Microsoft's Xbox 360, Sony's PS3 - A Hardware Discussion
by Anand Lal Shimpi & Derek Wilson on June 24, 2005 4:05 AM EST- Posted in
- GPUs
Introducing the Xbox 360's Xenon CPU
The Xenon processor was designed from the ground up to be a 3-core CPU, so unlike Cell, there are no disabled cores on the Xenon chip itself in order to improve yield. The reason for choosing 3 cores is because it provides a good balance between thread execution power and die size. According to Microsoft's partners, the sweet spot for this generation of consoles will be between 4 and 6 execution threads, which is where the 3-core CPU came from.
The chip is built on a 90nm process, much like Cell, and will run at 3.2GHz - also like Cell. All of the cores are identical to one another, and they are very similar to the PPE used in the Cell microprocessor, with a few modifications.
The focus of Microsoft's additions to the core has been in the expansion of the VMX instruction set. In particular, Microsoft now includes a single cycle dot-product instruction as a part of the VMX-128 ISA that is implemented on each core. Microsoft has stated that there is nothing stopping IBM from incorporating this support into other chips, but as of yet we have not seen anyone from the Cell camp claim support for single cycle dot-products on the PPE.
The three cores share a meager 1MB L2 cache, which should be fine for single threaded games but as developers migrate more to multi-threaded engines, this small cache will definitely become a performance limiter. With each core being able to execute two threads simultaneously, you effectively have a worst case scenario of 6 threads splitting a 1MB L2 cache. As a comparison, the current dual core Pentium 4s have a 1MB L2 cache per core and that number is only expected to rise in the future.
The most important selling point of the Xbox 360's Xenon core is the fact that all three cores are identical, and they are all general purpose microprocessors. The developer does not have to worry about multi-threading beyond the point of getting their code to be thread safe; once it is multi-threaded, it can easily be run on any of the cores. The other important thing to keep in mind here is that porting between multi-core PC platforms and the Xbox 360 will be fairly trivial. Anywhere any inline assembly is used there will obviously have to be changes, but with relatively minor code changes and some time optimizing, code portability between the PC and the Xbox 360 shouldn't be very difficult at all. For what it is worth, porting game code between the PC and the Xbox 360 will be a lot like Mac developers porting code between Mac OS X for Intel platforms and PowerPC platforms: there's an architecture switch, but the programming model doesn't change much.
The same cannot however be said for Cell and the PlayStation 3. The easiest way to port code from the Xbox 360 to the PS3 would be to run the code exclusively on the Cell's single PPE, which obviously wouldn't offer very good performance for heavily multi-threaded titles. But with a some effort, the PlayStation 3 does have a lot of potential.
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Doormat - Friday, June 24, 2005 - link
@#22: Yes 1080P is an OFFICIAL ATSC spec. There are 18 different video formats in the ATSC specification. 1080/60P is one of them.FWIW, Even the first 1080P TVs coming out this year will *NOT* support 1080P in over HDMI. Why? I dunno. The TVs will upscale everything to 1080P (from 1080i, 720p, etc), but they cant accept input as 1080P. Some TVs will be able to do it over VGA (the Samsung HLR-xx68/78/88s will), but still thats not the highest quality input.
Pastuch - Friday, June 24, 2005 - link
RE: 1080P"We do think it was a mistake for Microsoft not to support 1080p, even if only supported by a handful of games/developers."
I couldnt disagree more. At the current rate of HDTV adoption we'll be lucky if half of the Xbox 360 users have 1280x720 displays by 2010. Think about how long it took for us to get passed 480i. Average Joe doesnt like to buy new TVs very often. Unless 1080P HDTVs drop to $400 or less no one will buy them for a console. We the eger geeks of Anandtech will obviously have 42 widescreen 1080P displays but we are far from the Average Joe.
RE: Adult Gamers
Anyone who thinks games are for kids needs a wakeup call. The largest player base of gamers is around 25 years old right now. By 2010 we will be daddys looking for our next source of interactive porn. I see mature sexually oriented gaming taking off around that time. I honestly believe that videogames will have the popularity of television in the next 20 years. I know a ton of people that dont have cable TV but they do have cable internet, a PC, xbox, PS2 and about a million games for each device.
