6 ms·

I’m a bit puzzled by the recurring apparition of articles about learning faster on HN. I don’t think I have suffered from the speed at which material covers a

I’m a bit puzzled by the recurring apparition of articles about learning faster on HN. I don’t think I have suffered from the speed at which material covers a subject since I left school. Finding interesting material, properly structured with a good balance of introductory and in depth coverage and giving solid insight into a topic remains challenging — it already was when I was a student to be fair. Good teaching ressources are the exception rather than the norm. Finding the time to properly conceptualise and deeply think about what I’m trying to learn has been challenging. But the speed at which I can consume teaching material is not something I remember being bothered by this past decade. Thinking about it more often than not I wish I could actually go slower rather than faster. I’m curious about how the experience of others commenters differ here as it’s obviously a topic of interest to some in this community.

ramraj07 5y ago
After some level of learning the eloquence of the author (barring some minimum standards) is probably not as material, it’s more about the content itself. Talking about graduate level courses, presumably ones not too math heavy, I can see this working. Or for lectures and seminars on research by professors (though one rarely is trying to remember every detail).
kristaps 5y ago
Right up there with other techie superstitions such as "editor x makes me a better programmer, because typing faster".
- strken 5y ago
  When I read this I immediately thought "typing faster makes me a less annoyed programmer, and better would be a happy accident", then realised it was the same for speeding up or pausing audio. Having control over the speed at which ideas are launched at me is more about not getting distracted or frustrated than learning faster.
  - aspaceman 5y ago
    Patience is as much a skill as any other though. I don't quite understand this hyperoptimization. I'll speed up things I find a little dull or advertisements, but increasing the pace of everyone's speech for your sake seems....odd?
    - lalopalota 5y ago
      They are discussing speeding up the pace of the speech in videos they watch for their own sake. Nothing odd about that.
konschubert 5y ago
When I studied Physics as an undergraduate, I would regularly spend 3 hours just to really understand the content of the notes I had taken in a 1.5 hour lecture. The speed of consuming the content was never the limiting factor. When I listen to an interesting podcast, I often pause the track to think about implications of what was just said or to formulate a rebuttal in my head. I guess there are different kinds of learning and different levels of understanding something.
- dotancohen 5y ago
  With three or four two-hour lectures every day, multiplying the studying time by 3 would leave at most six hours for eating, sleeping, and maintenance such as buying food and bathing. Never mind working. I doubt that many university students could do that.
  - konschubert 5y ago
    There were only one or two lectures like this a day. The rest were labs and exercises. And only Mon-Fri. But you’re right, this still comes out to 30 hours of lecture review a week, which seems a bit more than I remember. 20 seems more realistic. I guess the average was less than 3 hours per lecture.
    - nottorp 5y ago
      You probably remember the ones that did take 3 hours to understand but you’ve forgotten all those that were simple enough that you already left the lecture hall with an understanding of the material.
      - konschubert 5y ago
        I know for sure that I had to go through every one of them in the first couple of semesters. :) But you are right in that there is a bias in how I remember it: Not all of them took 3 hours.
dlisboa 5y ago
It's mostly about efficiency. If you want to watch a 4 minute video and the first 2 minutes were ads, wouldn't you skip it? Same principle: people talk slower than necessary in many of these videos, or make unnecessary edits that slow it down content-wise. I think this search for faster learning is fueled by the realization that we only have so many lines of text, or minutes of video or audio content, that we can consume in life. I don't want to waste that on ads or someone's idea of a fancy video transition. It's the reason why I don't like podcasts or radio programs: too much of it is spent on introductions or random subjects. I have other shit to do, so if I can maximize the retention in a shorter timespan, that's much better. There's an ever-present desire to learn more, and the more you learn the more new topics you find out about. Personally I am a bit bothered. I bought a bunch of books over the years and recently I've realized maybe I won't be able to go through all of them at my current speed. So I'm trying to learn how to read faster (with retention) and be more methodical about it. For things you need to go in depth the learning is necessarily slow: a college course, a textbook, years of experience. But if I want to learn something small that has less relevance to my life, I don't want to waste that time.
jasode 5y ago
>I don’t think I have suffered from the speed at which material covers a subject since I left school. [...] Thinking about it more often than not I wish I could actually go slower rather than faster. I’m curious about how the experience of others commenters differ here For many listeners, they suffer from speakers talking too slowly which causes them to tune out and become disengaged. This handicaps learning instead of enhances it. A lot of people can read text at ~200 to 300 wpm. Since many speakers talk at ~100 wpm, accelerating videos to 2x or more just gets the audio in the same ~200 wpm range.
- TheFreim 5y ago
