As so happens, an article in the "popular press" totally misses the point.
This is about the "Megaprocessor" - a CPU built entirely from discrete components. It's an amazing project, superbly executed, and submitted/discussed here on HN many times.
You can see some of the previous submissions by using this search:
Recent submissions haven't had much discussion, but it deserves it. The testing and verification processes alone are fascinating - just how do you test something like this?
My thoughts exactly. This guy built an entire computer, complete with CPU, ALU, memory, storage, etc from transistors, and the article just says it plays Tetris? Sure, it was going to run some program, but that's missing the point.
Many people build computers of varying complexities, but they usually use IC-s from the 4000 and 7400 series. These IC-s are mostly simple things, like NAND gates, adders and such (there are some complex ones). Making discrete equivalents of those IC-s is rather easy, especially with modern high speed low capacitance FET-s.
I am impressed by this computer because it is verbose and thus educational.
Building a complete computer the size of a room isn't easy at all, because the connections between the elements have to be active transmission lines, and Vcc and GND still have to be clean enough to avoid spurious switching.
There's a whole order of magnitude of extra design pain involved in building something that big, including LEDS in all the elements, and making it run fast enough not to be completely useless.
Most used, and thus cheapest, transistor BC 639 is 100MHz (or 50MHz, i had a beer). Cheapest MOSFET is much faster then that. The Megaprocesor is 20kHz and the creator clearly states that it is for educational purposes.
While on that topic; i will read the docs and watch the videos for educational purposes. ;)
It's as impressive as someone building a dune buggy by welding axles onto steel tubes and making their own engine and transmission mounts. Quite a feat of engineering, but not really pushing the bounds of known science. And with limited utility.
It's more like building that dune buggy, including the engine, entirely out of glass. It's not very useful for driving, but you can see exactly how everything works.
As so happens, an article in the "popular press" totally misses the point.
As it happens I know Zoe (who wrote this) very well and would be happy to pass on constructive suggestions on what folks would like to see in this article (and other tech. articles from the BBC).
I would have appreciated a greater emphasis about the fact that a modern computer is made out of invisible transistors and that this is a fully discrete but working model, like a large cutaway steam engine in a science museum. Here, I'll take a wild stab:
"You may have heard that computer processors consist of billions of transistors crunching through 0's and 1's. But what is actually happening inside these processors?
A man has recently build a computer out of individual transistors, the components that control electric currents to perform computations. Instead of using one chip with billions of transistors, he has used individual transistors wired together, allowing him to visualize the individual computing structures and the electric currents that flow through them.
His completed computer has "only" 40,000 transistors, which is just enough to play a game of Tetris, but he hopes that the relative simplicity of this computer, as compared to a modern smartphone, can help educate the public on how computers actually work."
"You may have heard that computer processors consist of billions of transistors crunching through 0's and 1's. You've never seen them, but with this room-sized processor, you can."
I'd be surprised if Zoe picked her title, but that's a big point:
> Huge home-built computer used for Tetris
This makes it seem like the guy just wanted to play Tetris and took an extremely roundabout way to do it, where in fact he built the thing specifically to show the insane complexity we all carry around in our pockets and take for granted (I include myself in that statement 100%). Modern computers are nothing short of an engineering marvel and something like this, which is only a millionth as powerful and not capable of nearly as much built from scratch takes up an entire room.
It reminds me a lot of that photo from not terribly long ago showing an Air Force crew unloading a 50 MB hard drive that was roughly the size of a walk in freezer.
A good comparison would be someone who built their own aircraft to demonstrate how insanely complex an aircraft is, and then the news story about it says "Local Man Builds own Plane to jump down to Florida for a Burger."
She did good by not using the word "boffin". I cringe every time I read a tech article by the British press when they casually roll out such snide commentary. It's one the same scale of disrespect as "egghead" or "mad scientist". She needs to get the message out to her colleagues to start doing the same.
I've actually had this idea for a while now of creating snap-together redstone-like (from minecraft) cubes. Each would generate a signal, unless it's receiving a signal from a neighbor, making each one a NOT gate. You wouldn't literally build it with a transistor per block, they could have some fairly complicated logic inside with led's showing where the signal is going and so forth. You'd set each side to be input or output with a switch, and you could have different types of blocks (light or sound detectors, for example), or ones with usb ports for power/output, etc.
I went to James' home to see the Megaprocessor a year ago, when he thought there was only a few months more work to do.
It really is amazing to see the thing up close. Especially when you look at the sheer number of transistors that had to be soldered to make this.
My favourite part was when James said that he's started off by just wanting a better understanding of how logic gates worked, and it just escalated from there.
"My favourite part was when James said that he's started off by just wanting a better understanding of how logic gates worked, and it just escalated from there."
That's hilarious. Maybe a common thing. My posts on analog computing, esp neural or general-purpose, started similarly. I noticed analog and digital cell development used similar tools. Also that they used to build computers that way. The rabbit hole followed.
The Megaprocessor uses through hole components. Something similar using surface mount components could be substantially cheaper, mostly because it could be smaller. This means it will need less of all the expensive supporting parts. The components themselves are only a small part of the cost.
"How big would a modern CPU be at this scale?
The Apple A8X, found in the iPad Air 2, contains about 3 billion transistors. (This is comparable to the number of transistors in modern desktop computer CPUs as well.) At the scale of the MOnSter 6502, that would take about 885,000 square feet (82000 square meters) — an area about 940 ft (286 m) square."
People feel the need to rationalize with some vague "educate the public" business but its really a piece of performance art by people skilled in the EE and CS arts. So in that way you're telling the artist to use a different medium and that usually holds roughly zero interest for the artist. If the artist wanted to perform "Dueling Banjos" on xylophones that would be cool and they surely could have done so, but they didn't want to.
A good programming analogy is people confusing the purpose of a programming Koan collection and helpfully suggesting the participant should google the answers. Or even worse than programming Koans, ditto but for meditation Koans. The point of the experience is to do it your way, by yourself...
Personally I'd like to play with RTL gate logic using modern transistors "in my infinite spare time". There's a certain alternative history component aspect. Imagine if instead of leaky, low beta, low Ft, low breakdown voltage germanium transistors, RTL was implemented with top of the line 2010s discretes. Yeah yeah I know RTL begat DTL begat TTL using contemporary technology, but in alternate history world, how would life have changed?
Exactly. They can be installed on a FPGA. Plus, slow as old systems are, one might even be able to build connections to them into individual, logic gates or virtual transistors. Speed difference between FPGA and older hardware might cover performance losses.
And you still get blinkenlights per gate or transistor in emulated design.
There is an active home brew computer / cpu scene that demonstrates how to accomplish this cheaply. No need to spend anywhere near what this megaprocessor costs
This is about the "Megaprocessor" - a CPU built entirely from discrete components. It's an amazing project, superbly executed, and submitted/discussed here on HN many times.
You can see some of the previous submissions by using this search:
https://hn.algolia.com/?query=megaprocessor&sort=byDate&date...
Recent submissions haven't had much discussion, but it deserves it. The testing and verification processes alone are fascinating - just how do you test something like this?
Amazing project.