The PowerPC 405, like its predecessor, is an "embedded" chip--a low-profile processor that consumes as little power as possible.
IBM is aiming the 405 at a wide variety of markets, including consumer electronics, cellular phones, and other "information appliances" that combine the functions of portable phones, pagers, and email systems.
The 405 runs at speeds up to 200 MHz and is built on a 0.25-micron process. It's a tiny, 2-square-millimeter chip "core" that can be surrounded with other electronics to tailor-make different systems.
The chip uses a CodePack memory compression system, which compresses the 32-bit-long instructions for the chip into smaller instructions. The upshot is that less memory is required to perform the same task, but a special software utility is needed to prepare instructions for running on the chip.