Pannenkoek - Friday, June 24, 2005 - link
#19 fitten: That's the whole point, people pretend that even rotten fruit laying on the ground is "hard" to pick up. It's not simply about restructuring algorithms to accomodate massive parallelism, but also how it will take ages and how no current game could be patched to run multithreaded on a mere dual core system.Taking advantage of parallism is a hot topic in computer science as far as I can tell and there are undoubtedly many interesting challanges involved. But that's no excuse for not being able to simply multithread a simple application.
And before people cry that game engines are comparable to rocket science (pointing to John Carmack's endeavours) and are the bleeding edge technology in software, I'll say that's simply not the reality, and even less an excuse to not be able to take advantage of parallelism.
Indeed, game developers are not making that excuse and will come with multithreaded games once we have enough dual core processors and when their new games stop being videocard limited. Only Anandtech thinks that multithreading is a serious technical hurdle.
This and those bloody obnoxious "sponsored links" all through the text of articles are the only serious objections I have towards Anandtech.
jotch - Friday, June 24, 2005 - link
#26 - yeah i know that happens all over but I was just commenting on the fact that the console's market is mainly teens and adults not mainly kids.expletive - Friday, June 24, 2005 - link
"If you’re wondering whether or not there is a tangible image quality difference between 1080p and 720p, think about it this way - 1920 x 1080 looks better on a monitor than 1280 x 720, now imagine that blown up to a 36 - 60” HDTV - the difference will be noticeable. "This statement should be further qualified. There is only a tangible benefit to 1080p if the display device is native 1080p resolution. Otherwise, the display itself will scale the image down to its native resolution (i.e. 720p for most DLP televisions). If youre display is native 720p then youre better off outputting 720p becuase all that extra processing is being wasted.
There are only a handful of TVs that support native 1080p right now and they are all over $5k.
These points are really important when discussing the real-world applications of 1080p for a game console. The people using this type of device (a $300 game console) are very different then those that go out and buy 7800GTX cards the first week they are released. Based on my reading in the home theater space, less than 10% of the people that own a PS3 will be able to display 1080p natively during its lifecycle (5 years).
Also, can someone explain how the Xenos unified shaders was distelled from 48 down to 24 in this article? That didnt quite make sense to me...
John
nserra - Friday, June 24, 2005 - link
I was on the supermarket, and there was a kid (12year old girl) buying the game that you mention with the daddy that know sh*t about games, and about looking for the 18 year old logo.Maybe if they put a pen*s on the box instead of the carton girl, some dads will then know the difference between a game for 8 year old and an 18.
#21 I don’t know about your country, but this is what happen in mine and not only with games.
knitecrow - Friday, June 24, 2005 - link
would you be able to tell the difference at Standard resolution?instead of drawing more pixels on the screen, the revolution can use that processing power and/or die space for other functions... e.g. shaders
If the revolution opts to pick an out-of-order processor, something like PPC970FX, i don't see why i can't be competitive.
But seriously, all speculation aside, the small form factor limits the ammount of heat components can put out, and the processing power of the system.
perseus3d - Friday, June 24, 2005 - link
--"Sony appears to have the most forward-looking set of outputs on the PlayStation 3, featuring two HDMI video outputs. There is no explicit support for DVI, but creating a HDMI-to-DVI adapter isn’t too hard to do. Microsoft has unfortunately only committed to offering component or VGA outputs for HD resolutions."--Does that mean, as it stands now, the PS3 will require an adapter to be played on an LCD Monitor, and the X360 won't be able to be used with an LCD Monitor with DVI?
Dukemaster - Friday, June 24, 2005 - link
At least we know Nintendo's Revolution is the lozer when it comes to pure power.freebst - Friday, June 24, 2005 - link
I just wanted to remind everyone that 1080P at 60 Frames isn't even an approved ATSC Signal. 1080P at 30 and 24 frames is, but not 60. 1280x720 can run at 60, 30, and 24 that is unless you are running at 50 or 25 frames/sec in Europe.