Hot on the heels of the rollout of high-speed SDHC and SDXC UHS-I cards that approach 100 Mbytes/sec (see previous blog entry), the SD Association has unveiled plans to add more pins to the physical SD package to boost read/write transfer rates into the hundreds of Mbytes/sec. The UHS-I spec currently has a maximum transfer rate of 104 Mbytes/sec. The new 4.0 SD specification, due out early next year, adds a second row of pins behind the first row to boost bandwidth to as much as 300 Mbytes/sec through I/O parallelism. Cards with the second row of pins will be backwards compatible with the existing single-row cards. (Press release here.)