TI approach to MPEG-2 decoding. And perhaps encoding. In hardware. Just plug it into a DIMM memory socket...
eetimes.com
TI fields DSP-based media processor on a DIMM
By Anthony Cataldo
EE Times
(01/28/00, 11:47 a.m. EST)
TOKYO — Texas Instruments Inc. is quietly beating a path into what has proved to be a no man's land for the media processor. After virtually giving up on its quest to field a DSP-based media processor for the PC several years ago, the company is again exploring the notion of putting a high-performance digital signal processor on the desktop to handle hard-core programming chores that would otherwise throttle a CPU.
If TI is able to reach a few more milestones in coming months, and if early customers give the green light, DSPs could find themselves saddled with a dual-in-line memory module (DIMM) as early as this summer, primed for use in such applications as medical imaging and video decoding.
TI displayed its Performance Enhanced Memory Module (PEMM) at Microsoft Corp.'s Windows Hardware Engineering Conference in 1998. Since then, however, not much has been heard from the PEMM effort.
Module holds surprise
At TI's Tsukuba R&D Center, which is becoming the focal point of the Dallas-based chip maker's research and product development efforts in Japan, Yuji Itoh, senior member of the technical staff, is hovering over a PC, fingering a 32-Mbyte DIMM. But there's something different about this module. It's about 2 inches tall, larger than a standard DIMM. After turning it over, Itoh reveals why: There's a C6x DSP strapped to the back, along with a piece of programmable logic.
A media processor on a DIMM?
"We reached the idea that the DSP should handle lots of data, and data is available around the memory," Itoh said. "So we decided to put the DSP on a memory module."
Put it on a PCI bus and you encounter lots of contention over the bus, which will bog down the DSP. Put it on a DIMM, along with the right drivers supporting synchronization and multiplexing with the CPU, and you have high bandwidth coupled with quick access to memory.
"The DIMM approach is a brilliant way to get into an existing socket," said Will Strauss, president of the research firm Forward Concepts (Tempe, Ariz). "Perhaps the bandwidth is higher on a DIMM slot and it's much higher on memory [bandwidth]."
TI isn't trying to turn the idea of a CPU-centric PC upside down. But it is making a case for what it calls "heterogeneous multiprocessing." In other words, if you really need performance, TI is proposing to throw in a DSP — maybe with its own companion hardware accelerator — to take care of math-intensive multimedia applications.
The idea itself is not new. The idea of DSP-based processing gained steam during the latter part of the 1990s, as a way to solve the crush of multimedia applications invading the PC. These PC media processors came in many forms, and from a variety of companies, including Philips and Samsung, as well as Chromatic Research and its licensees, LG Semicon and STMicroelectronics.
Texas Instruments bowed out early when Microsoft turned thumbs down on Intel Corp.'s ill-fated Native Signal Processing (NSP) initiative. According to analyst Strauss, Intel realized it would need help from a DSP for NSP to work, and proposed to hang a TI C30 off the ISA bus.
But NSP relied on gaining access to Ring 0 at the heart of the operating system, which ran afoul of Microsoft's DirectX program.
Step aside
Meanwhile, Intel boosted the Pentium's speed and introduced the Accelerated Graphics Port, in large part obviating a DSP solution. "The Pentiums just got better and better," said analyst Strauss.
Yet the newest spin of media processor just entering the market today "is having success in things like HDTV and high-end stereos," Strauss said. "And so it looks like there will be a market for media processors . . . but not in the main PC chassis."
Faced with so many obstacles, TI is taking a cautious approach. Since it first publicly floated the idea of the media processor-based DIMM at WinHEC nearly two years ago, it has done what it can to build the software support and ensure motherboard compatibility. It even pushed through a new DIMM standard, the PEMM.
Motherboards made in Taiwan, China and the United States have unique data line inversion schemes, and the PEMMs needed to work in each one. "We solved the problem ourselves by introducing a mechanism in the driver to handle the data line conversion," Itoh said. "The driver is just above the operating system."
TI's prototype PEMM packs a TI C6201 running at 200 MHz. Running in a parallel configuration, it can burn 1.6 billion instructions per second, though Itoh said the actual performance would be lower. Next to the DSP is a bit of programmable logic to handle the data bus control. It could be converted into an ASIC for volume production, Itoh said.
TI doesn't expect the PEMM to replace, say, a 3-D graphics card. There's already plenty of specialized IC companies fighting over that market, Itoh said. Instead, the company is aiming at specialized application such as medical imaging or accelerators for photo-lab technicians.
While these uses may be considered a niche, they are stimulating the interest of DSP suppliers. Applications like volumetric imaging, where, for example, an ultrasound image can show a 3-D form as well as the internal structures, need more DSP horsepower, said Strauss.
"TI has been telling me they are beginning to add some emphasis on the medical imaging market," Strauss said. "Medical imaging is not big in volume, they buy thousands of chips a month. But it is lucrative. If you have [a medical imaging system] on a PC you have a good human interface."
TI is looking at other applications too, such as manipulating MPEG video images. For example, TI's PEMM can now handle MPEG-2 decoding and, with a little help, encoding.
|
