We've been investigating the boot process a bit.
First i dumped the internal boot rom, which turned out to do what we expected it do do, it's just what the manual describes about
the different boot modes. (http://gp32.misantrop.org/BootRom.txt)
The JXD boots up as a SPI slave.
Then Robbo, the mad electronics wizard intercepted the SPI data beeing send to the BF with his scope, and somehow, with black magic
he managed to make a binary out of it which we disassembled. (http://rafb.net/p/y0HqAD46.html)
There we found out that it loads the first block from NAND and appears to execute it.
So, i slapped some code together to dump the first NAND block. (http://rafb.net/p/myMfnw43.html)
This code contains what appears to be code that loads more stuff from NAND, and also some exception handlers.
I'm currently looking into more closely what it loads from NAND, and to where.
—
m