Note to self: create a motherboard company called Leg that specializes in Arm cpu sockets. Linus will have to buy my boards, the joke will be too tempting!
Man, LTT has become a *lot* more interesting lately with videos about Linux and RISC-V etc. I love this. =) Honestly I had kind of stopped watching LTT, but I'm starting to pay more attention to the channel now with this new content. =)
Would love to see an update on this two and a half years later, interesting how far its gotten Edit: now four years! Edit: after five years, the madlads did it.
I think the best part of x86/x86_64 is combing through the 4000ish page combined manual set from Intel and discovering that processor cores play musical chairs to decide which core runs when booting up the system.
You can find the description in section 8.4 (Multiple-Processor Initialization) of Intel's Software Developer's Manual Volume 3 (System Programming Guide: 8.4.3 MP Initialization Protocol Algorithm for MP Systems -- skipping stuff -- The logical processors begin monitoring the BNR# signal, which is toggling. When the BNR# pin stops toggling, each processor attempts to issue a NOP special cycle on the system bus. The logical processor with the highest arbitration priority succeeds in issuing a NOP special cycle, and is nominated the BSP (Bootstrap Processor). This processor sets the BSP flag in its IA32_APIC_BASE MSR, the fetches and begins executing BIOS boot-strap code, beginning at the reset vector (pysical address FFFF FFF0H). The remaining logical processors (that failed in issuing a NOP special cycle) are designated as APs (Application Processors). They leave their BSP flags in the clear state and enter a "wait-for-SIPI state." Vol. 3A 8-19
I think Intel uses a non-democratic bus arbitration system so it is really a rigged game of musical chairs. Even if they had "round robined" it with rotating priorities, the initial value in the priority register would mean a rigged game.
I like where these videos are going. I enjoy how you clearly breakdown why new technologies are relevant and important. Plus, you're introducing new ideas for all the nerds out there. Im going out to learn more about risc dev now.
it's good but he's clearly wrong about risc being better then cics or x86. x86 is currently the most efficient architecture and there is reason it has evolved the way it has.
Yeah, these videos about the current development of the underlying systems that let computing happen are really useful. Great reason for me to keep following.
Yes I have a line of cpu's in mind: LEG cpu (Legitimate Extreme Goodness) FINGER cpu (Fantasticly Inexpensive and Greatly Enduring Resillience) NOSE cpu (Never Overpowered Seriously Ecofriendly) BRAIN cpu (Benign and Really Artificial Intelligent Now) MOUTH cpu (Mostly Overrated and Unbelievably Terrible Heuristics) LIPS cpu (Largely Integrated Problem Solving) NAIL cpu (Nice, Another Indifferent Loser)... really 'nailed' it with this one.
dont forget the "Protected Environment and Neat Implemented Security"-cpu... for running code in a container of some sort, so it cannot harm other soft/hardware
@@sagichnichtsowiesonicht7326 mcaffe bought tunnel bear, they don't work with them anymore because of it, google macafee tunnel bear and you will find the answers i believe linus has a video about it, i was just curious if they went and pulled all the old ones after they stopped working with them but they have not
Am I a joke to you? Pfft. Yes. Tanenbaum was really good a teaching, but terrible at performance. ME TOO! Hey, have you heard about this io_uring thing? People are saying it's going to make my 350 syscalls look fat. Like the filesystem? God, that joke was cornier than grouping me with other limbs. I don't get it, is it the T2 in my name that makes people afraid of me? Nah mate, Sun died to death, like Motorola. At least it's not as bad as Hexagon. I ended up in the dreamcast, nobody will remove ME from GCC. I'm here too! Guys! Guys! Ignore him, I'm your microcontroller. ARM! He stole my peripherals! Lol, prove it in china. I, uh.. Wait, how did you all get in here, this is a mobile device! Shhhh. THEY'll notice your silly british walk. Who's they? You know. THEM. The ones who killed the sun. That's not all they killed. I thought you got better? ME TOO! No, no, I'M the one who killed the sun. Had help from One Rich Asshole Called Larry Ellison, and that other company with the dollar sign in their name. Everyone's ignoring me. At least you guys EXIST. I like trains! ME TOO! ... I'm surrounded by pretentious assholes. And idiots pounding their heads in the sand reinventing everything. But hey, at least the assholes are high functioning.
This video, like much of the material about RISC-V, is fueled on hype and misleading statements more than anything. Open ISAs have been around for a while. Pure RISC is impractical and all popular RISC ISAs end up using CISC-y instructions for the sake of performance. I very much support the notion of moving towards open hardware. But maybe we should take a look at what's already out there, including de facto free off-patent ISAs like SuperH, before jumping on the hype train.
@@KyussTheWalkingWorm Dude, anything out of the village idiot's mouth is hype or misleading. That's what he does. That's who he is. But it's still entertaining. Also, there's quite a few other open ISAs you're missing if you stick with textbook risc designs like SuperH. OpenSPARC T2 was solid, but not useful unless you have the resources to fab a board around it. But the real up-and-comer right now is parallax's propeller2; they opened the ISA around 2013/2014 IIRC. www.parallax.com/microcontrollers/propeller-1-open-source forums.parallax.com/discussion/170380/new-p2-silicon/p1 The successor is just leaving it's final tapeout and full production was supposed to commence in april, but.... coronavirus. So now it's looking like june/july. My RevB engineering sample just showed up not too long ago. It's amazing to have such a unique design just bang HDMI output from a header, while capturing four analog inputs. forums.parallax.com/discussion/171331/digital-digitizer-now-mixed-signal-scope-dds/p1
As a recent Comp Sci grad, I came here to make this comment. MIPS was used to run Irix, to make "Jurassic Park" (featuring Irix!), and it powered the PlayStation Portable! Plus, it is really easy to understand. Now, find a modern workstation that uses it... well, you can't, but it has a lot more real hardware than RISC-V has! (I do with RISC-V and the folks behind it all success, though.) Pour out one for our old pal, MIPS: I knew him well, Horatio.
Literally nothing happened in that video but it was incredibly well scripted so I was hooked from the start. Even not knowing anything about CPU architecture I still understood EVERYTHING
Check out Wiki..! Wow, This was only new 26 friggin' Years ago! Only reason I didn't buy one is, Because everyone else was Microsoft Cucked! If Your phone was using one of these right now it would literally KICK THE SHIT Out of the CPU's we have now! Only reason your phone isn't running one of these bad boys is...? Wait for it!!! Fucking Microsoft!!!!! Bill Gates is a thief and a Billionaire ASSHOLE! Let's see if this post makes it to the comment section. Controlled by yours truly! Also, Google and Facebook! The worlds biggest friggin' Controllers of FREE SPEECH! Let's not forget about YOU TUBE AND TWITTER! Fuck the MSN ( Main Stream Media)!!!!!!!!!! WOLVERINES!!! Red Dawn is a 1984 American war film directed by John Milius!!!! Watch it and the remake!! Think about it!!! Before it is too late.. Watch Alex Jones @www.Infowars.com or newswars.com or www.Prison planet.com.... Or get Infowars Official app! Top of news section. Or go to www.infowars.com and download the free app today.. To see why the Democrats and the New World order hates Alex so bad, That they would ban his 1st Amendment Right according to the United States of America Constitution! Silencing Free Speech is a CRIME!!!!
Actually, it's not so much new logo that's throwing my mind into a "loop"....it's the COLOUR scheme! So used to orange w/ white, black, grey....that the purple & red? is seriously just messing with my mind 😅
seeing as it's sponsered by Google and all the other tech giants I'm assuming that they really do mean FU in the sense that you find funny and they named it freedom unleashed as an even bigger FU, like Google would ever support freedom. hahaha.
Lorenzo Torres Yep, just like AV1 codec for video, with hundreds of companies behind it in the Alliance for Open Media. These big companies are getting rid of the shitty locked down world we're in and making open products for anyone to contribute to and work with/on. After hardware will be software giants death and then ISP giants deaths
This video is much more important than any of the normal videos on this channel. Projects like this are the only chance to defeat the disgusting surveillance monopoly corporations.
ThronRitter80 Yea, it seems so, unfortunately. Did you know that any Intel CPU after the core 2 duo have backdoors you can't get rid of even when instaling freest GNU\Linux distribution?
@@memoriasIT Why not? If anything, it's profiting more because companies can manufacturer their own processors, making it cheaper for them and possibly consumers.
Open source is not always better. The profit incentive produces tangible innovation, and often companies that do really well with proprietary technology stick around to support it and push the product to maturity. As consumers what we really want is fast and capable computers.
I love this! I can't wait until everything goes open source so that we can see faster advancement in computer technology development. You have given us great news, thanks!
This is a really interesting bit of tech, because it has a lot of growth potential. But when it becomes cheaper, this would be an amazing tool for many tech hobbyists.
@@benni5541 I disagree, if they make a bunch of these it has the potential to be cheaper. Hell, Raspberry could use it instead of ARM, as it would be cheaper because it's open source!
So 8 years ago when I was learning computer architecture, they taught us MIPS and x86 (32 bit). Looking forward to RISC-V tho, gonna be great to have open architectures!
Well open source software has been proven to be a major factor in software development and now runs super computers and 60+ percent of the servers on the internet. It only makes sense to do the same for hardware at some point. Proprietary lockdown and expensive licenses stifle innovation. I look forward to seeing this hardware evolve.
