A look at xbox 2 part 1

[arefx]

Source (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1)

The Xbox 2: Inside and Out – Part I
By: César A. Berardini - "Cesar"
Aug. 3rd, 2004


Table of Contents


Introduction (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1#intro)
The Processor (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1#cpu)


Microprocessor concept (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1#microconcept)
History of microprocessors (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1#history)
POWER to the People (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p1#power)
Microsoft teams up with IBM (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p2#microibm)
More POWER is needed (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p2#morepower)
Microsoft has the POWER (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p2#micropower)
Summary (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p2#summary)


The Graphics Chip (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p3#vpu)
HD Gaming (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p3#hdgaming)
Embedded VRAM (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p3#embedded)


Memory and Bandwith (http://editorials.teamxbox.com/xbox/858/The-Xbox-2-Inside-and-Out-Part-I/p3#memory)


Introduction
“Begun this console war has!”, Yoda would say after hearing the comments by both Microsoft Corp CEO Steve Ballmer, who proclaimed, “I am betting we can take Sony in the next generation,” and Ken Kutaragi, CEO of Sony Computer Entertainment, who promised a playable PlayStation 3 for E3 2005. Let’s not forget Nintendo’s Revolution and their European Managing Director slamming Microsoft.

As consoles’ life cycles approach their end, we start hearing news about the next generation of systems, with all the marketing strategies each company is known for. Sony is talking about its Cell processor, a microchip that is supposed to be years ahead of anything available on the market. We know Sony is all about “teraflops”, “Toy Story graphics in real-time” and the “Emotion Engine” when it comes its PlayStation. Nintendo doesn’t talk about hardware; they simply don’t discuss technology at all. For Nintendo, it is all about creativity toward gameplay design.

In regards to the Xbox, the Redmond giant initially emphasized its superior hardware… for the simple reason it was coming a year after the PlayStation 2. But now that the Xbox is an established player in the videogame industry, Microsoft is determined to have the next wave of console wars take place in their own backyard.

Microsoft is trying to convince us that software is what matters. After all, that has been the company motto for the last two decades. Following that trend, Xbox evangelists have only talked about next-generation software, a.k.a. XNA, and they have stated there won’t be any hardware discussion this year. But even those efforts can’t stop the “buzz” that is stirring from a handful of official announcements talking about “future Xbox products”, licensing agreements, and top-secret deals. Oh, and we can’t forget about those supposed leaked and rumored specs.

Being that without hardware there is no place to run software, today we begin our two part look at Microsoft’s next-generation console, the Xbox successor. While Microsoft continues to play the “no comment” card, there is plenty of substantial information that helps us draw a picture of what the Xbox 2 (Xenon, or whatever you’d like to call it) will be like. Let’s begin.


The Xbox 2 Processor

Let’s start with the true brain of any computer: the processor. Yes, after all, a videogame console is nothing more than a computer whose hardware is dedicated to play games instead of general purpose tasks (PC). The info we have so far tells us that the Xbox successor will be powered by a POWER processor. But before we can talk specifically about this architecture, it is important to make a summary of some basic concepts related to processors in general.


Microprocessor

A microprocessor, usually referred to as processor, is an integrated circuit chip that performs many arithmetic and logic operations in a short amount of time, acting as a central processing unit (CPU) of a system. Nowadays, there are processors controlling your car electronics, your microwave, your TV, etc.

A processor is made of transistors which are, basically, tiny electronic switches. The processor executes a collection of instructions based on whether these switches are on or off, with the two possible states usually represented by a binary logic; zeros and ones. The instructions the processor executes are Add and Subtract (therefore multiply and divide), which compares two numbers, and moves numbers from one area to another. These operations will be defined by the “instructions set” each processor design imposes.

This instruction set, plus its clock rate (or speed), and the widths of its internal and external buses, will define the different types and families of processors.

http://media.teamxbox.com/xbox2/powertimeline.jpg

The evolution of the Power architecture

A Little History

The first commercial microprocessor was the Intel 4004, introduced by Intel Corporation in 1971. This 4-bit processor was designed for calculators and it was followed by 8-bit and 16-bit processors; with the Intel 8086 being the most successful of all, because it started what is now known as the x86 architecture.

