Nikon and Sony have jumped the gun on CES by introducing a new DSLR camera (the Nikon D4) and a new series of Flash storage media (the Sony H Series). These announcements mark the beginning of the XQD Flash card era. The Compact Flash Association announced the XQD memory card format early in December. Physically, the XQD card footprint is slightly larger than an SD memory card and somewhat smaller than a Compact Flash card.
An XQD memory card is much thicker than an SD card; it’s the same thickness as a Compact Flash card.
The big change, however, is that XQD memory cards use the PCIe (PCI Express) interface rather than an existing hard disk or Flash-specific interface protocol. The current XQD interface format calls for a 2.5Gbps data rate, permitting write speeds of 125Mbytes/sec or greater. There’s a plan in place to move to 5Gbps in the future. Of course, this new Flash memory card format has some pretty big implications for SoC designers selecting an interface protocol for Flash cards.
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What is the need to adopt a completely new standard in this space? With SSDs shrinking and improving in performance (mSATA SSDs are a dime a dozen), wouldn’t it be simpler for everyone involved to just adopt the SATA standard and design card interfaces around that?
I have also found that PCI-E is integrated in chips where low power is not that much of a concern (Doesn’t SATA have much more penetration in that area compared to PCI-E?). This new interface will only make manufacturers integrate PCI-E PHYs where SATA could have sufficed. Now, card readers have to go to USB 3 and have a new slot / PC makers have to connect a new slot to the PCI-E lanes on the chipset. On the PC, users could have just used the eSATA port to connect the new card without any protocol conversion.
This new standard is just meant to create more work and be a hassle for everyone involved. SATA should have been used here instead of PCI-E. Bandwidth is also not the issue (SATA is at 3 Gbps and the latest standard goes up to 6 Gbps)
(I do know that SATA is also going the PCI-E route in the long run — http://semiaccurate.com/2011/09/13/sata-to-move-to-pci-express/ , but, the new standard and SATA should actually have worked together and moved on at the same time)
Ganesh, thanks for your well-considered comment. Whether PCIe or SATA, there’s a different PHY at work here so changes are required. There’s always a lot of friction at the introduction of a new memory card format. I remember that SD got (and still gets) a lot of criticism for its small size! Some people think it’s too easy to drop or lose those “tiny” SD cards. The original PCMCIA Flash cards were “too big” so we got Compact Flash, which took flak for requiring an adapter to fit into existing PCMCIA slots. XD cards took a big chunk of criticism as did Sony Memory Sticks. Canon has taken heat for incorporating SD cards into the Canon 60D DSLR instead of staying with CF. I bought one anyway. In these and all cases, the market will indeed decide. From the Cadence perspective, we support both SATA and PCIe in somewhat different ways, so we like to see both win.
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