Recent Advances in Microprocessor Design

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time and this circumstance is used for power saving. Basically can be fixed (Pentium bug), this works pretty much like a the CPU shuts down all non essential resources and consumes BIOS update.

LongRun power management is basically controlled by the less power this way. Nowadays this kind of CPUs also sleeps in between keystrokes of even the fastest writer. Code Morphing, allows the processor to adjust its clock This kind of CPUs is often easily distinguished from normal frequency and voltage on the fly. Because power varies desktop CPUs by a little ‘mobile’ in the name like Intel’s linearly with clock speed and by the square of the voltage, Mobile Pentium. adjusting both can produce cubic reductions in power consumption whereas conventional CPUs can adjust power C. Specially designed power saving CPUs only linearly. A conventional CPU, throttling back the Special CPU architectures promise even more energy processor speed by 10% cuts power by 10%, whereas under efficiency. The following architectures have been designed the same conditions, LongRun power management can reduce with the requirements for mobile computing in mind. power by almost 30%. Although this technology help to save a lot of power Transmeta hasn’t had very much success with it in 1) Intel Centrino the past few years.

The most well known brand in this sector is probably Intel’s Centrino Architecture. The designers of this architecture took 3) ARM - small and powerful

a close look at the Pentium architecture and tweaked it for ARM, whose Headquarter is based in Cambridge, United power saving as much as they could, without sacrificing too Kingdom, is the industry's leading provider of 32-bit much performance in the process [4]. embedded RISC microprocessors with almost 75% of the The Pentium-M only uses about 6 Watt in battery-operation market (2002)[7]. ARM is a “fabless” company - they only and under full-load while it’s Desktop sibling, the Pentium IV, sell ‚ “intellectual property‘ such as Core designs. Licensees uses above 24 Watt. A Pentium-M clocked at 1.5 GHZ should include big names like Intel, IBM, Motorola, Samsung… have the same performance as a 2 GHZ Pentium 4, not bad pretty much everyone in the semiconductor market! [8] when you keep in mind that it uses less than a quarter of the Jazelle is a technology that allows ARM CPUs that implement power. [5] it, to run Java bytecode natively. This technology is often used by mobile phone manufacturers to speed up execution of Java 2) Transmeta games and apps, which is probably what drove development of A different approach is used by the company Transmeta with the technology.

their Cruseo, or the newer version Efficeon, design. They are Thumb allows the 32bit ARM RISC processors to partly using a technology known as ‘Code Morphing’[6]. operate in 16bit mode to, simplified, save a little Memory. Transmeta CPUs can be seen as somewhat incomplete, the This has been introduced at a later stage of the development on Code morphing engine emulates all the missing functions. This demand by the manufacturers. This is out of the ordinary as special software is loaded right after the start of the system ARM has therefore gone 32bit -> 16bbt, and not the other way round like Desktop CPUs.

from a special BIOS-like chip on the main board. Therefore the CPU can be ‘updated’ to learn new instructions and bugs

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and the L2 cache, along with some management logic are

example a game can be forced to run on the second core while A. Hyper-Threading Technology