As you can imagine, the techniques used to place transistors has improved over time, thus allowing the manufacturers to place more circuits in the same area or to increase the density of transistors and therefore the computational power. Processors became more powerful and their word size increased, allowing them to process up to 32 bits of data in the 80s. Now, 64-bit processors (such as the Athlon 64 from AMD or the IBM PowerPC 970 used in the Apple PowerMac G5) can be found in desktop computers and they are no longer exclusive to workstations or servers. The x86 processors we hear about all the time, from the 486 to the latest Pentium IV from Intel or the Athlon family of processors by AMD, belong to a category known as CISC (Complex Instruction Set Computing) which, as the name implies, has a complex instruction set. This primarily means the instructions that the processor has to deal with can be variable in length. The word “complex” is utilized because each instruction can perform several operations, including memory access and address calculations, besides the standard arithmetic and logic operations any processor is capable of. CISC processors were created when memory was expensive and compilers were inefficient. The CISC term was created to distinguish the existing processors before the invention in the mid 1980s of the RISC processors.

RISC stands for Reduced Instruction Set Computing, which is characterized for the use of instructions with a fixed length. RISC architectures were developed when the price of memory was no longer a big deal and software compilers improved. RISC puts emphasis on software and uses simple instructions that can be performed in a single clock cycle. The advantage of RISC architectures is that it requires fewer transistors than its CISC counterpart and all instructions are performed in the same amount of time, allowing a feature called pipelining, which we’ll discuss later.


POWER to the People

In 1992, Apple, IBM, and Motorola formed a joint venture, known as AIM, to produce a Personal Computer processor derivate from the POWER1, a RISC CPU that IBM designed previously for servers and workstations. Based on IBM’s 801 processor (considered the first RISC CPU), POWER1 was the result of the America Project, which in the mid 80s, was looking to build the most powerful CPU. Right now, the POWER architecture is in its fifth iteration, the POWER5.

http://media.teamxbox.com/xbox2/ppc970.jpg

The IBM PowerPC 970 processor found in the Apple PowerMac G5

The result of the AIM alliance was the PowerPC; a mainstream processor intended for use in personal computers (hence the name) that had some of the features found in its big brother, the POWER1. The PowerPC processor has evolved in what today is known as the PowerPC 970, a 64-bit processor known in the Apple world as the G5.

That sums up the CISC, RISC and the POWER/PowerPC architectures. Now let's jump to 2003.

[arefx]

------------------
Pg. 2
------------------

If You Can’t Beat 'Em, Join 'Em

When in a world exclusive, we revealed that long-time rivals Microsoft and IBM were teaming up for the Xbox successor, everyone was shocked. Those who know about the videogame and PC industries thought this was a joke. How could Microsoft and IBM, the partner of both Sony and Nintendo, team up for the next Xbox? After IBM let Microsoft market MS-DOS (which Microsoft bought for only $50,000) in 1980, allowing Bill Gates to make his fortune, and later partner with Intel, how could it be possible that IBM and Microsoft would form an alliance?

As soon as you try to answer those questions, common sense takes another hit. Why would Microsoft choose the POWER architecture? If one of the key features of the Xbox was its ease of development, thanks to its Intel Pentium processor (an x86 architecture every programmer knows), why would Microsoft switch from the precious Wintel platform to another architecture? Things get more bizarre as soon as you also take into account that this is the same architecture Apple (another longtime rival of Microsoft) has been using. All of the sudden, there are company names (Apple, IBM, Intel, Microsoft, Nintendo, and Sony) that you can only associate with the idea of mixing oil and water.

Well, everything has an explanation. If you consider some of the things that are happening in this and other industries, you can see the correlation. The key to solving this puzzle is as simple as knowing some technology trends and using the “why not” approach?

Why not partner with IBM when they are the company behind the PS3’s Cell processor? Why not partner with Big Blue when they are making advancements in chip making techniques (like copper wires and Silicon-On-Insulator) way ahead of Intel?


We Need More POWER

The dilemma Microsoft faces is that, if the grid computing technology IBM is toasting for the Cell processor can do all the things they claim, the PS2 successor could be years ahead of any other solution its competitors come up with.

IBM, Toshiba, and Sony claim they will create a processor that breaks Moore’s Law, making the Cell processor truly state-of-the-art. For those who don’t know, Moore’s Law (named after Intel co-founder Gordon Moore) states that the number of transistors in a microprocessor doubles approximately every 18 months. The truth is that this prophecy has been fulfilled since it was first announced in 1965 and Intel has made huge investments in research just to extend the compliment of this principle until 2015. As you can see, Moore’s Law isn’t about computing power but more so about how many transistors can be placed within a predetermined area, thus having an indication of what kind of advancements can be achieved and the performance attainable.

