Happy Birthday, disk drive!

—Fifty years ago this week, IBM introduced the first hard disk drive as part of its Random Access Method of Accounting and Control (RAMAC) system. As the catchy name indicated, it was the first device to use random access to data (although it would take another 50 years for disk drives to start replacing sequential-access tape drives).

The RAMAC disk drive—dubbed the 350 Disk Storage Unit—weighed more than a ton (2,140 pounds, to be exact), was the width of two refrigerators and stored a then-astounding 5MB—on 50 24-inch platters. (For those of you keeping score, the RAMAC drive spun at about 1,200rpm, compared to 15,000rpm for today's drives.)

Quoted in a PC World article this week, Seagate chief operating officer Dave Wickersham said that if the automobile industry progressed as rapidly as the disk drive industry, cars would get 62,500mpg today. He also said that cars would cost $25, hold 160,000 passengers, weigh half a pound, and exceed 940mph, but let's not get carried away here.

Ok, let's. RAMAC's 350 Disk Storage Unit could hold the equivalent of the collected works of Shakespeare. Today, IBM's DS8000 Turbo disk array can hold the equivalent of 76 million copies of Shakespeare's works.

The RAMAC drive's cost per megabyte was approximately $10,000, or about $70,000 in today's dollars. That compares to about 3/100th of a cent for some of today's drives.

Flash forward 50 years: Commemorating the Golden Anniversary, Hitachi Global Storage Technologies (GST)—which bought IBM's disk drive business three years ago—demonstrated perpendicular magnetic recording (PMR) technology this week that it predicts will enable 3.5-inch disk drives to top the terabyte barrier in the first half of next year (or 345 gigabits per square inch) and 2TB by the end of the decade (or 400GB on 2.5-inch drives, 200GB on 1-inch drives, etc.). By the way, that 345 gigabits per square inch compares to 2,000 bits per square inch for the RAMAC drive. —Dave Simpson

This article was originally published on September 15, 2006