MOUNTAIN VIEW, Calif. — Aiming at designs that span TVs, PCs and set-top boxes, startup TeraLogic today will roll out what it calls the first digital-TV decoder chip to link to the desktop computer's familiar PCI bus.

The chip is likely to be the first of a small crop of decoders and DTV add-in cards that will be rolled out by companies, including LG Semicon Co. Ltd., at Comdex next week. The decoders will bring at least a basic level of digital-TV reception to the PC for a few hundred dollars, well below the several thousand required for a full HDTV system. But even with the latest decoders, the PC architecture is far from ready to handle the full feed of a 1,080-interlaced high-definition broadcast.

TeraLogic, based here, said the TL850 chip it will announce today is scheduled for sampling at the end of this year. The device combines DVB, DSS and ATSC transport, audio and MPEG-2 Main Profile @ High Level decoding, and up and down conversion among all 18 ATSC DTV formats. Also on-chip are a high-performance 2-D/3-D graphics processor.

Because the chip exploits TeraLogic's proprietary advanced memory-reduction scheme, all the format conversions, up and down, are done in 4 Mbytes of memory .

The use of PCI opens the door to pairing the decoder with any CPU in a set-top box or PC, said Kishore Manghnani, vice president of marketing at TeraLogic. "Once the PCI bus interface is in, any platform based on this chip will become suddenly expandable, as it can take advantage of a variety of low-cost Super I/O chips, including Ethernet, USB, printer port, hard-disk interface, telephone modem and infrared."

Until now, "all the existing DTV chip sets failed to pay attention to a PC interface like PCI," said Jim Hopkins, vice president of strategic marketing for STB Systems Inc. (Richardson, Texas), which makes graphics cards for Dell, Gateway, IBM and Compaq, among others. Previously announced DTV chips "were all aimed at televisions and set-top boxes," he said.

Many of these conventional DTV chips come with a proprietary bus interface, depending on a specific CPU used in a set-top or a TV. Manghnani said TeraLogic's TL855 will change that picture. "In essence," he said, "this chip with a built-in PCI-bus interface helps bring TV closer to PC."

However, it's unclear if the chip's ability to display all 18 DTV video formats will be considered overkill by some PC makers. Hopkins, for example, said that STB is aiming at PC DTV add-in cards that receive all 18 formats and then downcovert to 480i (interlaced) or 480p (progressively scanned) pictures.

The retail price of around $200 to add the TL855, Hopkins said, "is about one-fifth the price of similar consumer-electronics down-converter boxes." A Thomson model, for example, sells for $1,100.

However, some observers see little market for low-resolution DTV on a desktop computer. "I'm frankly a bit mystified," said Simon Dolan, vice president of marketing at LSI Logic Corp.'s consumer products group, which designs DTV decoders for set-tops. "Why would anyone want to watch HDTV displayed on a 480i or 480p PC monitor? Maybe I'm missing something here, but for the time being, that's a low-priority issue for us."

PCs still face major hurdles dealing with the highest-resolution HDTV signals. Over at Intel Corp., engineers are busy working on the All Format Decoder the company licensed from Hitachi Ltd. "In our lab," said Thomas Galvin, director of market development for entertainment and education at Intel, "we have proven that we can decode 1,080i in software, using our future-generation CPU product, and can display it on 560-line resolution."

Galvin predicted it would be at least 2001 before Intel can do native 1,080i decode and display. To do so, he said, "is more than a processor question, but a PC system-architecture decision." In other words, Intel hopes to utilize a host's processing power to reduce the overall cost of implementing DTV on a PC. But "that opportunity won't exist until the PC architecture accommodates it," Galvin said.

PC buses like PCI are not designed to handle the very high bit rates associated with the uncompressed digital-video data itself.

PCs also need a better interface between the DTV decoder and PC graphics chips, and are likely to use the Video Input Port (VIP) 2.0, whose spec was just ratified by the VESA standards body.

TeraLogic's Manghnani, however, said that his company has already done most of the groundwork necessary to implement its TL850 in a PC environment. A PCI card equipped with the company's DTV logic is connected to the graphics subsystem via a loopback cable. Instead of using a VIP 2.0, the current version of the chip uses a separate analog multiplexer to select the analog RGB data, horizontal sync and vertical sync from two sources: the TL850 and the graphics card.

The TL850 generates the signal to switch the multiplexer. The consumer can view a full-screen HDTV broadcast on the PC monitor when the TL850 video output is selected. This implementation also makes it possible to display a video window on a graphics desktop computer.

The TL850 can simultaneously output CCIR 601-compatible digital video along with the high-definition RGB video. The user can select either the full-screen HDTV output or can view the TV programming in a video window while working on a PC application. The choice is by mouse click, according to Manghnani.

Manghnani claimed that most competing DTV chips now on the market have little graphics capability and are designed to work with limited CPU processing power. "The first-generation DTV chips can't handle multimedia content, let alone support Personal Java or Windows CE APIs," Manghnani said. He described many of them as "designed for technology demonstrations rather than a mass-market product."

TL850, on the other hand, comes with a complete software package on its DTV reference platform, called Cougar. TeraLogic provides everything from device drivers, real-time operating system, source code, third-party browser, EPG as well as Personal Java and Windows CE API for development purposes. The TL850 is priced at $100 when sampled in 1,000 pieces.

As TeraLogic promotes DTV for every platform, Philips is taking a middle ground. Guenther Dengel, managing director of consumer ICs for Philips Semiconductors, said the company will show a DTV tuner card at Comdex, integrated with a tuner for NTSC and ATSC reception and a VSB demodulation chip, in three form factors. Asked if Philips will roll a DTV back-end solution based on a TriMedia core surrounded by hardwired blocks, he said, "It's not clear to us whether they [Intel and PC OEMs] want us to get involved in PC implementations."