Microsoft is well aware of the fact that Sony could have a processor that breaks Moore’s Law in the next round of the console wars, thus allowing the Japanese consumer electronic giant to win the battle once again. For the Xbox successor, Microsoft needs more power than what a standard solution can offer.

Basically, there are two choices. Either they can reach more computational power by achieving higher clock speeds as a result of placing more transistors within the same space (a faster processor), or they could simply combine current technology to increase performance. You’ve certainly heard the saying; “two heads are better than one”.

If the Cell is all what is promised and Microsoft chooses a standard solution (as it did for the first Xbox) for the Xbox successor, the risk of being left behind by the competition is high.

Now we have to figure out why the decision was made by Microsoft to drop the x86 option, and why IBM’s architecture was chosen.

http://media.teamxbox.com/xbox2/power5.jpg

The POWER5 processor featuring eight cores on a single die

[arefx]

"I Have the POWER!"(Performance Optimization With Enhanced RISC)

Whereas the first Xbox was labeled by its detractors as a downgraded PC in a box (because of the existing hardware specs found on PCs at that time), this time around Microsoft plans to have a “supercomputer in a box” by using the POWER architecture.

As explained previously, the POWER architecture is a totally different approach to the traditional x86 architecture. It has a RISC nature, in contrast to x86’s CISC design. POWER was designed from the beginning as a very powerful chip that can be scaled from the low to high end of the server environments it was designed for. It’s in the fifth generation, thus being a proven and mature technology and it is the first solution that allows other companies to design and make their own implementations of the architecture. This is exactly what Microsoft is doing. By now, you can start to gather why Microsoft is opting for a non-traditional architecture, and has chosen to break new ground instead.

According to the documents leaked last April, the Xbox 2 processor is a custom designed processor with simultaneous multithreading and real-time graphics in mind. For the sake of this article, we’ll call it POWERx.

POWERx unifies both the POWER and PowerPC architectures in one BMF chip built using the most advanced chip-making technologies. It has POWER, because it has three 64-bit 3 GHz+ cores, making it the first videogame system processor with a multi-core design on a single die (also known as "SMP on a chip," or "system on a chip"). That is why we say the Xbox 2 will be a supercomputer in a box.

It is a PowerPC because it descends from the POWER5+; it has been designed more as processor that will be used in a consumer device rather than in a server, so it has lower power consumption, and it is focused on floating-point performance and multiprocessing capabilities with the inclusion of a SIMD/Vector engine, a specialized unit not found in POWER processors. The POWERX is supposed to be a big-endian system, contrary to the latest PowerPC processors which support both big-endian and little-endian memory models.

As mentioned above, the POWERx features simultaneous multithreading (SMT), which allows each of the three cores to process two threads at time, thus making the Xbox 2 CPU a six-thread per clock cycle system. Some of you might be wondering what a thread is and what exactly SMT means. Although hundreds of pages could be written to explain these concepts, in simple terms a thread is an individual sequence of instructions and therefore simultaneous multithreading is the ability for a single processor to handle several threads at the same time.

In the case of the POWERX, its ability to process six threads simultaneously, will make the chip behave somewhat like six conventional processors. This will allow multiple applications to run independently on different cores or a single multithreaded application to perform multiple tasks all at once.

Each of the three cores of the POWERx include a 32 KB L1 instruction cache and a 32 KB L1 data cache, and all together they share 1 MB of Level 2 cache.

Finally, it has been said that POWERx will be built using the most advanced techniques, because it will be manufactured using Silicon-on-Insulator (SOI) low-k dielectrics and Strained Silicon techniques in order to get higher performance and lower power consumption.


The Vector Unit

The POWERX will include in each core a Single Instruction Multiple Data (SIMD) unit as an extension to the processor instruction set. This specialized unit is the AltiVec Technology and was jointly developed by Motorola, IBM, and Apple. Known in the Mac world as the Velocity Engine, AltiVec is IBM’s answer to Intel’s MMX and SEE/SEE2/SEE3, as well as the AMD 3DNow! vector engines.

The extension contains special instructions that help to speed up integer and floating-point-intensive applications, when they’re specially coded to take advantage of these new instruction sets. The AltiVec vector unit is designed to improve the performance of any application that can exploit data parallelism; something that particularly applies to real-time graphics.

