Updated from 12:47 p.m. EDT

Technology stocks were flat Tuesday, weighed by a mixed earnings report from chip giant Texas Instruments ( TXN) and sluggish activation numbers for Apple's ( AAPL) iPhone.

Apple's partner AT&T ( T) reported Tuesday that it had activated 146,000 iPhones on June 29 and 30 , about half of what analysts had expected. Apple's shares sank $8.81, or 6.1%, to $134.89.

Texas Instruments, in an announcement after Monday's market close, reported earnings that are in line with analysts estimates, but the company worried investors with slipping quarter-over-quarter sales. The chipmaker reported a gross profit of $1.78 billion in the second quarter, compared with $1.91 billion in the year-ago period. The company attributed the decline to a royalty settlement and sales tax refund in the year-ago quarter and sluggish sales this year. The stock closed down $1.72, or 4.5%, to $36.46.

Another chipmaker, PLX Technology ( PLXT) tumbled 13.6% after it posted disappointing second-quarter results. The company posted a loss of $82,000, or less than a penny a share, on revenue of $19.8 million. Analysts polled by Thomson Financial expected earnings of 5 cents a share on revenue of $20 million. Looking ahead, PLX sees third-quarter revenue of $20.5 million to $21.5 million. Analysts project revenue of $21.5 million. Shares closed down $1.78 to $11.31.

The Nasdaq 100 was down 35.78 points, to 2000.55.

Agreements, big orders and earnings helped boost several tech stocks.

Microvision ( MVIS) soared 12.4% after the maker of scanner displays signed an agreement with Motorola ( MOT) to develop pico projector display solutions for mobile applications. "We believe that our unique display technology, combined with Motorola's focus on delivering cool experiences, would allow mobile users to enhance their viewing of information and entertainment," Microvision said. Financial terms of the deal were not disclosed. Shares of Microvision closed up 60 cents to $5.45.

Meanwhile, shares of JDA Software Group ( JDAS) jumped 10.6% after the software company posted second-quarter adjusted earnings that topped expectations. The company earned $10.6 million, or 31 cents a share, on revenue of $90.8 million. Analysts expected earnings of 25 cents a share on revenue of $91.2 million. Shares closed up $2.17 to $22.59.

American Superconductor ( AMSC) rose 5.6% after the maker of electronic converters received a $70 million follow-on order from Sinovel Wind, a China-based company. The deal calls for one of AMSC's subsidiaries to ship electric systems to Sinovel in 2008. The equipment will be used in Sinovel's wind energy systems. Shares of American Superconductor closed up $1.10 to $20.68.

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