The Hard Drive Turns 50
Today, the hard drive is found everywhere--from the PCs we use daily to MP3 players and memory keys so small you can toss them in your pocket and forget you're carrying around a hard drive. But when the hard drive was first introduced on September 13, 1956, it required a humongous housing and 50 24-inch platters to store 1/2400 as much data as can be fit on today's largest capacity 1-inch hard drives.
Back then, the small team at IBM's San Jose-based lab was seeking a way to replace tape with a storage mechanism that allowed for more-efficient random access to data. The question was, how to bring random-access storage to business computing?
Enter the RAMAC, 1956
IBM's answer to this quandary was the Random Access Method of Accounting and Control, dubbed the RAMAC for expediency. The device's name is a direct reflection of the need for such capabilities in the enterprise. Led by project leader Rey Johnson, IBM's San Jose lab brought the RAMAC 305 system to market.
Recalls Al Shugart, who worked as a field engineer at IBM before joining the RAMAC project and went on to later found Seagate Technology: "They were starting from scratch in the lab. The RAMAC was not just a disk drive, it was a whole system. Nobody had made disk drives before."
The approach IBM's engineers came up with represented a clean approach to random data access, notes Shugart: "The concept of the whole disk drive was random access." To achieve random access, the device would have to move its read/write heads around to different data tracks. "The easiest way to do that," he says, "was a stack of disks."
The integrated RAMAC 305 system was about two refrigerators in width and not quite as tall, and it literally weighed a ton. Its hard drive, the RAMAC 350, had 50 24-inch platters in a stack inside the unit, in an assembly that spun at 1200 revolutions per minute. The unit used two magnetic recording heads. The RAMAC 350 could hold 5MB--about the storage that today is needed for one 5-minute MP3 encoded at 128 kilobits per second.
In order to read and write the data, the RAMAC heads moved across a series of circular tracks on each disk surface. Albert Hoagland, who helped build the first drive and is working to preserve the history of magnetic disk technology as executive director of the Magnetic Disk Heritage Center, elaborates: "A shaft ran the length of the disk stack, with a horizontal head and arm assembly that moved in and out to locate the selected track; that arm, which weighed three pounds, had to get from the innermost track on the top disk to the innermost track on the bottom disk in less than a second."
"The disks' surfaces were covered with a paint that had magnetic properties--very similar to the paint used on the Golden Gate Bridge," says Bill Healy, senior vice president at Hitachi (which bought IBM's storage division in 2003). "They needed a disk with magnetic properties, so it would be magnetically susceptible to recording 1s and 0s; and they needed a read element, such as a disk head, to detect, read, and write that data," he explains.
Shugart recalls12 initial prototypes. "From there on, we would design a system for production, including a disk drive. The production [version] was a vacuum tube machine, and I was in charge of designing the computer system for the vacuum tube machine."
Although the RAMAC shares only some characteristics with today's hard drives, they are important ones, says Hoagland. "The characteristics of all disk drives that still use ideas initiated on the RAMAC include: closely spaced disks or platters with magnetic film surfaces; positioning of read/write heads to service a large number of tracks; and and the use of head assemblies that create a small but finite separation between head and disk to avoid wear or damage to either one."
"The [technology] industry reinvented itself as the applications for the hard drive changed," adds Healy. "In the fifties and sixties, these devices were made for large corporations, government--the enterprise. The 24-inch diameter platter reduced in size in time. As the devices got smaller over that time, they were mainly aimed at the enterprise environment," he continues. Disk capacity doubled every two years, a 40 percent compound growth rate.
Adds storage industry analyst Tom Coughlin of Coughlin Associates: "Many companies started to make hard drives for computers, because it was a relatively inexpensive, high-performance way to make mass storage."
From the late fifties to the early seventies, hard drives were largely used in mainframe computer systems, the kinds found in large corporations and government. The rise of personal computers in the late seventies and early eighties opened the door of opportunity for hard drives--and in turn dramatically influenced where computer technology could go. "With the introduction of hard disk drives," notes Coughlin, "you had large amounts of storage that were always attached to the computer, and that enabled personal computers to achieve the levels of success they had. A hard drive allowed you to create higher-performance computers with more features because you could have a richer operating system running off the hard drive."