Overall tablet sales shrink for the first time as Apple continues to dominate mobile computer market

Worldwide sales of tablet computers declined by nearly 5 percent in the first quarter of 2014 — the first such fall since tracking began — but Apple's iPad maintained its dominant mobile PC position with nearly twice the market share of the closest competitor.

Tablet shipments dropped from 59 million units in the first quarter of 2013 to 56.3 million units in the first quarter of this year, according to a new report from market research firm NPD DisplaySearch. Apple accounted for some 20 percent of the market when laptops and ultrabooks are included, compared to 11 percent for Samsung, the next-largest competitor.

Apple shipped just 16.3 million iPads in the first three months of this year compared to 19.4 million one year ago. Samsung, meanwhile, is thought to have seen a modest shipment increase of around 200,000 units to 9.9 million over the same period.

Despite the downturn, tablets still represented more than half of mobile PC shipments. The iPad accounted for over 80 percent of Apple's own sales by that definition.

Apple is widely expected to bring the iPhone 5s's Touch ID system to the iPad later this year, possibly alongside a new fingerprint-authenticated mobile payments system. Both the iPad Air and iPad mini with Retina display are penciled in for updates this fall.

Even before then, the iPad may gain more powerful computing capabilities with the debut of Apple's next major iOS release, expected to be unveiled at next week's Worldwide Developers Conference. Specifically, iOS 8 is rumored to include support for split-screen multitasking on iPad Air, allowing users to accomplish two tasks at the same time.