The Zynq's HP ports: FPGA logic reaching the ARM's memory
How a core in the PYNQ-Z2's programmable logic uses the processor side's DDR3, with no operating system: the HP ports, and setting up the DDR controller over JTAG.
Notes
How retro-silicon’s cores and boards work underneath: the plumbing between the systems and the chips they run on, explained as it’s built.