Apple Inc. Tuesday introduced the iPad Mini, the first major extension of the company's product line in more than two years, in an effort to further solidify its leadership in the mobile market.

The smaller device, which was expected, comes with a 7.9-inch display, and is roughly half the weight of existing models, Apple said. It will start at $329 for a model with 16 gigabytes of memory and be available Nov. 2, with preorders beginning this Friday.

The iPad Mini would competesquarely with devices like Amazon.com Inc.'s Kindle Fire and Google Inc.'s Nexus 7, already on the market. These and other roughly seven-inch devices from Samsung Electronics Co. and others will account for about a fifth of the tablet market this year, according to Piper Jaffray.

Apple also unveiled a fourth-generation model of its existing iPad, just seven months after the company announced a new model it simply called 'the new iPad.' The latest iPad, Apple said, has a new processor chip, the A6X, and wider support for LTE wireless technology.

The event's marquee announcement, the iPad Mini, holds an odd distinction as being a product that Steve Jobs, Apple's late co-founder, had dismissed. Two years ago, Google, Samsung and others began releasing devices with a 7-inch diagonal screen, he said that smaller tablets were likely to fail in the market. Apple executives here suggested those products simply weren't very good.

'Others have tried to make tablets smaller than the iPad, and they have failed miserably,' said Phil Schiller, Apple's marketing chief, at an invitation-only event here.

Mr. Schiller added that competitors' products were less usable, and that Apple had taken its time to ensure features, such as the screen and performance, were good enough that they would offer a clear benefit to customers.

'Competitors are making compromises with their products,' he said. 'We don't.'

Following the product news Tuesday, Apple's shares dropped, finishing the day down 3.3% to $613.36.

The iPad Mini comes as the Cupertino, Calif., electronics giant continues to refine its focus on mobile computing. The iPhone, iPad and other mobile products have been at the heart of Apple's renaissance since it started selling the original iPod music player in 2001.

Apple said it has sold more than 100 million iPads since the product launched two years ago, though competitors' products, including Samsung's tablets and devices, such as the Galaxy Tab and Galaxy Note, have become increasingly popular among consumers. While Samsung's smartphones have topped Apple's as the most devices to have been shipped to customers throughout the world, Apple has been able to maintain a leadership position among tablet makers.

Despite increasing competition, Apple's devices have held onto the top spot world-wide, representing nearly two-thirds of the industry in 2011, according to industry researcher Gartner. Devices built using Google Inc.'s Android mobile operating system, such as Samsung's devices and Amazon.com's Kindle Fire tablets, represented nearly 37% of sales.

But, Gartner said, Apple's leadership is expected to fall to 53% of the industry this year and 44% in 2013.

Mr. Schiller said he expects the iPad Mini will help Apple maintain its momentum.

Earlier in the event, the company announced several other hardware developments, including a substantially restyled version of its popular iMac desktop computer that includes a much thinner design.

Apple said the new iMac measures just 5 millimeters in thickness, takes up 40% less space than its predecessor and comes with a new storagedevice that combines a spinning disk with flash-memory chips. A 21-inch version of the computer is expected to ship in November at a starting price of $1,299. A 27-inch model arrives in December at a starting price of $1,799, Apple said.

Apple also introduced a new version of its ultra-small desktop computer, the Mac Mini, at a starting price of $599.

IAN SHERR / JESSICA E. LESSIN

• device [di´vais]   n.装置；器具；策略   (初中英语单词)
• available [ə´veiləbəl]   a.可用的；有效的   (初中英语单词)
• beginning [bi´giniŋ]   n.开始，开端；起源   (初中英语单词)
• compete [kəm´pi:t]   v.比赛，竞争，对抗   (初中英语单词)
• account [ə´kaunt]   vi.说明 vt.认为 n.帐目   (初中英语单词)
• distinction [di´stiŋkʃən]   n.差别；特征；卓越   (初中英语单词)
• screen [skri:n]   n.银幕 vt.遮蔽   (初中英语单词)
• performance [pə´fɔ:məns]   n.履行；行为；工作   (初中英语单词)
• player [´pleiə]   n.游戏的人；选手   (初中英语单词)
• maintain [mein´tein]   vt.维持；保持；继续   (初中英语单词)
• competition [,kɔmpi´tiʃən]   n.比赛；竞争   (初中英语单词)
• system [´sistəm]   n.系统，体系，制度   (初中英语单词)
• computer [kəm´pju:tə]   n.计算机；电子计算器   (初中英语单词)
• extension [ik´stenʃən]   n.延长；扩展；延期   (高中英语单词)
• leadership [´li:dəʃip]   n.领导(能力)   (高中英语单词)
• roughly [´rʌfli]   ad.粗糙地；毛糙地   (高中英语单词)
• kindle [´kindl]   v.点燃；(使)激动   (高中英语单词)
• tablet [´tæblit]   n.碑；牌；匾额   (高中英语单词)
• announcement [ə´naunsmənt]   n.通告；宣布；言谈   (高中英语单词)
• thickness [´θiknis]   n.厚；浓；粗；稠密   (高中英语单词)
• storage [´stɔ:ridʒ]   n.贮存；存储器   (高中英语单词)
• spinning [´spiniŋ]   n.纺织 a.纺织品的   (高中英语单词)
• squarely [´skwɛəli]   ad.成方形地；正直地   (英语四级单词)
• refine [ri´fain]   v.精炼；提纯；改进   (英语四级单词)
• renaissance [rə´neisəns]   n.复兴；复活；新生   (英语四级单词)
• increasingly [in´kri:siŋli]   ad.日益，愈加   (英语四级单词)
• hardware [´hɑ:dweə]   n.五金器皿   (英语四级单词)
• version [´və:ʃən, ´və:rʒən]   n.翻译；说明；译本   (英语四级单词)
• predecessor [´pri:disesə]   n.前任；前辈   (英语四级单词)
• substantially [səb´stænʃəli]   ad.大体上；本质上   (英语六级单词)