History (1962): IBM Disk Packs Offer Portability and Security

This article comes from the Computer History Museum.

1962: Disk packs offer portability & security
Interchangable packs spawn Plug Compatible Manufacturers (PCM)

IBM 1311 Disk Storage Drive with disk pack access open

(Courtesy Mark Richards)

In 1959, Lou Stevens, development lab director at IBM San Jose, drafted Jack Harker who recruited Jim Carothers, Jack Clemens, Erik Solyst and others to design a disk drive offering half the size, performance, and cost of the RAMAC unit.

In October 1962 IBM Announced the Model 1311 that reduced the media diameter from 24 inch to 14 inch and introduced the concept of a removable disk pack that combined the direct access of disks, with the advantages of unlimited offline capacity, portability between separate computer systems, and secure offline storage characteristic of tape units.

The 1316 Disk Pack consisted of six 14-inch-diameter disks in a removable assembly. The four-inch high stack of disks with 10 magnetic surfaces for storage (top and bottom surfaces unused) had a capacity of 2 million characters. The interchangeable package weighed 9.4 pounds with polycarbonate plastic covers attached.

Improvements in electronics together with attachment to the new System/360 Model 40 computer made the successor Model 2311 announced in 1964 a significant commercial success and spawned a new IBM PCM industry that forever changed the nature of the disk drive market.

By 1969 Century Data, Memorex, Telex and others offered competitive 2311-like drives that accepted 1316 disk packs.

Established media suppliers including 3M, BASF, CDC, and Memorex, plus start-ups Athana, Caelus, and CFI sold compatible packs.

New model disk-pack drives, including non-IBM compatible versions such as the CDC Storage Module (SMD), continued to be announced into the 1980s.

First shipped in 1983, the Digital Equipment Corporation Model RA60 was one of the last significant removable disk pack products to enter production.

By the mid-1990s, the industry had returned completely to non-removable media, in order to enable further improvements in areal density.