CPU Introduction
The microprocessor or CPU (Central Processing Unit) is the heart of any computer device. There are two main types of microprocessors for PCs: The x86 processors (IBM/Intel originally, CISC based protocol) and the RISC based processors. Current Pentium designs now have incorporated some RISC technology.
Manufacturers of PC-CPUs are e.g. Intel, AMD, VIA (previously Cyrix) and Transmeta ('Crusoe' chip). RISC-based CPUs for e.g. Apple are made by IBM ("PowerPC") and Motorola. Current CPU brand names (for PCs) are Celeron, Pentium III, Pentium 4, Xeon, (Intel) and Duron, Athlon, Athlon XP (AMD).
CPUs can feature different processor-core technology with their own names: Intel's 180 nm cores for a Pentium 4 are called "Williamette", whilst the latest 130 nm cores for this CPU are called "Northwood". For Pentium III and Celeron there is the "Tualatin", whilst the Xeon chip can have a "Foster" (180 nm) or "Prestonia" (130 nm) core. The latest 130 nm core for the Athlon is called "Palomino".
Furthermore, the CPU is characterized by the socket geometry(socket 370, Socket A, etc.).
CPU performance is roughly determined by clock speed (the speed at which a microprocessor executes instructions) and data width/specific architecture (now 32 and even 64-bit, featuring also extended pipeline facilities, i.e. the ability to work on several instructions simultaneously but at different stages of execution). At present (March 2002) the state-of-the-art is a 2.8 GHz processor (e.g. Intel Pentium 4) with 130 nm technology. The design heat dissipation (TDP=Thermal Design Power) at that configuration is around 52-55 W (compare: a 180 nm Pentium 4 is around 76 W). For mobile applications, featuring 500-800 Mhz clockspeed, the TDP may be as low as 5 or 6 W (e.g. Transmeta Crusoe) or as high as 25-30W (180 nm Intel Pentium III mobile, at normal voltage).
Through smart power management (ACPI), task-specific decrease of clockspeed (e.g. SpeedStep, LongRun) and aggressive shut down of unused sections, the average power consumption will be far (40-60%) lower. Transmeta, using its VLWI processor, Code Morphing software (CMS 4.2) and LongRun power management, reaches e.g. around 1.8 W for Office 2000 applications and 2 W for WinAmp DVD playback. VIA's Eden processor (TDP of 7 W) and Intel's Ultra Low Volt Pentium III (TDP of 11,2 W at 800 MHz) are taking up the Crusoe-challenge and are roughly in the same league. In benchmarks simulating real-life office work, such as the Ziff-Davies Battery Mark 4.0.1. simulating various pauses, energy consumption may be even lower. Here even the Mobile version of the Pentium 4, running at 1,7 GHz (1,3 V) and in Battery Optimized Mode, is using less than 2 W on average. (Compare: TDP of the same Pentium 4 M is around 30 W).
CPUs are tradable goods in their own right, mostly as an upgrade product for the consumer market (if it fits the socket) and are performance-tested by various magazines for the consumer-market.
For more background on PC-CPUs and data-sheets specifying TDP and energy use in various standby modes see www.intel.com, www.amd.com, www.via.com and www.transmeta.com.
Courtesy of the French Energy Agency ADEME, Future Electronics project.
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