Magic isn't real

https://pthorpe92.dev/programming/magic/

by dvektor • 2 years ago

88 73 2 years ago

wruza4• 2 years ago

One interesting thing of (accidentally) starting with assembly is that you mostly can’t see magic at all, but instead you see learning magicians explaining computers in all sorts of funny ways.

My first “pc” was a clone of zx spectrum and all I had was a built-in BASIC and then some assembler on a cassette. Both went with “books” on how to use them, together with all of the unlimited time you have when you’re a kid.

This transferred to my first PC and eventually I learned how FAT, DOS, BIOS work, how to make a TSR and fool around B8000/A0000, first steps with 386+. It also helped that my granddad was an impulse electronics engineer and taught me how actual gates work and how computers count, sum and select numbers. He also had access to multiple books on hardware. I knew it all down to the silicon.

Other people had all sorts of magical ideas on how computers work. Special “hidden system areas”, “graphics card does X”, “computers multiply by addition”, etc etc. It’s a human thing that if we don’t understand something, our mind tries to yadda yadda it.

And the more you yadda yadda, the less chances it leaves that you’ll actually learn it. I tend to fight with these half-baked autogenerated explanations and try to dig down to how it really works. For no particular reason, that’s just what I like to do. It leaves a mark on how you work though.

Nevermark4• 2 years ago

yadda yadda

Like LLMs, we confabulate. We fill in knowledge holes, with imagined knowledge we don't really have.

jeffparsons• 2 years ago

Like LLMs, we confabulate.

Thank you for describing LLM behaviour that way. It's a much better description than the more popular but less apt "hallucination".

marcosdumay• 2 years ago

What the GP is explaining is actually the other way around. It's our brain leaving holes even though they are just explained on the text.

And yeah ML models do that too.

jl6• 2 years ago

Special “hidden system areas”

I guess "hidden" can be a matter of perspective, from filenames beginning with a period, right through to things like the Intel Management Engine.

vonunov2• 2 years ago

This (roughly) came up in a chat just yesterday. Someone posted a screenshot of a web browser using a font face with no glyphs or something, or I assume this is what causes this display of the codepoints(1). Reminded me of the kind of amateur magic lessons I see regularly:

So, people on the internet who feel like they are some kind of computer wizards will try to school each other online about how computers work. They will go on, like, Quora and ask weird questions like "what is one programming language every real hacker should know?" And someone will come along and write an incredibly definitive-sounding and confident essay about how a real hacker has to know the language of binary, because everything that's happening in a computer is all just binary, 1s and 0s. They heavily imply (at the least) that a real hacker regularly peruses binary values. Not like how you might use a hex editor. Rather, as if wannabe hackers read source, but real hackers read the raw binary. Some kind of M-x Butterfly shit. Assembly language is rarely mentioned.

I don't blame them for it, it's just kind of funny. I can kind of imagine that the way low-level things are glossed over for the sake of explaining high-level things has reasonably left some people with the impression that binary is somehow expressive and that people who truly know computers are fluent in it. And I probably had stranger conceptions than that on my own journey.

Anyway, this screenshot is what they must imagine a turbohacker's computer looks like all the time

1. https://i.vgy.me/qNU6J5.jpg

wruza4• 2 years ago

Ah, this is the reason I avoid internet squares and chats filled with those who started but didn’t go deep. I just cringe to almost fainting everytime I read something there and my ears burn. Programmer’s humor sections are especially triggering. Surprisingly, HN is not that programmy at all (there’s lots of tech but no code nor “hacker secrets”), so it’s relatively nice to be in.

shermantanktop• 2 years ago

So many frameworks and dev-oriented features are sold with the claim that domain X is super complicated and full of esoteric useless trivia, so instead someone has put a clean facade on that which simplifies everything and protects the hapless dev from having to learn. Which is nice, it’s a tidy abstraction, we all have other things to do, now we go fast.

Except…the dev has to learn the new API, which we can call domain Y, and which can become quite complicated and hard to map conceptually to domain X (e.g. React events vs browser rendering, or Java GC vs real memory).