all other applications run at the first core. However this is just 2*32 is also 64. Because AMD was faster than Intel in a stop-gap solution. In the future, programs need to be releasing 64bit for the mass market, Intel had to come up with differently designed, that is they need to be multithreading. something new in order to stay competitive. The impressive Big tasks need to be chopped down into smaller ones which marketing term Hyper-Threading was created and the first can then be processed by different cores at the same time. processor which used this technology hit the market in Professional software often supports multithreading or can February 2002 [9]. easily be adapted to do so but the rest of the software industry In simple terms, Hyper-Threading Technology is multiple needs to adapt to the new requirements to their software. logical CPUs on one chip. When this technology was Old software however, that isn’t designed for multi-core PCs introduced this meant that an operating system which supports and software which won’t be updated to use the available multiple CPUs - and up-to-date operating systems doresources might often run slower on multi-core platforms. suddenly has 2 CPUs to work with. However there aren’t Because cooling is still a problem, multi-core CPUs are really 2 CPU cores on the chip but 2 registers, another clocked slower than their single-core siblings today. Software interrupt controller and some basic management patterns. But which uses only one core will therefore be limited to the power as far as the operating system is concerned it can work with 2 this individual core has to offer. So if you are a gamer don’t real CPUs. The amount of needed transistors is only raised by buy a shiny new multi-core PC just yet. around 1% and, according to Intel, the performance boost can The question is not if multi-core will come but when it will be as high as 35% [10]. come. Paul Otellini, CEO of Intel, estimates that in 2006 In practice it depends very much on what applications run on a around 40% of the Desktop PCs sold will come with a dual-CPU with Hyper-Threading, however at virtually no additional core CPU [11]. It’s simply not practical to get more cost the additional performance is quite impressive. As every performance out of single-core CPUs and therefore multi-core major CPU manufacturer is now focusing on real multi-core

is the future of CPU technology.

CPUs the fate of Hyper-Threading is already sealed. But in the meantime it offers an easy way to increase the performance of CPUs without too much of an effort. V. VIRTUALIZATION

Virtualization is a technology that allows a platform to run B. Multi-core CPUs multiple operating systems in independent partitions at the Not until too long ago a PC that had multiple CPUs was called same time [13].

a server or a workstation and was very expensive. With the This sounds like old news and in fact it is. Since the dawn of recent speed improvements single core CPUs are producing modern computing installing multiple operating systems on the too much waste heat to be cooled effectively and speeding up same PC was nothing to uncommon. However nowadays it is those CPUs is very complex. So complex in fact that new CPU possible to run Operating Systems at the same time. A typical factories would’ve been needed to be built. To counter this example would be someone using Linux and emulating problem nearly every major CPU manufacturer has shifted Windows in order to be able to play some games. In the last their attention to building multi-core CPUs [11]. The first few years Virtualization software like VMWare or Microsoft’s wave of products was mostly dual-core. “2 are better than 1” is VirtualPC has become quite popular. This software however is also an effective marketing tool that can be understood even often considered to be slow and memory hungry because a lot by a complete layman. Unlike Intel’s Hyper-Threading of the actual hardware has to be emulated in software. Other Technology, multi-core CPUs have 2 real cores and often hardware can’t be probably shared like RAM for example. The those cores have their own L1 cache. Only the bus interface virtual-machine software just takes a fix amount of RAM, no matter what the OS that runs on it uses. Wouldn’t it be better if

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Code Morphing™ Software”. Whitepaper. Available: the virtual machine could just share the resources of the host http://www.transmeta.com/pdfs/paper_aklaiber_19jan00.pdf operating system? A lot of resources would be saved and [7] A. Stiller, “Die ARM-Story - Von der kleinen Architektur zum großen because not everything would need to be emulated the speed

Marktführer” (The Arm story - From the little architecture to the big of the Virtualization software would increase dramatically. marked leader) c’t, german magazine for computer engineering, vol.

20/2002 pp. 70-73 This is exactly what Intel and AMD are currently working on - [8]M. Markowitz et al. (2002-2006) “ARM architechture”. From hardware support for Virtualization. Wikipedia, the free encyclopedia Available:

Intel calls its approach Vanderpool Technology [14]. http://en.wikipedia.org/wiki/ARM_architecture The first processors implementing this technology have been [9] Intel Technology Journal, Intel corp. volume 6, issue 1, ISSN sold at the end of 2005 [15]. 1535766X Available:

http://www.intel.com/technology/itj/2002/volume06issue01/vol6iss1_hy AMD calls its Virtualization technology Pacifica and first per_threading_technology.pdf

processors with this technology are expected to hit the market [10] M. Withopf, “Virtuelles Tandem - Hyper-Threading im neuen Pentium in early 2006 [16]. 4 mit 3,06 GHz” (virtual tandem - hyper-threading in the new Pentium Pacifica can be compared to Vanderpool, however both 4 3.06GHZ) c’t german magazine for computer engineering, vol.

