IBM 2311

IBM 2311. The IBM 2311 Disk Storage Drive was a pivotal magnetic disk storage unit introduced by International Business Machines Corporation in 1964 for its revolutionary IBM System/360 family of computers. It utilized removable IBM 1316 disk packs, offering a substantial storage capacity that facilitated new levels of data processing and accessibility. Its reliable design and integration with the S/360 architecture made it a cornerstone of commercial data processing installations throughout the mid-to-late 1960s.

Overview

Announced alongside the groundbreaking IBM System/360, the 2311 provided a critical secondary storage solution for the new computer architecture. It was designed to be a standard peripheral across the S/360 line, supporting a wide range of applications from scientific computing to business data processing. The drive's use of interchangeable disk packs, a concept popularized by its predecessor the IBM 1301, allowed for offline storage and data transport between systems. This flexibility was instrumental for operations requiring large databases, such as those in banking, insurance, and government agencies.

Technical specifications

The 2311 housed a single IBM 1316 disk pack, which contained six 14-inch magnetic disk platters with ten recording surfaces. The unit achieved a total formatted capacity of 7.25 megabytes, a significant amount for its era. Data transfer occurred at a rate of 156 kilobytes per second, with an average seek time of 85 milliseconds. The drive employed a moving-head actuator mechanism to access data stored on 200 cylinders, each containing 10 tracks. It connected to the central processing unit via the IBM 2841 Storage Control Unit, which managed the interface and data flow for up to eight 2311 drives.

Models and variants

The primary model was the IBM 2311 Model 1, which was the standard disk drive attachment for the IBM System/360. Its design and electromechanical components were heavily influenced by earlier storage technology from the IBM 1400 series. While fundamentally similar, certain engineering adjustments were made to ensure compatibility across the different processing units within the S/360 family, from the smaller Model 30 to the larger Model 75. The 2311's fundamental design and disk pack interface were directly evolved into the subsequent and higher-capacity IBM 2314 storage system, which offered a multi-drive configuration.

Operation and usage

Operation required an operator to manually mount the 10-pound IBM 1316 disk pack onto the drive's spindle, a common procedure in data centers of the time. The drive was used for storing operating system software, such as OS/360, application programs, and large data files. Its reliability and capacity made it ideal for batch processing tasks like payroll preparation, inventory control, and accounting. System administrators often maintained libraries of disk packs for different applications, swapping them as needed, which was a foundational practice in early data management.

Historical significance

The IBM 2311 was a landmark product that helped cement the success of the IBM System/360 by providing a practical, high-capacity storage solution. It played a crucial role in the widespread adoption of disk storage over magnetic tape for online processing in commercial environments. The drive's design philosophy influenced a generation of IBM storage products and established the removable disk pack as a dominant storage medium for over a decade. Its introduction represents a key moment in the transition of computing from scientific and military applications to pervasive use in corporate and administrative functions worldwide. Category:Computer storage devices Category:IBM products Category:1964 introductions