Domipheus, a hardware hobbyist, writes about designing CPUs in VHDL, FPGA projects, a Z80 on Teensy, and Raspberry Pi hardware.
HN commenters recommend his VHDL CPU design series as amazing, and link his post showing PCI Express working on the Raspberry Pi 4.
Alas, this is a surprisingly hard question to answer, at least for FPGA design.
Here are a few sites that helped me learn:
* https://www.fpga4fun.com
* http://fpgacpu.ca
* https://www.nandland.com/verilog/tutorials/index.html
* https://1bitsquared.com/pages/chat (Discord)
And a few interesting blogs:
* https://blackmesalabs.wordpress.com/
* https://tomverbeure.github.io
* http://labs.domipheus.com/blog/
None of the introductory FPGA books have impressed me, so I don’t have any recommendations there. Maybe some other HN readers will have some suggestions?
Would anyone familiar with the various qualities of FPGA boards care to weigh in on how to pick a good development board for this project? I personally know nothing about FPGA specs.
Additionally, the first blog post in this series can be found at http://labs.domipheus.com/blog/designing-a-cpu-in-vhdl-part-1-rationale-tools-method/
Some guy started a series some weeks ago on designing a CPU for an FPGA:
http://labs.domipheus.com/blog/designing-a-cpu-in-vhdl-part-1-rationale-tools-method/
For those interested in a more complex processor, RISC-V seems to be a processor on par with ARM in terms of features: http://riscv.org/
There's at least one reported case of a PCIe multiplier card working with the Pi4: http://labs.domipheus.com/blog/raspberry-pi-4-pci-express-it-actually-works-usb-sata-gpu/
This series is also amazing:
http://labs.domipheus.com/blog/designing-a-cpu-in-vhdl-part-1-rationale-tools-method/
In the end he switches to RISC-V as well
And here’s the link without the twitter wrapping: http://labs.domipheus.com/blog/raspberry-pi-4-pci-express-it-actually-works-usb-sata-gpu/