Mobile Processors Begin to Grow Up
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TECHNOLOGY NEWS have been developing faster mobile processors. For example, Intel recently Mobile Processors demonstrated a 1-GHz processor. Designers will achieve faster clock speeds the same way they do in PC processors: with smaller feature sizes Begin to Grow Up and optimized designs. The optimized designs include the integration of mem- David Clark ory and other functions on a single chip. The challenges The key challenge that designers face is providing consumption, high inte- dvances in wireless technol- gration, and low cost in a package ogy have increased the small enough to fit in a handheld demand for more functional device, said Laurie Pegrum, platform A mobile devices that can take architect for Intel’s Handheld Com- advantage of these improved puting Division. To keep mobile pro- capabilities. Developing better proces- cessors small, vendors have adopted sors to power these devices is a key smaller feature sizes and system-on- part of meeting that demand. More chip (SoC) approaches. functional processors enable devices Lowering power consumption is the to offer the complex communications most significant challenge because it features, PC-like programs, and other has the biggest impact on chip size, advanced applications that a growing cost, and performance, according to number of users want. NEW TECHNOLOGIES Cornish. As the chips have improved, the Until recently, mobile applications Designers reduce power consump- mobile-processor marketplace has haven’t been particularly complex. At tion (and, in the process, heat genera- begun to change. Traditionally, numer- the same time, vendors have had to tion) by lowering the voltage at which ous companies have designed and sold design mobile chips to minimize power chips run, minimizing capacitance, and these processors. Now, wireless-device consumption, both to make batteries using a technique called clock gating. vendors are focusing on just a couple last longer and to prevent heat buildup With clock gating, a chip can execute of chip architectures, and they are in devices that lack space for fans or an instruction without switching tran- increasingly licensing cores and archi- other cooling mechanisms. Moreover, sistors or involving gates that aren’t tectures predesigned by ARM Hold- vendors have wanted to hold prices needed for the operation. ings. ARM licensees include Intel, down on small devices, which required Other techniques involve power Motorola, and Texas Instruments. using inexpensive processors. management schemes implemented in In fact, providing ARM-based chips In the past, therefore, mobile proces- hardware and software, said Markus is now required to compete in the mar- sors have run at no more than 30 MHz Levy, senior analyst at MicroDesign ketplace, said Ed Valdez, director for PalmOS PDAs, 80 MHz for cellu- Resources, a processor-industry analy- of wireless platform marketing for lar phones, and 200 MHz for devices sis company. For example, most Motorola’s Wireless and Broadband that run Microsoft’s Pocket PC OS. mobile processors have multiple or Systems Group. However, many mobile-device users variable power-use modes. Also, Levy And the importance of this market- now want and will pay for advanced said, recent chip designs include more place is growing with the demand for features like wireless Web access and sophisticated power-scaling techniques smart handheld devices. The global location-oriented services, such as find- that adjust to the application in use. market for the devices will have grown ing a nearby restaurant. This requires Thus, Motorola’s Valdez said, even 43 percent annually between 1998 and more processor power than basic cell though mobile-processor speeds will the end of this year, according to mar- phones or simple information-man- increase, power consumption and heat ket-research firm IDC. By the end of agement PDAs have. generation should decrease. this year, IDC estimates, vendors will Higher chip performance is thus be shipping about 25 million devices becoming increasingly desirable, said System on chip generating about $13 billion in revenue John Cornish, ARM’s director of CPU Companies such as ARM, IBM, annually. programs. With this in mind, vendors Intel, National Semiconductor, and 22 Computer Texas Instruments (TI) have estab- ARM’s most common 32-bit instruc- chips are used in several smart cellular lished an important mobile processor tions compressed into 16-bit operation phones, including NTT DoCoMo’s trend: integrating many system func- codes. On execution, Thumb translates popular iMode, as well as the Compaq tions on a single chip. According to the code to expand the 16-bit instruc- iPaq and Hewlett-Packard Jornada Levy, SoC designs can lower prices, tions to a 32-bit format in real time. PDAs. Other handheld vendors have increase reliability by reducing the Most of the company’s current announced plans to use StrongARM number of system components, lower