Techniques in electronic systems, such as in systems including a processing chip and one or more external memory chips, provide improvements in one or more of system security, performance, cost, and efficiency. In some embodiments, the processing chip includes immutable hardware that is enabled, without a use of any CPUs, to determine and/or confirm an expected configuration of one or more external memory chips (such as with a Serial Presence Detect operation), and/or to enable communication with the one or more external memory chips. The immutable hardware is further enabled to copy executable code from a non-volatile one of the one or more external memory chips to another of the one or more external memory chips so that a CPU of the processing chip is able to securely boot by fetching initial instructions from the copy of the executable code.