Here's the legend: at a computer trade show in 1981, Bill Gates supposedly uttered this statement, in defense of the just-introduced IBM PC's 640KB usable RAM limit: "640K ought to be enough for anybody."

The initial PC was based on the Intel 8088, which was a hybrid 8/16-bit processor — thus the reason for the 640KB memory limit. Though tiny by today's standards — 64-bit systems can support up to 128GB of memory — 640KB at that time was an order of magnitude larger than the 64KB limit that faced users of 8-bit computers, such as the Apple II+ and the Commodore 64 (see more coverage on our "Bill Gates Moves On" page).

Even so, Gates' alleged statement looks like one of the most dogmatic, short-sighted comments ever, a verbal blunder perhaps topped only by Digital Equipment Corp. founder Ken Olsen's 1977 quip, "There is no reason for any individual to have a computer in his home." (Olsen did actually say that, but he said later that the quote was taken out of context, and that he was referring not to PCs but to computers set up to control houses.)

Despite the enduring popularity of the legend about the 640K comment, though, it's hard to find solid proof that Gates ever said it. For example, Wikiquote, an offshoot of Wikipedia, offers no strong evidence.

A claim that a profane variation of the quote was included by author Stephen Levy in his seminal book Hackers turns out to be untrue. And in March, the Bits technology blog published by The New York Times reported that the chief editor of The Yale Book of Quotations had tried without success to verify the quote. Fred Shapiro, the editor in question, said last week that he's still convinced the comment was apocryphal, despite receiving about 100 responses to his plea for information.

Gates himself has strenuously denied making the comment. In a newspaper column that he wrote in the mid-1990s, Gates responded to a student's question about the quote: "I've said some stupid things and some wrong things, but not that. No one involved in computers would ever say that a certain amount of memory is enough for all time." Later in the column, he added, "I keep bumping into that silly quotation attributed to me that says 640K of memory is enough. There's never a citation; the quotation just floats like a rumor, repeated again and again."

Gates, who is retiring from his day-to-day role at Microsoft Corp. on June 30, also insisted in a 2001 interview with U.S. News & World Report that he hadn't made the comment. "Do you realize the pain the industry went through while the IBM PC was limited to 640K? The machine was going to be 512K at one point, and we kept pushing it up," he told the magazine. "I never said that statement — I said the opposite of that."

Author and magazine writer James Fallows likens the 640K comment to the infamous "Let them eat cake" quote popularly, but apparently incorrectly, attributed to the French queen Marie Antoinette. The alleged remark about the memory limit "became the [IT] industry's equivalent of 'Let them eat cake' because it seemed to combine lordly condescension with a lack of interest in operational details," Fallows wrote in a 2002 article for The New York Review of Books.

Fallows added that after asking a mutual acquaintance whether the comment was accurate, he had received a lengthy e-mail from Gates "laying out painstakingly the reasons why he had always believed the opposite of what the notorious quote implied." As in the 2001 magazine interview, Gates said that 640KB limit was caused by the processor design and that he had pushed to increase it.

"Yet despite Gates's convincing denial, the quote is unlikely to die," Fallows wrote. "It's too convenient an expression of the computer industry's sense that no one can be sure what will happen next."

See more coverage: Bill Gates Moves On.