| ARM9's exception vectors are hardcoded to point at ARM9 RAM. While the bootrom does set them up to point to itself at some point during boot, it does not do so immediately. As such, a carefully-timed fault injection to induce an invalid instruction will cause execution to fall into ARM9 RAM.
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Since RAM isn't cleared on boot, one can immediately start execution of their own code here to dump bootrom, OTP, etc.