Embedded Microprocessors

Computerworld - You can't see them, but they're everywhere, exerting more and more influence on our lives, sometimes spelling the difference between life and death. We're talking about embedded microprocessors: the hidden chips that control everything from cell phones and microwave ovens to jumbo jets and antilock brakes.

Processors for PCs, workstations and servers get all the attention, but embedded microprocessors make the world go 'round.

Where the Sales Are

In terms of unit sales, PC processors like Intel Corp.'s Pentium series; Sunnyvale, Calif.-based Advanced Micro Devices Inc.'s Athlon; and IBM and Schaumburg, Ill.-based Motorola Inc.'s PowerPC account for only 6% of the world market, according to audited reports in the World Semiconductor Trade Statistics' blue book. The remaining 94% - 5 billion chips - consists of embedded microprocessors.

That startling statistic is more understandable when you realize how pervasive microprocessors have become. It's estimated that the average U.S. household has about 60 embedded microprocessors.

Some embedded microprocessors are hand-me-downs from the desktop market - chips that are obsolete for today's PCs but perfectly adequate for less-demanding tasks. The Z80 and 6502 processors that powered early PCs like the TRS-80, Apple II and Commodore 64 are still big sellers. In fact, 8-bit processors outsell the latest 32- and 64-bit processors by a 10-to-1 margin. Even the most feeble 4-bit processors far outsell 32-bit processors like the Pentium. Old microprocessors rarely die, and they hardly ever fade away - they just become embedded.

As a result, the embedded-microprocessor market is unusually broad. At any given moment in the PC market, microprocessors span a performance range of only about 3 to 1 - the fastest chips currently run at 1 GHz (1,000 MHz), while the slowest commonly available chips are about 333 MHz. In contrast, the performance range just for 32-bit embedded microprocessors is 500 to 1. If you factor in the 4- and 8-bit processors, the performance range is thousands to one.

Despite having thousands of off-the-shelf chips to choose from, many product designers need something unique. So they create their own embedded chips, called application-specific integrated circuits.

A designer starts by licensing an embedded-microprocessor core from a company such as U.K.-based ARM Holdings PLC or Mountain View, Calif.-based Mips Technologies Inc. and then adds features specific to his application. For a digital-camera processor, he might add a controller for the charge-coupled device chip; for an Internet-enabled appliance processor, he might add an Ethernet interface.

The designer takes the design to a foundry - a company that owns "fabs" (chip factories) and sells part of its manufacturing capacity to other companies. Popular fabs are United Microelectronics Corp. and TSMC in Taiwan and IBM Microelectronics in the U.S.