Trivia quiz: how many drives have been made in all of history?

If you guessed approximately 2 billion, you'd be right, according to John Monroe, an analyst at Gartner.

The hard drive-which was invented by IBM--debuted on September 13, 1956, nearly fifty years ago, and the devices have become fairly indispensable to the computer industry. (Electronic computers had their big coming out party with the ENIAC sixty years ago this year.)

The drive industry and organizations such as IDEMA plan to celebrate with an event at the Computer History Museum on September 12.

More fun facts from Monroe: roughly 201.6 million drives got produced in the first half. "We anticipate 428-435 for the entire 2006 calendar year," he wrote. That's 46 to 48 million terabytes in total storage.

Prices continue to drop. The average price for a gigabyte (GB) costs 50 cents. Leasing hard drives fifty years ago cost several thousand dollars and you only got a few MB of storage.