How computer processors run conditions and loops
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- Опубликовано: 13 сен 2024
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In the final episode of this low-level series, we learn the fundamentals of how computers evaluate conditions and loops, a very important feature that makes them as useful as they are today.
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the AI voice ruined the experience
I still cannot believe this channel exists man. Generational content
where the fuck was this during my CS degree ffs
@@Dreamer66617 I don’t mean to sound like a grandpa, but kids really don’t understand how lucky they are to have these sorts of resources these days. NONE of this existed when I was in school. You read a textbook and that was it.
Dude not only do you have the talent to explain low level concepts in an intuitive way to understand. You provide stunning visuals as well, what a gem for the computer science community
We're truly living in a golden age of educational content on RUclips when we have access to these kinds of videos. I love it and thank you for it.
Question: Have you considered making a video about Virtual Memory sometime in the future? I still remember how mindblown I was when I learnt about it in college.
I would LOVE a video about virtual memory
Core Dumped is the GOAT of Computer Science teaching videos
i honestly was barely even interested in learning about how lower level programming works until i stumbled across this channel. truly incredible content
At 8:15 I was like, wonder if it would be turing complete.. and you just made a cliffhanger 😂
With all the instructions in this video it's Turing Complete.
I am developer, as job. Man, the "from the transistor to the code" thing was bugging me for years. This channel exists and explained it all to me, and continues to do excelent job at that. The amount of questions I happened to have over +- 15 years that are just casually explained in plain english and plain animations here.... Insane. Since these questions were bugging me in long time, I had fragments of knowlage that I managed to get on my own, you managed to fill in the gaps and make it make sense in total. Nobody in uni managed to make it happen.
Thank you very much for this channel. Like, actually. Thank you for this. I mean it.
I come from the electronics world, first - doing band filters, op amps, and flip flops before getting into logic gates and registers.
I always thought I was missing something when I would go to program in C. I could easily dissect what other programs were doing, but I always felt like I was not understanding what the computer was actually doing or how to actually tell it how to move the data as I visualized things.
Then, I started playing ExaPunks and realized the problem is that I should have just learned assembly, as assembly is exactly what I was expecting a programming language to be and made sense to me.
I can work in higher level languages, but it is so much easier, now that I understand just how fundamentally different "programming languages" are from hardware programming. Programming languages are math languages - platonic constructs which are mapped onto assembly instructions by glorified macros. The people writing in them may know assembly and what is going on in the computer, but the language itself is not usually designed to control the machine, but to describe an abstract flow of concepts without knowing anything about the machine.
OMG BRO THANK YOU!!!!!!!!!!!!!!!!!I built a computer about a month ago in minecraft and still couldn't figure out how to make conditions and cycles, but thanks to you, I can complete my computer and present it to my subscribers. If I do make a video and post it, I will definitely leave a link to your video
Glad I was helpful!
Your videos are so great! It would be excellent if you could also explain how multistate conditions using AND/OR are processed in your future videos
I think for AND, first do the check for the first condition, and then do a conditional jump to the code after the if branch when the first condition is not met. Then, put the code to check the second condition right after the jump. Then after the code checking for the second condition, put a conditional jump to the code after if when the second condition is not met. Then put the body of the if statement after that jump.
For OR, first check for the first condition and do a conditional jump to the start of the if branch code when the first condition is met. After the jump, put the code checking for the second condition and then do a conditional jump to the code after if branch when the second condition is not met. Then put the if branch's code after the jump
This also implies the short-circuit-ness of the logical AND and OR
Here's some example code, where "jump_if cond location" means to jump to the location if the condition is satisfied. Addresses are replaced by flags (such as code_start) because that's how you write assembly without having to change address locations all the time. code_start is obvious, but code_end always refers to immediately after the code, not the last line of the code. "any" just means that the instruction doesn't matter for the integrity of the conditional logic.
OR:
jump_if A code_start
jump_if B code_start
jump code_end
code_start: any
...
code_end: any
AND:
jump_if A b_cond
jump code_end
b_cond: jump_if B code_start
jump code_end
code_start: any
...
code_end: any
Bro is helping me make a 16bit CPU inside a game running on a cpu inside a plastic box
My dude just made assembly look simple and easy !
