Acer kicked off the Consumer Electronics Show (CES) on Sunday by previewing a free cloud service for storing images and other documents online, and showing a novel ultrabook that hides its I/O ports in a hidden pop-up section at the back.

The cloud service, called AcerCloud, will allow people to upload all their images, video and documents to an online service hosted by Acer, and access them over the Web from any PC, mobile phone or tablet running Windows or Android. That includes devices from other vendors.

The service will come free with all new consumer PCs from Acer and include "unlimited" storage, Acer officials said. It will be rolled out in North America and Greater China in the second quarter, and worldwide by the end of the year.

Acer has struggled this year with declining PC sales, and it hopes its emphasis on ultrabooks and the cloud service will help revive its fortunes. The AcerCloud will be "a strategic differentiator for Acer in the long term," Acer Chairman and CEO J.T. Wang said at the press event.

However, following the launch of Apple's iCloud service last year, other PC makers are expected to also outline cloud service plans here at CES.

Acer showed several new ultrabooks Sunday, an emerging class of slim-form-factor PCs intended to challenge Apple's MacBook Air.

One of them, the Aspire S5, will be a follow-on to the S3 Ultrabook that Acer launched in September. It has the same display size -- 13.3 inches -- but is lighter in weight, at 1.35 kilograms (less than 3 pounds), and is just 0.59 inches thick at its widest point, making it "the world's thinnest Ultrabook," according to Wang.

To keep the laptop slender while still including several I/O ports, Acer included what it calls the "MagicFlip I/O port panel." The user pushes a button next to the keyboard and the back of the laptop expands by about a centimeter to reveal ports for HDMI, USB 3.0 and Intel's high-speed Thunderbolt networking technology.

The S5 will start shipping in the second quarter, Acer officials said. They didn't give a price.

Acer is betting big on ultrabooks -- it expects them to account for 25 percent to 35 percent of all the laptops it ships this year, and to become mainstream in the next two years, Wang said.

The company also showed 14- and 15-in. versions of its Aspire Timeline Ultra ultrabook. They'll provide eight hours of battery life and come in a two-spindle design, including a DVD drive and solid-state hard drive. They're due to start shipping this quarter, but Acer didn't give prices for those products either.

All the new ultrabooks include Acer's Green Instant On technology, which lets them wake up from sleep mode in 1.5 seconds, according to Acer. They also sport Acer Always Connect, which allows them to be woken from sleep mode remotely even when they're in standby mode.

That will allow users of the AcerCloud service to access files from their PC on a cell phone or other device even when the PC is in sleep mode, Acer said. A demonstration of its PicStream technology, which lets users move pictures from a smartphone to their PC via the AcerCloud, didn't go smoothly, however. Acer officials blamed poor connectivity.

Acer was holding the first press conference of CES, where the show floor doesn't open until Tuesday morning. Most of the other big vendors are holding their press events Monday, and Microsoft CEO Steve Ballmer will give the company's last-ever CES keynote on Monday night.

The Acer Aspire S5 will ship in the second quarter of the year.

James Niccolai covers data centers and general technology news for IDG News Service. Follow James on Twitter at @jniccolai. James's e-mail address is james_niccolai@idg.com

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