Texas Instruments said Monday after the market closed that it's going to buy rival National Semiconductor for about $6.5 billion cash.

Chip groupie Nathan Brookwood called it simply "the passing of an era."

TI is offering 25 bucks a share for the analog chipmaker, a hefty 78% premium. The deal, more than half of which will take debt financing, should close in six-nine months.

The analog chip market was worth 42 billion last year on the back of the upsurge in mobile phones whose analog chips make phone calls understandable (though not as much as the old rotary phones).

Together the companies will have an analog portfolio of 42,000 products, 12,000 of them National's, used in everything from weapons guidance systems to kidney dialysis machines.

National is particularly known for its power management widgetry.

TI CEO Rich Templeton said the acquisition was "about strength and growth. National has an excellent development team, and its products combined with our own can offer customers an analog portfolio of unmatched depth and breadth. In recent years, National's management team has done an outstanding job of improving margins and streamlining expenses, which upon close will increase TI's profitability and earnings per share, excluding transaction costs. Our ability to accelerate National's growth with our much larger sales force is the foundation of our belief that we can produce strong returns on our investment. The combined sales team will be 10 times larger than National's is today, and the portfolio will be exposed to more customers in more markets."

With the acquisition, sales of analog semiconductors will represent almost 50% of TI's revenue.

TI is the market leader with 2010 analog revenue of $6 billion, or 14% of the market. National's revenue