And when the cool facade doesn’t quite work for some exotic use case, now what? The dev gets to learn the original domain X anyway, plus how X and Y interact. In the worst case they have rewrite all their Y-using code.

Great abstractions are good magic; bad abstractions are evil magic. And yet good vs evil is often hard to tell apart when you pick up the problem.

dartos2• 2 years ago

The only areas I’ve ever seen that were truly super complicated were when synchronization is involved.

It’s so hard to wrap my head around how a CPU reorders instructions and I need to think very slowly and very carefully whenever I work with synchronization.

Same with distributed systems. I implemented a toy version of raft forever ago, but just wrapping my head around it took a month, and I still think I don’t really grasp it.

Haven’t even looked into paxos yet.

xxs• 2 years ago

Sync is easy. Concurrency is hard. Partly b/c as humans we can't multitask.

CPU reordering instructions (and speculative execution) should be not be hard to understand. It tries to do as much work as it could before it has to stall due to lack of data

mst• 2 years ago

Corollary: Sufficiently well encapsulated magic is indistinguishable from technology.

zavec• 2 years ago

Now I kind of want to read a story where it turns out the technology we use in our modern lives is actually very carefully hidden magic. Sort of like the opposite of (rot13 for book spoilers) gur fgrrefjbzna frevrf.

anymouse123456• 2 years ago

TFW the real wizards are the ones working in the strata just below the one I understand...

After nearly 30 years of persistent excavation, I'm finally at bedrock with registers, some assembly and embedded C.

Lifting my head up to find the mess we've created for graphical application development is admittedly disheartening, but also thrilling as there are ways to make it better.

noelwelsh• 2 years ago

There is at least one more layer, which lies behind the abstraction boundary the ISA presents. E.g. x86-64 specifies only 16 general purpose registers, but the Zen 4 has 224. Even as far back as Pentium II the CPU had more registers than the ISA.

josh-sematic• 2 years ago

You’re not even close to hitting rock bottom on explanations of the layers below until you find yourself comparing proposed theories of quantum gravity :-)

niemandhier• 2 years ago

Going the other direction, towards higher levels of abstraction tends to strip away the magic too!

I recently write some robotics code using ROS, taking a step back I looked a the result and thought: Actually that is not much different conceptually from running K8s deployments coupled by Kafka.

tehmillhouse2• 2 years ago

When understanding a new "magic", there's this beautiful moment when you grok it, and the abstraction poofs away.

It's when you take apart a mechanical clock and keep looking for the time-keeping part, until you figure out that there isn't a time-keeping part in there, it's just gears and a spring.

It's when you learn about integrated circuits and full-adders, and keep trying to understand how a bunch of transistors can do Mathematics, until you figure out that there isn't a mathematics-doing part in there, it's just circuits and wires, arranged in a way that makes the voltages come out right.

It's when your understanding of the top-down structure snaps together with the bottom-up mechanics of the building blocks. There's no space left for the ghost in the machine to haunt, and you go "Oh. huh". I live for that moment.

Lerc• 2 years ago

That's the difference between technology magic and illusionist magic, When you see how the trick is done with illusions it's always a bit of a letdown because the answer is usually prosaic, the 'magic' vanishes and it becomes a trick.

When you understand how a piece of technology works you get that beautiful moment.

tialaramex3• 2 years ago

I've never got that. I feel the same way in either case, if your trick was easy everybody would do it. Sleight of hand tricks for example, if you're good they're completely seamless, I could never hope to reproduce and yet I know exactly how it's done.

Take that Penn & Teller trick where the live audience is just lying - that's a bit lazy, we're not supposed to have some great admiration for this trick they're just showing you it's an option to just have the live audience lie to the recorded audience and that "works". Whereas their transparent version of cups and balls is the opposite, you must be a sleight of hand master or this won't look like anything.

quesera• 2 years ago

I was certain that you were going to conclude with a paragraph about LLMs.

tehmillhouse2• 2 years ago

I was this close to concluding with a paragraph about Buddhism and the Self. Which is basically the same thing, but from the first-person perspective.