  > For many listeners, they suffer from speakers talking too slowly which causes them to tune out and become disengaged. This handicaps learning instead of enhances it. When I was in school last year I really loved online, pre-recorded, lectures for this reason. I could put speed on 1.5x or even 2x speed. If I missed something I'd tap my left arrow to go back a few seconds or write the time stamp down and come back later. Slow speaking videos drive me crazy.
- NikolaNovak 5y ago
  This. There are semi-mandatory courses we need to take occasionally at work; and both the speed, and ratio of useful content, are dismal. E.g. Oracle University releases these 24 or 40hr courses which probably have, dunno, 6 hrs of content? Maybe? It is brutal to try to spend a week going through something so atrociously slow and informationally sparse. Ability to speed it up (sometimes 1.25, 1.5 or 2.0 times) brings it into actually manageable.
jimhefferon 5y ago
What an interesting comment. I also find that there is a lot of not great learning materials available. Perhaps it is not surprising, but the really quite good is uncommon. And, I expect that poor materials lead to poor learning, missed things, misunderstood things, etc. But another point is that the presentation is not the main place where people learn, at least in math, which is the field I teach in. The main place people learn is in doing the exercises. I will pull a number out of my posterior and say it is 80% exercises (a matter of opinion, I concede, but what else can you do with opinions besides spread them around?). Obviously twiddling with video speeds doesn't apply at all to that.
jacquesm 5y ago
A lot of IT is centered around staying current, which occupies a substantial portion of your time. Being able to do that quicker is an immediate boost for your productivity. This isn't all at the level of learning physics or rocket science, it can simply be a tutorial about a new framework (every 6 months or so) or a library, a new development tool or orchestration method. Personally I prefer to read but with the easy way that video can be monetized a lot of things that in the past would be blog posts and long form articles or web based tutorials are now posted on youtube. And sometimes there aren't any alternatives so you're forced to use video even if you'd rather use some other medium.
- biztos 5y ago
  I'm not convinced that being "more current more quickly" is going to boost your productivity but it will probably boost your paycheck if you're willing to job-hop.
  - jacquesm 5y ago
    Compared to most other fields IT moves relatively fast, learning is a part of being active in this field if not you'll never be able to make a career out of it even if you stay in the same place. Very rarely do you find companies where the tech doesn't meaningfully change over the period of a lifetime's employment, and that by itself is very rare if only due to the speed with which companies come into being, merge, split or get acquired and do wholesale technology changes. IT and learning go hand in hand.
    - biztos 5y ago
      > IT and learning go hand in hand. I couldn't agree more. But learning twice as many new frameworks twice as fast is, in my opinion, unlikely to give you a net gain in productivity. Unless your job is to use twice as many frameworks as the other guy, in which case congratulations on your employment at Google. /s Every professional should be learning new things as they go along. But you're not going to learn everything, and being good at This Thing Here also takes a lot of concentration, so I suggest that picking your skill-acquisition battles and diving deeper into some of the new things will make you more productive than having a larger set of latest-greatest notches on your belt.
xwolfi 5y ago
For me, I think I understand attention is the most important factor in learning, followed by practice. The material is the base, sometimes a bad quality material can even reinforce practice and attention. I remember how I learned serious programming at 14: a badly translated manual in French and a casio scientific calculator, no internet. I had to try each command, see what it did, guesstimate what it meant. I plowed through variables, goto/labels, printing, conditionals, had lots of problems conceptualising loops but figured it out talking with friends at school who struggled too, and ended up doing decent things with the calculator. When I started C at uni, nothing was new (except pointers, I admit lol): the very good material didnt help my fellow students much, in fact I remember helping them a lot gain a more intuitive understanding on what programs were and to love programming for the sake of it, me who learned from sheer frustration and trial and error with basically rope and wood. So I dunno... maybe I could have optimized my time but I still believe the sheer will to learn how machines ticked is what mattered, more than anything and that s always how I teach someone new to it: love the result and the process, independently of the details of implementation and you ll be able to program anything or at least know you CAN program anything eventually given enough courage and commitment. And at work, I m the multi hat guy who code on all the systems, on all the languages, always coming in as a humble idiot but slowly gnawing at the problems until I become expert and people at it for years start asking me questions, because I just never give up and never think it's too hard.
strangeattractr 5y ago
Have you tried watching things at 2x speed? I watch anything educational at 2x stopping to replay (often several times) anything I don't understand, watching at normal speed. I end up powering through the bits I understand and focusing on parts I don't. I also find the fact that I really have to concentrate to decipher what's being said means I don't get distracted. While some stuff that gets posted here veers into productivity cult status, I personally don't think this deserves to be lumped in with that. In spite of speeding it up, I probably spend the same amount of time watching the lecture as I would at normal speed. I do it because in my experience any concept that's novel or hard in a lecture won't be understood by me on the first viewing. So will require several attempts and usually reading something.
