I have a question about the speed of rs-mmc cards.
If you look through the various offers you see claims of different speeds, from 20mb/s to 80mb/s and from 7MByte/s to 12MByte/s.
Sometimes you even see very different ratings on what appears to be the same card (same brand, same size, same look).
Meanwhile i have read in another thread that the typical speed is only 1.5MByte/s.

Now, which card can i buy if i want the fastest one available?

http://www.internettablettalk.com/fo...php/t-298.html

As you can see there could be huge differences between cards.
A bench of all card could be very interesting.
Just make a small protocol and let the users post their results

Just buy the cheapest card you can find.
The 770 uses the older 7-pin (1-bit serial) interface and a maximum 20 MHz clock, the theoretical maximum transfer rate of the interface is 2.5 MByte/sec. Having a fancy new card that supports 52 MByte/sec won't help.
RS-MMC, MMC-Mobile, Single Voltage, Dual Voltage, doesn't matter, they all work with the 770.

thanks for the solid info, where do you know that from?

Look down in the mmc slot. Only 6 pins in there. The MMC spec v3.31 calls for a 20MHz clock.
The newer v4.1 spec provides for a 26 MHz and a 52 MHz clock and also a 4-bit and 8-bit data path with a 13-pin connector. 52 MHz times an 8-bit path yields 52 MByte/sec.

The specs are available at the MultiMedia Card Association website: http://www.mmca.org/home