IBM 350

from Wikipedia, the free encyclopedia
IBM 305 RAMAC, left and center IBM 350
Disk stack of an IBM 350

The IBM 350 was the world's first hard disk drive and was introduced to the public on September 4, 1956 as part of the IBM 305 RAMAC computer . RAMAC stands for Random Access Method of Accounting and Control .

Development of the drive began in the early 1950s in a new IBM research center in San José (California) under the direction of Reynold B. Johnson . Until then, punch cards were still the state of the art and the basis of IBM's business. The users had to rearrange them according to their task and often lay them out on tables. IBM only looked for alternatives when Remington Rand, the leading manufacturer of drum storage systems ( ERA ) and the UNIVAC with magnetic tape ( EMCC) bought up. The new team from IBM was looking for a solution that combined short access times with large storage capacity . The decision to implement the idea of ​​a disk storage was made in April 1953.

An IBM 350 is 173 cm high, 152 cm wide and 74 cm deep. It holds around 5 million 6- bit characters. That is the equivalent of 3.75 megabytes. It contains 50 aluminum plates with a diameter of 61 cm, coated on both sides so that they can be magnetized and stacked on a shaft at 8 mm intervals . The plate stack rotates at 1200 revolutions per minute. To store and read data, two arms with read and write heads are moved vertically to the respective disks and then moved under or over them. The heads are kept at a distance from the plates with compressed air. A corresponding compressor is included in the IBM 350. The average access time is 0.6 seconds.

IBM 350s weren't sold, but rented for $ 650 a month. On August 18, 1969, they were all taken off the market.

Individual evidence

  1. ↑ a b c d Emerson W. Pugh: RAMAC in Historical Perspective (PDF; 57 kB) Magnetic Disk Heritage Center. Archived from the original on September 28, 2007. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved January 15, 2012. @1@ 2Template: Webachiv / IABot / www.magneticdiskheritagecenter.org
  2. ^ Keith Thuerk: IBM impact on storage . January 16, 2014 .: "stored 5 million 6-bit characters (the equivalent of 3.75 million 8-bit bytes)"

Web links

IBM 350: The world's first hard drive! ( Memento from May 31, 2017 in the Internet Archive )