page_title: History of IBM magnetic disk drives
section_title: IBM 1311
hierarchical_section_title: History of IBM magnetic disk drives / Early IBM HDDs / IBM 1311
caption_attribution_description: IBM 1311 Disk Drives (Model 2 and Model 3 - clipped from photo of an IBM 1620 Model II in A FOURTH SURVEY OF DOMESTIC ELECTRONIC DIGITAL COMPUTING SYSTEMS from the BRL at Aberdeen Proving Ground.
context_page_description: IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive and floppy disk drive were invented by IBM and as such IBM's employees were responsible for many of the innovations in these products and their technologies. The basic mechanical arrangement of hard disk drives has not changed since the IBM 1301. Disk drive performance and characteristics are measured by the same standards now as they were in the 1950s. Few products in history have enjoyed such spectacular declines in cost and physical size along with equally dramatic improvements in capacity and performance.
  IBM manufactured 8-inch floppy disk drives from 1969 until the mid-1980s, but did not become a significant manufacturer of smaller-sized, 5.25- or 3.5-inch floppy disk drives. IBM always offered its magnetic disk drives for sale but did not offer them with original equipment manufacturer terms until 1981. By 1996, IBM had stopped making hard disk drives unique to its systems and was offering all its HDDs as an original equipment manufacturer.
context_section_description: The IBM 1311 Disk Storage Drive was announced on October 11, 1962 and was designed for use with several medium-scale business and scientific computers. The 1311 was about the size and shape of a top-loading washing machine and stored 2 million characters (12,000,000 bits) on a removable IBM 1316 disk pack. Seven models of the 1311 were introduced during the 1960s. They were withdrawn during the early 1970s.
  Each IBM 1316 Disk Pack is 4 inches (100 mm) high, weighs 10 pounds (4.5 kg) and contains six 14-inch (360 mm) diameter disks, yielding 10 recording surfaces (the outer surfaces are not used). The 10 individual read/write heads are mounted on a common actuator within the disk drive which moves in and out hydraulically and mechanically detented at the desired track before reading or writing occurred. The disks spin at 1500 rpm. Each recording surface has 100 tracks with 20 sectors per track. Each sector stores 100 characters. The disk pack is covered with a clear plastic shell and a bottom cover when not in use. A lifting handle in the top center of the cover is rotated to release the bottom cover. Then the top of the 1311 drive is opened and the plastic shell lowered into the disk-drive opening (assuming it is empty). The handle is turned again to lock the disks in place and release the plastic shell, which is then removed and the drive cover closed. The process is reversed to remove a disk pack. The same methods are used for many later disk packs.
  There were seven models of the 1311 disk drive:
  Has to be drive 1 on an IBM 1440, IBM 1460, or IBM 1240 system. Contained the controller and could control up to four Model 2 drives. Introduced October 11, 1962. Withdrawn February 8, 1971.
  Slave drive. Could have any special feature incorporated that the master drive (drive 1) has incorporated. Introduced October 11, 1962. Withdrawn January 6, 1975.
  Has to be drive 1 on an IBM 1620 or IBM 1710 system. Contains the controller and can control up to three Model 2 drives. Does not support any special features. Introduced October 11, 1962. Withdrawn May 12, 1971.
  Has to be drive 1 on an IBM 1401 system. Contains the controller and can control up to four Model 2 drives. Introduced October 11, 1962. Withdrawn February 8, 1971.
  Has to be drive 1 on an IBM 1410, IBM 7010, or IBM 7740 system. Contained the controller and could control up to four Model 2 drives. Direct Seek came as standard on this model. Introduced January 7, 1963. Withdrawn May 12, 1971.
  No information available, probably a master drive (drive 1). Introduced March 5, 1968. Withdrawn February 2, 1971.
  No information available, probably a master drive (drive 1). Introduced March 5, 1968. Withdrawn February 2, 1971.
  The optional special features are:
  Direct Seek: Without this option every seek returned to track zero first.
  Scan Disk: Automatic rapid search for identifier or condition.
  Seek Overlap: Allows a seek to overlap ONE read or write and any number of other seeks.
  Track Record: Increases the capacity of the disk by writing ONE large record per track instead of using sectors.
  Drive 1 (the master drive: models 1, 3, 4, and 5) was about a foot wider than the other drives (the slave drives: model 2), to contain extra power supplies and the control logic.
caption: IBM 1311 Disk Drives – Model 2 (slave) & Model 3 (master)
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