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Under the Hood of the Xbox 360
An anonymous reader writes "IBM DeveloperWorks is running a behind the design story for the making of the Xbox 360. The 360 has but a single chip with 165 million transistors for it's CPU " From the article: "This chip is in fact a three-way symmetric multiprocessor design. The three PowerPC cores are identical, except that they are physically reflected through the X and Y axis. Each of the CPU cores is a specialized PowerPC chip with a VMX128 extension related to (and partially compatible with) the VMX instructions in the G4 and G5 CPUs. The three CPU cores share a 1MB Level2 cache. Each processor has 32KB each of data and instruction Level1 cache. The chip's front-side bus/physical interface has a 21.6GB/second bandwidth, and runs at 5.4GHz."
I haven't been doing microelectronics since my university days (over 10 years ago) and the block named "testing/debug" intrigued me quite a bit: exactly what test/debug functions do you put on CPUs nowadays? do they contain burned in test cases? some sort of programmable logic to get access to internal CPU states? I'd definitely be interested in learning more about this.
-- the cake is a lie
Yes, I'd prefer this be filtered through at least a couple of blogs.
What's the deal with the tiny cache? My ten year old HyperSparc has more cache than that... You'd think that when dealing with high throughput graphics applications, a larger cache would make far more of a difference than a few hundred MHz either way.
PowerPC's mainly an IBM-designed and promoted architecture, borne from the Apple-IBM-Motorola alliance.
Apple are simply one of IBM and Motorola's (now Freescale) customers.
What's the frequency, Kenneth?
Microsoft went to ATI and IBM in order to "own" the designs for the graphics/processor chips. This way MS is able to get the parts fabbed out without having to get approval from ATI/IBM. (This is from memory of what I've read in the past). The CPU and graphics/bridge design in the XBox are owned and by Intel/Nvidia (respectively). MS had to buy the parts from them, which costs them more in the long run than being able to get their own produced.
Correct me if I'm wrong...
The PlayStation 3 will be made by Sony, a company which distributes software that renders a personal computer quite unstable and open to attack by malfeasant users from across the Internet.
The Xbox 360, on the other hand, is made by Microsoft.
The choice is yours.
For more information, click here.
A beowulf Heater of these... :)
so wait... we've got a Microsoft operating system (whatever the Xbox 360 OS is) running on what is commonly considered Apple-type processors *and* we'll soon have an Apple OS running on top of what is commonly considered Microsoft-type processors?
What's next, dogs and cats living together?
A computer once beat me at chess, but it was no match for me at kick boxing -- Emo Phillips
"PS3 will have better graphical performance, up to 2x. High definition. Blu-ray. Up to 7 wireless controllers - those actually mean something. Xbox 360, will just have improved graphics over the original Xbox."
Who says the PS3 will have two times the graphical performace? Speculation does, perhaps.
The Xbox 360 is high definition out of the box.
The Xbox 360 does NOT use proprietary disc formats that can, at the vendor or manufacturers will, brick your box.
WHO NEEDS SEVEN CONTROLLERS ON ONE BOX!? Jesus. What average Joe with a TV is going to be able to support seven players? Maybe the rare Super Smash Bros. style game, but nothing big.
The Xbox 360 has several things the PS3 does NOT have:
1) Xbox Live. The Playstation 3 has no unified online service at all and has no plans to. Xbox Live is an awesome way to play your video games online. One fee. No ten bucks a month here, five bucks a month there... $50 a year.
2) Time. Xbox 360 is here now whereas the PS3 is going to offer comparable hardware and games in a year.
3) Developer backing. Bungie and Rare are both developing for the Xbox 360, and that's only naming two big name developers. Also Final Fantasy will be coming to Xbox 360 too. EA is also signed on.
The question is why NOT buy an Xbox 360? Would you rather wait and get less for the same, or maybe more, amount of money?
-Eric Smith
Must be this "reversible computing" I keep hearing about...
"Not an actor, but he plays one on TV."
Much like Duffman, Sony promises lots of things. There were a lot of features that were supposed to be available on the PS2 that just never ended up in the final system. Not wanting a 360 because it's not that much an improvement over the current XBox is good reasoning. Not wanting a 360 because you just bought a new console a couple of years ago is good reasoning. Not wanting a 360 because of all the things Sony claims will be on the PS3 is just silly. We don't know the "Top 10 reasons for a PS3" because we don't know exactly what the PS3 is yet.