Hardware and software development is quite different though. If I design a piece of software, I write it, test it and distribute it quite easily directly from my computer. If I design a cpu, I have to first write it in hardware design language, test it in simulation, get it manufactured, physically test it, set up a supply chain to manufacture and distribute it. As you can see, the costs for hardware development is quite high. Even then you can't guarantee the success of your product if you can't beat existing architectures at certain niches. That's why no one is really designing new architectures outside of academia and large corporations.
that is just about to change. RISC V takes advantage on software development techniques and make easy to make cpu. I think Intel and AMD are scary as hell,in a few years I see tons of cpu brands using RISC V.
+Bob Berg you got it right if you lived in 1985 Making a cpu core is relatively straight forward to code in VHDL. If you license the core, like ARM does, you can leave the design of the chip up to third party manufacturers. Here is a list of major open source soft cores: www.embecosm.com/2013/11/20/softcores-for-fpga-the-free-and-open-source-alternatives/ I don't know why this is all of a sudden a "new" thing.
The fact that for my senior design project in electrical engineering we are designing a RISC-V computer demo for classrooms just makes this video all that more amazing!
And the ones who claim to be "way MORE open source and knowledgeable about this" and dislike because some facts are wrong. They need to get over it and stop being a butthurt Stallman. It's a bunch of random dudes on the Internet, they only have popularity because unlike everyone else, they _act upon this_ and created a RUclips channel.
I saw the Rambus logo in there. Who let those crooks in on RISC-V? Has everyone forgotten how they sneakily filed patents on RDRAM when it was supposed to be an open and royalty free replacement for SDRAM, spearheaded mainly by Intel and Micron? DDR came about, without the Rambus crooks involved, because of those patents. RDRAM died a fairly quick and well deserved death, but that didn't stop Rambus from suing everyone they pretty much stole the RDRAM IP from.
I was wondering how many companies joined to move things forward and how many joined to bog things down or else sneaky profit on it at the expense of everyone else.
When p4 fist came out, along with rdram. A friend insisted that i build her a top of the line system so that she could compile faster. Well it was horribly underwhelming, performing about the same or even worse than her p3 system. When intel finally jumped ship to ddr2 i upgraded her ram/mobo and it finally ran well.
@white That is the problem with it. It is needed to motivate people to innovate, but it can be misused by some unscrupulous ones. Tough choice. What Linux did for software is what RISC V is targeting as a model. But in the hardware space the ecosystem is much smaller, given not everybody can get into hardware design as easy as software.
I'm actually kind of surprised. Right now Apple pays shittons of royalties to license ARM patents so they can legally manufacture compatible CPUs. You'd think they'd jump at the chance to kick ARM in the balls the same way they did to Imagination Technologies...
Nicolai Weitkemper one would say that if Chris Cotton said "I hate the old logo" but Chris did not say that therefor Chris is completely allowed to say this
@@deletevil You are aware that back doors could still be installed on open source hardware and it'd get out there the same way. Like just because it is open source doesn't mean stuff can't be snuck in.
@@johnkiser1410 The main difference is if the architecture is open source, everyone can see it, and if there is a back door, it can't be hidden forever. Intel could hide one in their closed-source software, and it becomes much more difficult to find it. With open source, the community can slowly patch these sorts of things, so the dirty NSA can't watch us all.
@@alexwolfeboy You do know there is a difference between open source hardware and software there yeah? A hardware backdoor is rather easy to install on any system. You would be right when we are talking about software, but it is rather easy to install spying hardware on hardware that is shipped out even if the "core" hardware is open source. Backdoors and random shit happen in open source software frequently all the time too. There have been instances of software repos being messed taken over by nefarious people and most people simply don't give a shit one way or another. In fact open source purists are one of the reasons Linux has so many damned issues in the public eye and even from private companies that feel they are being pressured by those type of people.
Before, the MIPS was used in textbooks. The authors of MIPS were the same ones of the first book that is shown in the video. MIPS chips used to power SGI workstations and now they can still be found in appliances. The MIPS was a very clean architecture and it was very suitable for teaching. About the complexity of x86 / x64: they are complex but the complexity is meant to be hidden by the compiler as you are probably not supposed to code in assembly any more. The various OP codes that were introduced during the years are used for very specific optimizations, such as vectorization, and they are used to enable some very specific compiler made optimizations or (re)write bits and pieces of specific libraries, e.g., the inner loop of some decoding algorithm. Other architectures were open sourced in the past, such as PPC and, on some extent, SPARC but they never landed anywhere. As for the customization part, ARM does the customization too for many customers and that seems to be the game AMD is playing as well in more recent times (especially for the consoles market).
The problem with the x86 having too much instructions is it leads to inefficiencies in the micro-architectural design. Basically it doesn't use the silicon area on the chip as well as it should. Intel with its massive resources still keeps up building better and better processors but still their momentum has been slowing down over the years. Also note that Intel architectures are only good for laptop, server and desktop areas, they are not very successful in low power, low area situations, probably owing again, to the garbage accumulated in the ISA. Furthermore, closed architectures lead to security problems, a good example is the Meltdown and Spectre vulnerabilities that remained undiscovered for decades, arguably due to lack of a large open community. An open source architecture fixes many of these problems and with enough public interest, and interest from universities RISC-V could become the future.
I am actually not convinced by this argument: > Furthermore, closed architectures lead to security problems, a good example is the Meltdown and Spectre vulnerabilities that remained undiscovered for decades, arguably due to lack of a large open community The reason why I am not convinced is that open source software isn't flawless either and fixing hardware problems is way more difficult than fixing software ones. RISC-V is meant to be expandable and create a bunch of different derived processors with more / custom instructions. The compatibility will be guaranteed only for the strict subset of initial instructions and / or a set of standardised ones, e.g., if I decide to create 10 new instructions to do X better, I am actually creating a new processor incompatible with the other ones (for the X part). If you do not think that this could be a huge problem, think to the fact that there will be a lot of small compilers and / or a huge number of backends for gcc to target specific extensions that are maintained by a small amount of people with limited resources and for that reasons they could be buggy and introduce errors in the applications built for that RISC-V flavour.
Beware, I see a huge potentiality for the RISC-V in the super-computing space as you can build your own super custom chip to do all the fancy operations that you want super fast but I would not consider that a mainstream application for a processor. Another important point is that in the super-computing space, nowadays, the CPU does very little and the bulk of the work is done by GPUs anyway
leaningtoweravenger: in the subject of Open Source and security, I need only say one name: Heartbleed. Also Meltdown and spectre would not be easier to discover if you had the source code, in fact it would be easier to discover those with just the manual than with the code.
i agree though i doubt it will be as fast as ARM SoCs any time soon but when it is i see phones going over to RISC-V instead of ARM as RISC-V will be better and they'll just get everyone to get a new version of the app recompiled for RISC-V instead of ARMv6, ARMv7, ARMv8, or whatever version they are on by then but RISC-V is only the CPU not the CPU, GPU, hard drive controller, webcam interface receiver, etc. and so on an ARM processor deals with alot of stuff that a single CPU package does not
Don't need to re-compile the app, that's all handled by the java VM stack when you run it, just publish the apk and off it goes. - Someone who writes android apps.
At 8:49 - 8:53 that transition was really really well done. At first the board was wobbly and blurry, it got glares and whatnot and then the person turns it around and the picture is really sharp and the board is stable. That's really well done. Give a bonus to that guy who did that. He deserves it. That's shockingly good contrast and gives a real effect out.
Like the new videos doing deep down geeky stuff, docker, Linux gaming, risc, etc. All great, well scripted and a welcome departure from just another pc build. Keep them coming.
Wow this is actually really awesome. I've always wondered how Intel and AMD were pretty much allowed to be the only two major cpu manufacturers on the planet. This is really cool.
They weren't "allowed", It was market forces. There were a few microprocessor manufacturers in the 90's. Some died out to mismanagement. (Motorola) Some for missing market trends. (Cyrex, along with some mismanagement) Some were bought up (and then shut down, thanks to Intel). And, some just shut down their lines and bought chips from other manufacturers, because it was in some way better or more cost effective. (IBM/Lenovo) And, every now and then, A startup will pop up to challenge AMD and Intel on this level. Sadly, due to expenses (like engineers and fabrication plants), this has a very high entry cost barrier. Plus, with most people not trusting a company that hasn't been tried and tested, it means a very slow adoption rate. Maybe this new chip standard will take hold.
Mostly because Intel and AMD are protected by the government via patent on the various parts of the x86 architecture and black box reverse engineering like Cyrix did becomes increasingly more expensive and difficult as both Intel and AMD add more and more to the architecture. And in spite of the shady practices, the reality is that both companies have been amazingly innovative and have dedicated an obscene amount of money towards R&D for much of their history, which is hardly a bad thing. A company should be justly rewarded for things like that with majority market share. Any other company attempting their way into the market requires a lot of capital simply playing catchup, let alone attempting to be on par or ahead of either, just for the risk of gathering market share. Of course, as a company slows down or begins to take advantage of that market share, people and companies will begin looking towards alternatives.
For commercial products in most of the world; Yes, Intel and AMD. Don't forget, IBM is still around. They are the big ARM processor manufacturer and special tailor-made ASIC processors for things like Super computers. Also, China has started development of their own architecture separate from all of the above. Cause, y'know, they can. www.pcworld.com/article/3086107/hardware/chinas-secretive-super-fast-chip-powers-the-worlds-fastest-computer.html 2016, so kinda old news.
This system reminds me of how the Altair computer worked in the 1970's where your CPU was a a smaller board that plugged into a FPGA like board, and connected to the RAM, and other cards via a plug.
