SD Card

SD cards are little FLASH cards, or the SDIO variant allows for I/O devices to fit into an SD slot.

SD card slots can take MMC Cards.

The SD card can be accessed via the MMC Card protocol (SPI based) or its own SD card protocol (the fastest, 4 bits parallel). (Actually MMC has it's own protocol. Some (most?) MM cards also support SPI)

See http://www.sdcard.org/ for more information. They make a subset of the specs freely available:

• http://www.sdcard.org/sdphysical_simplifyed_Ver101.PDF - basic specification
• http://www.sdcard.org/SDIO-SimpleSpec-1.00_A.pdf - SDIO specification
• http://www.sdcard.org/Simple_of_SDIO_Card_Type-A_Spec_v1.0_Draft_C_20020524.pdf - SDIO Bluetooth

Also, SanDisk have some helpful information at http://www.sandisk.com/oem.html (the files below are hidden at the sandisc pages)

• http://www.sandisk.com/download/Product%20Manuals/Product%20ManualSDCardv1.7.pdf older specs
• http://www.sandisk.com/pdf/oem/ProdManualSDCardv1.9.pdf the full specs
• http://www.sandisk.com/pdf/oem/ProdManualminiSDv1.1.pdf MiniSD specs