designs, including various manufac- chips in the near future. power consumption, and increase per- turers’ ARM7-core-based processors Unlike most chip makers that use formance by reducing the distance over and Intel’s StrongARM chips, use ARM technology, Intel has an ARM which data must travel. ARM’s v5 instruction set. However, architectural license. Instead of licens- According to Heikki Liimatta, a high-end devices use chips with the ing predesigned processor cores, Intel senior research manager at Nokia, SoC more expensive and more functional licenses the ARM instruction set and platforms would include microproces- ARM9 core, which also works with builds its own cores. sor cores and such additional func- the v5 instruction set. StrongARM chips are based on tionality as digital signal processing, ARM’s v4 instruction set and currently memory, and application program run at up to 200 MHz on about 0.5 W ARM is taking a interfaces for software developers. of power. However, Intel said it expects dominant position in the next-generation StrongARM proces- VENDORS TAKE NEW APPROACHES mobile chip market. sors to have smaller feature sizes and In response to user demand and deliver up to 600 MHz and 750 MIPS technological developments, several while using 40 to 450 mW. mobile-processor vendors have taken The company has announced the Intel has also released a new mobile- new approaches to their products. ARM10 core, but it has not appeared processor platform called XScale, which in products yet. uses ARM’s v5 instruction set, as well ARM ARM also recently announced ver- as digital signal processor, Thumb, and ARM doesn’t make chips itself but sion six of its instruction set, whose Java extensions. XScale is faster than instead develops instruction sets and primary improvement over v5 is the StrongARM. It also has more signal processor core architectures that have addition of multimedia functions. processing capabilities and thus runs begun to dominate the market. Other v6 enhancements include im- multimedia better. Many companies—such as IBM, proved memory management, better In addition, XScale will be highly NEC, and 3Com—have licensed the support for dividing tasks among mul- scalable. Intel uses a new dynamic volt- ARM core. Their products provide tiple processors, and single-instruction age management technique that adjusts similar functionality, although they multiple-data technology. The SIMD processing power and power usage to may differ in a few ways. For example, approach increases performance by let- application and operation demands. TI’s ARM cores typically provide dig- ting one microinstruction operate at the Intel has demonstrated speeds of up ital signal processing, while Motorola’s same time on multiple data items. to 1 GHz and very low power con- new ARM products include wireless ARM’s first v6-based core, named sumption. Therefore, a single chip communication capabilities. Jaguar, is due by the middle of this could be used in various devices or in According to Cornish, ARM focuses year. Jaguar chips, which will use a 32- devices that experience a range of user on maximizing performance while cre- bit architecture, will run up to 1.6 bil- and application demands. Some ating cores and a development envi- lion operations per second at 400 MHz smaller devices could even run on a ronment that make it easy for chip and 3.2 billion operations per second standard AA battery. vendors to implement the technology. at 800 MHz. In practice, initial XScale-based prod- The optimized instructions, as well as ARM has designed the core for use ucts will probably clock at 600 MHz clock gating and other techniques, also in high-end PDAs, smart phones, and and consume no more than 0.5 W. make ARM’s chips energy efficient. entertainment devices. Cornish said Intel has designed XScale for use in ARM offers instruction-set exten- Jaguar-based products could be on the high-end PDAs and cellular phones, sions that add functionality to its core market by the end of 2004. devices such as wireless routers, and architectures. For example, Thumb is a applications such as embedded micro- popular extension of ARM’s 32-bit Intel’s StrongARM and XScale controllers, explained Intel’s Pegrum. RISC architecture designed to optimize Intel acquired StrongARM processor code density so that applications will technology from DEC in 1997 and has Motorola run better on systems with small mem- used it to carve out a strong position in Motorola traditionally has been the ories. Thumb works with a subset of the mobile chip market. StrongARM leading mobile processor manufacturer. March 2002 23 Technology News As MicroDesign Resources’ Levy noted, the company has been able to use its Power CGM ICE Bootstrap GPIO control (DPLLx2) chips in its own popular mobile phones, System control PWM and until now, market-leading Palm’s Timer 1 & 2 PDAs have used only Motorola chips. Motorola DragonBall Super VZ In addition, Motorola has been build- RTC ing mobile microprocessors longer than WD MMC/SD most vendors.