IBM 0661

IBM Magnetic Disk Storage Devices

Company type	Division
Industry	Computer storage
Founded	1956
Defunct	2003
Fate	Sold hard disk drive business to Hitachi
Products	Hard disk drives, floppy disk drives
Owner	IBM

IBM manufactured magnetic disk storage devices from 1956 until 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, with its employees driving many key innovations in these technologies. The fundamental mechanical design of hard disk drives has remained consistent since the IBM 1301, and performance metrics have followed the same standards established in the 1950s. These products have seen remarkable reductions in cost and size alongside significant gains in capacity and performance.

IBM produced 8-inch floppy disk drives from 1969 through the mid-1980s but did not become a major manufacturer of smaller 5.25- or 3.5-inch FDDs. Although IBM always sold its magnetic disk drives, it only began offering them under original equipment manufacturer (OEM) terms in 1981. By 1996, IBM had ceased producing HDDs exclusive to its own systems, instead marketing all drives as OEM products.

IBM has used various terms for its magnetic disk drives, such as direct-access storage device (DASD), disk file, and diskette file. Here, the industry-standard terms hard disk drive (HDD) and floppy disk drive (FDD) are applied.

IBM 350

The IBM 350 disk storage unit, the first disk drive, was introduced by IBM as part of the IBM 305 RAMAC system on September 14, 1956. A similar product, the IBM 355, was announced for the IBM 650 RAMAC system. RAMAC stands for "Random Access Method of Accounting and Control". The first prototype shipped to Zellerbach Paper Company in June 1956, with production shipments starting November 1957 to customers like United Airlines.

Designed for real-time business accounting, the 350 stored 5 million 6-bit characters (3.75 MB) on fifty-two 24-inch disks using 100 recording surfaces and tracks spinning at 1200 rpm. It featured a dual-head access mechanism and transferred data at 8,800 characters per second. The system leased for $3,200 per month and was withdrawn in 1969.

Patent US3,503,060 from the RAMAC program is considered fundamental for disk drives. Initially canceled by IBM's board due to concerns over its impact on punch card business, development continued under IBM’s president's approval.

The unit measured 60 inches long, 68 inches high, and 29 inches wide, weighing about one ton and requiring forklift transport. IBM marketing initially resisted higher capacity models, but double capacity versions were announced in January 1959 and shipped later that year.

In 1984, the RAMAC 350 Disk File was designated an International Historic Landmark by The American Society of Mechanical Engineers. Restoration efforts began in 2002 led by Al Hoagland in collaboration with Santa Clara University and moved to the Computer History Museum in Mountain View, California in 2005, where it is displayed publicly.

IBM 353

The IBM 353, used on the IBM 7030, was similar to the IBM 1301 but featured a faster transfer rate. It had a capacity of 2,097,152 (2²¹) 64-bit words (134,217,728 bits) and transferred data at 125,000 words per second. A prototype shipped in late 1960 was the first disk drive to use one head per surface flying on compressed air, similar to the IBM 350 disk storage (RAMAC). Production models employed self-flying heads akin to those in the IBM 1301.

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IBM 355

Introduced on September 14, 1956, the IBM 355 enhanced the functionality of the well-known IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms instead of just one as in the IBM 350, and it could store 6 million decimal digits along with 600,000 signs. This device transferred entire tracks to and from the magnetic core memory of the 653, an optional component for the IBM 650 that held sixty signed 10-digit words—enough to accommodate a single disk track or tape record—and offered additional capabilities.

IBM 1405

The IBM 1405 Disk Storage Unit, unveiled in 1961 for the IBM 1400 series business computers, came in two variants: Model 1 provided storage for 10 million alphanumeric characters (equivalent to 60 million bits) across 25 disks; Model 2 doubled this capacity with 20 million characters (120 million bits) on 50 disks. The disks rotated vertically at a speed of 1200 rpm.

Each side of a disk contained 200 tracks divided into five sectors; sectors numbered 0–4 were located on the top surfaces, while sectors 5–9 appeared on the bottom. Each sector could hold between 178 and 200 characters. One to three forked access arms, each fitted with two read/write heads servicing both disk surfaces, moved vertically to select disks (ranging from 0 to 49) and horizontally to pick tracks (numbered from 0 to 199). Reading or writing a sector took approximately 10 milliseconds.

Access times varied from as low as 100 milliseconds up to a maximum of 700 milliseconds for Model 1 and extended to 800 milliseconds for Model 2. The latter model contained 100,000 sectors capable of holding either 200 characters in move mode or 178 characters in load mode, which incorporated an additional word mark bit per character. Model 1 was equipped with half that number of sectors, totaling 50,000.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered specifically for use with the IBM 7070. Although IBM announced a second model in 1959, the launch of the IBM 1301 on June 5, 1961, shifted customer preference toward the newer system among users of both the IBM 7070 and IBM 7074. The technology employed in the IBM 7300 shared similarities with that found in the IBM 350, IBM 355, and IBM 1405.