Fun fact: AMD always push open-sourced initiatives, such as OpenGL, OpenCL and Vulkan. Wouldn't be surprised if in the near future AMD starts to back this idea.
Founder: I have developed a new tech that will revolutionize this and that at a lower cost; a win for the people. Nvidia: $$,$$$,$$$ Samsung: $$$,$$$,$$$ Intel: $,$$$,$$$,$$$,$$$
Thank god for this. Closed-source ISAs need to die, especially CISC ones like x86. x86 is burdened with needing to have backwards compatibility; it has glaring security issues like its backdoor Intel Management Engine (IME, or for AMD their PSP) which, theoretically, means that Intel (or national governments) could see everything in memory including your passwords, commandeer microphones or webcams, remotely shut down your computer, etc.; there are hundreds of undocumented instructions which have already been shown to introduce various vulnerabilities; and to top it off, it's not even efficient or anything. For the above security reasons, the FSF does not recommend any Intel hardware made since c. 2008. For the sake of security, especially, it is important that people are freely able to audit not just their software, but their hardware as well.
Open source is actually more secure because unlike other companies that produce hardware using open source CPU can create their own instructions, so malware using CPU instructions could just solved using updates.
@@AliceTheSpider But it should be made legally impossible that open source oportunistically gets closed. The ones who collaborate are shareholders and should be able to reap the fruits of the effort.
They use BSD license, so anyone can fork the code and close it. But RISC-V itself will be open. No one in the hardware business will even had looked at it if it was GPL.
@@framegrace1 Yes, obviously. What I was questioning however was the genuineness of their intent to keep it open source in the spirit of open source. I'm supportive of open source but not of clickbait.
Just to clarify a point that was lightly insinuated. If you do a little bit of research about what the risk architecture is compared to other architectures, It doesn't actually have to do with the number of instructions. It's pretty counter intuitive, but it's actually referring to the length of the instruction word. Just a heads up!
I think he said on WAN show that he didn't want to go to their PR event, specifically so he didn't have to go under NDA. Maybe he changed his mind though.
Your historical dates are off by a decade... "Core" memory was developed during the 50s, not the 60s... The Space Race and Integrated Circuit developement occurred during the 60's, not the 70s. The first microprocessor, the Intel 4004 was developed as a controller for military jets in the late 60s and the later 8008 was used as a traffic light controller and was also the first really programmable hobbyist chip. The first "personal computer" kit came out in 1972 using yet again an updated CPU, the 8080. PC history did not start in 1982 with the 8088 and the IBM PC (NOT the 8086 as you imply)… There was a full decade of computers like Altair, Imsai, NorthStar, Compupro, Cromemco and more on the Intel side. There were a few Motorola 6800 based systems and of course the 6502 based systems like Apple, Commodore, Atari, etc. for the hobbyist before then.
While you are correct in most counts (the Space Race decade being a particularly egregious error), Linus does not claim or imply the 8086 was in the IBM PC. He says the IBM PC processor used the x86 architecture. Perhaps his wording was not the most clear, but "it was gonna become the de facto home computer architecture...thanks to its use in the original IBM PC" doesn't make sense otherwise.
Core was still in common use into the 1970s. There was a huge installed base and a lot of industrial stuff used computers based on core memory. Phone exchanges used core memory till quite late in the change over.
unhappyjap: It happens all the time IRL because the name is so common. Waaaaay back when people took what they did as a last name. Bill the blacksmith became Bill Smith Bill the tinsmith became Bill Smith Bill the silversmith became Bill Smith Then as people migrated into the US Bill Xyjotulblometretski became Bill Smith Then when slaves got freed in the US. Bill the slave became Bill Smith
Programs compiled for CISC should be smaller than RISC but RISC V with compressed instructions is smaller than x86(CISC) or x64(CISC). That shows how bad x86 ISA is
thing is, modern hardware versions of either architecture are bastardized and are both mixed breed, sharing features of both philosophies. nothing is pure CISC or pure RISC anymore. CPUs are mutts now.
@@framegrace1 do you even know how many instructions are implemented in hardware for the cortex A8 ? it is in no way fitting the conventional definition of RISC. That's also why ARM is no longer calling itself Advanced RISC machines but just ARM.
ARM was a joint venture between Acorn and Apple and was derived from the CPUs from the BBC Microcomputer and the Acorn Archimedes. Amiga's had a Motorola CPU.
ARM originally stood for Acorn RISC Machines until Acorn started going under the '80s. ARM and RISCOS were spun off before the company went tits up at which time it became Advanced RISC Machines . Apple had tried an ARM CPU in the Newton and, while the Newton was a dismal failure like the Lisa, they could see the possibilities and and bought into the company.
I love this! First, your video rules! Second, I was a z-80 and 8080 Assembly programmer in my younger days. We used the same dozen instructions ALL THE TIME. So definitely, I can understand the need for a small-but-useful instruction set. I have designed a CPU with only 16 instructions, and they are the ones I used all the time when I was programming. Makes the silicon very efficient and cheap when you can do that.
It's not only the case for software but also hardware. People tend to know only about software but computer languages are also used to make hardware. Hardware in this case is integrated circuits or LSI (Large Scale Integration, processors and such) made of logic gates (AND, OR, XOR etc) and we use a Hardware Description Language (HDL, such as Verilog or VHDL) to make these integrated circuits. So you can make your own chip using these HDL sources, either hardwired or reprogrammable as in FPGAs. As an FPGA engineer, I started trying out RISC V recently, and I've been using small IPs (Intellectual Property, eg functional blocks such as Ethernet, i2c, video processors or pretty much anything you could find on a chip) from opencores.org
@@mebossyounothing well, the spy parts aren't open source both (Google's Android and ChromeOS) are only partially open source, so, if you want to put these things out, you could flash your phone with another (maybe android-based) OS like Sailfish OS or LineageOS or ChromiumOS (so ChromeOS without the closed source parts)
Before this RISCV architecture we studied MIPS. Hennesse-Patterson previous books were based on it, and this is pretty much not invented just for learning purposes, as exists market for MIPS. But this new one seems much more interesting due to the personalization available. Cool
Would love to see more educational and promotional content for a free instruction set like this. Im a college student & today after I come back from an Algebra exam I have, Ima take up risc-v assembly. It seems fun, and seems like an easier 80386 which I've already had a course on.
11:38 "speaking of time , if you find yourself with some time with your hands..." linus predicted what's gonna happen even 1 year and a half before it happened
Risc was already around for decades. Besides, ARM is a RISC architecture. RISC was always efficient due to its nature. Remember how Apple earned our love and respect using PowerPC back in the time. RISC was in the server scene as well. And UNIX was there too... On the other hand, it is a fact that it is not probable for x86 to beat RISC / ARM in their game (multiple tiny and scalable cores). It's also true that ARM has taken the CPU / pipeline architecture / optimizations to another level. They must have seen the nm barrier long time ago to have come with such genius ideas. Whatever... Nothing new, not the first RISC nor the first open computing ideal. Still good effort and thanks for sharing...
There were a few inaccuracies about microcode, microcode isn't in current cpus for backwards compatibility or legacy, it is needed. The microcode tells the cpu what every instruction means and what to do in general, it takes care of dirty bits, deals with interrupts, latches and much more, it also makes sure that no app is reading data it shouldn't. Microcode is an essential part of any cpu
So I'm studying to be a computer engineer and I've never heard of RISC-V before! HOW!! This sounds incredible! I've taken a computer architecture class and we ended up creating a software CPU from a made up ISA that the professor gave us. That really was fun but I'm never going to use that ISA ever again. I hope to get to l use RISC-V in classes and develop some cool stuff. Thanks LTT for this great video!
@@kensmith5694 that is true. I just wish I was taught a bit about this. Linus did mention FGPAs and I did take another class that introduced me to that architecture and hardware description language. What I really meat to say was this was a cool video, I wish I could have some hands on experience with it.
Zach Smith: I have lots and lots and lots of experience. Experience is what you get when stuff doesn't work :> :> Remember that HDL is just a way for you to describe your intentions to some software. You also want to know some of what actually happens inside the FPGA. That way, you can grasp what the tool is doing so you aren't completely at sea when the tool fails to do what you asked it to. Trust me on this: It seems that the more you pay for a tool and the more it promises to do the greater the odds that towards the end of the project it will simply refuse to do it just when there is a deadline to meet.
I implemented a Brainfuck-like CPU core in SystemVerilog, so it ran under a FPGA. It's technically 8-bit and pretty much as simple as it gets, but it shows that it's far from being unreachable. You can of course write an ISA, an assembler and an emulator for it without having to deal with HDLs, which is what I did a few times (but never got to anything significant). You might want to hop on r/emudev on reddit and read a few threads, look up for resources, etc. and write a CHIP-8 simulator (I wrote one that can boot a tetris ROM in 3 hours), which is a popular and fairly simple architecture. You could try Brainfuck too, which is further away from a real CPU architecture, but might help you deal a little with emulation. Look up the MIPS R3000 ISA, it is a good inspiration for how small a functional ISA can get (the R3000 is the CPU used in the PSone). Look up z80, x86, ARM instruction encoding. Try to mess a bit with that and through trial and error you'll get to an increasingly legit instruction set.
I'm currently writing a GameBoy emulator, which I wouldn't really recommend if you didn't ever deal with CPU architectures. I hope to get Tetris to show up the first screen soon... But it can be definitively fun.
Well good luck, because ill tell you right now its gonna be hell and months of energy drinks at 3AM along with a lot of education in Digital Electronics and the likes.