That's the thing, it really is simple. Just verbose and fiddly with all the memory management and different for each architecture.
Incredible, most people think assembly is worse compared to hlls but that always confused me.
Since most ppl with any hll experience usually start with coding before undertanding the circuits at the hardware level that would naturally be the case.
Meanwhile, I began my journey trying to build something turing complete with just a clock, some memory and some gates in a simulator.
It came naturally to me as I designed the ram and alu(alu needs at least only add and invert functions, rest can be derived), that you just need 3 special registers(accumulator, instruction reg, address reg), the ability to define variables, and most importantly the final piece; at least one flag and a instruction for conditional jumping to finally make something turing complete.
Most people want results . Python gives them ML . Do you meet people who claim to understand C++, Haskell, and all of C# ?
When I see a new video, I am excited as same as the release of a new episode of my favorite TV show.
Congrats man, I can't believe how those basic concepts weren't explained this good in my university. Fantastic content keep it up!
You are seriously talented.
I am learning embedded software programming right now and your channel is helping me deeply understand what is going on at the low level.
Also, the CPU emulator tool you made is beautiful.
I hope you get the recognition you deserve && get to do what ever you want to do (which I selfishly hope is to continue to make great content like this) && be properly compensated for it.
You are making a difference.
when youtube notifications actually work:
This is one of the best channels I have ever encountered in RUclips. Thanks for your work, man!
I envy CPU architecture students. When I studied it, there wasn't all this high quality content available online. You're doing a wonderful job!
Man i really love this channel, it makes low lever programning easier
Very clearly explained.
Your instruction set is very close to the language I started with at school, many years ago (using 3B pencil and 40-column cards).
It was CESIL (Computer Education in Schools Instruction Language), which had only 14 instructions.
All operations (IN OUT LOAD STORE ADD SUBTRACT MULTIPLY DIVIDE) were done through the accumulator and numeric constants or user-named variables.
It had JUMP JINEG JIZERO, which is enough to do most things.
And the remaining instructions:
PRINT [some_text] to the printer
LINE to start a new line on the printer (sometimes useful after OUT and PRINT).
Finally, HALT to end the program.
It was a good introduction to programming, makign you think about every step required to solve your problem.
On the subject of educational programming, I recently encountered Scratch. Looking at its available blocks, I think it is a very good educational tool.
I'm taking a coumputer architecture course at uni. This is super useful and easy to understand. Thank you very much!
I can't believe how good these videos are, I remember taking computer architecture at uni and its was nowhere near as clear and well said as this video, congrats!
Dude is making an "all of computer science" series, amazing :)
This channel is underrated. Great work!
Man, your videos have really helped me get into computer science and understand the process behind coding. You completely changed my perception of coding and finally answered my questions about how computers work in a clear and enlightening manner. Please continue!
Now you gotta explain how a MMU works.
Couldn’t find better content explaining this concept
You are genuinely my favourite youtuber - please never stop making these videos man!!
Info surrounding these concepts is usually very dense. You do an amazing job of making them not.
This is very well explained. Thank you!
While watching this video I realized something. While loops use mutiple jump instructions but if we place the body of the while loop first and place the conditional jump at the end of it, we will get a do-while loop which takes less lines of code. I always found do-while loops useless but now I see why they exist. Thanks for making this video. I always learn something new with each video.
Thank you very much for making this high quality and free accessible video for us ❤
what a stunning explanation and illustration, pretty useful♥.
The more you make videos, the more I get hyped for the next ones !
oh my God, bro I cannot believe that there is such a channel you're amazing bro please can you make the same tutorial videos with that low level but this time with functions and objects and classes how are these things and entities are implemented in the hardware level, please I've been searching for all of that the whole of my life.
do function call next.
very interested in this and vtables as well
In case you can't wait, this is my barely self-educated understanding for a simple subroutine that doesn't take arguments or return a value:
Store the address of the next instruction to be run after the function returns into a memory location (the current position in the call stack) then increment or decrement (depending on which way your call stack grows) the current position in the call stack (push operation) then jump to the address of the function you are calling (might want to check for stack overflow during the push operation)
At the end of the function, roll back the current position on the call stack (pop operation) and jump to the location stored there.