IBM 1301

Announced on June 2, 1961, the IBM 1301 Disk Storage Unit targeted mainframe computers within the IBM 7000 series as well as the IBM 1410. Each module could store up to 28 million characters (168 million bits), or slightly less at approximately 25 million characters when used with the IBM 1410. The modules contained twenty-five large disks featuring forty user-recordable surfaces and supporting up to two hundred fifty tracks per surface. The Model 1 consisted of a single module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute, delivering data transfer rates reaching ninety thousand characters per second.

A notable advancement was its use of individual arms and read/write heads for every surface that moved simultaneously like a comb. This configuration eliminated delays caused by head movement between disks and reduced maximum access time to just one hundred eighty milliseconds. Additionally, the IBM 1301 was pioneering in employing aerodynamically designed heads that hovered on a thin cushion of air above disk surfaces, significantly enhancing performance.

Connection was facilitated through the IBM 7631 File Control unit, allowing compatibility with either a IBM 1410 or a system from the IBM 7000 series, including shared access between two computers.

The leasing cost for the IBM 1301 Model 1 was $2,100 per month or $115,500 for purchase; Model 2 leased at $3,500 monthly or $185,000 outright. The IBM 7631 controller was available for $1,185 per month lease or $56,000 purchase price. All versions were retired from service by the year 1970.

IBM 1302

Introduced in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in storage capacity over the IBM 1301, accommodating 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and data transfer speeds reaching 180,000 characters per second, more than double that of its predecessor. Each unit incorporated two separate access mechanisms dedicated to the inner and outer cylinder groups. The Model 2 variant enhanced capacity by stacking two such modules. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, while purchase prices stood at $252,000 and $355,500 respectively. Additionally, the IBM 7631 controller was available for lease at $1,185 monthly or for outright purchase at $56,000. Production of the 1302 ceased in February 1965.

IBM 1311

Unveiled on October 11, 1962, the IBM 1311 Disk Storage Drive was designed primarily for mid-range business and scientific computing systems. Comparable in size to a top-loading washing machine, it stored up to two million characters using the removable IBM 1316 disk pack. Throughout the 1960s, seven different models were launched before being phased out by the early 1970s.

Each IBM 1316 disk pack stands approximately four inches tall, weighs around ten pounds, and comprises six fourteen-inch disks with ten usable recording surfaces (the outer surfaces are not utilized). Data access is performed by ten read/write heads mounted on a hydraulically controlled arm that moves across tracks while the disks spin at 1,500 revolutions per minute. Every surface contains one hundred tracks divided into twenty sectors each; each sector holds one hundred characters. The entire disk pack is enclosed within a plastic casing featuring a detachable bottom cover to facilitate handling.

The seven IBM 1311 models consist of master drives—equipped with controllers—and slave drives managed by these masters. Master units can control multiple slave drives depending on system compatibility (for example, with IBM 1440 or IBM 1401 systems). Variations among models include differences in supported systems and features such as Direct Seek.

Notable optional capabilities include:

• Direct Seek: Removes the need to return to track zero before accessing a target track.
• Scan Disk: Enables fast automatic searching for specific identifiers or conditions.
• Seek Overlap: Permits concurrent seek operations alongside read/write processes when multiple drives are active.
• Track Record: Increases storage efficiency by writing a single large record per track instead of multiple sectors; this raises total storage capacity to roughly eighteen million bits.

Master drives (Models 1, 3, 4, and 5) are wider than Model 2 slave drives due to additional power supplies and control circuitry.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the IBM 1302 drive, reconfigured to align with the S/360 Direct Access Storage Device (DASD) architecture rather than that of the earlier 7000 series. It features a fixed module containing twenty-five platters with forty-six recording surfaces. The Model 3 includes a single module while Model 4 incorporates two modules. Each module is equipped with two independent access mechanisms—referred to as access groups—that serve the innermost and outermost sets of 250 cylinders respectively. Each access group provides one read/write head per track. Rotational latency averages seventeen milliseconds with a maximum delay of thirty-four milliseconds; maximum seek time per access group reaches up to one hundred eighty milliseconds. Tracks hold approximately 4,985 bytes; after accounting for formatting and alternate tracks, each module offers around 112 megabytes of storage capacity. The IBM 2302 interfaces with mainframe systems through the IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970, the IBM 2305 fixed-head storage device, along with its companion IBM 2835 Storage Control, initially connected to the 360/85 and 360/195 systems via the IBM 2880 Block Multiplexor Channel. It became highly sought after for System/370 environments featuring Virtual Storage, frequently employed as a paging storage unit on models such as the 3155, 3165, and 3158. Additionally, it was well-suited for managing high-transaction small data sets like catalogs and job queues.

