The one thing flash drive recovery had going for it was easy direct access to the underlying storage medium. Inside the casing of that USB thumb drive or camera card is an industry-standard NAND flash memory chip. Whereas hard disk platters can realistically only be read by the drive that recorded to them, that memory chip can be removed from the circuit board and read by any number of device programmers available online. The real challenge is turning that raw memory dump into something useful. What you get directly from the memory chip looks nothing like what your PC sees when the drive is plugged in a USB port. Instead, it looks more like a jigsaw puzzle spread out on your coffee table. Intermixed with user data are bits of information the drive uses for its own internal operation. To get at individual files, this information must be stripped, error correction codes applied, and finally all the pieces reassembled in the correct order.
Greg Andrzejewski, Gillware’s Director of Research & Development, talks more about how Gillware recovered data from a failed monolithic drive in this video.