There are assembly instructions that will do some of this work for you. You don't actually have to manually manage your own call stack (although you can if you want more stuff to manage), there are 'call (address)' and 'return' instructions that do the pushing popping and jumping.
To pass values to and from functions you will need a stack that also stores the size of the data pushed in each push operation in order to be able to pass arbitrary amounts of data and pop the stack later (for the simple call stack, addresses are all the same size and only one at a time is pushed so no need). The reason you want to use stacks for function calls is so that you can call functions from within functions from within functions etc. including recursive functions that each have their own memory that isn't overridden by other calls and doesn't require complicated code to keep track of where each part of the memory is.
One way you can make (non-recursive) functions with arguments and return values is to:
- Write input values to parts of memory dedicated to the function's input
- Write an address to the end of the function for it to jump to when finished
- Jump to the start of the function, have it do whatever it does (with input and output addresses in mind)
- Read from a dedicated output location in memory to get results after the function finishes
It could do with a better explanation than what I've given, but that's a way to do it if you have a process that can only have one instance running at a time. If you do want to get multiple instances/recursive functions involved, you need to get list management involved and all that jazz, which isn't the worst but takes a little extra work.
You can add to a list of values without worrying about it running into something else by splitting it into blocks, with each one specifying its length and where the next list block starts for if you need to look up something beyond the current block. All you need is a way to check where is allocated and where isn't so you know when and where to make a new block, which isn't too bad.
Once you can make lists, you can convert each function's input set and exit location to jump to (but not necessarily the output set) into a few lists, and you can read the input values of the current stack layer by looking up the last values in the list. Assuming you remove items from the list after you use them, you have a functioning stack. It'll still work if you don't deallocate, but you'll have a memory leak identical to one on a modern framework and eventually will run out of memory and run into whatever edge case you've set up for when you cannot make more list blocks.
The simpler way to do this if you're fine with a limited number of stack layers is to make arrays instead of lists, (the difference being an array has a set length while a list does not) and use an address to keep track of which stack layer you're currently on. This is all fine and good, but if you want to continue recursing you'll want my previous solution.
I hope this explanation is good enough until we get a video on it, and if there's anything to clarify or correct I'm happy to hear it. Bot-ass way to finish a comment but still.
This is so incredibly well put. Wish i had this during my undergrad in CS
11:04 some CPUs dont have flags, for example the xtensa CPU on the older ESP32 MCUs have some instructions like "branch if zero", "branch if less than" etc that take registers as parameters and the target offset as a immediate, I recall reading somewhere that it was done this way to make the circuitry simpler since its a customizable CPU... but who knows if this is actually the case
MIPS RISCV
No decepcionas nunca Jorge :) gracias por el video ❤
Sweet!
Makes me want to learn Assembly more :)
You are so great at teaching!
Assembly always seemed like it was orders of magnitude more complex and arcane than C.
But if what you said in this video was in any way accurate, i feel like i could make comparable program in x86 assembly if i took the time to learn it.
Thank god you exist bro
Very clear explanation, thanks!
Look forward to your Turing completeness video ;) good job!
That's why with a NPU we just need to input the values we need to calculate and let it iterates, respecting the flags conditions. 12:05
Your videos would've helped me tremendously when I was a CS major, 22 years ago.
Oh that last slide of the making from ur set to the arm/x86
Pure gold
I love your content. It has been the most clear and thorough explanation of low level computer processes i've seen on youtube. And I honestly don't mind that you are using an AI generated voice. if anything its a testament to what kind of absurdly complex things you can make with simple switches. It really kind of drives the point home how ridicilous modern computers actually are and it just makes me appreciate what we have more.
You content and production is awesome. Great channel, congrats. 🎉How do you do your animations ?