- VeninVidiaVicii 5y ago
  I use 2-3x speed to get through the recorded videos of my “umm”-ing prokaryotic molecular biology professor (during COVID). However, when I’m watching something for fun, I hate to speed through it, because I enjoy the watching process.
  - strangeattractr 5y ago
    Would never speed up something I was watching for enjoyment. I was slightly puzzled when I saw Netflix enable speeding up video, I suppose someone out there must have wanted it.
    - Cpoll 5y ago
      I know a few people who like doing that when they decide they don't like a movie they're watching but still want to finish it. I've watched Man on Fire this way and found it very comedic at 1.75x speed.
      - dahart 5y ago
        I suffer from feeling like I should finish watching things I started even after realizing I don’t like it. I’ve also come to the realization that it is freeing and making progress and good use of my time to force myself to decide to stop watching the show. It might be a kind of sunk cost fallacy that I’m fighting, feeling the need to check if there’s a surprise or if the ending gets better, feeling like I have to make sure I didn’t miss out on something good after all. Never tried speed-ending a video on Netflix, but I have on YouTube. But thinking about it now, I’m going to try harder to double down on consciously turning something off instead of wasting my time more quickly.
SuoDuanDao 5y ago
I certainly wish I was able to learn more quickly, and I'm sure that would be true no matter how quickly I was able to learn. The availability of quality material is an orthogonal issue to me, the worse the material the longer it takes to digest. I would also of course enjoy being able to take my time more, but there's so much I'm interested in that I wish I was able to get through more of it.
watwut 5y ago
For me, when speaker talks slowly, I tend to loose attention. I get bored, start to think about something else or just daydream. Then I have no idea what was told and have to rewind back. Speeding it up helps a lot, I stay engaged. Imo, speakers in educational videos tend talk very slowly. They do not talk in normal talking speed, they are slowed and speeding it up is basically moving them to normal speed.
briga 5y ago
> Good teaching ressources are the exception rather than the norm I have to disagree here. There has never been a time in history where it has been easier to access high quality educational materials. See, for instance, MIT OpenCourseWare. Many other great universities have similar programs (Stanford, Berkeley). That, combined with the countless people putting out educational content on platforms like YouTube and Coursera, means that it’s basically possible for anyone with an internet connection to learn from some of the world’s best teachers.
- WastingMyTime89 5y ago
  My experience at a university comparable to Stanford and Berkeley is that lectures perfectly conform to what I said: good ones are the exception rather than the norm. Most lectures are mostly useless as a form of teaching material outside of offering you the ability to ask the question you have to a specialist and the syllabus hopefully pointing you towards good books while telling you which chapters you can skip if you just want a sound but basic overview of a subject. I would much rather read than listen or watch something. I think the problem remains the same nowadays that it was before when people in large cities had access to good learning material through their public libraries: knowing which are the good resources amongst all that is available.
hliyan 5y ago
> Finding the time to properly conceptualise and deeply think about what I’m trying to learn has been challenging This reminds me of something that happened to me 20 years ago, and cemented my view that teaching should be bottom-up: waiting for our computer architecture lecturer to arrive for the day's lecture -- Interrupts -- I quipped to a friend "I hope he doesn't just walk in and say 'There's something called interrupts'". In a comedic bit of prophecy, the lecturer just then walks in, walks over to the board and says, "There's something called interrupts". Today, if I were him, I would never start by defining the solution. I wouldn't even name it at first. I would first state the problem: we know that a traditional CPU can process only one instruction at a time. And last time we learned that it looks at the program counter at the end of each instruction to see what instruction needs to be executed next. Now if the CPU keeps breathlessly executing the instructions from memory, it's never going to have time to check if I/O devices have any data. How do we solve this problem? A good student will start by suggesting that we have the program poll the I/O devices regularly. Then someone will likely mention the overhead of repeated polling, especially when when there are no inputs most of the time. This should eventually lead to the idea that the CPU itself (rather than the program) should check some sort of input signal between the execution of every instruction. An I/O device would set this input to an active state when it has input for the CPU, and the CPU will catch it immediately after the current instruction. Now at that point, there is no way to tell the CPU which set of instructions to run in response. Instead, we'll have to store those instructions in some specific location that is known to the CPU. Now what do you call this scheme? Interrupts.
- butwhywhyoh 5y ago
  This is excellently put and explained. I wish most educators took this approach as well. It seems a large part of education is handing out solutions to barely-defined problems, and the idea is to memorize the solutions.

