I finally got it working after re-reading the posts here-- you must supply power to both the USB device (keyboard, flash drive, etc.) and the 770. If the 770 USB power lead isn't connected to 5V+ it doesn't know anything is plugged in. Once I did that it was all good. I have a mini 4-port USB 2.0 hub (not that the 770 is USB 2.0, but it was what Walmart had) and it works great. I have one port used up because I have a USB cable end plugged in to steal power from the hub for waking up the 770; the black and red wires are connected to the 770's. Using an older 48MB flash card it writes at about 300KB/sec ("time dd if=/dev/zero of=testfile_on_flash bs=1024k count=20" was what I tested with-- a 20MB file is created). Nothing amazing, but definitely usable.