Also, while the Revolution's controller does pose some unique possibilities for gameplay, it's only a controller. Any of the modern gaming consoles could implement such a controller. If it's that big a deal, expect MS and Sony to have their own versions by the end of 2006.
Little endian, or Big endian?
Long answer; yes with an if...
How is it a miracle when this is exactly what's been happening with consoles for many years?
NES looked better than nearly any computer of its day. Ditto Genesis and SNES. Playstation and N64 packed an incredible amount of power into a cheap bundle. Remember the hype about PS2's Emotion Engine? There were rumors that exporting it would be restricted because it was going to be classified as a super computer. People were saying Iraq was going to use it to guide missiles. Xbox literally was a cheap PC, but gave more bang for the buck than your average beige box.
Consoles do this by taking the right shortcuts. They have a very focused performance target for very specific tasks. No need to add anything more than the minimum. Plus, they sell more than nearly any OEM PC maker so they get good prices on the parts.
The global economy is a great thing until you feel it locally.
The PS2 Emotion Engine has the same design philosophy: choosing to do small memory/cache in favor for very wide bandwidth. It makes for some interesting programming juggling and kung-fu since the data comes straight from memory dumped to the graphics so nothing is cached. The results speak for themselves since the PS2 is the oldest and the most dated performance the fact that the performance is extremely dynamic and probably *still not maxed*. People are still pulling tricks that no one could predict the PS2 to do. I suspect we wouldn't have games on the PS2 like GT4 or the beautiful Shadow of the Collosius if it had been made with more cache yet small bandwidth.
Anyone who thinks it crashes regularly or that more than 1% of units are overheating is simply a moron. A lot of people here seem to have a fixated fantasy that they are so desperate to believe that they ignore the facts. The fantasy basically consists of that MS has rolled out an overheating worthless machine that when not overheating 95% of the time is crashing. Get real, I'd imagine the failure rates for units are about the same for any piece of consumer electronics.
Unless of course you don't care about any of that stuff. I own both a PS2 and an Xbox, and the Xbox gathers dust simply because the PS2 delivers a lot more quality single-player games than the Xbox does. I had a Live subscription for a while and didn't use it that much. I guess the appeal of having 12 year olds tell me how teh ghey you are is lost on some people.
I ain't evil, I'm just good looking.
Seriously, though, these are fascinating little beasts. It looks as if the concept has its roots in the Transputer, which also relied on fast and narrow point to point external links. When I first read the blurb I guessed from the description that there were 4 cores per chip and the bad ones were disabled to get the yield up, but clearly the yield is much much better than that. However, anybody silly enough to think about overclocking will need to note that the working CPU voltage is hard coded; it looks like, to get the yield at the clock speed, each device has to be individually tuned. Which suggests that the tolerances for reliable functioning are tight. Perhaps the overall error rate is not good enough for a truly general purpose computer which needs to be able to tolerate a range of operating conditions without significant error. Which doesn't suggest a range of motherboards and retail boxed processors any time soon. Just like Apple, in fact. This reminds me of good old ECL based computers (whose CPU voltage had to be adjusted on the fly for reliable operation rather than set up once for all, but I'm sure you take the point).
It's perhaps a pity that the design teams for the Mac Mini and the XBox couldn't be locked up in a development lab with a progressively increasing caffeine level in the coffee until they create the hybrid that would really be the future of home computing. Apple's thermal management and sound level control, IBMs obvious chip development capability, and Microsoft's willingness to spend some of its cash pile would be a formidable combination. The trouble is, you'd probably end up with Apple's's ability to design chips, IBMs willingness to lose money, and Microsoft's thermal management and general aesthetics.
Pining for the fjords
Games often have far smaller cache requirements than many other applications, and as a result, it is preferable to go with a higher speed cache and higher CPU speed than a slower but larger cache/CPU.
:)
The Celeron in the 300A era are one of the best examples of this. They had half the cache of their Pentium III counterparts, BUT the P3 cache ran at half the CPU speed while the Celeron cache ran at full speed. The Celeron's performance was crap despite the faster cache for many applications (including server machines and most office applications) due to its smaller cache, but gamers discovered that for games, the situation was exactly the opposite - clock for clock the Celeron was significantly faster than the P3 due to the fact that most games in that era could fit almost all of their rendering pipeline within even the Celeron's small cache. Rare cache misses and twice the cache speed = much better performance. It also happened that that on-die cache allowed the Celerons to be overclocked like crazy, a significant added bonus.
