Chapter 4. Processors

Certainly, one of the most important parts in any computer is the central processing unit, or CPU. The CPU can also be referred to as a microprocessor, or just processor, for short. Several types of processors are used in portable systems from several different companies. Processors for portable systems can be the same as those used in desktop systems, but several processor companies also make special processors specifically optimized for use in portable systems. They are generally referred to as mobile processors. This chapter examines primarily the mobile processors used in laptop/notebook and other portable systems.

Currently, Intel and AMD both manufacture processors designed for either desktop or mobile use, and Transmeta makes a series of processors under the Crusoe and Efficeon names that are exclusively for mobile use. As with desktop systems, the majority of mobile systems use Intel processors, and creating chips designed specifically for mobile systems is a major part of Intel's development effort. Over the years, Intel has introduced many different processors for mobile use. Intel has focused on mobile processors since the 386SL came out October 1990 and since then has dramatically expanded mobile processor technology and features. Today the Pentium M processor and the Centrino mobile platform, which is composed of the Pentium M processor, motherboard chipset, and support for Wi-FI, have the largest market share in laptop computers and have gone through several revisions since their initial introduction in 2003. By comparison, AMD was late in catering specifically to the mobile processor market. AMD's first major mobile-only processors were mobile versions of the K6-2 and K6-III released in 1998. In May 2001, AMD announced a line of mobile Athlon 4 (Palomino) and Duron CPUs. The mobile Athlon XP came in April 2002, and the mobile XP-M processor was introduced in March 2003. In 2004 AMD migrated its Athlon 64 desktop processor to laptop computers and named it the Mobile Athlon 64 processor. Today, AMD has just introduced its Turion 64 mobile processor, which builds on the Mobile Athlon 64 processor and is designed to offer similar performance and battery efficiency as Intel's Centrino platform.

Transmeta has had some success in small form factor designs, but generally its processors have failed to keep pace with the mobile offerings from AMD and Intel. Transmeta's processors can, however, be found in subnotebooks, PDAs, and other portable devices. Intel more or less outclassed Transmeta's processors by introducing the Pentium M processor that had similar power consumption and battery efficiency as Transmeta's processors but offered vastly better performance. Transmeta's Efficeon processor succeeds the Crusoe and is, like the Crusoe processor before it, not actually an x86-based processor like Intel's or AMD's. Instead, it uses a different internal logic, Very Long Instruction Word (VLIW), and uses a software layer to convert data from x86-instructions into code the processor can understand.