I would rather binge watch your content than any content available on Netflix. It's just so GOOD!
True! RUclips Education is a revolution in itself. My COA professor taught me this topic and this weird assembly syntax just yesterday and no one understood anything, and today I see this video. Truly Brillant!
What an amazing video. Please do more of assembly videos❤❤❤
This is like the best channel. Now i wonder how functions work? Or r they just variables interconnected to each other
It's the compiler doing it's job, the compiler is essentially a library of how high level complex functions are performed by a series of low level instructions, and replaces the text of a typed function with a longer list of instructions automatically before feeding it to the computer.
I like that preview picture in this video with randomly added code
Can't wait to see your next videos
Thanks for all the work, time and love you put into this, it's awesome
This is the best channel i could ever discover
This video was really great I really enjoyed and learned a lot, I am so thankful that channels like yours exist ❤❤❤❤
This channel is pure gold
This is great stuff! I built a 12-bit (16-bit if you're talking about the address data length, but 12-bit numbers) computer in Scrap Mechanic with programming it in mind, and this is the exact thing I have to do! I mean, I built the jump operations around comparing the two registers it has instead of ALU flags, (my computer doesn't have an ALU, the registers do incrementing/decrementing and there's no other arithmetic other than the comparison I've mentioned) but the style of code I have to make is identical. I'm looking forward to upgrading it to 256 or even 4096 addresses and seeing what I can make with it!
Forth and a class on 6502 helped me figure this stuff a long time ago. Although you're going on to other topics, a part 2 for this video would be the case statement. When done in assembly language its an exercise in table lookup.
One of the things I would add is that "modern" processors have had the ability to load immediate values from the stream of instructions for many decades. It's a significant improvement on data loading efficiency and that's how it should be modeled. Also, optimizing compilers would convert that addition in the code into a single value. Some will do it without optimizations turned on.
We'll discuss this in the video about Compiler-Optimizations.
Really excited for scheduling and threading.
Btw, a little optimization could've been made with the conditional code: instead of a JMP_NEG addr followed by a JMP halt_addr, a JMP_ZERO halt_addr would've been enough. :)
I second the compiler optimizations video
Pls do more videos on making optimised programs. Or rather explaining the underlying stuff so we can write good code. Love ur work ❤
It's Core Dumped Again!!🙌🏾 Timeless!
Beautifully explained! Ive always loved assembly language
This video is great, easy to understand! Thank you for the amazing content!
Please make a video about how instructions (commands) are decoded and encoded in the processor at the binary level
Learnt more in 15 minutes than I did in an entire semester
👍👍👍👍👍Well, I pushed the "Like button" even though I did not learn some new thing, but I very much enjoy the way you made it. I would have learn with such videos 50 years ago. I envy a lot the young programmers who can learn from your content. You might want to elaborate on the different Assembler syntax, the Intel syntax type {operand / destination / source} opposite to AT&T syntax {operand / source / destination } Peace & Prosper. ❤🖖
It is not a video about computer programming, it is art of presentation on its best
this is amazing , great explanation
I can't wait for the next episode date and details. Kindly provide now.
I learned about a really simple instruction set made for learning in school. It is called "Bonsai Computer" and consists only of 4 instructions, increment, decrement, jump and test (+ the hlt instruction). I think it was developed by some German teacher, so I couldn't find English resources. It is really interesting tho, as it is turing complete
What's Hlt? How many flags did it have? You need only one.
Bro this channel is a hidden gem i ve paid dollars for courses that served me nothing and you my friend for absolutely 0 dollars are giving this knowledge god bless ❤❤❤
Great and simple explanation ❤
🤯 what a video!! Amazing, I finally understood asambly, ty
Absolutely Goated Channel!
The PDP-11 did this much more efficiently with its macro-11 assembly language.
Back in the 70's (when taking Comp Sci courses in college..)
I used a text book called "Structured Computer Organization" -- Tanenbaum (pub: Prentice Hall 1976)
It explains all this kind of low level "machine code" for different popular machine "architectures" of the day.
I guess books like that don't get written anymore...still have that book...