The Xbox 360's CPU takes the whole idea much farther. While most desktop CPUs are designed to perform well over the widest range of situations (with some tradeoffs always being evident - note that Athlons eat P4s for lunch in many cases such as games, while Athlons do actually lose most of their advantages in performance per clock cycle when performing video compression and decompression because most video codecs don't have significant amounts of branching resulting in pipeline stalls from branch mispredictions.) The Xbox 360 CPU goes a step further by optimizing for one thing and one thing only - gaming. Instruction reordering which is critical in most desktop CPUs turns out to be not as necessary for gaming (specifically graphics rendering), and as a result the 360 drops instruction reordering capability completely in favor of having multiple cores at a low cost. (Instruction scheduling takes a LOT of die space in modern CPUs compared to the size of the rest of the CPU core.)
retrorocket.o not found, launch anyway?
That is until you realize that the features that IBM and MS removed from the 360's CPU because they weren't needed for gaming cripple the CPU for most other applications.
retrorocket.o not found, launch anyway?
You forgot the most interesting option...
- The Nintendo Revolution
I don't want to sound like too much of a fanboy, but what can these consoles really give me that my PC can't? I'd rather have a console thats sole focus isn't trying to outpace my PC in terms of graphics... but to push the limits with new controllers, unique games and not costing me my 1st born child or my left arm to acquire.
"The choice is yours."
Nintendo, I choose you!
</pokemon reference>
Am I open minded towards open source, or closed minded towards closed source?
But mentioning live as the deciding factor is ignoring history. The x-box had it and it didn't sell. Nobody has ever in my opinion come up with a satisfactory reason for the failure of the x-box. The gamecube is easy. It just didn't have the right image. While I thought about 1 or 2 games as worth playing that was it. The rest I considered to cutsey and consoly for my tastes. I don't mind this on my handhelds where it actually helps (don't want to scream like a girl playing fear in public) but not at home.
Another one that amazed me is that one post said the x-box had signed the big names. Bungie and EA. Wtf? Bungie IS NOT a big name. They got 1 game and that is it. EA is big but EA signs on to anything. Getting EA to endorse your new console is like getting a hooker to go out with you for money. Even /.ers should be able to manage that.
The only real advantage that MS has over both Sony and Nintendo that MS doesn't have to win the money race. They can afford to loose money on this generation and the next and the next.
As for the graphics being amazing. Oh please. I already play at higher resolutions on my now 2yr old PC. Richer friends won't accept anything less then 1600x1200 while sony's own games like eq2 can already make use of 512mb video cards despite the fact they were not even out. Other recent games to can make use of hardware features that even top of the range pc's don't have let alone these weak consoles.
I still remember console fans being excited over star fox while I was playing x-wing.
No saying that anyone is going to win the current battle is insanity. The 360 is lacking launch titles and has not got the mindshare with the general public. The PS3 is an unknown quantity and Sony's reputation might be damaged (but this should equally have counted against MS with the X-box) and Nintendo seems to try another gamecube wich didn't work well the first time. The PC (often not counted) has such titles as WoW wich simply cannot run on any of the consoles yet is a huge earner for its parent company. Oh and has all that live crap except at no-charge.
Frankly I find these discussions very amusing but only as an outsider. I remember people defending their console in each of the battles and use the same arguments regardless of the wether they made sense before.
Console fans are like generals. Always willing to fight the last war again regardless of the outcome.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
Hate to burst alot of bubbles, BUT:
0 -2.ars/2
The Xenon CPU IS NOT the same as 3 G5's all on one chip! Read the arstechnica article here:
http://arstechnica.com/articles/paedia/cpu/xbox36
Basically it says: "The basic idea behind both Cell and Xenon is to make the execution core less complex by stripping out hardware that's intended to optimize instruction scheduling at runtime. Neither the Xenon nor the Cell have an instruction window, which means that these two processor designs largely forget about instruction-level parallelism. Instead, instructions pass through the processor in the order in which they're fetched, with the twist that two adjacent, non-dependent instructions are executed in parallel where possible."
This means that standard PPC code (OS X, etc) WILL NOT RUN on this. This is also the reason that IBM is selling these things at only $106 a pop to M$. Have you checked the prices for SINGLE CORE G5s for Apple? Their like $600-700 a piece! So, I am guessing that stripping these down makes them much easier and therefore faster and cheaper to mass produce, and therefore the price difference.
Anyway, there are reports that only one core is availble to intitial game developers, and one of the cores is strictly for M$ bullshit content protection TC such as the hypervisor, etc.