It is a pretty common project for college students learning Hardware Description Languages like Verilog. But if you don't plan using FPGA then that can be hell challenging
Non-binary pansexual ginger call it BS all you want, dissassemble a file and look for yourself. Youll find some variations of MOV, LEA, ADD, XOR, TEST, CALL, JMP, and etc, but these new instructions take time and a lot of effort to implement into a compiler, and are therefore rare.
I'm just seeing this now but this kind of stuff gets me so excited for the future of computing! I hope some day we see more openness in these kinds of things, wether it be architecture or even the hardware. If you like stuff like this like me, definitely check out raptor computing systems and power9 by IBM.
"There were opensource instruction sets before that never took off" - Not sure about that one, OpenSPARC, OpenPower etc... have all been somewhat successful in their own space, OpenSPARC led to the UltraSPARC T1 physical CPU which sold in reasonably high volume in the Sun Fire server range..
Were actually learning the ins and out of RISC-V at university. Talking about Pipelining Speculative execution And the basic layout of a CPU Architecture. It's quite amazing and fun to learn about.
@@NobodyYouKnow98 Why is learning about cpu architecture and how pcs work brainwashing? you actually know that Intel and amd also use risc right? they implement that at below the x86 instruction and have hardware decoding to a risc code. for Intel called yOPS.
Note to self: create a motherboard company called Leg that specializes in Arm cpu sockets. Linus will have to buy my boards, the joke will be too tempting!
ZeikJT I'll invest
SapphFire I'll invest too
I could give you a hand with that
Fun thing, ARMs 16 bit instruction set is called Thumb, it is a subset (with the most common instructions) of the ARM instruction set.
If you wanted to destroy said computer cpu would you use an Arm hammer?
Man, LTT has become a *lot* more interesting lately with videos about Linux and RISC-V etc.
I love this. =)
Honestly I had kind of stopped watching LTT, but I'm starting to pay more attention to the channel now with this new content. =)
Luredreier =)
Would love to see an update on this two and a half years later, interesting how far its gotten
Edit: now four years!
Edit: after five years, the madlads did it.
Same
Agreed
Same
Agreed
well uh RISC-V has been kinda thrown to the wayside in favor of ARM
Linus: "have you ever sat in the bath and thought 'how can I build my own CPU'?"
Me: How did you know?
Lol same
same diferent room
this guy needs an FPGA
Same here
can i get say 40-50 years old fab equipment for photolitographing my own cpu dies in a garage sale?
I think the best part of x86/x86_64 is combing through the 4000ish page combined manual set from Intel and discovering that processor cores play musical chairs to decide which core runs when booting up the system.
You can find the description in section 8.4 (Multiple-Processor Initialization) of Intel's Software Developer's Manual Volume 3 (System Programming Guide:
8.4.3 MP Initialization Protocol Algorithm for MP Systems
-- skipping stuff --
The logical processors begin monitoring the BNR# signal, which is toggling. When the BNR# pin stops toggling, each processor attempts to issue a NOP special cycle on the system bus.
The logical processor with the highest arbitration priority succeeds in issuing a NOP special cycle, and is nominated the BSP (Bootstrap Processor). This processor sets the BSP flag in its IA32_APIC_BASE MSR, the fetches and begins executing BIOS boot-strap code, beginning at the reset vector (pysical address FFFF FFF0H).
The remaining logical processors (that failed in issuing a NOP special cycle) are designated as APs (Application Processors). They leave their BSP flags in the clear state and enter a "wait-for-SIPI state."
Vol. 3A 8-19
I think Intel uses a non-democratic bus arbitration system so it is really a rigged game of musical chairs. Even if they had "round robined" it with rotating priorities, the initial value in the priority register would mean a rigged game.
@@kensmith5694 Interesting. I figured it would probably be the same core each time unless it was unable to function properly.
It is likely it is almost always the same code.
Tavi, this is the RUclips comments section. Please keep your comments argumentative and devoid of real information.
0:28 Did you know the group promoting the use of ARM CPUs in servers is called the Linaro Enterprise Group, or LEG for short?
Ah. Thanks for that information: now I get his joke for the full 100% *lol*
Is this information gonna cost me?
@UniversalExpanse Now that's some funny chit!
They're nice but they'll cost you an arm and a leg.
@@TAWithiam BASTARD! Took my line lol.
My CPU brought me here
Same tbh
Naturally
literally
My GPU showed me this
Only in Soviet Russia does CPU own you
2021: RiscV starts producing 12nm, outperforms Intel
We don't know if that would be successful, if they start producing 10nm or 7nm then it really is outperfoming intel.
its not all about the conductor size. A cpu with 12nm process can very well be worse than a 14nm++++++ Processor
@@thegamingpickle4177 How about 1um with million plusses. That surely be better than 14nm++++++
@@richardlighthouse5328 :DD
Dont hold your breath. Riscv is essentially vaporware at this point, with constant delays, promises, and claims it's being "worked on"
I like where these videos are going. I enjoy how you clearly breakdown why new technologies are relevant and important. Plus, you're introducing new ideas for all the nerds out there. Im going out to learn more about risc dev now.
it's good but he's clearly wrong about risc being better then cics or x86. x86 is currently the most efficient architecture and there is reason it has evolved the way it has.
@@marshalcraft6734 efficient in what way and at what cost ?
@@marshalcraft6734 totally not its a monopoly i hate monopolies
I'm happy with Linus's recent interest in the world of open source. Keep up the coverage!
Yeah, these videos about the current development of the underlying systems that let computing happen are really useful. Great reason for me to keep following.
would be cool if someone would be getting into open source GPU as well :)
Maybe he will stop using GPL violating unraid then...
Then there should be a lot more linux over windows as of being the os used on the test benches though.
Super dope ✅?
That is the cutest CPU cooler I've ever seen
A lot of early CPU heatsinks for the 486DX looked similar.
Northridge coolers
my intel atom cooler is simular but its just runing 1 kw cnc macine so
Well, old cpus used to have similar coolers.
Back in the day CPU's didn't even have coolers let alone fans in the case except for the power supply
Yes I have a line of cpu's in mind:
LEG cpu (Legitimate Extreme Goodness)
FINGER cpu (Fantasticly Inexpensive and Greatly Enduring Resillience)
NOSE cpu (Never Overpowered Seriously Ecofriendly)
BRAIN cpu (Benign and Really Artificial Intelligent Now)
MOUTH cpu (Mostly Overrated and Unbelievably Terrible Heuristics)
LIPS cpu (Largely Integrated Problem Solving)
NAIL cpu (Nice, Another Indifferent Loser)... really 'nailed' it with this one.
dont forget the "Protected Environment and Neat Implemented Security"-cpu... for running code in a container of some sort, so it cannot harm other soft/hardware
@@chrisakaschulbus4903 wow
THUMB is a thing
Thanks for your play on the ARM architecture that actually exists!
Linus dropped the old logo and broke it didn't he?
Benji DROP what's ligma?
@@Thatonedud212 sugondese nuts
ma nama jeff
lolllllllllll
I liked the old logo...
Linus: "After I tell you about our sponsor..."
Me: "Tunnel Bear!"
Linus: "Noble Chair!"
...... close enough
Did they pull all the tunnelbear adds out of old videos
@@Spacecadet3890 why ?
@@sagichnichtsowiesonicht7326 mcaffe bought tunnel bear, they don't work with them anymore because of it, google macafee tunnel bear and you will find the answers i believe linus has a video about it, i was just curious if they went and pulled all the old ones after they stopped working with them but they have not
h
I never watch sponsors, there are blocks for these out there
Honestly this technology makes me more excited than the launch of RTX.
Radon Technologies what? :P
@@TheBlackSkimmer The new GeForce RTX line of GPUs.
@@MineBro56 I know. I am just messing with you. Have you seen the lastest wan show on this GPU?
Honestly, anything does :D
@@TheBlackSkimmer oof
10:59 Linus: "Previously some fantasy architecture would have to be used"
MIPS: "Am I a joke to you?"
Gotta catch that rabbit
Am I a joke to you?
Pfft. Yes. Tanenbaum was really good a teaching, but terrible at performance.
ME TOO!
Hey, have you heard about this io_uring thing? People are saying it's going to make my 350 syscalls look fat.
Like the filesystem?
God, that joke was cornier than grouping me with other limbs.
I don't get it, is it the T2 in my name that makes people afraid of me?
Nah mate, Sun died to death, like Motorola.
At least it's not as bad as Hexagon. I ended up in the dreamcast, nobody will remove ME from GCC.
I'm here too! Guys! Guys!
Ignore him, I'm your microcontroller.
ARM! He stole my peripherals!
Lol, prove it in china.
I, uh.. Wait, how did you all get in here, this is a mobile device!
Shhhh. THEY'll notice your silly british walk.
Who's they?
You know. THEM. The ones who killed the sun.
That's not all they killed.
I thought you got better?
ME TOO!
No, no, I'M the one who killed the sun. Had help from One Rich Asshole Called Larry Ellison, and that other company with the dollar sign in their name.
Everyone's ignoring me.
At least you guys EXIST.
I like trains!
ME TOO!
... I'm surrounded by pretentious assholes.
And idiots pounding their heads in the sand reinventing everything. But hey, at least the assholes are high functioning.
This video, like much of the material about RISC-V, is fueled on hype and misleading statements more than anything. Open ISAs have been around for a while. Pure RISC is impractical and all popular RISC ISAs end up using CISC-y instructions for the sake of performance. I very much support the notion of moving towards open hardware. But maybe we should take a look at what's already out there, including de facto free off-patent ISAs like SuperH, before jumping on the hype train.
