pin for data transfers, the SD card added a four-wire bus mode for higher data rates. The SD card added Content Protection for Recordable Media (CPRM) security circuitry for digital rights management (DRM) content-protection. Addition of a write-protect notch Full-size SD cards do not fit into the slimmer MMC slots, and other issues also affect the ability to use one format in a host device designed for the other. SDHC The Secure Digital High Capacity (SDHC) format, announced in January 2006 and defined in version 2.0 of the SD specification, supports cards with capacities up to 32 GB. The SDHC trademark is licensed to ensure compatibility. SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in version 2.0 (see below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system. Version 2.0 also introduces a High-speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 25 MB/s. SDHC host devices are required to accept older SD cards. However, older host devices do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade. Older Windows operating systems released before Windows 7 require patches or service packs to support access to SDHC cards. SDXC The Secure Digital eXtended Capacity (SDXC) format, announced in January 2009 and defined in version 3.01 of the SD specification, supports cards up to 2 TB, compared to a limit of 32 GB for SDHC cards in the SD 2.0 specification. SDXC adopts Microsoft's exFAT file system as a mandatory feature. Version 3.01 also introduced the Ultra High Speed (UHS) bus for both SDHC and SDXC cards, with interface speeds from 50 MB/s to 104 MB/s for four-bit UHS-I bus. (this number has since been exceeded with SanDisk proprietary technology for 170 MB/s read, which is not proprietary anymore, as Lexar has the 1066x running at 160 MB/s read and 120 MB/s write via UHS 1, and Kingston also has their Canvas Go! Plus, also running at 170 MB/s). Version 4.0, introduced in June 2011, allows speeds of 156 MB/s to 312 MB/s over the four-lane (two differential lanes) UHS-II bus, which requires an additional row of physical pins. Version 5.0 was announced in February 2016 at CP+