Write caching would store data to be written on the HDD in flash memory initially until enough data was in the flash cache to do an efficient write to the HDD disks.
Combining the performance of SSD, USB 3.0 and DRAM cache technology, the FastKey can write small files up to 100 times faster than your average USB 2.0 hard drive.
Of course, the exploit that they've actually released is completely harmless, but it demonstrates that the CPU cache can be "poisoned" to let folks read and write into the otherwise protected SMRAM memory.
The Brahma15 is a 21, 000 DMIP Quad-core ARMv7-A instruction set compatible multiprocessor. 32KB instruction and 32KB data caches per processor are backed by a shared 2MB L2 cache and feed the multi-issue, out-of-order superscalar 15-stage plus write back pipeline of the Brahma15.