from the manual:
REPLACING THE FACTORY CORE IN SLOT 0
Replacing the core in slot 0 is not recommended, because if it ever gets corrupted, it
will “brick” the machine. This will require you to connect a TE-0790 JTAG programmer,
by opening your MEGA65 case, installing the module, going through some rather con-
voluted software preparation steps (similar to if you were creating your own bistream/-
core) and then restoring a working bitstream into the slot.
The MEGA65 is an open system though, so it’s possible for you to do all of this, but
it’s very hard. There is a secret key-press combination in the Flash Menu that will then
challenge you with a series of questions with increasing difficulty to ensure that you
know what you are doing. Only after you have correctly answered these questions will
you be given the option to erase and/or replace the contents of slot 0. Details of the
questions asked are purposely not documented.
There really should be no reason for using this method to replace the contents of slot
0: If you want to make your own bitstreams/cores, you can either write them to other
slots and use the Flash Menu to activate them, or you can simply use a TE-0790 JTAG
programmer, and then use Vivado or other FPGA development tool to write to the flash
directly. This method is also somewhat faster than flashing through the Flash Menu.
You have been warned!
