On Wednesday, industry researcher Canalys released a new report which found that worldwide PC shipments increased by 12 percent year-over-year for the fourth quarter. The company considers the tablet to be a kind of personal computer , and it described Apple as leading the PC market with a market share that exceeded 20 percent for the first time.

In their data , Hewlett-Packard -- which other surveys often find to be the leading computer maker in the world -- is second, followed by Lenovo and then Samsung, with Dell in fifth.

Dell 'Continues to Fade'

The report found that notebook computers were flat for the quarter, compared with 2011, which included the impact from Windows 8 devices entering the market. However, tablets grew by 75 percent.

Canalys said "Dell's reputation in the PC market continues to fade," with a 19 percent decline compared with 2011. Tablets with a Microsoft operating system represented only 3 percent of those shipped in the fourth quarter.

Avi Greengart, an analyst with industry research firm Current Analysis, said that, in some ways, asking if a tablet is a PC is like asking if "an SUV is a car or a truck," in that it's a matter of methodology.

Greengart said he prefers to address the issue as a question of platforms and vendors, and in that view, Apple's iOS "is a major computing platform." But those definitions are continually evolving, he told us, and sometimes depend on the market in question. "In some markets," he said, such as in developing countries, "the smartphone is the key computing platform."

RT's Outlook 'Bleak'

The report also said that the ARM-based Windows RT tablet's outlook "appears bleak." Canalys blamed that on high pricing and poor channel strategy, among other things.

There have also been reports of considerable consumer confusion because the Windows RT tablet does not run Windows legacy applications. Canalys suggested that Microsoft might turn the fate of the RT tablet around if it dropped the price by 60 percent and conducted "a strategy to educate consumers as well as attract developers" to create RT tablet-specific apps .

Apple's strength in Q4 was driven by the iPad mini tablet, which also qualifies under Canalys' definition of a PC. The research firm said the mini accounted for more than half of Apple's total tablet shipments, and it was cannibalizing both iPad and PC sales.

Interestingly, this was the first quarter in Canalys' reports when Apple's tablet share dipped below the majority, to 49 percent. If not for the mini, Canalys said, Apple's market share would have dropped further.

Samsung saw a phenomenal increase of 226 percent in tablets for Q4, which the research firm said was attributable to lower pricing. It also noted that Amazon 's worldwide shipments grew by 18 percent, and that the two companies together now account for 46 percent of tablets.

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