WASHINGTON — Worried about filling up your DVR? The nation's largest cable TV provider, Comcast Corp., is rolling out a new TV platform that does away with the hard drive and saves your TV shows online.

Comcast unveiled the platform, called X2, on Tuesday at the annual gathering of cable TV companies, The Cable Show. The system takes its name from the X1 platform that it introduced last year, and will be available to customers later this year.

The update is akin to a new operating system for cellphones or computers and will also work on X1 set-top boxes through an optional update delivered over the Internet. Comcast also unveiled a small set-top box for secondary TVs in a home. It is a third the size of a normal set-top box.

X2 is one of many offerings from cable TV companies that seek to improve the living room experience. Time Warner Cable Inc. showed off an updated channel guide with personalized recommendations that it plans to roll out on new set-top boxes this year.

Cable and satellite TV companies have faced criticism for offering hundreds of channels while providing clunky guides that make it difficult to find shows. As they seek to keep customers, cable providers are updating channel grids. Newer guides do a better job of showing off what's available on-demand, what's saved on the digital video recorder, and what's on live TV.

The X2's channel guide acts more like a website than traditional channel guides. Customers can customize the view to include weather and road traffic apps. Program listings include movie ratings from Rotten Tomatoes, as well as a "buzz" meter showing how many posts from Twitter a particular show is getting each hour. The guide also displays video from the Web, and includes voice-enabled search results for the first time.

Comcast CEO Brian Roberts demonstrated the new guide's search ability by saying, "Find Don Cheadle." The guide pulled up 25 movies and TV shows featuring the actor as well as videos from the Web.

"The whole look and feel is meant to be easy, personal, smart, fast and fun," Roberts said. "And I think we're just scratching the surface."

The company says that because its new guides rely on Internet technology, they can be changed as easily as updating a website. Comcast has updated its guide 1,200 times since the X1 set-top box was introduced in May 2012. Its new guide will work on tablet computers and smartphones as well.

Comcast, with 21.9 million TV subscribers, expects to save money in the long run with its X2 platform by eliminating the hard drive from digital video recorders. Executives also said it would help TV network operators by giving them the chance to insert TV commercials into shows that customers have saved online.

That ad-insertion technology represents a shot at Dish Network Corp., which irked broadcasters with its Hopper DVR because it automatically strips commercials from prime-time shows for playback later.

"You notice we don't skip commercials here," said Comcast's chief technology officer, Tony Werner.

Time Warner Cable, the nation's second largest cable TV company with 12.1 million TV subscribers, also this week conducted private showings of the guide it plans to test in New York, Los Angeles and Syracuse, N.Y., this fall before rolling it out to new customers and its top-tier subscribers this year.

Its guide also uses Internet tools for easy updating from afar.

It recommends shows based on a user's history and what they're searching for; allows people to browse shows by genre and title; and adds cover art to everything. One channel surfing function displays cover art of what's playing on half a dozen channels in either direction on the lineup. Flipping through the channels scrolls through cover art until you settle on a channel to watch.

Time Warner Cable's updated set-top box has a 1 terabyte hard drive capable of saving 150 hours of high-definition content. Smaller boxes are also being prepared for other TV sets that use the central DVR on the home network.

"It's about making a seamless and frictionless experience for customers to more easily find the shows they want," said Alix Cottrell, group vice president of video for Time Warner Cable. Cottrell said the company expects the improved guide to help increase TV usage "dramatically" as well as make customers more satisfied.

Customer retention is seen as increasingly important for the cable TV industry, which has lost about 10 million TV subscribers in the United States over the last decade — down to 56.4 million in 2012, from 66.9 million in 2001, according to research firm SNL Kagan.

Most of them have switched to satellite companies such as DirecTV or Dish, or gone with TV services from phone companies including Verizon and AT&T, lured by promotional prices and fancier interfaces. Overall, the number of pay TV subscribers across all providers has been steady at about 100 million U.S. homes.