PA Semi’s engineers, most of them veterans from other chip companies in Silicon Valley, had just the type of expertise that a company making music players, laptops and phones would want.

Over all, the A4-powered iPad’s battery life and speed seem similar to those of computers running on competing chips. A wave of tiny laptops known as smartbooks will arrive shortly after the iPad starts selling in March, running at the same speed as the iPad while offering up to 16 hours of battery life when playing video. These will run on chips by Nvidia and Qualcomm that have designs reminiscent of the A4.

Apple has a history of trying to ostentatiously best the competition. It promoted the MacBook Air, introduced in 2008, as the thinnest laptop ever. By building the A4 into the iPad, Apple appears to have bought a small lead over rivals  or at least kept pace with them  in this emerging class of mobile devices.

“From what we have seen so far, Apple’s product seems to stack up evenly with the competition,” said Dean McCarron, a chip analyst with Mercury Research. “Clearly, Apple is using their own metric for whatever ‘best’ is.” Apple’s laptops and desktops run on Intel chips, while Samsung has been selling Apple the primary chips for the iPhone. Analysts believe Samsung is actually manufacturing the A4 as well, using a common industry design for the core of the chip, while Apple has tweaked other parts of the processor package to suit its needs.

Apple’s other mobile devices like the iPhone and iPod Touch could conceivably all run on Apple-designed chips someday. Analysts point out that it often takes about two years for chip designers to create something from scratch, test it and have a finished product arrive from a factory.

Some of the chip engineers Apple gained in its purchase of PA Semi appear to have already left the company. According to partial records on the job networking site LinkedIn, at least half a dozen former PA Semi engineers have left Apple and turned up at a start-up called Agnilux, based in San Jose. The company was co-founded by one of PA’s leading system architects, Mark Hayter.

Neither Mr. Hayter nor other onetime PA workers who left Apple for Agnilux were willing to discuss either company’s plans. According to two people with knowledge of the two companies, who were unwilling to be named because the matter is delicate, some PA engineers left Apple a few months after the acquisition because they were given grants of Apple stock at an unattractive price.