Specifications

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MultiMedia cards operate at either 2.7 volts or 3.6 volts from the power source. These cards will
work in Secure Digital card slots as well as MMC slots; but because the SD cards (described
below) are slightly thicker, the reverse is not true. Music stored on an MMC card, however, will not
play back on an SD device because the SD audio devices only work with encrypted music files.
The insertion end of a MultiMedia card has seven gold slide contacts on the back. In all other
respects, the MultiMedia card is similar to its bigger brothers. A new version called MMCplus
follows a new standard referred to as “MMC4.” This new standard increases the number of
contacts from 7 to 11 and allows higher performance in terms of speeds and capacities, with a
maximum capacity of up to 8GB. MMC cards follow an open standard, which allows companies to
develop improvements with fewer restrictions such as licensing agreements. This arrangement
has led to a number of other confusing versions of MMC cards:
1) smaller version of the MultiMedia card is available as a “Reduced Sized-MMC” or
RS-MMC intended for the smaller, lighter devices that need memory storage such
as camera-phones, for example. The RS-MMC card (18mm x24mm x1.4mm)
has the same width as a standard MMC or SD card, and this design feature allows
the card to fit into those standard slots with attachment of a simple mechanical
adapter. Capacities of 2GB are possible for the RS-MMC.
2) The MMC4 standard update also introduced a new version of the RS-MMC with a
lower operating voltage of 1.8V (or a dual voltage that includes 1.8V) to reduce
battery power consumption in cell phones. This version is known as the
MMCmobile.
3) MMCmini is similar to the RS-MMC but has 11 pins and a smaller profile (20mm x
21.5mm x 1.4mm) to fit into smaller card slots.
4) The MMCmicro card (12mm x 14mm x 1.1mm) replaced the RS-MMC as the
smallest flash card available when it was introduced in 2005. This card is the size
of a keyboard key--one-fourth the size of the MultiMedia card and one-third the
size of the RS-MMC. The design is intended to make a card even smaller and
with lower power consumption for mobile phones in particular. It operates at
voltages of either 3.3V or1.8V and requires just one-sixth the power consumption
of the MultiMedia card. The tiny card can write at 7MB per second and read at
10MB per second. Maximum capacity will reach 4GB with four NAND chips
stacked in the tiny devices. These tiny cards can fit into adapters that allow them
to be used in standard MMC and SD card slots (Figure 9).
Adapter with MMCmicro miCard compared to MMC Card
5) SecureMMC is a MultiMedia card with encryption features similar to those applied
to the Secure SD and Sony’s MagicGate Memory Stick (see below). The
secureMMC has not reached the market yet.
As if things were not confusing enough in the MMC camp, the miCard seen in Figure 9 is a
USB memory device based on MMC electrical specifications and not a card at all, despite its
name. Measuring only 21mmX12mmX1.95mm, the miCard is for the moment the smallest
Figure 9