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> The idea of implementing a CPU core inside an FPGA is not new, of course. Indeed. I took a computer engineering class in undergrad. The capstone project was

> The idea of implementing a CPU core inside an FPGA is not new, of course. Indeed. I took a computer engineering class in undergrad. The capstone project was implementing from scratch a multi-pipeline RISC CPU (including the ALU and a very basic L1 cache) in Verilog that we flashed to FPGAs that we then programmed to play checkers using hand-compiled C. The FPGA was easier to flash and debug than the Spartan-6 mentioned in TFA but was significantly more expensive as well. It was a brutal class, but it totally demystified computers and the whole industry in a way that made me feel like I really could understand the "whole" stack. Nothing scares me any more, and I no longer fear "magic" in software or hardware.

erosenbe0 5y ago
Awesome Base to start with! Lot of things in the next step though: PCIE, JTAG, differential signaling protocols, debuggers/monitors, UEFI firmware, cache coherency, TPM type modules, linkers, loaders, vector instruction sets, sound codecs, DACs, GPUs, multi channel SDRAM, MMUs, display protocols, device trees. Plus latency, throughout, and thermal management in any of the above in a real system.
adamgordonbell 5y ago
Wow, that sounds like an amazing experience. Challenging though I bet.
mayli 5y ago
full stack engineer vs "whole" stack engineer.
- tomxor 5y ago
  There's also adjacent stacks... like being able to build your own computer out of crabs and rocks if you get stranded on a desert island. So that you can get them to write SOS in the sand and play pong while you wait.
  - ultimape 5y ago
    Unconventional computing platforms FTW. https://phys.org/news/2012-04-scientists-crab-powered.html https://phys.org/news/2012-04-scientists-crab-powered.html
plandis 5y ago
> Nothing scares me any more, and I no longer fear "magic" in software or hardware. You sound exactly like my professor for computer architecture. “Computers are not magic!” He mentioned this at least once during every lecture and my experience was similar to yours
- FPGAhacker 5y ago
  It really depends on how many steps down the ladder of abstraction you go. Computers are still magic if you step down a few more rungs.
  - tuatoru 5y ago
    At the third to bottom rung, all electronics are analog.
  - picture 5y ago
    Down to the physics of FETs and the underlying chemistry? How much further doe it go?
    - Cyph0n 5y ago
      Quantum effects, particle physics, and then the unknown (for now).
      - Dylan16807 5y ago
        I'd say the field effects on electrical flow are probably the weirdest part to look at, and they don't reach 'magic' levels. The atoms below that are relatively straightforward, and them being made up of building blocks is fine I guess, increasingly irrelevant to the issue of a computer. And going up everything starts to get very non-magical as you turn response curves into binary signals and then string gates together.
        ngcc_hk 5y ago
        Qm is still magical as you sort of use it but do not really understand it. It is so weird. And that is magically part. Btw I read your below word as above.
jwineinger 5y ago
I had a similar course, using VHDL going on to Spartan-3E kits (which I still have sitting in a box 14 years later). Our professor gave us three C programs -- with the input that would be entered and expected output -- and we had to implement everything to make it work: CPU, VGA output (with "font" definition), keyboard input, and translation of the C programs to our CPU's instruction set. That was a difficult yet extremely rewarding class. My wife, then girlfriend, still remembers that semester because she barely saw me. IIRC, bonus points were given to the team with the highest clock speed. I didn't win, but I seem to remember mine being somewhere in the 18MHz range and the winner in the low to mid 20s.
moritonal 5y ago
Yep, not nearly as hardcore, but writing a TCP stack changed how I saw the Internet.
vvanders 5y ago
As someone who started pretty high up the stack(Visual Basic!) and kept peeling layers away out of curiosity I will say working with a CPLD/FPGA was really eye-opening. Latency difference between SRAM/DRAM and the "why" in pipelining made a bunch of disjointed approaches to optimization just drop into place.
- necovek 5y ago
  Nostalgia is high with this one :D I've started with gwbasic, then QBasic and moved up to "Visual Basic for DOS" (ncurses-style UI stuff, similar to Turbo Pascal iirc — I don't think many people even knew it existed since Win 3.11 was already big, but I loathed it and only switched to it because of... Trumpet Winsock for the internet!), but that did not stop me from playing with driving serial (COM) ports or parallel ports (LPT) with printer escape sequences. Not really FPGA level low (not even close), but DOS-based stuff was really easy to start hacking up!
garfieldnate 5y ago
Are there any resources online that would let me do a similarly deep study myself? I'm enjoying the famous "Nand to Tetris" course, but it uses a simplified architecture (no pipelining, no cache, no interrupts) and runs in an emulator instead of an FPGA.