@@KyussTheWalkingWorm Dude, anything out of the village idiot's mouth is hype or misleading. That's what he does. That's who he is. But it's still entertaining. Also, there's quite a few other open ISAs you're missing if you stick with textbook risc designs like SuperH. OpenSPARC T2 was solid, but not useful unless you have the resources to fab a board around it. But the real up-and-comer right now is parallax's propeller2; they opened the ISA around 2013/2014 IIRC.
www.parallax.com/microcontrollers/propeller-1-open-source
forums.parallax.com/discussion/170380/new-p2-silicon/p1
The successor is just leaving it's final tapeout and full production was supposed to commence in april, but.... coronavirus. So now it's looking like june/july. My RevB engineering sample just showed up not too long ago. It's amazing to have such a unique design just bang HDMI output from a header, while capturing four analog inputs.
forums.parallax.com/discussion/171331/digital-digitizer-now-mixed-signal-scope-dds/p1
As a recent Comp Sci grad, I came here to make this comment. MIPS was used to run Irix, to make "Jurassic Park" (featuring Irix!), and it powered the PlayStation Portable! Plus, it is really easy to understand. Now, find a modern workstation that uses it... well, you can't, but it has a lot more real hardware than RISC-V has! (I do with RISC-V and the folks behind it all success, though.) Pour out one for our old pal, MIPS: I knew him well, Horatio.
Literally nothing happened in that video but it was incredibly well scripted so I was hooked from the start. Even not knowing anything about CPU architecture I still understood EVERYTHING
linus in a nutshell.
Just because you didn't understand it doesn't mean nothing happened in the video 😂
@@claudiolluberes111 he did understand
Check out Wiki..! Wow, This was only new 26 friggin' Years ago! Only reason I didn't buy one is, Because everyone else was Microsoft Cucked! If Your phone was using one of these right now it would literally KICK THE SHIT Out of the CPU's we have now!
Only reason your phone isn't running one of these bad boys is...?
Wait for it!!!
Fucking Microsoft!!!!!
Bill Gates is a thief and a Billionaire ASSHOLE! Let's see if this post makes it to the comment section. Controlled by yours truly! Also, Google and Facebook! The worlds biggest friggin' Controllers of FREE SPEECH! Let's not forget about YOU TUBE AND TWITTER! Fuck the MSN ( Main Stream Media)!!!!!!!!!! WOLVERINES!!! Red Dawn is a 1984 American war film directed by John Milius!!!! Watch it and the remake!! Think about it!!!
Before it is too late.. Watch Alex Jones @www.Infowars.com or newswars.com or www.Prison planet.com.... Or get Infowars Official app! Top of news section. Or go to www.infowars.com and download the free app today.. To see why the Democrats and the New World order hates Alex so bad, That they would ban his 1st Amendment Right according to the United States of America Constitution! Silencing Free Speech is a CRIME!!!!
@@claudiolluberes111 sorry I meant the video didn't change setting or anything it was just him talking
Actually, it's not so much new logo that's throwing my mind into a "loop"....it's the COLOUR scheme! So used to orange w/ white, black, grey....that the purple & red? is seriously just messing with my mind 😅
Aepek didn’t even notice lik
I just noticed it a little before reading your comment.
color
*LoganPaul
BAHAHAHAHAH
I love the "fu540" naming more than I should...
freedom unleashed
seeing as it's sponsered by Google and all the other tech giants I'm assuming that they really do mean FU in the sense that you find funny and they named it freedom unleashed as an even bigger FU, like Google would ever support freedom. hahaha.
Fu540 times
Lorenzo Torres Yep, just like AV1 codec for video, with hundreds of companies behind it in the Alliance for Open Media. These big companies are getting rid of the shitty locked down world we're in and making open products for anyone to contribute to and work with/on. After hardware will be software giants death and then ISP giants deaths
FU-540 => f.. you-sword art online
And so Huawei likely will go for RISC-V to build their next Kirin processor without any worry of US ban (ARM license)
That would be cool as fuck.
@@mritunjaymusale guess what
@@mritunjaymusale samsung is starting to use risc-v
I'm pretty sure Kirin is by SK hynix isn't owned by huawei but instead south korean
yeah that’s not how that works
This video is much more important than any of the normal videos on this channel. Projects like this are the only chance to defeat the disgusting surveillance monopoly corporations.
wow ..... i bet google told you that right
What do you mean?
I think AMD and Intel will dominate the market for at least the next decade.
ThronRitter80 Yea, it seems so, unfortunately. Did you know that any Intel CPU after the core 2 duo have backdoors you can't get rid of even when instaling freest GNU\Linux distribution?
So you say google spy on porn history, then you say no one has surveillance. Rather contradictory.
I really would love for an Open Source architecture would become standard. It would benefit everybody in the long run.
Animated Freak I doubt it would be as profitable for other companies tho
@@memoriasIT Why not? If anything, it's profiting more because companies can manufacturer their own processors, making it cheaper for them and possibly consumers.
wouldn't benefit intel or AMD, so it won't happen
@@memoriasIT open source/'free' doesnt mean free as in cost. People could still turn a profit on modifications of it
Open source is not always better. The profit incentive produces tangible innovation, and often companies that do really well with proprietary technology stick around to support it and push the product to maturity. As consumers what we really want is fast and capable computers.
*Shoutout to linus media group for making the ads and intro only 10 seconds each so i can easily skip over it*
Can't remember what the first ad was about.
I think I when someone skips a ad immediately they don’t get any revenue or just very little
@@rockbros100 they are talking about the in video ad which the advertisers probably pay for in advance
shhhh don't tell everyone
Backwerds if you love the video, you should consider support it by watching the ads
I love this! I can't wait until everything goes open source so that we can see faster advancement in computer technology development. You have given us great news, thanks!
This is a really interesting bit of tech, because it has a lot of growth potential. But when it becomes cheaper, this would be an amazing tool for many tech hobbyists.
John J it will be difficult to drive down over 1k product down to 35$ like a raspbery pi
true, but getting the price down to even 500 dollars would be fantastic. Since it offers some really interesting opportunities.
@@benni5541 I disagree, if they make a bunch of these it has the potential to be cheaper. Hell, Raspberry could use it instead of ARM, as it would be cheaper because it's open source!
@@saltysoysauce954 or arduino
Getting it from 28 to 7nm would already help + large scale production also helps mitigate costs.
Who else misses the old logo
DaintierFox not me
🙋♂️(imagine it with a sad face)
It burns my eyes! Reeeeeeeeeeeeeeeeeeeee.
Not Me! I Like The New Logo!
I dont like me
"FU" 540, later more FUs will be released.
Real base
wrg, say any s ok
Fuck
Many, Many more FUs will indeed be released.
So 8 years ago when I was learning computer architecture, they taught us MIPS and x86 (32 bit). Looking forward to RISC-V tho, gonna be great to have open architectures!
Well open source software has been proven to be a major factor in software development and now runs super computers and 60+ percent of the servers on the internet. It only makes sense to do the same for hardware at some point. Proprietary lockdown and expensive licenses stifle innovation. I look forward to seeing this hardware evolve.
Hardware and software development is quite different though. If I design a piece of software, I write it, test it and distribute it quite easily directly from my computer. If I design a cpu, I have to first write it in hardware design language, test it in simulation, get it manufactured, physically test it, set up a supply chain to manufacture and distribute it. As you can see, the costs for hardware development is quite high. Even then you can't guarantee the success of your product if you can't beat existing architectures at certain niches. That's why no one is really designing new architectures outside of academia and large corporations.
that is just about to change. RISC V takes advantage on software development techniques and make easy to make cpu. I think Intel and AMD are scary as hell,in a few years I see tons of cpu brands using RISC V.
Thought in this context "making a CPU" simply means microcoding an update to an existing (micro)code. Did I get it right?
+Bob Berg you got it right if you lived in 1985
Making a cpu core is relatively straight forward to code in VHDL. If you license the core, like ARM does, you can leave the design of the chip up to third party manufacturers.
Here is a list of major open source soft cores:
www.embecosm.com/2013/11/20/softcores-for-fpga-the-free-and-open-source-alternatives/
I don't know why this is all of a sudden a "new" thing.
+MsLia32 oh wait i should have watched the video first
The fact that for my senior design project in electrical engineering we are designing a RISC-V computer demo for classrooms just makes this video all that more amazing!
Who follows a tech channel and dislikes a video about an open source processor?
KeeperOfKale kid : gugguhuguguuu this is not over priced laptop review with Fortnite guguguguguughhh disliked
Ikr
This guy
And the ones who claim to be "way MORE open source and knowledgeable about this" and dislike because some facts are wrong. They need to get over it and stop being a butthurt Stallman. It's a bunch of random dudes on the Internet, they only have popularity because unlike everyone else, they _act upon this_ and created a RUclips channel.
Intel
"After a word from our sponsors"
Me: skips 20 seconds
linus is more presenter reading scripts then tech.
Linus: :o
Shift right right
Why are you proud of the fact that you're not supporting content creators?
@@granitbajraktari1600 did I say I was proud. Btw I bet that when you get an add you skip as soon as 5 seconds are over. Smh
I saw the Rambus logo in there. Who let those crooks in on RISC-V? Has everyone forgotten how they sneakily filed patents on RDRAM when it was supposed to be an open and royalty free replacement for SDRAM, spearheaded mainly by Intel and Micron? DDR came about, without the Rambus crooks involved, because of those patents. RDRAM died a fairly quick and well deserved death, but that didn't stop Rambus from suing everyone they pretty much stole the RDRAM IP from.
