XQD card
XQD card is a memory card format primarily developed for flash memory cards. It uses PCI Express as a data transfer interface.
The new format is targeted at high-definition camcorders and high-resolution digital photo cameras. It offers target read and write speeds from 1 Gbit/s (125 Mbyte/s) to about 4 Gbit/s (500 Mbytes/s) and storage capabilities beyond 2 TB.
The cards are not backward compatible with CompactFlash or CFast cards. XQD and CFast were both designed as a replacement of the then-16-year-old (in 2010) CompactFlash standard.
The format was first announced in November 2010 by SanDisk, Sony and Nikon, and was immediately picked up by the CompactFlash Association for development. The final specification was announced in December 2011.
XQD version 2.0 was announced in June 2012, featuring support for PCI Express 3.0 with transfer rates up to 8 Gbit/s (1000 Mbyte/s). The older XQD cards will not work with the new XQD 2.0 card readers. The reason that this exists is because the older XQD cards do not have their controller chips inside of the card, they are located in the readers and adapters that support them. The new XQD 2.0 card have the controllers chips located inside of the card, not the reader. As such, when you use an old XQD card with a new XQD 2.0 reader, there is not controller chip in the set up. Without a controller chip, there is no way to read or process the card.