erosenbe0 5y ago

Awesome Base to start with! Lot of things in the next step though: PCIE, JTAG, differential signaling protocols, debuggers/monitors, UEFI firmware, cache coherency, TPM type modules, linkers, loaders, vector instruction sets, sound codecs, DACs, GPUs, multi channel SDRAM, MMUs, display protocols, device trees. Plus latency, throughout, and thermal management in any of the above in a real system.

adamgordonbell 5y ago

Wow, that sounds like an amazing experience. Challenging though I bet.

mayli 5y ago

full stack engineer vs "whole" stack engineer.

tomxor 5y ago
There's also adjacent stacks... like being able to build your own computer out of crabs and rocks if you get stranded on a desert island. So that you can get them to write SOS in the sand and play pong while you wait.
- ultimape 5y ago
  Unconventional computing platforms FTW. https://phys.org/news/2012-04-scientists-crab-powered.html https://phys.org/news/2012-04-scientists-crab-powered.html

plandis 5y ago

> Nothing scares me any more, and I no longer fear "magic" in software or hardware. You sound exactly like my professor for computer architecture. “Computers are not magic!” He mentioned this at least once during every lecture and my experience was similar to yours

FPGAhacker 5y ago
It really depends on how many steps down the ladder of abstraction you go. Computers are still magic if you step down a few more rungs.
- tuatoru 5y ago
  At the third to bottom rung, all electronics are analog.
- picture 5y ago
  Down to the physics of FETs and the underlying chemistry? How much further doe it go?
  - Cyph0n 5y ago
    Quantum effects, particle physics, and then the unknown (for now).
    - Dylan16807 5y ago
      I'd say the field effects on electrical flow are probably the weirdest part to look at, and they don't reach 'magic' levels. The atoms below that are relatively straightforward, and them being made up of building blocks is fine I guess, increasingly irrelevant to the issue of a computer. And going up everything starts to get very non-magical as you turn response curves into binary signals and then string gates together.
      - ngcc_hk 5y ago
        Qm is still magical as you sort of use it but do not really understand it. It is so weird. And that is magically part. Btw I read your below word as above.

jwineinger 5y ago

I had a similar course, using VHDL going on to Spartan-3E kits (which I still have sitting in a box 14 years later). Our professor gave us three C programs -- with the input that would be entered and expected output -- and we had to implement everything to make it work: CPU, VGA output (with "font" definition), keyboard input, and translation of the C programs to our CPU's instruction set. That was a difficult yet extremely rewarding class. My wife, then girlfriend, still remembers that semester because she barely saw me. IIRC, bonus points were given to the team with the highest clock speed. I didn't win, but I seem to remember mine being somewhere in the 18MHz range and the winner in the low to mid 20s.

moritonal 5y ago

Yep, not nearly as hardcore, but writing a TCP stack changed how I saw the Internet.

vvanders 5y ago

As someone who started pretty high up the stack(Visual Basic!) and kept peeling layers away out of curiosity I will say working with a CPLD/FPGA was really eye-opening. Latency difference between SRAM/DRAM and the "why" in pipelining made a bunch of disjointed approaches to optimization just drop into place.

necovek 5y ago
Nostalgia is high with this one :D I've started with gwbasic, then QBasic and moved up to "Visual Basic for DOS" (ncurses-style UI stuff, similar to Turbo Pascal iirc — I don't think many people even knew it existed since Win 3.11 was already big, but I loathed it and only switched to it because of... Trumpet Winsock for the internet!), but that did not stop me from playing with driving serial (COM) ports or parallel ports (LPT) with printer escape sequences. Not really FPGA level low (not even close), but DOS-based stuff was really easy to start hacking up!

garfieldnate 5y ago

Are there any resources online that would let me do a similarly deep study myself? I'm enjoying the famous "Nand to Tetris" course, but it uses a simplified architecture (no pipelining, no cache, no interrupts) and runs in an emulator instead of an FPGA.