Hi all.
I spent some time on reversing the mc9620.
I have almost found the jtag interface (I say almost because it is not
reliable, and I cannot use it to stop and debug the processor)
Nevertheless, I managed to dump the firmware of the tetrapol 55522d
chipset, an Atmel arm7tdmi that share some design with old at91 chips
I found some stuff (message queue, state machine, gui).
But what is important and that I would like to share with you is that I
found some info on how it interfaces to the Texas C54 dsp, and that I
was able to extract the dsp firmware, where surely all the undocumented
things happen (voice and encryption).
I am know focusing on reversing the dsp firmware (not an easy task).
If anybody is interested in helping, don't hesitate !
Best