The 2305-1 variant provides a capacity of 5.4 MB and supports data transfer rates up to 3.0 MB/s through a two-byte channel interface, with an average access latency of 2.5 milliseconds. In contrast, the larger 2305-2 model offers an 11.2 MB capacity, operates at a transfer speed of 1.5 MB/s, and has an average access time of approximately 5 milliseconds.

Engineered for rapid and continuous access to modest-sized data volumes, the IBM 2305’s combination of capacity and speed makes it ideal for system-resident functions, work files, job queues, indices, and frequently accessed datasets. Its minimal response delay is especially advantageous when utilized as a paging device in heavily burdened systems processing over 1.5 transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive debuted in 1964 alongside the 2841 Control Unit and was designed to serve the IBM System/360 family as well as the IBM 1130 and IBM 1800 systems. It also connected directly to the IBM System/360 Model 20 and Model 25. This drive employed the removable IBM 1316 Disk Pack, which originated from the IBM 1311 design.

The Model 1 version connects to most IBM mainframes through the 2841 Control Unit; for the System/360 Model 25, connection is established via a Disk Attachment Control that provides comparable functionality. The disk packs utilize IBM's count key data variable-length record format.

Models 11 and 12, integrated with the Model 20’s control system, use a fixed sector format instead. Due to these differing formatting schemes, disk packs are not interchangeable between Model 1 and Models 11 or 12.

While mechanically similar to the IBM 1311, the IBM 2311 features enhanced recording technology and stores up to 7.25 megabytes on a six-platter removable disk pack. It employs ten read/write heads mounted on a hydraulically actuated arm, covering surfaces with 200 tracks each plus three additional spare tracks for defect management. The average seek time is approximately 85 milliseconds with a data transfer rate of about 156 kB/s.

Uniform electrical interfaces across System/360 models allowed third-party vendors to manufacture plug compatible disk drives, fostering a competitive marketplace for IBM-compatible storage solutions.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms. Equipped with an optional Two Channel Switch feature, it could connect simultaneously to two channels. Building upon the foundation of the IBM 2311 design, it delivered increased data density.

This drive accommodated roughly 29 million characters on an IBM 2316 disk pack composed of eleven platters (yielding twenty recording surfaces), surpassing the earlier six-platter configuration. Twenty read/write heads were hydraulically positioned by an actuator across surfaces containing 200 tracks each. Initial access times were comparable to those of the IBM 2311 but improved subsequently due to enhancements in actuator technology. Its data transfer rate doubled to approximately 310 kB/s.

The original Model 1 was offered as a nine-drive package including one storage control unit, one single-drive module, and two four-drive modules. Drives were installed in pull-out drawers facilitating convenient disk pack replacement; this arrangement earned them the nickname "Pizza Ovens." Although nine drives were included, only eight could be accessed concurrently—the ninth served as an offline spare allowing maintenance without interrupting operations. Drive addresses within the system were configurable by swapping plugs, enabling straightforward reassignment of spare units.

An optional IBM 2844 Control Unit allowed two System/360 channels simultaneous access to different drives within the facility.

Subsequent versions of the IBM 2314 were introduced later:

IBM 2314 direct access storage system - Variants

In 1969, IBM segmented the original facility into distinct models, each capable of supporting up to nine drives (with eight accessible online) connected to a 2314 Storage Control. These included:

• The 2312 Disk Storage, designed as a single-drive unit.
• The 2313 Disk Storage, comprising four drives.
• The 2318 Disk Storage, featuring two drives.

IBM 2319

To address challenges posed by plug-compatible manufacturers producing subsystems equivalent to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. This line was developed by removing one drive from the four-drive 2313, rebranded as the 2319 A1, and offered at significantly lower rental prices. This approach reduced expenses for new clients while preserving higher charges for existing customers. The 2319-A1 interfaces with integrated controllers for System/370 Models 135 and 145. Traditional 2314 DASD units such as the 2312 or 2318 are compatible with the 2319-A1. Meanwhile, the 2319 B series supports configurations of three, six, or nine drives connected to a newly designed 2314 Model B Storage Control Unit.

IBM 3310

Released on January 30, 1979, the IBM 3310 Direct Access Storage Device was tailored for IBM 4331 midrange computer systems. Each drive delivered a storage capacity of 64.5 MB and utilized fixed-block architecture (FBA). Support for this device was limited to the DOS/VSE and VM operating systems on S/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, debuted in June 1970 targeting IBM System/370 and System/360/195 machines. Initially available in two configurations—Model 1 with two drives and Model 2 with one—the system employed removable disk packs with a capacity of 100 MB each. It offered a 30 ms access time and a data transfer speed of 806 kB/s. Notably, it introduced fire code error correction to enhance reliability and reduce costs by accommodating surface flaws.

