I have an SD Card FAT class I built, and all works fine, but I have noticed that not all cards that have the TRAN_SPEED in the cards CSD set to 32(signaling a max clock of 25MHz) can handle data read at 10MHz and write at 20MHz from the propeller. For now, I have my class setup to auto detect the max speed. Does anyone know why certain cards that say they will support up to 25MHz with the TRAN_SPEED setting do not actually support it? I would like to get rid of the auto speed detection if possible, but I want to know why it is a problem in the first place. BTW, when I use to high of a speed, the R1 response is correct from the card, but the data I receive is all jumbled with no discernible pattern. Also, some cards do work with 10Mhz read and 20MHz Write fine(1GB sandisk microSD), i mostly have the problem with read and write not working at max speed on older 64MB or 256MB cards. Thanks!