Mobile devices like tablets and smartphones typically use solid-state drives with eMMC interfaces. These single-chip SSDs are incredibly small, but they're not very fast. For example, the 64GB eMMC device Samsung introduced in November is rated for sequential read and write speeds of 260 and 50MB/s, respectively.
Fortunately, there are faster alternatives. The Serial ATA governing body has a µSSD specification that brings the latest 6Gbps interface to single-chip drives. Innodisk has released what it's calling the "world's first industrial-embedded" SSD based on the SATA µSSD spec. Dubbed the nanoSSD, the device crams up to 64GB of flash onto a BGA package measuring just 16 x 20 x 2 mm. That single chip also includes the drive controller and a DRAM cache.
The press release says the nanoSSD is ideal for ultra-thin mobile devices like smartphones, tablets, and ultrabooks. With a claimed sequential read rate of 480MB/s and a write speed of 175MB/s, the nanoSSD isn't exactly short on speed. However, that write rate appears to be limited to SLC versions of the drive, which top out at 16GB according to this product page. The MLC variant writes at only 90MB/s according to the product page for that device.
Oddly, that page also lists the maximum MLC capacity as 32GB, despite the 64GB maximum mentioned in the official announcement. The picture in Innodisk's press release shows a 32GB chip, too. Hmm.
Higher-capacity alternatives already exist. SanDisk's iSSD lineup offers single-chip solutions with the same footprint as the nanoSSD and capacities up to 128GB. These devices have 6Gbps SATA interfaces, as well, and they boast sequential write speeds up to 350MB/s. Sequential reads top out at only 450MB/s, however. The iSSD also looks a little power-hungry: its 2.7W active power draw is nearly three times higher than the 1W maximum power consumption of the nanoSSD.
WD is using SanDisk's iSSD to serve as the cache in its Black SSHD hybrid drive. I suspect we'll see cache-specific µSSD implementations in other hybrid drives—and in ultra-slim notebooks with mechanical storage. The standard's Serial ATA roots should allow it to interface easily with modern PC platforms, including AMD's Kabini and Temash SoCs.