ramraj07 5y ago

After some level of learning the eloquence of the author (barring some minimum standards) is probably not as material, it’s more about the content itself. Talking about graduate level courses, presumably ones not too math heavy, I can see this working. Or for lectures and seminars on research by professors (though one rarely is trying to remember every detail).

kristaps 5y ago

Right up there with other techie superstitions such as "editor x makes me a better programmer, because typing faster".

strken 5y ago
When I read this I immediately thought "typing faster makes me a less annoyed programmer, and better would be a happy accident", then realised it was the same for speeding up or pausing audio. Having control over the speed at which ideas are launched at me is more about not getting distracted or frustrated than learning faster.
- aspaceman 5y ago
  Patience is as much a skill as any other though. I don't quite understand this hyperoptimization. I'll speed up things I find a little dull or advertisements, but increasing the pace of everyone's speech for your sake seems....odd?
  - lalopalota 5y ago
    They are discussing speeding up the pace of the speech in videos they watch for their own sake. Nothing odd about that.

konschubert 5y ago

When I studied Physics as an undergraduate, I would regularly spend 3 hours just to really understand the content of the notes I had taken in a 1.5 hour lecture. The speed of consuming the content was never the limiting factor. When I listen to an interesting podcast, I often pause the track to think about implications of what was just said or to formulate a rebuttal in my head. I guess there are different kinds of learning and different levels of understanding something.