Joker_vD2• 2 years ago

I've recently done reading "Digital Design and Computer Architecture" by Harris and Harris, and the part about microarchitecture had this exact impression on me: "oh, so we just demux the opcode, enable/disable the necessary signals/paths and it all... just works out in the end, if the clock is fine. Huh. Well, in retrospect it's kinda obvious."

asimovfan• 2 years ago

“The true delight is in the finding out rather than in the knowing.” ― Isaac Asimov

dvektor2• 2 years ago

Keeping true to your username :)

Man I'm not going to lie tho... I just could not make it through the foundation series

hiAndrewQuinn3• 2 years ago

I went through an EE degree instead of a CS degree in undergrad specifically so I could peel back this magic and really understand what's going on, to some detail, down to the electromagnetism level. It is indeed a very freeing feeling to be resting atop so many layers of abstractions, with the understanding that if you ever had to, you could go down to any one of them and kind of feel your way around.

I think for me the biggest magic-killing moment was when I realized that CPU clock cycles, timing trees, etc. were all just ways for us to shoehorn a fundamentally analog thing (how much voltage is in area X?) to a digital thing (does area X have enough voltage? yes? OK, call it a 1 and let's move on already!). Somehow to me that feels like the ultimate "leaky" abstraction, although of course decades and trillions of dollars have gone into making it ever more watertight for 99.99-several-more-9s% of the time. At least to the end user. Your mileage may vary if you're a TSMC researcher or something, of course.

pclmulqdq• 2 years ago

I work with FPGAs and embedded systems occasionally, and you have no idea how amazingly watertight the phone/desktop/server CPU abstraction is in comparison to what you get the moment you do something slightly weird. A combination of the chips, the firmware, and the OS does so much work to give you the abstraction of "machine runs code and it just works."

bena• 2 years ago

I've always felt the whole binary/digital thing was one of the most clever bits of compromise with the real world I've ever seen.

You have this thing, you want to be able to translate its value into something useful. In this case, the amount of voltage in a circuit to a number. And you spend so much time trying to make sure the voltage level passed is rock solid, that your read is equally solid, etc. Until you realize that you'd have to invent so many more industries just to do this one thing that you just give up and say the only thing you can know with certainty is that there is or is not voltage passing through the circuit.

Then you need to be able to translate "ON" and "OFF" into actual usable values. And eventually coming down to a base 2 counting system so that 4 circuits gives you 16 distinct values seems obvious in hindsight, but had to be a revelation when they realized it.

fragmede• 2 years ago

for me, it was latches and creating a CPU which instructions could be fed into. but it wasn't a "lost the magic" feeling, it was a "that's amazing!" feeling.

AnimalMuppet• 2 years ago

It's when you take apart a mechanical clock and keep looking for the time-keeping part, until you figure out that there isn't a time-keeping part in there, it's just gears and a spring.

The time-keeping part is arranging gears and a spring in a way that will, in fact, keep time.

It's when you learn about integrated circuits and full-adders, and keep trying to understand how a bunch of transistors can do Mathematics, until you figure out that there isn't a mathematics-doing part in there, it's just circuits and wires, arranged in a way that makes the voltages come out right.

The mathematics-doing part in there is the arrangement of circuits and wires in ways that can actually do arithmetical operations on voltages.

It's not magic. But an adder, while never more than a bunch of circuits and wires, is still a mathematics-doing part.

harperlee• 2 years ago

Well to be pedantic: the time-keeping part isn’t the gears but a pendulum.

The spring gives energy to the pendulum, but that can’t effect more than in its amplitude: the period of a given pendulum is constant. Later springs demultiply the tick tack of the pendulum into desired units.

The heart of the clock is that choke on energy though a period.

Thats also why the famous phrase: clocks dont measure time but other clocks.

(Please dont mind the grammar: writing on mobile)

GrantMoyer• 2 years ago

Sufficiently understood magic is by definition technology.

nuancebydefault• 2 years ago

You will indeed find the _magic_ to be no such thing when you dig deep down in the abstactions. Each part makes sense and is comprehensible.

