Seagate announced Tuesday that it has shipped 1 billion hard drives since pioneering an industry that shows no signs of slowing down 29 years later.

In 1979, the Scotts Valley, California, company was a trailblazer in hard drives that were small enough for the early PCs then emerging. Its first product, the ST506, was 5.25 inches (13.3 centimeters) wide and weighed about 5 pounds (2.27 kilos). It was compact compared with the 14-inch and 8-inch drives that had been standard up to that time.

But what most distinguishes that device from today's drives is capacity and cost: The ST506 held just 5M bytes of data and cost US$1,500, for a cost of $300 per megabyte. Today, a typical Seagate drive may hold 1T byte (or 1 million megabytes) and cost just 1/5000th of a cent ($0.0002) per megabyte, according to the company.

Seagate claims to be the first to ship 1 billion units, which IDC analyst John Rydning doesn't doubt. The company had a leading 35 percent market share last year, with its nearest competitor being Western Digital at about 23 percent, he said. And the business is growing so fast that Seagate expects to ship its next billion drives within five years.

What it's shipped already has amounted to 79 million terabytes, enough for 158 billion hours of digital video or 1.2 trillion hours of MP3 songs. Neither of those existed in 1979, possibly because the ST506 would have held only about one song.

And it's that kind of content, rather than the spreadsheets and word-processing documents for which PCs were originally built, that is driving much of the growth in storage, Rydning said. The fastest-growing place for hard drives is personal video recorders, and coming up behind those are personal storage devices for collecting and backing up music, video and photo collections, he said. IDC expects this area to explode over the next five years, because only a small fraction of households with PCs have external hard drives for backing up their data, he said.

But although it's still a good idea to back up hard drives in case of failure, they both work better and last longer than they did 25 years ago, Rydning said. A major breakthrough was the introduction of error-correcting code in firmware to ensure data is properly written and read, he said.

Hard drives are here to stay despite the emergence of SSDs (solid-state drives) for iPods, other consumer electronics and now laptops, he added. It will take five years for SSDs to gain a significant foothold in laptops, just because they are so much more expensive per byte, Rydning said. Hard-drive vendors as a whole shipped 505 million units last year, totaling about 84 million terabytes, with an average capacity of 170G bytes. Unit sales should hit 600 million per year by 2010, IDC believes.

Seagate alone ships 111,600 terabytes every day, according to the company, which means more than 1 terabyte of Seagate storage is produced every second.