dotancohen 5y ago
With three or four two-hour lectures every day, multiplying the studying time by 3 would leave at most six hours for eating, sleeping, and maintenance such as buying food and bathing. Never mind working. I doubt that many university students could do that.
- konschubert 5y ago
  There were only one or two lectures like this a day. The rest were labs and exercises. And only Mon-Fri. But you’re right, this still comes out to 30 hours of lecture review a week, which seems a bit more than I remember. 20 seems more realistic. I guess the average was less than 3 hours per lecture.
  - nottorp 5y ago
    You probably remember the ones that did take 3 hours to understand but you’ve forgotten all those that were simple enough that you already left the lecture hall with an understanding of the material.
    - konschubert 5y ago
      I know for sure that I had to go through every one of them in the first couple of semesters. :) But you are right in that there is a bias in how I remember it: Not all of them took 3 hours.

dlisboa 5y ago

It's mostly about efficiency. If you want to watch a 4 minute video and the first 2 minutes were ads, wouldn't you skip it? Same principle: people talk slower than necessary in many of these videos, or make unnecessary edits that slow it down content-wise. I think this search for faster learning is fueled by the realization that we only have so many lines of text, or minutes of video or audio content, that we can consume in life. I don't want to waste that on ads or someone's idea of a fancy video transition. It's the reason why I don't like podcasts or radio programs: too much of it is spent on introductions or random subjects. I have other shit to do, so if I can maximize the retention in a shorter timespan, that's much better. There's an ever-present desire to learn more, and the more you learn the more new topics you find out about. Personally I am a bit bothered. I bought a bunch of books over the years and recently I've realized maybe I won't be able to go through all of them at my current speed. So I'm trying to learn how to read faster (with retention) and be more methodical about it. For things you need to go in depth the learning is necessarily slow: a college course, a textbook, years of experience. But if I want to learn something small that has less relevance to my life, I don't want to waste that time.

jasode 5y ago

>I don’t think I have suffered from the speed at which material covers a subject since I left school. [...] Thinking about it more often than not I wish I could actually go slower rather than faster. I’m curious about how the experience of others commenters differ here For many listeners, they suffer from speakers talking too slowly which causes them to tune out and become disengaged. This handicaps learning instead of enhances it. A lot of people can read text at ~200 to 300 wpm. Since many speakers talk at ~100 wpm, accelerating videos to 2x or more just gets the audio in the same ~200 wpm range.

TheFreim 5y ago
> For many listeners, they suffer from speakers talking too slowly which causes them to tune out and become disengaged. This handicaps learning instead of enhances it. When I was in school last year I really loved online, pre-recorded, lectures for this reason. I could put speed on 1.5x or even 2x speed. If I missed something I'd tap my left arrow to go back a few seconds or write the time stamp down and come back later. Slow speaking videos drive me crazy.
NikolaNovak 5y ago
This. There are semi-mandatory courses we need to take occasionally at work; and both the speed, and ratio of useful content, are dismal. E.g. Oracle University releases these 24 or 40hr courses which probably have, dunno, 6 hrs of content? Maybe? It is brutal to try to spend a week going through something so atrociously slow and informationally sparse. Ability to speed it up (sometimes 1.25, 1.5 or 2.0 times) brings it into actually manageable.

jimhefferon 5y ago

What an interesting comment. I also find that there is a lot of not great learning materials available. Perhaps it is not surprising, but the really quite good is uncommon. And, I expect that poor materials lead to poor learning, missed things, misunderstood things, etc. But another point is that the presentation is not the main place where people learn, at least in math, which is the field I teach in. The main place people learn is in doing the exercises. I will pull a number out of my posterior and say it is 80% exercises (a matter of opinion, I concede, but what else can you do with opinions besides spread them around?). Obviously twiddling with video speeds doesn't apply at all to that.

