Double take: Reassessing x86 CPUs in embedded-system applications

Designing an embedded system based on PC-industry building blocks is like dancing with the devil. The chips and subsystems, including add-in cards, hard-disk drives, optical drives, and power supplies, are low-cost and abundant, thanks to the high-volume-manufacturing efficiencies of the PC market.
However, although you measure your design's anticipated production life span in years or even decades, the fickle fortunes and fast evolution of the PC industry drive rapid obsolescence of your raw materials. Design smartly, planning the ability to later upgrade, and you'll be able to nimbly sidestep any supply-chain potholes. Failure to plan for future substitutions and advancements, on the other hand, means you'll soon—and perhaps repeatedly—redesign.

The PC industry's rapidly spinning product treadmill will become abundantly obvious to you if you revisit 2004's two-part article series (references 1 to 3 ). Then-state-of-the-art high-end systems are now mainstream products or have even moved to bargain-basement closeout status. Some of those systems' constituent pieces, such as Rambus DRAM and RDRAM-cognizant core-logic chip sets, have disappeared from today's PC designs. And multicore x86 CPUs, which in early 2004 were placeholders on manufacturers' future product road maps, now take center stage.

The Intel Pentium M processor, which in early 2004 was only beginning to establish a beachhead in the mobile-computer market it now dominates, has today also become a popular CPU in single-board-computer designs. Its combination of high performance and low power consumption makes it a natural fit not only in laptops, but also in many embedded systems. With Core Duo (formerly known as Yonah) now in production on Intel's 65-nm process, dual-core capability is now part of the Pentium M stable. Core Duo chips for the embedded-system world are now in short supply because companies such as Apple and Dell are gobbling up as many wafers as Intel can fabricate. As a result, this hands-on project substitutes laptops for single-board computers, tweaking test conditions to as closely as possible mimic embedded-system configurations (Figure 1 and Table 1 ).