Sparkie, do you ever plan to work on newer ECUs?
I have factory tuned 1UZ VVTi ECU (1997-2000), it's still based on Toshiba 9000 series CPU, which is still mask ROM based, I believe (though I may be wrong here)
The add-on board found in the ECU seems to have the Toshiba processor, two UV EPROM chips (one being removable) and a FPGA
There's also a jumper which enables the CPU to run off ints internal memory
I dumped both memories just incase
The removable one is connected to FPGA and it seems to have maps only
The fixed one's content looks more like some code