Technology: Hooray, Hard Disk! Experts agree that the amazing gains in storage density at low cost will continue for decades.

Byline: Steven Levy

If there's a bottle of vintage champagne you've been saving, next month is the time to pop it open: it's the 50th anniversary of hard-disk storage. Don't laugh. On Sept. 13, 1956, IBM shipped the first unit of the RAMAC (Random Access Method of Accounting and Control) and started a process that would change the way we live.

The RAMAC, designed in Big Blue's San Jose, California, research center, is the ultimate ancestor of that 1.8-inch drive that holds 7,500 songs inside your pocket-size $299 iPod. Of course, the RAMAC would have made a lousy music player. The drive weighed a ton, and to lease it you'd pay $250,000 a year in today's dollars. Its 50 spinning iron-oxide-coated disks stored 5 megabytes--not quite enough to hold two MP3 copies of Elvis Presley's "Hound Dog."

Yet those who beheld the RAMAC were astonished. "It was the first to offer random access, whereas before you would have to wind a tape from one end to the other to access data," recalls Jim Porter, who worked at Crown Zellerbach in San Francisco in the mid-'50s, which had what he says was the first unit delivered by IBM.

That feature, and the fact that every year scientists compress more information on cheaper hard drives, has led to a revolution just as dramatic as the one triggered by the ...