Academic theory collided head-on with the status quo of the high-tech marketplace in the Microsoft antitrust case on Tuesday, Dec. 7. Neither vehicle was totaled -- but both had to be towed from the scene.

The academic was David Farber, a government witness who is a professor at the University of Pennsylvania. He argued that, technically, there is no reason why functions such as a graphical user interface and a Web browser should not be separate products that PC makers, retailers, or consumers could choose to install on top of an operating system -- which would still perform basic functions such as storing and retrieving information on a disk drive or printing a file. Bottom line: Microsoft's integration of its Internet Explorer browser into Windows 98 offers no compelling advantages to computer users over a mix-and-match method of adding browsing to the PC, Farber asserted. "The operating system environment should be like a library. I come into a library to pick things off the shelf that I need," he said.

This view was a red flag for Microsoft, which has defended many of its decisions by arguing that integrating more and more functions into the basic computer operating system -- Windows -- provides consumers with the greatest value. Microsoft Attorney Steven Holley labeled Farber's theories as out-of-touch with the realities of the software marketplace. Holley pointed out that, notwithstanding Farber's theoretical arguments, in the market Internet Explorer and Windows are now a single, integrated product -- although he didn't prove that integration per se was necessary for computer users to have a satisfying experience.

THREE LAYERS. Farber got off to a rough start -- admitting that he's no Windows expert and conceding that he had done no research to determine what computer users, software developers, or PC makers want in an operating system. Instead, he said he relied on 30 years as an academic specializing in the Unix operating system as the basis of his testimony.

The software world, according to Farber, consists of three principal pieces: a basic kernel operating system, middleware that provides for functions like the appearance of graphics on a page, and applications that let computer users calculate, draw, or write. "An operating system just sits there by itself and vibrates. It doesn't do very much," Farber said.

Holley disagreed -- offering up textbook definitions and industry analyst reports that described operating systems as much more capable pieces of software than what Farber envisions. To make his case, he even recycled earlier testimony from Apple executive and Microsoft critic Avadis "Avie" Tevanian Jr. -- who provided a long list of components that are included in Apple's Macintosh operating system as well as Microsoft's Windows.

Holley got Farber to concede that computer industry people have a much different definition of an operating system than he does. Farber noted that if you count every piece of software in the Windows box as an operating system component, you've got to include its solitaire game -- "and that's absurd."

DUELING OVER DLLs. But Holley retorted that dozens of small programs within Windows software -- so-called dynamic-linked libraries (DLLs), which perform specific key functions within application programs and are often shared among programs -- are widely considered essential to a modern operating system. A report by market researcher International Data Corp. comparing operating systems, for instance, listed that kind of software as a key element of Sun Microsystems' Solaris operating system -- a variant of Unix.

About two hours of detailed discussion of the proper classification of DLLs failed to yield a clear winner -- much less a clear point. Holley then asked whether it wasn't a better idea for Microsoft engineers rather than, say clerks at Walmart, to choose which such programs might be sold with a PC. Rather than only selling Microsoft DLLs, Farber blurted, "Walmart might find some other libraries they want to sell."

The entertainment highlight came near the end, when Holley asked Farber if he disagreed with an appellate court ruling last June that urged Judge Thomas Penfield Jackson and the Justice Dept. not to interfere in the design of software. Farber said he had a hard time understanding the ruling but added, "I'm not going to criticize the court." To which Judge Jackson replied quickly: "Oh, go ahead." That got a laugh out of the spectators and the attorneys from both sides.

Farber is expected to testify for part of the day on Wednesday, followed by a resumption of testimony by James Gosling, Sun's chief scientist.

By Steve Hamm in Washington