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5:56 Better late than never but multiplication actually does work the same for unsigned and two's complement signed integers, as long as you truncate the result to the same number of bits as the inputs. This is why, for example, the ARM mul instruction is used for both. This makes sense when you remember that multiplies basically dissolve into adds and left shifts in both software and hardware implementations, and neither of them care about signedness.

Is the index.ts file supposed to synchronise with the receiver first? When i run the code without any breakpoints, it builds packets after receiving a random number of packets. How can i fix this?

This is really informative... I am currently taking a course in operating systems engineering and feel completely lost, I finally feel like I can actually understand what is going on! Thank you

How Does An Operating Boot? - 50 minutes... Thank you. I'll just ask this ChatGPT or Bard. Lol

awesome video

Awsome work, i hope u do more videos that i can learn fron :)

Putty and screen show no output My code compiles and runs the LED blinks as expected. But when i use putty, it says that unable to connect to the /dev/ttyUSB0 and then closes. when i use screen without sudo, it says screen is terminating. When i use screen with cudo, it simply opens the terminal and i get no response from the device. The USB adapter is connected and is being detected by the "dmesg | grep tty* ". The same problem persists even on windows, where the terminal is open on putty, but when i type something, no data gets displayed. I am using a f4 discovery board and have made all the necessary changes in the code, makefile and the linkerscript. did anyone else face the same issue? edit: found a work around for now: After some testing i figured out that the issue is with my USB to UART converter. I am using a CH340 module as shown in the video and it is being recognized by both Linux and Windows as ttyUSB0 or COM3, but when i try to access it using either putty or screen, i get no data. However, i have a F411 nucleo board lying around and it's integrated st-link works directly without any external module. I am able to send and receive data as expected. I tried the CH340 with both F411 Nucleo and F407 discovery, and in both cases, it deoesn't work. Later, I will use an oscilloscope to look into the TX and RX lines of the Discovery board and the CH340 module and try to findout if the module is broken. I think it might be a driver issue but i am not yet sure. But for now, the Integrated St-link of the F411 Nucleo works wothout any external module needed on Linux. If someone finds a solution to the problem, then please let me know.

Oh my god, I just found out about this this channel it's absolutely AWESOME! I love it I'm watching all your videos now

I found an easier way to get to `d`: using `undefined`. Attempting to access a part of an array or object that doesn't exist, will NOT throw an error, but rather, return undefined. The simplest way to do this is `[][[]+[]]` (the function `` of the Array object). Then casting to a string and returning the character with index 2; i.e. `([]+[][[]+[]])[+!![] + +!![]]`; yields the character `d`. Additionally, there is a better way to convert the numbers: using your ORIGINAL example of type coercion: The expression `+!![] + !![]` evaluates to `1 + true`, or 2. This can be written in the form `+!![] +!![]` (two copies of `+!![]` back-to-back), so it's easy to extrapolate; for example, 7 becomes `+!![] +!![] +!![] +!![] +!![] +!![] +!![]`. (NOTE: I like to write the number 1 as `+!+[]` instead of `+!![]`, which reads `+! 0` instead of `+! false`.)

I love your videos. Thank you 😊👍👍

malloc also uses this type of unstructured memory access like this kalloc function (so even for userspace we don't use more structure). We just have a chunk of memory and write an address to the next free chunk in the first few bytes. Also, these chunks can be of variable sizes, so you would even need to insert more implicit structure and markers into the memory locations. (Plus we have several lists, mechanisms to prevent and resolve fragmentation etc.). So if you find this kind of structuring interesting, definitely have a look at the common malloc implementation and other allocators in general.

I can imagine that this method leads to memory fragmentation, but is that an issue? Does it affect the process performance at all?

Somehow the youtube algorithm landed me on this goldmine. great job!

I don't know how to thank you. I just applied for a software embedded developer job and your videos are worthy like water for me

Just wonderful. Thank you !

Core locked up: I am using a STM32 Discovery board with a F407 chip. I am able to flash the code onto the MCU but it is not being executed. Earlier it was working fine with systick but when i powered it on yesterday, the blue led (which i configured to blink) was not blinking. I was using st-flash on CLI for this. I installed STM32CubeProgrammer, which after flashing the code, tells me that the core is locked up. Can someone please guide me on what to do? Edit: i tried flashing the same code onto a nucleo board with f411re and the core immediately locked up as well.

