The first hard disk drive was introduced on September 13, 1956. It utilized platters the size of pizza trays, weighed over a ton and stored a mere 5 megabytes of data.

Almost exactly 50 years later, Seagate has demonstrated technology capable of storing nearly 2.5 terabytes of data in the standard 3.5″ hard drive form factor. The drive uses perpendicular magnetic recording (PMR) to pack in 421 Gigabits per square inch.

“At the demonstrated density level, Seagate expects the capacity ranges to result in solutions ranging in 40GB to 275GB for 1-and 1.8-inch consumer electronics drives, 500GB for 2.5-inch notebook drives, and nearly 2.5TB for 3.5-inch desktop and enterprise class drives.”

Seagate says that you can anticipate storage at these density levels sometime in 2009.

We’ve mentioned PMR technology a few times before .