I wanted to add an eMMC (16GB) mass storage to the Mainboard. But currently I am unable to find any documentation about the chips from the big vendors. I tried Micron and bounced at the form to get an NDA. I tried Toshiba and did not get any information at all. I can buy them from mouser for sure, but no datasheet what so ever.

This is very upsetting. But I am going on to try and find a suitable eMMC. I do not want to stick to SD card for the main operating system since they have the tendency to die after a while of usage. They also only have 4 bit compared to the 8 bit data bus of eMMC.