What you say is great. It is easy to follow but the low energy growl in your voice really grates on my nerves and I can't listen to you for very long at a time. I hope you can deliver more energy while speaking and get over the growl. Thanks, either way.

Can't thank you enough for this series. This is incredibly useful.

I found your channel yesterday when I searched for "write a regex parser". Even though I don't use JS myself, I found your back catalog very interesting. Thanks for the great work.

Hey love the video!!! Quick question, how is the memory that is alloted to the stack0, in the entry.S ( 4096* NCPU) actually allotted? If the kernel is still not yet started, who manages and allots stack memory? I got into a chicken egg dilemma..

i ve been learning java script for 3 months now and i wanted to do a new project and thought a 16 bit computer will be interesting enough. upon trying to grasp the logic behind arrayByBuffer and DataView and misserably failing i ve come to the conclusion that i know way less about computers then i thought i do. Maybe someday i ll be ready for this.

"javascript is open source"

Bro actually used backspashes to produce back slashes 💀

Why didnt you just "map['\\'] = '\\';"?

i am facing issue with running make on the firmware.c file. I get the error make: *** No rule to make target 'firmware.elf', needed by 'elf'. Stop. Someone please help.

Good stuff mate!

when are you doing #6? great content

Excellent.

When there are multiple timed operations I prefer to do it this way to avoid constant fetching of the ticks value and math inside every if statement: while(1){ uint64_t tick_now = get_ticks(); if(tick_now > start_tick){ start_tick += 1000; .... } .... }

Is it possible that the fact the nop instructions don’t consume time consistently as you add them is because a NOP on ARM is not guaranteed to consume time, the processor is allowed to remove them from the pipeline?

I am a bit in the latter camp. You can write an assembler, compiler, or CPU in JavaScript. Please don’t run around screaming that it is the best tool for that job. I start getting upset when people go doable in language X means language X is the best possible tool for job Y. If you boil most tasks down enough they turn into finite state machines. That doesn’t mean an FSM is the most productive way of tackling a task. I am finding other videos pretty cool.

Pdos? Clergy's favourite OS

hmmm i guess 5 dislikes were having a very bad day xd. thanks alot sir for sharing you knowledge with us, i cant wait to finish all of it 🙏🙏do you suggest books or certifications!

Great video! Thank you very much for such high quality content. One question though: The `start` function is written in C. Which means it has a functioning stack somewhere. I guess that is the purpose of `_entry` assembly function to prepare the stack for `start`. How does the c code (or the c compiler) know that the stack must begin at `stack0 + hartid * 4096` for the `start` function?

libopencm3 won't compile on window. Error with the nvic.h linker line 63: from the make file. Did anyone have a work around this since the include Header file is dynamic link

No unit tests?

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Best *nix series on youtube by far!! I really hope there will be a continuation!

11:46 just use desmos to illustrate concept lol

Generally kalloc(size_t sz) takes the size of memory to allocate, but in this os code why kallaoc(void) suppose if i want to allocate memory for a structure of 25 bytes, I get whole 4096 bytes, Is this inefficient Correct me if I am wrong

This is simply amazing! Best OS explaining video I've seen so far. Thank you so much and please keep it up!

Too Interesting Please continue the series😊

Another way to define a expression is as: expr: term ("*" term)* term: factor (("+"|'-") factor)* factor: literal | variable | "(" expr ")"

in the uart_usr, shouldn't the if statement check for !overrun ?

nice video

I guess how do you know what is needed to boot the kernel and all the steps required for the architecture? Is there a manual that describes all of that?

24:55 Question: initlock() is passed a pointer to a string (“cons” for example) with type (char *) to retain that information for debugging. But that points to a string in the caller’s data. Can you be sure that the string persists? If it is ephemeral, the pointer would no longer be valid. Do you have to do anything in the code calling initlock() to ensure that the string can always be accessed with the original pointer value? (And yes, this series of videos is amazing. Instant subscription. I’m retired so I no longer write code for embedded CPUs, but your explanations are a delight to follow.)

well explained

excellent tutors! could you share your vscode experience for another video?