But your automation makes it all the more "comprehensible" than just reading about it with B&W illustrations.
Also the classic work: "The Art of Computer Programming Vol 1" (Donald Knuth) introduces the student to "Assembly language"
using the "make believe" MIX language. I guess today if you need super fast code..you just write it in "C".
"No Assembly Required" 🤗
I watched every single video you uploaded. Thank you.
a video about how variables and pointers are actually stored would be fantastic 😅 like I belive I am speaking for a lot of begginers when I say Its realy hard to conceptualize what does something like double x = 123456; and int * x = &y; actually do in low level
Pointers arent as bad as they are made out to be. What is often confusing is how/when they are used and the implementation of them.
A pointer is just a memory address. On its own, it doesn't tell you anything more. Think of it like a RUclips video time stamp, "go to this part of the video".
When you store data, say a 20 character string, you might store it back-to-back (contiguous). A pointer to that string just puts the cursor at the front of the string in memory.
As I said, often the implementation is confusing, but in fundamental principle it's not difficult
@@penfold-55 Yeah, the fact that pointers have a type is just so the compiler knows how to handle the data the pointer points to. Any form of indirection (like pointers) adds more you might have to think about.
I LOVE this , really really LOVE it.
The content of this channel is pure gold on information, thank you so much sir😎😎
Great job man!, love this kind of videos. Thanks!
Wow just wow
Thank you so much
Great video! I only have one minor note. I think it would be more consistent to name the instruction JMP_POS instead of JMP_ABV.
I am learning so much from your videos. Incredible content. Thank you so much.
Wonderful and informative content! Very well done, this sort of knowledge is extremely important to keep available for anyone who is interested in these kind of topics.
Please do a video detailing interaction between CPU and IO devices
George is the man!! Fantastic content
Your content is going to go down in history as the easiest and best to understand computer science education out there. I am just glad to be catching it as it's made that way I can keep up at my own pace while I study my own stuff. Your gonna get a star 🌟 on some future road marking kings and queens of educational content.
Hello Core Dumped, this video is really cool and simple explanation how to computer works. I understand that it is oversimplified but there are some mistakes.
1. Single numbers never stored in special segments of ram, they just baked into instructions: LOAD R0 1001; ADD R0, 5; STR R0 1001, it works only for arrays, strings and etc.
2. Static data and variables (local/static, global/dynamically allocated) are not mixed in same memory. real memory layout looks like that:
start (0x00) [Code] [Static data] [Global vars] [Heap] ..... [Stack] end (0x00), static data is stored next to code, not at end of memory
3. Real local variables usually don't allocate on stack (ram) if it not necessary, it means no STR instruction will be executed until you call function
4. Virtual memory is not topic of this video, but when we talking in terms of 'start' and 'end' of memory, there are many questions about other programs on same computer
5. 7:18 Real programs don't store zeros in bin files, there are only code and data in files
6. Some mistakes in condition work: actually, there is only one conditional jump with inversed condition that skips condition code
P.S. I am not computer engineer and also could have made some inaccuracies
P.S. #2 I did not say that include all of that into 17-minute oversimplified video
Thanks for you video again ❤
Where'd you learn all this.
He was showing sort of a bytecode more than machine code. That's why there are different instructions and functionality compared to x86_64 and ARM.
And layout isn't fixed in stone either. A port of System V release 2 for the 286 to simplify things had a slightly different layout. For modern stuff, between the Heap and Stack is an area where shared binaries are mapped into the address space. Having static data together with code allows that portion of memory to be read-only and shared with other processes using the same program.(more advanced stuff).
This making me more and more excited to learn assembly!
Many thanks for another great video on computer science !
This is the best content of whole world about computer science!!!! Thanks a lot :)
Awesome! Tks for this video!
Absolutely amazing man!
This one was exceptionally good 👏👏👏
Been trying to implement an optimizing compiler for a while now. I would LOVE a video on the topic.
What if you don’t have a linker or some JIT? I think that it should be possible to assign registers for small procedures and blocks. Callers will probably run out of registers and will have to shuffle around some.