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The reset vector is the wrong entry: it starts POST, which re-programs the board window from a state a payload has already changed. The firmware has a second entry, 0x3F5788C0, where the boot gate at 0x3F2042D0 branches when it skips level 1. It begins with DINT, CSR0=STOP on the LANCE, and a board-window re-program -- exactly what a takeover breaks. MAME, from the LANCE access log: the payload's last access and the OS's first are 130 us apart, then pc=3F578940 writes CSR0=0x0004 (STOP) and pc=3FDDCAE0 (the OS driver) re-initialises the chip, after which the OS keeps servicing it. cmd 6 / vtcmd.py osboot. Unit run pending; the report section is 73.