Not to mention from the article:
Microsoft and IBM engineers worked together during the definition phase of the project to specify a design to satisfy the constraints of a mass-produced consumer device
Sounds like a shitload of TC shit build right into the chip, so I am NOT holding my breath for linux to be ported to this (not that I wouldn't be thrilled to see this). Cetainly not when the port to STI Cell architecture has been under dev for what, over a year? Damn, can't wait for PS3 release.
Agreed, the price is a big stopper for some people and, I also agree, there are not a ton of must-have games on the Xbox 360.
:)
However, it does have Perfect Dark: Zero, Project Gotham 3, Kameo (don't knock it 'till you try it) and soon, DOA4 and Battlefield.
Battlefield + Xbox Live = Heaven.
Granted, I don't know a whole lot about what games are coming soon to the Xbox 360 for lack of time, but by the time the Playstation 3 comes out, Xbox 360 will have a lot more games by great developers and I'm going to venture a guess and say the premium system won't cost as much as the PS3 will.
That was my point, was that waiting for a PS3 was stupid. You get less (no unified online service, which is a BIG, BIG portion of why you should get an Xbox 360 over PS3, no titles from Rare or Bungie) and get some things that are somewhat unpleasant (blu-ray: Who really wants a disc format that can brick your system of the manufacturer tells it to? How long before it's cracked and a virus is written? Who really would be angry about getting up every few hours to change a disc? Big deal. None of us had problems with it in the PSX days.)
Just forget for one second that Microsoft makes the Xbox. It's one of the products of theirs I really, really like and is well put-together by a great team.
Go Microsoft?
-Eric Smith
We are sorry to report that your XBox 360 crashed during the final race online of the world online championship of World Rally Cup 2006 V3. Would you like to play Patience, Minesweeper or Reboot?
So the big difference is that the 360 is more like current multicore PC's while the PS3 seems to lean more towards a cluster setup like openmosix.
As to wich is better? Well look at recent PS2 games. They show such graphical improvement that it might be true that PS2 still has untapped capabilties. The X-box on the other hand is pretty much at its limit. This was clear by developers complaining the PS2 was hard to develop for and the x-box was easy. Same with the next generation.
Given that the cores have the same basic design (64bit power) and Sony claims the same or even higher clockspeeds it would be easy to assume that 7+1 core > then 3 cores. I also seen larger cache sizes being claimed and even faster bus speeds. Is it all true? And even if it is will game developers succeed in tapping those resources? And even if they do, will that result in fun games?
Remember that currently the fast majority of games do not take advantage of dual core PC's even hyperthreading is rarely supported worse having it on can sometimes degrade performance. Now imagine having to write your code in such a way that it can be split across 7 processors. OR is that central core in te Cell processor capable of splitting up non- threaded applications? (Just random quesswork). After all it is supposed to be become more then the current PS3 chip it is supposed to be included in the next generation of TV's and other entertainment products.
That would be a huge advancement. The holy grail of grid computing (the cell is supposed to be like that) were you no longer have to worry about the specifics of your enviroment but can just run your code and the system will take care of it.
What I find a far more intresting proposition that with the PS3 supposedly so powerfull yet also so similar to the 360 is that it might just be possible to run 360 games on the PS3.
As for using consoles for number work. Already being done with both systems. They are so cheap yet so powerfull that all you have to do is wait for someone to break them open. Same as PC GPU's are being used for number crunching work. However GPU's is no problem wereas circumventing the PS3 or 360's protections might be in more repressive goverments (such as found in the west).
All off the above is just random speculation based on hilarious press reports. Any resemblance to the facts is unlikely.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
This is a fully PowerPC compliant chip. Make no mistake. It WILL run standard PowerPC code, as will Cell BE. From where did you get that the singe core G5 costs 5-600 dollars? An iMac G5 (singe core PowerPC 970FX costs $1300 and that's a complete computer with a GPU, harddrive, DVD-burner, webcam, 512 MB RAM, an 17" TFT, package, shipping, advetising and about 30% margin.
The cost of a processor is directly related to the die size and since the size of the Xenon is larger than the dual core G5 (about 130 million transisotrs compared to 165 million in the Xenon) there's a good chance that Xenon is actually more expensive than the PowerPC 970MP to manufacture.
Linux will run just fine on an Xbox 360 if one would fins a way around the DRM stuff. OSX too if Apple would want to. Same goes with the PS3. Hell.. Sony's boss even said so!
- Henrik
- when the Shadows descend -