However the magic is what emerges when the parts come together, the system becomes more than the sum of its parts.

Think of a car or a cellphone, an llm, it feels magical what it does, while the elementary parts do not consist of magic.

Joker_vD2• 2 years ago

On the topic of how that implementation comptime in Go works: I've toyed with a similar idea for implementing constant folding/beta reduction — generate a temporary file with the relevant subset of definitions, insert the constant expression/function call you'd like to evaluate and... compile and run this file. It may not be the most performant thing to do but at least you get the correct semantics without writing a separate constexpr interpreter.

zaphar• 2 years ago

Magic isn't real. But unnecessary magic can be annoying and sometimes doesn't pull it's weight.

dvektor2• 2 years ago

Indeed. If it magically works, it can magically break.

bananaflag• 2 years ago

The only two examples of real "magic" I've encountered (would be interested in more):

1) You cannot do preemptive multitasking except by having a timer interrupt (okay, maybe one can also allow emulation).

2) Quantum key distribution (starting with BB84) depends crucially on the fact that the world is not classical.

But in general I agree with the article, it's more or less why I did not become a programmer.

mistercow2• 2 years ago

Sometimes a remnant of the magic remains in the math, though, even after you understand why the math must work. The Burrows-Wheeler transform used in bzip2 is an example of this for me. I get why it works, but it just feels too damned convenient, almost as if this is one of the universe’s APIs, and you don’t get to look into the source code of this one to find out why such a simple maneuver is so effective on exactly the sort of data we like to compress.

criddell• 2 years ago

I've always thought the Diffie-Hellman key exchange is pretty neat.

mistercow2• 2 years ago

My own mental picture of that makes it just feel very clever, rather than magical. If you imagine that addition is easy, but division is hard, it’s pretty easy to see how you can build fast integer multiplication out of addition, and create hard to reverse operations like key exchange.

Now replace “addition” with modular multiplication, and “division” with the logarithm, and you have the trick behind DH. Swap out addition for this weird operation that involves jumping around elliptic curves, and you have the trick behind ECDH (admittedly, the fact that that jumping around thing works as a group operation is still pretty magical).

What I like about this way of thinking about it is that you can fully implement the key exchange in terms of integer addition, and the fact that it lets you pass around secrets in a world without “division oracles” seems pretty mundane.

abdellah123• 2 years ago

Birds aren't real

highfrequency• 2 years ago

I’m sure I’m not alone, in that each time you pull the curtain off a piece of ‘magic’, you have the same thought: Oooooh yeah. I mean, well duh.. how else would you do that? I can't believe I couldn't see it.

This is the great paradox of good ideas. The best ideas are obvious, but only in retrospect. You would be very unlikely to encounter the idea by randomly fumbling around, yet it feels so simple and obvious (and often even easy to implement!) after someone else points it out and you mull it over. Usually it requires looking in a different dimension than the one you were focused on rather than looking further along familiar dimensions, which is our default behavior.

In this way there’s a parallel to modern machine learning, where backprop on gigantic models allows us to find very short paths in very high dimensions, rather than finding very long circuitous paths in low dimensions. It turns out this also solves the overfitting problem, in the same way that “retrospectively obvious” is a good filter for ideas.

tayloramurphy• 2 years ago

Charles Petzold's book "Code" was the book that revealed the magic behind computers for me. While I don't fully understand everything that happens with a computer, there's a confidence that I could if I needed to. It made tough problems feel solvable in a way I hadn't felt in other disciplines.

dvh• 2 years ago

In recent video about reverse game of life Alpha Phoenix hinted that sat solvers are magic: https://youtu.be/g8pjrVbdafY

gradientsrneat• 2 years ago

One of the cool things about being a kid is I didn't know how tf anything works. So I thought long and hard about how things work and just randomly guessing. When it turns out later there's a clear answer, it's very satisfying. But knowledge can also weigh down and discourage curiosity.

metalman• 2 years ago

interesting how a click bait title works just like magic and even more so gets people debating a so so premise in mystical terms

Magic isn't real

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