jacquesm 5y ago

A lot of IT is centered around staying current, which occupies a substantial portion of your time. Being able to do that quicker is an immediate boost for your productivity. This isn't all at the level of learning physics or rocket science, it can simply be a tutorial about a new framework (every 6 months or so) or a library, a new development tool or orchestration method. Personally I prefer to read but with the easy way that video can be monetized a lot of things that in the past would be blog posts and long form articles or web based tutorials are now posted on youtube. And sometimes there aren't any alternatives so you're forced to use video even if you'd rather use some other medium.

biztos 5y ago
I'm not convinced that being "more current more quickly" is going to boost your productivity but it will probably boost your paycheck if you're willing to job-hop.
- jacquesm 5y ago
  Compared to most other fields IT moves relatively fast, learning is a part of being active in this field if not you'll never be able to make a career out of it even if you stay in the same place. Very rarely do you find companies where the tech doesn't meaningfully change over the period of a lifetime's employment, and that by itself is very rare if only due to the speed with which companies come into being, merge, split or get acquired and do wholesale technology changes. IT and learning go hand in hand.
  - biztos 5y ago
    > IT and learning go hand in hand. I couldn't agree more. But learning twice as many new frameworks twice as fast is, in my opinion, unlikely to give you a net gain in productivity. Unless your job is to use twice as many frameworks as the other guy, in which case congratulations on your employment at Google. /s Every professional should be learning new things as they go along. But you're not going to learn everything, and being good at This Thing Here also takes a lot of concentration, so I suggest that picking your skill-acquisition battles and diving deeper into some of the new things will make you more productive than having a larger set of latest-greatest notches on your belt.

xwolfi 5y ago

For me, I think I understand attention is the most important factor in learning, followed by practice. The material is the base, sometimes a bad quality material can even reinforce practice and attention. I remember how I learned serious programming at 14: a badly translated manual in French and a casio scientific calculator, no internet. I had to try each command, see what it did, guesstimate what it meant. I plowed through variables, goto/labels, printing, conditionals, had lots of problems conceptualising loops but figured it out talking with friends at school who struggled too, and ended up doing decent things with the calculator. When I started C at uni, nothing was new (except pointers, I admit lol): the very good material didnt help my fellow students much, in fact I remember helping them a lot gain a more intuitive understanding on what programs were and to love programming for the sake of it, me who learned from sheer frustration and trial and error with basically rope and wood. So I dunno... maybe I could have optimized my time but I still believe the sheer will to learn how machines ticked is what mattered, more than anything and that s always how I teach someone new to it: love the result and the process, independently of the details of implementation and you ll be able to program anything or at least know you CAN program anything eventually given enough courage and commitment. And at work, I m the multi hat guy who code on all the systems, on all the languages, always coming in as a humble idiot but slowly gnawing at the problems until I become expert and people at it for years start asking me questions, because I just never give up and never think it's too hard.

strangeattractr 5y ago

Have you tried watching things at 2x speed? I watch anything educational at 2x stopping to replay (often several times) anything I don't understand, watching at normal speed. I end up powering through the bits I understand and focusing on parts I don't. I also find the fact that I really have to concentrate to decipher what's being said means I don't get distracted. While some stuff that gets posted here veers into productivity cult status, I personally don't think this deserves to be lumped in with that. In spite of speeding it up, I probably spend the same amount of time watching the lecture as I would at normal speed. I do it because in my experience any concept that's novel or hard in a lecture won't be understood by me on the first viewing. So will require several attempts and usually reading something.

