Specifications

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contributed to SD cards’ greater acceptance in the market than that for the MultiMedia card. Since
MultiMedia cards do work in Secure Digital slots, they will not face obsolescence if the format is
ever discontinued. The backs of the Secure Digital cards have nine gold slide contacts, two more
than those on standard MultiMedia cards.
There are additional versions of smaller SD cards in addition to the standard size. The MiniSD
(20mm x 21.5mm x 1.4mm) is 60% smaller than the original in order to fit into cell phones and
expand to PDAs where small size and light weight are important. The MiniSDs have a capacity of
up to 4GB. Adapters will allow them to be used in SD devices (Figure 12), and they share most of
the same features except the write/protect tab. An even smaller version (11mm x 15mm x 1mm)
formerly known as “Transflash” is now called “microSD.” This tiny card is available for cellular
phones and other devices where small size and low weight are critical characteristics. These
media are capable of storing 8GB with write speeds of 6MB/s and read speeds as fast as 16MB/s.
Adapters allow the microSD cards to work in standard sized SD slots (Figure 12).
MiniSD Adapter MicroSD Adapter
Write/protect tab
Locked to prevent
writing/erasure
Unlocked for writing
SD
MiniSD
MiniSD
microSD
microSD
Secure Digital Family
Figure 11
Figure 12