1950s - 1970s


The IBM 350 Disk File, invented by Reynold Johnson, was introduced in 1956 with the IBM 305 RAMAC computer. This drive had fifty 24 inch platters, with a total capacity of five million characters A single head assembly having two heads was used for access to all the platters, making the average access time very slow (just under 1 second).
The IBM 1301 Disk Storage Unit announced in 1961, introduced the usage of a head for each data surface with the heads having self acting air bearings (flying heads).
Also in 1961, Bryant Computer Products introduced its 4000 series disk drives. These massive units stood 52 inches (1.3 m) tall, 70 inches (1.8 m) wide, and had up to 26 platters, each 39 inches (0.99 m) in diameter, rotating at up to 1200 rpm. Access times were from 50 to 205 ms. The drive's total capacity, depending on the number of platters installed, was up to 205,377,600 bytes, or 196 MiB.
The first disk drive to use removable media was the IBM 1311 drive, which used the IBM 1316 disk pack to store two million characters.
In 1973, IBM introduced the IBM 3340 "Winchester" disk drive, the first significant commercial use of low mass and low load heads with lubricated media. All modern disk drives now use this technology and/or derivatives thereof. Project head Kenneth Haughton named it after the Winchester 30-30 rifle because it was planned to have two 30 MB spindles; however, the actual product shipped with two spindles for data modules of either 35 MB or 70 MB.
Also in 1973, Control Data Corporation introduced the first of its series of SMD disk drives using conventional disk pack technology. The SMD family became the predominant disk drive in the minicomputer market into the 1980s.

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