Thought the exact same thing!
I was wondering how many companies joined to move things forward and how many joined to bog things down or else sneaky profit on it at the expense of everyone else.
Who let? Can anyone stop them from joining an open source project?
When p4 fist came out, along with rdram. A friend insisted that i build her a top of the line system so that she could compile faster. Well it was horribly underwhelming, performing about the same or even worse than her p3 system. When intel finally jumped ship to ddr2 i upgraded her ram/mobo and it finally ran well.
@white That is the problem with it. It is needed to motivate people to innovate, but it can be misused by some unscrupulous ones. Tough choice. What Linux did for software is what RISC V is targeting as a model. But in the hardware space the ecosystem is much smaller, given not everybody can get into hardware design as easy as software.
Not even remotely surprised Apple wasn't on that list of companies...
for real xD
Surprised he didn't mention Qualcomm being on there though, they're massive.
Probably because they can't control it and use it for themselves
Glyn Davies APPLE BAD
I'm actually kind of surprised. Right now Apple pays shittons of royalties to license ARM patents so they can legally manufacture compatible CPUs. You'd think they'd jump at the chance to kick ARM in the balls the same way they did to Imagination Technologies...
Aren't they developing their own CPU's again?
I would invest in this, but my advisors say this is too RISCy
I see what you did there. I bet they are closed minded because they are onto closed source.
0:55 "and i can not wait, to tell you about this thing"
"to tell you about this sponsor- wait what?"
content has been really intresting lately keep up the good work @linustechtips
I didn't hear a thing... JUST LOOK AT QUAKE 2 !!!
This make me feel deja vu because i pass this game again few days ago
rite lol
I miss the old Logo
Nicolai Weitkemper one would say that if Chris Cotton said "I hate the old logo" but Chris did not say that therefor Chris is completely allowed to say this
this new logo is just weird, to messy
You would say that, with your Windows 95 pfp xD
Same
Danielle Spargo I use windows 95 all the time for offline things even tho I’m only 14
i like how AMD is always pushed out of the way even though they made x64
Doesn't matter, CPUs of both companies contain hardware backdoor, it's time we really need open-source backed hardware as well.
@@deletevil You are aware that back doors could still be installed on open source hardware and it'd get out there the same way. Like just because it is open source doesn't mean stuff can't be snuck in.
@@johnkiser1410 The main difference is if the architecture is open source, everyone can see it, and if there is a back door, it can't be hidden forever. Intel could hide one in their closed-source software, and it becomes much more difficult to find it. With open source, the community can slowly patch these sorts of things, so the dirty NSA can't watch us all.
@@alexwolfeboy You do know there is a difference between open source hardware and software there yeah? A hardware backdoor is rather easy to install on any system. You would be right when we are talking about software, but it is rather easy to install spying hardware on hardware that is shipped out even if the "core" hardware is open source. Backdoors and random shit happen in open source software frequently all the time too. There have been instances of software repos being messed taken over by nefarious people and most people simply don't give a shit one way or another. In fact open source purists are one of the reasons Linux has so many damned issues in the public eye and even from private companies that feel they are being pressured by those type of people.
I don't (like the way AMD are pushed out of the way).
Before, the MIPS was used in textbooks. The authors of MIPS were the same ones of the first book that is shown in the video. MIPS chips used to power SGI workstations and now they can still be found in appliances. The MIPS was a very clean architecture and it was very suitable for teaching.
About the complexity of x86 / x64: they are complex but the complexity is meant to be hidden by the compiler as you are probably not supposed to code in assembly any more. The various OP codes that were introduced during the years are used for very specific optimizations, such as vectorization, and they are used to enable some very specific compiler made optimizations or (re)write bits and pieces of specific libraries, e.g., the inner loop of some decoding algorithm.
Other architectures were open sourced in the past, such as PPC and, on some extent, SPARC but they never landed anywhere. As for the customization part, ARM does the customization too for many customers and that seems to be the game AMD is playing as well in more recent times (especially for the consoles market).
The problem with the x86 having too much instructions is it leads to inefficiencies in the micro-architectural design. Basically it doesn't use the silicon area on the chip as well as it should. Intel with its massive resources still keeps up building better and better processors but still their momentum has been slowing down over the years. Also note that Intel architectures are only good for laptop, server and desktop areas, they are not very successful in low power, low area situations, probably owing again, to the garbage accumulated in the ISA. Furthermore, closed architectures lead to security problems, a good example is the Meltdown and Spectre vulnerabilities that remained undiscovered for decades, arguably due to lack of a large open community. An open source architecture fixes many of these problems and with enough public interest, and interest from universities RISC-V could become the future.
I am actually not convinced by this argument:
> Furthermore, closed architectures lead to security problems, a good example is the Meltdown and Spectre vulnerabilities that remained undiscovered for decades, arguably due to lack of a large open community
The reason why I am not convinced is that open source software isn't flawless either and fixing hardware problems is way more difficult than fixing software ones. RISC-V is meant to be expandable and create a bunch of different derived processors with more / custom instructions. The compatibility will be guaranteed only for the strict subset of initial instructions and / or a set of standardised ones, e.g., if I decide to create 10 new instructions to do X better, I am actually creating a new processor incompatible with the other ones (for the X part). If you do not think that this could be a huge problem, think to the fact that there will be a lot of small compilers and / or a huge number of backends for gcc to target specific extensions that are maintained by a small amount of people with limited resources and for that reasons they could be buggy and introduce errors in the applications built for that RISC-V flavour.
Beware, I see a huge potentiality for the RISC-V in the super-computing space as you can build your own super custom chip to do all the fancy operations that you want super fast but I would not consider that a mainstream application for a processor. Another important point is that in the super-computing space, nowadays, the CPU does very little and the bulk of the work is done by GPUs anyway
leaningtoweravenger: in the subject of Open Source and security, I need only say one name: Heartbleed.
Also Meltdown and spectre would not be easier to discover if you had the source code, in fact it would be easier to discover those with just the manual than with the code.
i imagine that the cost to license CPU architecture would be a bit... DisARMing
i agree though i doubt it will be as fast as ARM SoCs any time soon but when it is i see phones going over to RISC-V instead of ARM as RISC-V will be better and they'll just get everyone to get a new version of the app recompiled for RISC-V instead of ARMv6, ARMv7, ARMv8, or whatever version they are on by then but RISC-V is only the CPU not the CPU, GPU, hard drive controller, webcam interface receiver, etc. and so on an ARM processor deals with alot of stuff that a single CPU package does not
Don't need to re-compile the app, that's all handled by the java VM stack when you run it, just publish the apk and off it goes.
- Someone who writes android apps.
Epic win is epic
"after I tell you about our sponso-" *presses forward arrow a couple times*
Guilty
dont skip the intro or ban
Shhhhh....he doesnt have to know
Alden Prokup
you mean the L key.
Yes
At 8:49 - 8:53 that transition was really really well done. At first the board was wobbly and blurry, it got glares and whatnot and then the person turns it around and the picture is really sharp and the board is stable. That's really well done. Give a bonus to that guy who did that. He deserves it. That's shockingly good contrast and gives a real effect out.
Like the new videos doing deep down geeky stuff, docker, Linux gaming, risc, etc. All great, well scripted and a welcome departure from just another pc build. Keep them coming.
Wow this is actually really awesome. I've always wondered how Intel and AMD were pretty much allowed to be the only two major cpu manufacturers on the planet. This is really cool.
Others went bankrupt (eg. Cyrix). Intel left AMD alive because didn't want US government to intervene (anti-monopoly laws).
there is also MIPS
They weren't "allowed", It was market forces. There were a few microprocessor manufacturers in the 90's. Some died out to mismanagement. (Motorola) Some for missing market trends. (Cyrex, along with some mismanagement) Some were bought up (and then shut down, thanks to Intel). And, some just shut down their lines and bought chips from other manufacturers, because it was in some way better or more cost effective. (IBM/Lenovo)
And, every now and then, A startup will pop up to challenge AMD and Intel on this level. Sadly, due to expenses (like engineers and fabrication plants), this has a very high entry cost barrier. Plus, with most people not trusting a company that hasn't been tried and tested, it means a very slow adoption rate.
Maybe this new chip standard will take hold.
Mostly because Intel and AMD are protected by the government via patent on the various parts of the x86 architecture and black box reverse engineering like Cyrix did becomes increasingly more expensive and difficult as both Intel and AMD add more and more to the architecture.
And in spite of the shady practices, the reality is that both companies have been amazingly innovative and have dedicated an obscene amount of money towards R&D for much of their history, which is hardly a bad thing. A company should be justly rewarded for things like that with majority market share. Any other company attempting their way into the market requires a lot of capital simply playing catchup, let alone attempting to be on par or ahead of either, just for the risk of gathering market share.
Of course, as a company slows down or begins to take advantage of that market share, people and companies will begin looking towards alternatives.
For commercial products in most of the world; Yes, Intel and AMD. Don't forget, IBM is still around. They are the big ARM processor manufacturer and special tailor-made ASIC processors for things like Super computers. Also, China has started development of their own architecture separate from all of the above. Cause, y'know, they can.
www.pcworld.com/article/3086107/hardware/chinas-secretive-super-fast-chip-powers-the-worlds-fastest-computer.html
2016, so kinda old news.
I never thought that I'd see the day that Linus uses a $5 HD 6450. I thought that he'd put at least a GTX 1060 in there.
