Barnes & Noble Inc. makes a variety of Nooks with black-and-white screens, dedicated to reading, and the Nook Color and Nook Tablet, which add color screens, third-party applications and Internet browsing to the mix.
Hewlett-Packard Co. is showing signs of recovery as it strengthened its position as the world's largest maker of personal computers and gained back some of the business it had lost while weighing whether to dump its PC division.
Samsung Electronics Co., Apple's biggest competitor in the market for iPad-sized tablet computers, is updating its line to include a feature that lets a tablet act as a universal remote control for an entertainment center.
The number of personal computers shipped worldwide rose more than expected in the first quarter, but the bump did little to mask the larger challenges for the industry.
Worldwide shipments of personal computers will pick up in the second half of the year with the debut of a new Windows operating system and the broader availability of notebooks that are thin like tablet computers, according to the research group IDC.
Research group IDC increased its forecast for tablet computer shipments this year after 2011 ended stronger than it had anticipated.
Thanks to strong demand for Apple's iPad and competing devices such as Amazon's Kindle Fire, worldwide shipments of tablet computers are likely to grow faster than expected this year, according to a newly revised forecast from a leading market-research group.

The growing move to "cloud computing," in which consumers and businesses store their data, applications and resources online instead of on their own systems, is expected to create more than a million American jobs by 2015, according to a new study from Microsoft.
Personal computer shipments dipped during the final three months of last year amid a shortage of key parts or compelling innovations.