The performance of this special vector unit is as good as the latest Intel offer, the SEE3. However, AltiVec has one key advantage over its competitors; it doesn’t require programmers to write in assembly code. By using the AltiVec C Programming Model, developers can use their C, C++ knowledge to code for this unit.


Microprocessor Summary

The POWERX is a cutting-edge processor based on the execution core of IBM’s 64-bit POWER5+ architecture and will be a highly parallel implementation of the PowerPC architecture, combining vector engines with superscalar, superpipelined execution cores. With this design, Microsoft is also joining the industry trend that is moving towards multithreading, multi-core designs.

This processor will be fabricated using IBM’s state-of-the-art chip making technology using silicon-on-insulator transistors, copper interconnects, and strained silicon techniques to build a processor that achieves higher performance while consuming less power.

[arefx]

------------------
Pg. 3
------------------

The VPU

Yes, this time the right term to describe the graphic chip is: Visual Processing Unit, a term that ATI Technologies coined for its graphic processors. The GPU designation doesn’t apply anymore since Microsoft decided to drop nVIDIA in favor of the Markham, Ontario-based company to develop custom graphics technologies for “future Xbox products”.

-

The ATI X800 VPU (codename R420)

What we know so far is that the Xbox 2 will feature a custom silicon derivative of ATI’s next generation VPU, code-named R500. This graphic chip could be ATI’s first VPU supporting DirectX 9.0’s Shader Model 3.0, since its current line-up only offers support up to the second version of both Pixel and Vertex Shader models. A previously leaked document claims the Xbox successor will support Shader Model 3.0 and beyond, which can be interpreted as some of the features we’ll see in the next version of DirectX, set to be shipped with Windows Longhorn.

Microsoft revealed at its Meltdown conference that the next DirectX will have new features such as dynamic geometry/topology modification and allow graphic chips to generate shadow volume, extrude shadow polygons, and other graphic routines that must be performed on the CPU in the actual DirectX 9 API. Finally, Microsoft promises a unified shader model, which will be called Shader Model 4.0. Whether these features will be included in the Xbox 2 is still unknown.

The document also claims the Xbox 2 VPU will run at 500 MHz or a clock speed slightly above that number, which is not an impressive spec considering today’s GPU clock speeds. However, when it comes to graphics it is not just about speed. According to the leaked document the VPU has 48 Arithmetic Logic Units that can execute 64 simultaneous threads on groups of 64 vertices or pixels. These ALUs are automatically assigned to either pixel or vertex processing depending on the load, with each one having the ability to perform one vector and one scalar operation in a single clock cycle, thus having a Shader core that can execute 96 shader operations per clock cycle.

The Xbox 2 VPU is supposed to have a real peak pixel fill rate of 4 gigapixels per second, which doesn’t sound too impressive either considering today’s graphic chip specs. We’ll have to wait for the official announcement regarding this matter to make further conclusions.


HD Gaming

Microsoft knows that HDTV is becoming a reality, as cable and satellite TV providers grow their HD offerings and more people purchase high-end televisions. By the time the next generation consoles ship, HDTV will no longer be a thing of early adopters and will finally become a mainstream consumer electronic.

In this scenario, it’ll be important that videogames catch the wave and deliver an experience that resembles HDTV, known for its sharper and clearer visuals which are up to seven times the resolution of regular TV. It’d be a terrible letdown to have a videogame system that uses a lower resolution than a TV broadcast. Right now something similar happens when HDTV owners watch a DVD movie where there is a noticeable downgrade in resolution. Soon there will be HD DVDs, which will finally offer a film-like resolution at home. Therefore, next-generation videogame consoles will need to keep up with other mainstream electronics and deliver a high definition experience.

-


Although the current Xbox is capable of delivering HDTV video signals using the High Definition AV Pack, in practice only a few titles have been able to run above 480p. This not because of laziness by developers but more so due to hardware restrictions that make it virtually impossible to run some engines above standard resolutions. It would be impossible to run games like Unreal Championship, Halo, Splinter Cell, The Chronicles of Riddick, or the upcoming Doom 3 and Halo 2, at resolutions above 480p without sacrificing a lot of visual effects and features to run at a playable framerate.

