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Definition: MMC

(1) See Microsoft Management Console.

(2) (MultiMediaCard) A flash memory card for cellphones, PDAs and other handheld devices. Introduced in 1997 by the MultiMediaCard Association with 4MB of storage, capacity increased to 2GB in the mid-2000s. MMCs were superseded by SD cards, but SD readers support both formats.

MMC Versions
Numerous versions of MMC were introduced, including the encrypted SecureMMC with licensing data in a tamper-proof section of the card. A one-time programmable (OTP) version was available, and a read-only (ROM-MMC) card was used in Palm PDAs. Three smaller MMCs also debuted (see chart below).

Embedded MMC (eMMC) and miCARD
eMMC is flash memory and an MMC controller in a BGA package for direct mounting on a circuit board. miCARD is a high-capacity MMC (up to 2TB) that plugs into a USB port and with an adapter into an MMC slot. In 2008, eMMC and miCARD were turned over to the JEDEC division of EIA.

MultiMediaCards vs. SD Cards
MMCs look like SD cards; however, the thicker SD cards (2.1mm vs. 1.4) have two more pins. MMCs can be read in SD readers, and dual-format SD/MMC readers (bottom) accept both. See SD card.

MMC vs. Reduced-Size MMC (RS-MMC)
RS-MMC, Dual-Voltage RS-MMCs (DV RS-MMCs) and MMCmobile cards can be used in full-size MMC slots with an adapter (see below). See SD card.

               Size             Transfer
  MMC TYPE     (mm)     Voltage  (Mhz)

  MMC        32x24x1.4  Hi        20
  MMC+       32x24x1.4  Hi        26/52

  RS-MMC     18x24x1.4  Hi        20
  DV RS-MMC  18x24x1.4  Lo/Hi     20
  MMCmobile  18x24x1.4  Lo/Hi     20

  MMCmicro   14x12x1.1  Lo/Hi
  miCARD     21x12x1.95 Lo/Hi/5v
  eMMC       BGA chip   Lo/Hi

  Lo=1.7 to 1.95v    Hi=2.7 to 3.6v