In addition to the drums used as

main memory Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer ...

by IBM, e.g.,

IBM 305 The IBM 305 RAMAC was the first commercial computer that used a moving-head hard disk drive (magnetic disk storage) for secondary storage. The system was publicly announced on September 14, 1956,

IBM 650 The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s. It was the first mass produced computer in the world. Almost 2,000 systems were produced, the last in 1962, and it was the first ...

, IBM offered drum devices as

secondary storage Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer ...

for the 700/7000 series and System/360 series of computers.

IBM 731

The IBM 731 is a discontinued storage unit used on the

IBM 701 The IBM 701 Electronic Data Processing Machine, known as the Defense Calculator while in development, was IBM’s first commercial scientific computer and its first series production mainframe computer, which was announced to the public on May ...

. It has a storage capacity of 2048 36-bit words (9,216 8-bit bytes).

IBM 732

The IBM 732 is a discontinued storage unit used on the

IBM 702 The IBM 702 was an early generation tube-based digital computer produced by IBM in the early to mid-1950s. It was the company's response to Remington Rand's UNIVAC—the first mainframe computer to use magnetic tapes. As these machines wer ...

. It has a storage capacity of 60,000 6-bit characters (45,000 8-bit bytes).

IBM 733

The IBM 733 is a discontinued storage unit used on the

IBM 704 The IBM 704 is a large digital mainframe computer introduced by IBM in 1954. It was the first mass-produced computer with hardware for floating-point arithmetic. The IBM 704 ''Manual of operation'' states: The type 704 Electronic Data-Pro ...

and

IBM 709 The IBM 709 was a computer system, initially announced by IBM in January 1957 and first installed during August 1958. The 709 was an improved version of its predecessor, the IBM 704, and was the third of the IBM 700/7000 series of scientific com ...

. It has a storage capacity of 8192 36-bit words (36,864 8-bit bytes).

IBM 734

The IBM 734 is a discontinued storage unit used on the

IBM 705 The IBM 700/7000 series is a series of large-scale (mainframe) computer systems that were made by IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use vacuum-tube lo ...

It has a storage capacity of 60,000 6-bit characters (45,000 8-bit bytes).

IBM 7320

The IBM 7320 is a discontinued storage unit manufactured by IBM announced on December 10, 1962 for the

IBM 7090 The IBM 7090 is a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computer that was designed for "large-scale scientific and technological applications". The 7090 is the fourth member of the IBM 700/7000 ser ...

and 7094 computer systems, was retained for the earliest System/360 systems as a

count key data Count key data (CKD) is a direct-access storage device (DASD) data recording format introduced in 1964, by IBM with its IBM System/360 and still being emulated on IBM mainframes. It is a self-defining format with each data record represented by a ...

device, and was discontinued in 1965. The 7320 is a vertically mounted head-per-track device with 449 tracks, 400 data tracks, 40 alternate tracks, and 9 clock/format tracks. The rotational speed is 3490 rpm, so the average rotational delay is 8.6 milliseconds. Attachment to a 709x system is through an IBM 7909 Data Channel and an IBM 7631 File Control unit, which can attach up to five random-access storage units, a mix of 7320 and

1301 Year 1301 ( MCCCI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events By place Europe * January 14 – With the death of King Andrew III (the Venetian) (probably poisoned), ...

DASD. One or two 7631 controllers can attach to a computer system, but the system can still attach only a total of five DASD. When used with a 709x, a track holds 2796 six-bit characters, and a 7320 unit holds 1,118,400 characters. Data transfer rate is 202,800 characters per second. The 7320 attaches to a System/360 through a channel and an 2841 Storage Control unit. Each 2841 can attach up to eight 7320 devices. When used with System/360, a track holds 2081 eight-bit bytes, and a 7320 unit holds 878,000 bytes. Data transfer rate is 135,000 bytes per second. The 7320 was superseded by the IBM 2301 in mid-1966.

IBM 2301

The IBM 2301 is a magnetic drum storage device introduced in the late 1960s to "provide large capacity, direct access storage for IBM System/360 Models 65, 67, 75, or 85." The vertically mounted drum rotates at around 3500 revolutions per minute, and has a head-per-track access mechanism and a capacity of 4 MB. The 2301 has 800 physical tracks; four physical tracks make up one logical track which is read or written as a unit. The 200 logical tracks have 20,483 bytes each. Average access time is 8.6 msec, and the data transfer rate is 1.2 million bytes per second. The 2301 attaches to a System/360 via a selector channel and an

IBM 2820 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 (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible ...

Storage Control Unit, which can control up to four 2301 units.

IBM 2303

The IBM 2303 is a magnetic drum storage device with the same physical specifications as the IBM 2301. The difference is that the 2303 reads and writes one physical track at a time, rather than the four in the 2301, reducing the data transfer rate to 312.5 thousand bytes per second. The 2303 attaches to System/360 through a channel and an

IBM 2841 Beginning with its 1964 System/360 announcement, IBM's mainframes initially accessed CKD (Count key data) subsystems via a channel connected to separate Storage Control Units (SCUs) with attached Direct Access Storage Devices (DASD), typically a ...

Storage Control Unit, which can attach up to two 2303 units.

References

{{Reflist History of computing hardware 7320 Computer storage devices