Thankfully, the technology keeps evolving and now the latest generation of graphic processors are able to run the most modern engines in high resolutions. Those video cards powered by nVIDIA’s GeForce 6800 and ATI’s X800 chips are able to run the most graphically demanding PC games (including Painkiller, Far Cry, Doom 3, and Half-Life 2) in 1600x1200 at a playable framerate, with all the effects turned on. As of yet, there is only one engine that promises to put the current generation of graphic chips on their knees; that being the Unreal Engine 3.0. However, there won’t be any games using this engine until 2006, when hardware will once again catch up with the software.

So ATI knows that the VPU it is making for the Xbox successor will have to allow game developers to run their games at least at 720p (1280x720) and if possible at 1080i (1900x1080) resolutions. Considering the fact that their Radeon series of VPUs integrates a set of technologies designed to make games playable at high resolutions, it’ll be easy to make the Xbox 2 VPU high definition capable.

[arefx]

Embedded VRAM

One new trick to make HD gaming a reality will be the embedded video RAM that will supposedly be used in the Xbox 2. Video memory bandwidth is one of the most critical aspects in today’s graphics paradigm. In order to increase memory bandwidth you can boost memory clock speed or have a wider path. The latest graphic cards, such as the Geforce 6800 and ATI X800, are using 256-bit interfaces to reach peak memory bandwidths above 30 GB/sec. Other methods to increase this resource are bandwidth saving techniques, such as data compression.

The leaked document revealed that Microsoft plans to incorporate 10 MB of dedicated memory for use by the VPU. This is what is known as embedded RAM because the memory is embedded directly onto the chip. The advantage of embedded RAM is that it offers a speed and bandwidth far superior to conventional out-of-the-chip memory. Think of it as comparing system memory with a microprocessor's cache memory. Of course, this memory will be of a limited size because it a lot more expensive that regular external memory. The basic idea is to offer the VPU a fast memory where it can move data at extremely high speeds, with reduced latency. Whether this embedded RAM will be used as a frame or a texture buffer, or a combination of both, is unknown.

Microsoft wants to eliminate current architecture bottlenecks and this embedded RAM solution might be the key to enable the most advanced visuals at high resolutions. It remains to be seen if the similarities (ATI’s chip, IBM’s PowerPC) with the Nintendo Gamecube continue with the use of MoSys’ embedded 1T-SRAM memory for the Xbox 2 hardware.


Memory and Bandwidth

According to the leaked specs, the Xbox successor will have the same UMA architecture its predecessor used. That is a unified memory architecture equally accessible to both the VPU and CPU. The paper claims the bandwidth available for the processor and graphic chip to access the system memory is 22.4 GB/sec; meaning that, the memory clock speed should be around 700 MHz. Again, we have our doubts regarding these specs as they don’t sound too impressive for hardware that is shipping in a year and a half at the earliest.

The Xbox successor will supposedly have 256 MB of system memory, but again this number will likely change in the future. There are already games out there (such as Doom 3 for the PC) that require 512 MB of video memory to run in a mode called Ultra Quality where nothing is compressed.

Finally, the paper claims the embedded RAM has a 32GB/sec bandwidth, which means this memory could have a clock speed around 1 GHz DDR, which sounds like a logical number considering the VPU clock speed. This bandwidth allows the embedded RAM to receive eight pixels every VPU clock cycle, and these pixels can be expanded through multisampling techniques to 4 samples, for up to 32 multisampled pixel samples per clock cycle. With alpha blending, z-test, and z-write enabled, this is equivalent to having 256 GB/sec of effective bandwidth.

Another thing the leaked specs touched on is the possibility of offloading some of the work from the VPU to the AltiVec vector units found in each core.


We can only imagine what kind of visuals these hardware specs will make possible, but the tech demos shown by Epic Games to promote their Unreal Engine 3.0 might be a good example of the graphics we’ll see once the Xbox 2 ships.


What’s Next in Part II

Be sure to check back tomorrow as we continue our in-depth look at the Xbox successor. We’ll venture into the Xbox 2’s console and controller design, the hard drive (or lack thereof), backward compatibility, and Microsoft’s XNA initiative. Plus, we’ll reveal which development houses are already working on the Xbox 2.


there you have that.. :) long read I know

[Halo Master Chief]

Old news buddy.

[MageMasher]

im confused

[arefx]

Old news buddy.

well it wasnt to me

[RUcOs]

you could of just gave a link to teamxbox.com...

[Komposit]

The ATI X800 VPU, Ha, that alone makes me laugh at those spent over a grand to build they're PC around that card... :smt082