DriVErS
@@thronritter6295 Yes of course, I was talking about in general because usually he focuses on high end components.
Then your new here. Huntrin.....
Good luck getting Nvidia drivers to work on a non-x86 system
Well, they ARE on the list of companies that'll use this. Eventually they'll have to have drivers for it, won't they?
This system reminds me of how the Altair computer worked in the 1970's where your CPU was a a smaller board that plugged into a FPGA like board, and connected to the RAM, and other cards via a plug.
It looks like this will help smaller companies become semi popular instead of having Intel and amd hog the market and I'm all for competition.
Yes we definitely need some competition so the prices drop a bit 🙏
I think AMD would probably have no problem joining them. They have been talking to ARM as well in the past.
Fun fact: AMD always push open-sourced initiatives, such as OpenGL, OpenCL and Vulkan. Wouldn't be surprised if in the near future AMD starts to back this idea.
Founder: I have developed a new tech that will revolutionize this and that at a lower cost; a win for the people.
Nvidia: $$,$$$,$$$
Samsung: $$$,$$$,$$$
Intel: $,$$$,$$$,$$$,$$$
@ETM Nation - Best ETM Music nah more like $$$$ but long run
Thank god for this. Closed-source ISAs need to die, especially CISC ones like x86. x86 is burdened with needing to have backwards compatibility; it has glaring security issues like its backdoor Intel Management Engine (IME, or for AMD their PSP) which, theoretically, means that Intel (or national governments) could see everything in memory including your passwords, commandeer microphones or webcams, remotely shut down your computer, etc.; there are hundreds of undocumented instructions which have already been shown to introduce various vulnerabilities; and to top it off, it's not even efficient or anything. For the above security reasons, the FSF does not recommend any Intel hardware made since c. 2008. For the sake of security, especially, it is important that people are freely able to audit not just their software, but their hardware as well.
You think this is true open source? Can the MakerBot story repeat? Maybe open source has become clickbate for cheap labour enthousiasts.
Open source is actually more secure because unlike other companies that produce hardware using open source CPU can create their own instructions, so malware using CPU instructions could just solved using updates.
@@AliceTheSpider But it should be made legally impossible that open source oportunistically gets closed. The ones who collaborate are shareholders and should be able to reap the fruits of the effort.
They use BSD license, so anyone can fork the code and close it. But RISC-V itself will be open. No one in the hardware business will even had looked at it if it was GPL.
@@framegrace1 Yes, obviously.
What I was questioning however was the genuineness of their intent to keep it open source in the spirit of open source. I'm supportive of open source but not of clickbait.
Just to clarify a point that was lightly insinuated. If you do a little bit of research about what the risk architecture is compared to other architectures, It doesn't actually have to do with the number of instructions. It's pretty counter intuitive, but it's actually referring to the length of the instruction word. Just a heads up!
Lmao what happened to the profile picture
Edit: why tf did this get so many likes for a genuine question? Lmao ty tho
Linus said it will change eventually. They're just searching for something refreshing
LTT
@@forgettd pheww
It actually says L T T if u can read
Mr.Gl0ck0 it looks like a channel super fun kind of logo
linus is the man that does not give a damn about a new graphics card,all tech channels focus on thw new gpu's
Techlinked has videos on the new Graphicscards and techlinked is part off linusmediagroup
Probably released on floatplane and will reach us in a few days
He could already have a sample and be under NDA.
Prob waiting to make a huge rant against them.
I think he said on WAN show that he didn't want to go to their PR event, specifically so he didn't have to go under NDA. Maybe he changed his mind though.
Connected to European vpn. Damn wish ads are annoying.
here in iraq there is no ads 😌
yeaa it's like a aids in europe.
Tell me about it... No I dont need "fancy roze bangle drunkard" shit or the damn mop socks...
use ublock origin on mozilla or adblock plus i never see again other ads
The smartwatch ad .... Reeeeeeeeeeeeee the wish ads are so stupid
The FU 540, soon to be included with the SUX 9000 graphics chip.
Which would have a manufacturer called SHT make their own SUX 9000s.
@@scriptedreality2330 hahahahaha!
@@MorrisChannel4 and of course another competitor called PIS, known for their great overclocking.
Your historical dates are off by a decade... "Core" memory was developed during the 50s, not the 60s... The Space Race and Integrated Circuit developement occurred during the 60's, not the 70s.
The first microprocessor, the Intel 4004 was developed as a controller for military jets in the late 60s and the later 8008 was used as a traffic light controller and was also the first really programmable hobbyist chip. The first "personal computer" kit came out in 1972 using yet again an updated CPU, the 8080.
PC history did not start in 1982 with the 8088 and the IBM PC (NOT the 8086 as you imply)… There was a full decade of computers like Altair, Imsai, NorthStar, Compupro, Cromemco and more on the Intel side. There were a few Motorola 6800 based systems and of course the 6502 based systems like Apple, Commodore, Atari, etc. for the hobbyist before then.
While you are correct in most counts (the Space Race decade being a particularly egregious error), Linus does not claim or imply the 8086 was in the IBM PC. He says the IBM PC processor used the x86 architecture. Perhaps his wording was not the most clear, but "it was gonna become the de facto home computer architecture...thanks to its use in the original IBM PC" doesn't make sense otherwise.
Core was still in common use into the 1970s.
There was a huge installed base and a lot of industrial stuff used computers based on core memory. Phone exchanges used core memory till quite late in the change over.
ken smith and john smith. what a coincidence
unhappyjap:
It happens all the time IRL because the name is so common.
Waaaaay back when people took what they did as a last name.
Bill the blacksmith became Bill Smith
Bill the tinsmith became Bill Smith
Bill the silversmith became Bill Smith
Then as people migrated into the US
Bill Xyjotulblometretski became Bill Smith
Then when slaves got freed in the US.
Bill the slave became Bill Smith
and will smith became The Fresh Prince of Bel-Air
But can it run club penguin hentai at 4K resolution
why do u get likes
LOL
did you mean: "club penguin roblox hentai"?
excuse me what the fuck
Damn you, now I'm curious.
There is a startling lack of RISC v. CISC arguments in the comments.
Programs compiled for CISC should be smaller than RISC but RISC V with compressed instructions is smaller than x86(CISC) or x64(CISC). That shows how bad x86 ISA is
There's no such thing as white CISC male privilege. Kappa
thing is, modern hardware versions of either architecture are bastardized and are both mixed breed, sharing features of both philosophies. nothing is pure CISC or pure RISC anymore. CPUs are mutts now.
Just made one
no one uses cisc, if you want a CPU that actually does piplining when its a risc cpu.
Can Huawei use this cpu architecture instead of arm.
Update÷ Huawei is using this cpu architecture for all their new CPU 's
Cool
What's the source of the news?
Sauce?
Lol Awesome, open source hardware on shady chinese software. Sure that will cure all the privacy concerns with them
@@MrMozkoZrout isn't open-source android huawei's software? Noob question maybe
I expected a new intro with the new logo :(
levi T Nahhh
smh it would be as shit as the logo
This video is on Floatplane first so it did not have the new logo
@@lilball8956 agreed
Same
ARM is also RISC (Advanced Risc Machines). Just FYI. Intel and AMD are CISC.
Acorn.
Lol. Maybe long ago but ARM is no longer RISC
locknight It is still RISC. You clever guys. Go read a little
@@framegrace1 do you even know how many instructions are implemented in hardware for the cortex A8 ? it is in no way fitting the conventional definition of RISC. That's also why ARM is no longer calling itself Advanced RISC machines but just ARM.
> Intel and AMD are CISC.
Only ISA-wise. Internally Intel became RISC in 1995 with the Pentium Pro. AMD followed shorty after.
Did the old logo die when you crashed the plane?
Welp. It stopped floating anymore then.
I’d like to take a moment To thank Linus and his team for doing a great job of explaining this. Keep up the great work!
Burn: Risc architecture is going to change everything.
Crash: Yeah, Risc is good.
- Hackers
No shit scrolled thinking to myself "really? No hackers reference?" Lol
It's a movie quote from Hackers. Angelina Jolie and Johnny Lee Miller. Good movie.
I wondered how far I would have to scroll for this comment. Not as far as I thought.
I hope you don't screw like you type. . . .
Thank you for ARM and RISC, Cambridge!
Acorn :)
I was gonna comment, wernt arm cpus risc based? that were evolved from an amiga design just before they went under?
ARM stands for "Advanced RISC Machine" but it's really leaning towards CISC...
ARM was a joint venture between Acorn and Apple and was derived from the CPUs from the BBC Microcomputer and the Acorn Archimedes. Amiga's had a Motorola CPU.
ARM originally stood for Acorn RISC Machines until Acorn started going under the '80s. ARM and RISCOS were spun off before the company went tits up at which time it became Advanced RISC Machines . Apple had tried an ARM CPU in the Newton and, while the Newton was a dismal failure like the Lisa, they could see the possibilities and and bought into the company.
Well... I have to say I've been thinking how can I design my own CPU!! Ben Eater has a great video which started my path into that treacherous path...
I love this! First, your video rules! Second, I was a z-80 and 8080 Assembly programmer in my younger days. We used the same dozen instructions ALL THE TIME. So definitely, I can understand the need for a small-but-useful instruction set. I have designed a CPU with only 16 instructions, and they are the ones I used all the time when I was programming. Makes the silicon very efficient and cheap when you can do that.
"That kinda thing is gonna cost you an ARM and a leg" - Linus 2018
Conor Matthews Well, works with Fullmetal Alchemist too XD
open source is the future of computing and software.
