ATARI
   (real Disk Drive)

http://home.arcor.de/grasel/sio2usb_e.htm   or
http://home.arcor.de/grasel/sio2usb_d.htm