Boot sequence

macroalpha — 09/08/2021

Near as I can tell the A64 used in the Pocket PC boots off of SD0 (the SD card), then SD2 (the emmc), then the SPI NOR flash, then if it fails all 3 it goes to FEL mode. If the FEL key is pressed it skips everything and goes straight to FEL mode. So if I'm reading the schematics right yes, it will preferrentially boot from the SD card assuming one is present and has the correct signature on it. The external SD card appears to be wired to the SD0 bus on the SoC.

Sources:

https://linux-sunxi.org/BROM

http://files.pine64.org/doc/datasheet/pine64/A64_Datasheet_V1.1.pdf

https://github.com/PopcornComputer/PocketPC-Hardware/blob/master/Design/Pocket_PC_Rev2p1_Release_Schematic.pdf