I agree
It's not only the case for software but also hardware. People tend to know only about software but computer languages are also used to make hardware. Hardware in this case is integrated circuits or LSI (Large Scale Integration, processors and such) made of logic gates (AND, OR, XOR etc) and we use a Hardware Description Language (HDL, such as Verilog or VHDL) to make these integrated circuits. So you can make your own chip using these HDL sources, either hardwired or reprogrammable as in FPGAs. As an FPGA engineer, I started trying out RISC V recently, and I've been using small IPs (Intellectual Property, eg functional blocks such as Ethernet, i2c, video processors or pretty much anything you could find on a chip) from opencores.org
Well google android is open source, chrome is open too, and both of them are nothing more than spyware packages.
die windows die
@@mebossyounothing well, the spy parts aren't open source
both (Google's Android and ChromeOS) are only partially open source, so, if you want to put these things out, you could flash your phone with another (maybe android-based) OS like Sailfish OS or LineageOS or ChromiumOS (so ChromeOS without the closed source parts)
One of the best presentation and video from Linus. I love this polished format, please cover more revolutionary tech like this one.
2018: What architecture is ever replacing x86 at home?
2020: ARM-based Apple M1 said HELLO.
Before this RISCV architecture we studied MIPS. Hennesse-Patterson previous books were based on it, and this is pretty much not invented just for learning purposes, as exists market for MIPS. But this new one seems much more interesting due to the personalization available.
Cool
Is that quake in the background
I guess it is
Yes, that is Quake 2 running in the background.
The IBM Personal Computer actually used the slightly older Intel 8088 (although the 8086 had already been invented).
Wrong way around .. the 8086 came first. 8088 was a later reduced cost (and slower) version.
@@BruceHoult I stand corrected.
Would love to see more educational and promotional content for a free instruction set like this. Im a college student & today after I come back from an Algebra exam I have, Ima take up risc-v assembly. It seems fun, and seems like an easier 80386 which I've already had a course on.
Never ever in my life have I clicked on a video faster...
And never in your life you will make a fresh joke.
RISC V is pretty old arch, should try to keep up to date
Better Fly
By the way I was not making a joke I clicked on it real fast...
Thought it was a mistake...
It happened...
Stallman approves
Stallman would want to call it GNU/RiscV
New logo confused me. I thought this was a repost channel
So next video... how to set it up and then how to overclock it!
0:13 My answer: OMG, yes I thought I was the only one!
Linus: Ok, maybe not.
Me: Oi what!? God dammit.
11:38 "speaking of time , if you find yourself with some time with your hands..."
linus predicted what's gonna happen even 1 year and a half before it happened
RISC architecture is going to change everything. Yeah, RISC is good...
Nice quote
My Archimedes A3000 says you are correct
Risc was already around for decades.
Besides, ARM is a RISC architecture.
RISC was always efficient due to its nature.
Remember how Apple earned our love and respect using PowerPC back in the time.
RISC was in the server scene as well. And UNIX was there too...
On the other hand, it is a fact that it is not probable for x86 to beat RISC / ARM in their game (multiple tiny and scalable cores). It's also true that ARM has taken the CPU / pipeline architecture / optimizations to another level. They must have seen the nm barrier long time ago to have come with such genius ideas.
Whatever... Nothing new, not the first RISC nor the first open computing ideal.
Still good effort and thanks for sharing...
Karl Lundblad The RISC is just too high with this architecture...
Understood the 1995 reference lol
Is this the same guy from LinusTechTips?
I just wanna run my fingers through his hair
This is linus tech tipps ?!
PLASMA chicken whoosh
And look at the new profile pic
I don’t get it
Yep, he still butchered the subject and got things wrong. Implying ARM is CISC when RISC is IN THE NAME!
There were a few inaccuracies about microcode, microcode isn't in current cpus for backwards compatibility or legacy, it is needed.
The microcode tells the cpu what every instruction means and what to do in general, it takes care of dirty bits, deals with interrupts, latches and much more, it also makes sure that no app is reading data it shouldn't.
Microcode is an essential part of any cpu
CPU: "It's definitely a person, no doubt about it"
Also CPU: "It might be a _potted plant_ though"
EDIT: 7:38
"After a word from our sponsors"
Me panics and rushes to skip the sponsors.
Same here!
Are you too wondering " Who is playing the game in the gaming rig in front to Linus ? "
No
I really love your videos!
So I'm studying to be a computer engineer and I've never heard of RISC-V before! HOW!! This sounds incredible! I've taken a computer architecture class and we ended up creating a software CPU from a made up ISA that the professor gave us. That really was fun but I'm never going to use that ISA ever again. I hope to get to l use RISC-V in classes and develop some cool stuff. Thanks LTT for this great video!
The skills you learned were more important than the specific instruction set.
@@kensmith5694 that is true. I just wish I was taught a bit about this. Linus did mention FGPAs and I did take another class that introduced me to that architecture and hardware description language. What I really meat to say was this was a cool video, I wish I could have some hands on experience with it.
Zach Smith:
I have lots and lots and lots of experience. Experience is what you get when stuff doesn't work :> :>
Remember that HDL is just a way for you to describe your intentions to some software. You also want to know some of what actually happens inside the FPGA. That way, you can grasp what the tool is doing so you aren't completely at sea when the tool fails to do what you asked it to. Trust me on this: It seems that the more you pay for a tool and the more it promises to do the greater the odds that towards the end of the project it will simply refuse to do it just when there is a deadline to meet.
You've never heard of it because the education system is for training tech monkeys to serve for corporate overlords.
Ah yes, DEEEBian, my favorite Linux distro.
You know, that distro named for it's creator Ian and his wife DEEEBra.
“It’s funny that they are now divorced” WTFF
@@SLLabsKamilion oh, just googled that... was completely unaware. Will remove my comment, sorry.
@@sweatzera not only that, it gets much darker. Ian (the creator) killed himself as an act of awareness for police brutality
i prefer to use arch
@@sweatzera Linux Ian.
"FU 540 which stands for Freedom Unleashed"
That's like a Stallman joke :D
My uni just integrated RISC-V into the curriculum this year so I learned RISC-V assembly instead of ARM assembly.
Actually I was thinking about creating my own 8-bit CPU.
RxZ95sssPG You might like Ben Eaters videos if you are interested in Computer architecture. :)
I implemented a Brainfuck-like CPU core in SystemVerilog, so it ran under a FPGA. It's technically 8-bit and pretty much as simple as it gets, but it shows that it's far from being unreachable.
You can of course write an ISA, an assembler and an emulator for it without having to deal with HDLs, which is what I did a few times (but never got to anything significant).
You might want to hop on r/emudev on reddit and read a few threads, look up for resources, etc. and write a CHIP-8 simulator (I wrote one that can boot a tetris ROM in 3 hours), which is a popular and fairly simple architecture. You could try Brainfuck too, which is further away from a real CPU architecture, but might help you deal a little with emulation.
Look up the MIPS R3000 ISA, it is a good inspiration for how small a functional ISA can get (the R3000 is the CPU used in the PSone). Look up z80, x86, ARM instruction encoding. Try to mess a bit with that and through trial and error you'll get to an increasingly legit instruction set.
I'm currently writing a GameBoy emulator, which I wouldn't really recommend if you didn't ever deal with CPU architectures. I hope to get Tetris to show up the first screen soon... But it can be definitively fun.
Well good luck, because ill tell you right now its gonna be hell and months of energy drinks at 3AM along with a lot of education in Digital Electronics and the likes.
It is a pretty common project for college students learning Hardware Description Languages like Verilog. But if you don't plan using FPGA then that can be hell challenging
"RISC architecture is going to change everything" -AcidBurn
Compilers often dont support all of the latest instructions, either. There are about 20-40 instructions that are actually commonly used.
nice pic m8
btw i use arch
Arch users unite!
Non-binary pansexual ginger call it BS all you want, dissassemble a file and look for yourself. Youll find some variations of MOV, LEA, ADD, XOR, TEST, CALL, JMP, and etc, but these new instructions take time and a lot of effort to implement into a compiler, and are therefore rare.
@@ref3665 where can i start learning this stuff, im curious, but google isnt very helpful, and i dont feel like making a reddit post
I'm just seeing this now but this kind of stuff gets me so excited for the future of computing! I hope some day we see more openness in these kinds of things, wether it be architecture or even the hardware.
If you like stuff like this like me, definitely check out raptor computing systems and power9 by IBM.
me:*hears IBM*
*stein's gate flashback*
*IBN
@@nottenouun8539 IBM*
@@danke1150 el psy congroo
Linus the pun master
pingu the top master.
"There were opensource instruction sets before that never took off" - Not sure about that one, OpenSPARC, OpenPower etc... have all been somewhat successful in their own space, OpenSPARC led to the UltraSPARC T1 physical CPU which sold in reasonably high volume in the Sun Fire server range..
Must not have taken off too far, I've never heard of them.
Yeah, but SPARC has register windows. Ugh en.wikipedia.org/wiki/Register_window
Were actually learning the ins and out of RISC-V at university. Talking about Pipelining Speculative execution And the basic layout of a CPU Architecture. It's quite amazing and fun to learn about.
Oh so they've already started the brainwashing at universities? How predictable.
@@NobodyYouKnow98 Why is learning about cpu architecture and how pcs work brainwashing? you actually know that Intel and amd also use risc right? they implement that at below the x86 instruction and have hardware decoding to a risc code. for Intel called yOPS.