The RAMAC's memory consisted of a magnetic process drum that ran at 6,000 rpm. A separate magnetic core memory unit synchronized the I/O flow in and out of the RAM. Another separate address register with 100-character blocks located data on the RAMAC's disk drives in six-tenths of a second. That's about a million times slower than today's desktop and laptop computers, Spicer said.

The RAMAC 305 was the precursor to the . When released in 1961, the 1301 was the first storage system that used "flying heads" on actuator arms to read and write data to its 50 24-inch magnetic platters. The 1301's head and actuator arm assembly looked something like a bread-slicing machine turned on its side because each drive platter had its own read/write head.

The 1301 had 13 times the capacity of the RAMAC, and its platters rotated at 1,800 rpm -- compared with a spindle speed of 100 rpm for the RAMAC -- allowing heads to access the data more quickly.

"The difference was that the flying heads were able to be closer than the air-bearing heads. You got more tracks and linear density with flying heads ... and the access time was about a tenth the time," Hoagland said. "It had the kind of performance that allowed hard disks to eventually percolate through the whole computer world."