24/2002, pp. 128-133 technologies are incompatible. Virtual machine producers have [11] R. Hülsenbusch, “Krieg der Kerne - Multicore-Techniken im Vergleich” already announced they will support both approaches. (War of the cores - multicore techniques in comparison) c’t, german In the end of 2006 AMD will introduce the next step of its magazine for computer engineering, vol. 04/2006, pp. 46-51 Available: virtualization technology codenamed Hypervisor which will http://www.heise.de/ix/artikel/2006/04/046/

[12] E. Bonnert, A. Stiller, “Kernzeiten und Plattformierungen - Intel make life for the manufacturers of Virtual Machine software Developer Forum Herbst 2004 ” (core times and plaforms - Intel even easier.

Developer Forum autumn 2004) c’t, german magazine for computer Other CPU and chipset manufacturers like ARM, ARC and engineering, vol. 20/2003, pp. 18-21 Texas Instruments are working on virtualization support or [13] A. Shilov, (2005, Januar) “Intel Vows to Bring Virtualization to Desktops in 2005 - Intel Speeds Up Vanderpool Roadmap”. Online have already released products with support for it. Article from X-bit labs Available: The future of Virtualization is unclear. In the business and http://www.xbitlabs.com/news/cpu/display/20050120184415.html professional market it will surely play an important part. [14] R. Uhlig et al, (2005) “Intel Virtualization Technology”. Article written Testing software on many different platforms with just one PC by Intel corp. employees for the IEEE magazine Available: ftp://download.intel.com/technology/computing/vptech/vt-ieee- orconsulting multiple servers onto one machine is becoming computer-final.pdf more and more popular and the hardware support will make [15] A. Stiller, “Prozessorgeflüster- Von Dresden bis Babylon” (processor life easier a lot. This kind of application doesn’t really play an whispering - From Dresden to Babylon) c’t, german magazine for important part for the consumer market and it remains to be computer engineering, vol. 25/2005, pp. 20-21 [16] Advanced Micro Devices - AMD, AMD I/O Virtualization Technology seen if this technology will really kick of or if it will just be (IOMMU) Specification, PID 34434 Rev 1.00 - February 03, 2006 one of many technologies that are there for their own good, not Available: http://www.amd.com/us- beingused by anyone.

en/assets/content_type/white_papers_and_tech_docs/34434.pdf

VI. CONCLUSION

The gigahertz mania seems to be finally over therefore the manufacturers need new arguments to sell their products. We’ve given a small introduction on what’s going on in the CPU market and these technologies will surely play an important part in the future.

REFERENCES

[1] A. Stiller, “Doppelbreit - 64 Bit kontra 32 Bit” (double-wide - 64 Bit contra 32 Bit) c’t, german magazine for computer engineering, vol.

20/2003, pp. 106-112

[2] A. Stiller, “Prozessorgeflüster- Intel mit AMD Inside” (processor whispering - Intel with AMD Inside) c’t, german magazine for computer engineering, vol. 05/2004, p. 24 [3] C. Windeck, “Diät Prozessoren - Mobil-Prozessoren im Desktop-Einsatz” (Diet Prozessors - mobile prozessors in desktop use) c’t, german magazine for computer engineering, vol. 06/2004, pp. 164-174 [4] A. Stiller, “ Die Quelle des Jordan - Optimierte Mikroarchitektur für

[5] M. Schmidt, “Intel Centrino Technologie: Pentium-M-Prozessore”. Online article. Available: http://www.pcerfahrung.de/Index.html?NotebookCPUIntelCentrino.html [6] A.Kleiber, (2002, Januar) “The Technology Behind Crusoe™ Processors - Low-power x86-Compatible Processors Implemented with