UK chip plays high-def on less than a watt

A UK-designed media processor can play 720p high-definition video using the H.264 codec while drawing less than 1W

The dual-core DMS-02 processor would allow a pocket media player to drive a full-size HD screen, and is expected to be used in a new generation of GPS navigators supporting 3D views of cities.

But though developer 3DLabs Semiconductor describes it as a media processor, it can also act as the CPU of a general-purpose or multifunction handheld device.

It consists of two 200MHz ARM 926EJ cores with an array of 24 16-bit floating-point processing elements (PEs) arranged in three clusters, each with a controlling sequencer unit. The PEs can also perform 32-bit, 16-bit and 8-bit integer processing.

Applications are run on the ARMs, which offload to the PEs tasks that lend themselves to parallel processing. This general structure is reminiscent of the Cell processor used on Sony's Playstation 3. A block diagram, will be posted on our Test Bed blog shortly.

Two aspects make it very different from other processors targeted at the same markets, according to 3DLabs technical director Nick Murphy. Most have separate units for tasks such as 3D processing. "This is very inefficient because only part of the processor is being used and the rest may be idle," Murphy said.

Instead the DMS-02 time-slices the tasks in hand so that the entire PE array processes each in turn.

Murphy says the DMS-02 is also unique for a device of this class in stepping down both the frequency and operating voltage when full power is not required. Power drain is proportional to frequency and to the square of the voltage, so that reducing both has a pronounced effect: a task requiring half the maximum processing power might draw only a fifth of the peak drain.

AMD and Intel CPUs do this sort of thing, of course, but they do their own manufacturing and it is not usually available on chips from fabless companies such as 3DLabs, whose designs are manufactured by third parties.

The problem is to make the chip so that changes in the power drain, voltage and frequency do not catastrophically affect the timing, Murphy said. "Our engineers have found a way to do this."

3DLabs Semiconductors has just been spun-off as a separate company by Creative. It was originally formed in 1984, and was bought by Dupont Pixel, who sold it on to Creative.

The DMS-02 is only the first of a projected range of media processors. Murphy said: "It scales very well. We can have one or two ARM cores, and as many processing clusters as we need."

The chip was designed by engineers at the company's labs in Egham and Bristol.