VeninVidiaVicii 5y ago
I use 2-3x speed to get through the recorded videos of my “umm”-ing prokaryotic molecular biology professor (during COVID). However, when I’m watching something for fun, I hate to speed through it, because I enjoy the watching process.
- strangeattractr 5y ago
  Would never speed up something I was watching for enjoyment. I was slightly puzzled when I saw Netflix enable speeding up video, I suppose someone out there must have wanted it.
  - Cpoll 5y ago
    I know a few people who like doing that when they decide they don't like a movie they're watching but still want to finish it. I've watched Man on Fire this way and found it very comedic at 1.75x speed.
    - dahart 5y ago
      I suffer from feeling like I should finish watching things I started even after realizing I don’t like it. I’ve also come to the realization that it is freeing and making progress and good use of my time to force myself to decide to stop watching the show. It might be a kind of sunk cost fallacy that I’m fighting, feeling the need to check if there’s a surprise or if the ending gets better, feeling like I have to make sure I didn’t miss out on something good after all. Never tried speed-ending a video on Netflix, but I have on YouTube. But thinking about it now, I’m going to try harder to double down on consciously turning something off instead of wasting my time more quickly.

SuoDuanDao 5y ago

I certainly wish I was able to learn more quickly, and I'm sure that would be true no matter how quickly I was able to learn. The availability of quality material is an orthogonal issue to me, the worse the material the longer it takes to digest. I would also of course enjoy being able to take my time more, but there's so much I'm interested in that I wish I was able to get through more of it.

watwut 5y ago

For me, when speaker talks slowly, I tend to loose attention. I get bored, start to think about something else or just daydream. Then I have no idea what was told and have to rewind back. Speeding it up helps a lot, I stay engaged. Imo, speakers in educational videos tend talk very slowly. They do not talk in normal talking speed, they are slowed and speeding it up is basically moving them to normal speed.

briga 5y ago

> Good teaching ressources are the exception rather than the norm I have to disagree here. There has never been a time in history where it has been easier to access high quality educational materials. See, for instance, MIT OpenCourseWare. Many other great universities have similar programs (Stanford, Berkeley). That, combined with the countless people putting out educational content on platforms like YouTube and Coursera, means that it’s basically possible for anyone with an internet connection to learn from some of the world’s best teachers.

WastingMyTime89 5y ago
My experience at a university comparable to Stanford and Berkeley is that lectures perfectly conform to what I said: good ones are the exception rather than the norm. Most lectures are mostly useless as a form of teaching material outside of offering you the ability to ask the question you have to a specialist and the syllabus hopefully pointing you towards good books while telling you which chapters you can skip if you just want a sound but basic overview of a subject. I would much rather read than listen or watch something. I think the problem remains the same nowadays that it was before when people in large cities had access to good learning material through their public libraries: knowing which are the good resources amongst all that is available.

hliyan 5y ago

> Finding the time to properly conceptualise and deeply think about what I’m trying to learn has been challenging This reminds me of something that happened to me 20 years ago, and cemented my view that teaching should be bottom-up: waiting for our computer architecture lecturer to arrive for the day's lecture -- Interrupts -- I quipped to a friend "I hope he doesn't just walk in and say 'There's something called interrupts'". In a comedic bit of prophecy, the lecturer just then walks in, walks over to the board and says, "There's something called interrupts". Today, if I were him, I would never start by defining the solution. I wouldn't even name it at first. I would first state the problem: we know that a traditional CPU can process only one instruction at a time. And last time we learned that it looks at the program counter at the end of each instruction to see what instruction needs to be executed next. Now if the CPU keeps breathlessly executing the instructions from memory, it's never going to have time to check if I/O devices have any data. How do we solve this problem? A good student will start by suggesting that we have the program poll the I/O devices regularly. Then someone will likely mention the overhead of repeated polling, especially when when there are no inputs most of the time. This should eventually lead to the idea that the CPU itself (rather than the program) should check some sort of input signal between the execution of every instruction. An I/O device would set this input to an active state when it has input for the CPU, and the CPU will catch it immediately after the current instruction. Now at that point, there is no way to tell the CPU which set of instructions to run in response. Instead, we'll have to store those instructions in some specific location that is known to the CPU. Now what do you call this scheme? Interrupts.

butwhywhyoh 5y ago
This is excellently put and explained. I wish most educators took this approach as well. It seems a large part of education is handing out solutions to barely-defined problems, and the idea is to memorize the solutions.