Take a look at the senior management of Apple. Every senior executive is male. At IBM, it's 10 of 12. And at Texas Instruments, it's 3 of 12.

Then consider how many technology companies have a female CEO. There's Yahoo, of course. Xerox. Hon Hai Precision Industries, Apple's biggest contract manufacturer. Then it gets more difficult.

Indeed, there are a number of top women executives slightly below the CEO level. Safra Catz has been one of Oracle's presidents since 2004 and started her second stint as CFO this year. Sheryl Sandberg is COO of Facebook after being a VP at Google. Linda Sanford is a Senior VP at IBM for enterprise computing.

But why so few at the top? Given that women are more than half the population and that young women now outnumber men in graduate schools, there ought to be more. Surely, as far as consumption of technology products goes, from iPhones to Kindles, women are a huge market.

As the U.S. heads into the Labor Day weekend, one wonders if there will be some change over the next decade. Signals are mixed. But women were 50.8 percent of the U.S. population, the 2010 census reported.

For one, girls are nearly 50 percent of high school students who take the Advanced Placement exam in calculus but only 19 percent of the AP computer science test takers, the College Board reports.

But in college, something happens. By graduation, women received only 18 percent of degrees in computing and information sciences in 2009, a sharp decrease from the 37 percent in 1985, according to the National Center for Women & Information Technology.

There are similar disparities in electrical engineering, the traditional source for semiconductor and computer industry talent. Both Bill Hewlett and David Packard were electrical engineers.

Of the 407,000 members of the Institute of Electrical and Electronic Engineers (IEEE), 90 percent were male in 2010, despite years of supporting technical education for women. The IEEE also supports a Women in Engineering initiative.

Statistics also show that women engineers and technologists often leave the workforce in mid-career because they want to raise children or spend time at home. But other figures show they leave the technology sector for another. So that by the time comes for promotions, there are fewer women to choose from.

In Silicon Valley, there are many women just below the CEO's office, like HP's Ann Livermore, an Executive VP, who have long been regarded as potential CEOs. Livermore was twice passed over for HP CEO and now, at least is a director.

One reason why Ursula Burns was elected Xerox CEO in 2009 was that then-CEO Ann Mulcahy was afraid to lose her to another company.

Livermore has an MBA; Burns is a mechanical engineer.

Then there are several stars who have either been serial successes or persistent innovators. Judith Estrin, an E.E., co-founded Bridge Networks, which helped form 3Com, then co-founded Packet Design which was bought by Cisco Systems, which made her Chief Technology Officer. Now she runs JLABS, another networking company.

Carol Bartz, now CEO at Yahoo in part because of shareholder agitation by investor Carl Icahn, is a computer scientist. After a high-paced rise at Sun Microsystems, she was recruited as CEO of Autodesk, the design-software developer. After 12 years, she stepped aside in 2006 because she didn't want to lose her male COO, Carl Bass, to another company, she said in an interview.

Sandra Kurtzig, who founded ASK Group in 1972, is a mechanical engineer who built that company into one of Silicon Valley's biggest mid-range computer software developers. She moved to Hawaii after selling ASK to CA Technologies in 1994. This year, she started Kenandy, another software developer, with $10.5 million from Kleiner Perkins Caufield Byers, Salesforce.com and the Wilson Sonsini law firm.

Kurtzig has said Kenandy has management software for cloud computing which may be disclosed later this year.

There are also several younger CEOs, like Kim Polese, a former Sun Microsystems Java developer, who founded Marimba, a software developer acquired by BMC Software. Polese started another company, SpikeSource, which was bought by Black Duck Software.

Right now, Polese, 39, a biophysicist, is serving as a fellow at Carnegie Mellon University, but probably will start another company before long.

Another younger executive is Diane Greene, 57, a mechanical engineer who co-founded VMware, the virtualization software specialist, and was CEO until 2008. Greene and her spouse, Mendel Rosenbaum, a computer scientist, got a large part of the $625 million EMC paid for VMware in 2004 and then profited when VMware went public, so chances are she will be heard from again.

To inspire and recruit women to engineering and technology, it's probably a good thing that several of the best U.S. research universities have women presidents with science backgrounds.

Princeton has Shirley Tilghman, a molecular biologist who is also a director of Google; Massachusetts Institute of Technology has Susan Hockfield, a neuroscientist who is a director of General Electric. Rensselaer Polytechnic Institute has Shirley Ann Jackson, a physicist, who is a director of IBM and Medtronic, among others.

These academics can encourage women students as well as agitate for more women in top management. Clearly, Jackson has plenty of work to do at IBM. As does Tilghman at Google. And Hockfield at GE where one of her co-directors is Avon Products CEO Andrea Jung, an Apple director.

At Apple, Jung is the only female director. There's a place to start.

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