The original architecture featured one storage control unit (3830 Model 1) managing up to four drives arranged in a string (with a maximum of eight drives). In August 1972, IBM unveiled the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated the control unit from the drive string. The upgraded 3830 served as a director-type controller overseeing multiple strings; meanwhile, the initial unit in each string—the 3333—integrated controller functionality with two drives and could handle up to three attached 3330 drives, totaling eight per string. The enhanced 3830 Model 2 supported connections to two such 3333 units, enabling up to sixteen drives per control unit. Additionally, an optional string switch on the 3333 allowed linkage to two separate controllers.

In 1973, IBM introduced double-density (-11) versions: the models named 3333–11 and 3330-11, along with larger-capacity 3336–11 Disk Packs that held up to 200 MB. Mixing single-density and double-density drives within a single string was not supported. Upgrades from original models to Model-11 versions were feasible in the field but necessitated drive conversion and data migration.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and 3344

While sharing many characteristics, the IBM 3340 and IBM 3344 differ in that only the IBM 3340 can function as the head of a string; there are no A model variants of the IBM 3344. Consequently, an IBM 3344 must be connected under a head-of-string IBM 3340 A model unit.

IBM 3340

Launched in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility, known by its codename Winchester, came in three variants: the 3340-A2 featuring two drives plus a controller, and the B2 (two drives) and B1 (single drive) units. Up to eight B-units could be connected to a single A2 controller.

This system utilized removable data modules that housed the head and arm assembly; during mechanical load and unload operations, the module's access door opened automatically, removing the need to detach covers as was required with earlier disk packs. It offered an access time of 25 milliseconds and supported data transfer speeds of 885 kB/s. The IBM 3348 Data Module was available in three versions, providing capacities of 35 MB and two types of 70 MB modules—one of which included a 500 KB fixed-head segment for faster data retrieval. Integrated error correction was part of the design, and the product line was discontinued in 1984.

Developed under Ken Haughton’s leadership in San Jose, the initial concept revolved around two removable 30 MB modules—hence the nickname Winchester, inspired by the Winchester .30-30 rifle. Although storage capacities grew over time, the original codename remained.

A major breakthrough was the introduction of an economical head design that allowed heads to land on and lift off from spinning disks without unloading, significantly simplifying mechanics and lowering costs. This innovation, dubbed "Winchester technology," became a foundational standard in hard disk drive production.

The terms Winchester or Winnie were commonly used to describe hard drives well into the early 1990s before gradually falling out of global usage.

IBM 3344

The IBM 3344 shares similarities with the 3340 but differs by employing fixed media rather than removable IBM 3348 data modules. Each spindle supports four logical drives, each matching the capacity of a 3348–70 module. This model is only offered as a dual-drive configuration and does not include an A (head of string) variant. The 3344-B2F differs from the 3344-B2 by featuring fixed heads over certain cylinders on both drives. Both require a 3340-A2 or 3340-A2F unit to serve as head of string. Internally, the IBM 3344 is essentially identical to the IBM 3350; distinctions arise exclusively from control unit microcode variations.

IBM 3350

Introduced in 1975 for IBM System/370, the IBM 3350 Direct Access Storage Facility carried the codename Madrid. It featured sealed, non-removable head-disk assemblies (HDAs) that integrated both head and arm components, setting a precedent for sealed HDAs in subsequent IBM DASD products. The disk architecture comprised 555 cylinders, 30 heads, and tracks containing 19,069 bytes each, resulting in an HDA capacity of approximately 317.5 million bytes.

Models such as A2, A2F, B2, B2F, C2, and C2F each incorporated two HDAs. The A2 and A2F models included an additional electronics board to interface with the control unit; these are often referred to as controllers or head-of-string units. Installation configurations began with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. Typically, the A2 unit was equipped with a string switch enabling simultaneous connections to two storage control units, allowing parallel input/output operations across different HDAs.

Compatible storage control units encompassed models like the 3830 Model 2 and ISC found within CPUs such as the 3148, 3158, or 3168; later control units like the 3880 maintained backward compatibility. The C2 model contained a backup controller functioning as a secondary path if the primary controller on an A unit failed; however, its connectivity capabilities were more limited compared to those of the A unit. Valid IBM 3350 configurations included combinations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

The "x2F" variants (e.g., A2F) incorporated fixed-head areas spanning the first five cylinders on both HDAs. This design eliminated seek time for these cylinders and was optimized for frequently accessed checkpoint regions like HASP or JES2 spooling areas. Additionally, it supported TSO swap data along with system swap data for SVS and MVS environments, enhancing efficiency during context switches between TSO users or batch jobs.

The IBM 3350 series was officially retired from commercial availability in September 1994.

IBM 3370

Debuting in January 1979 for IBM 4331, 4341, and System/38 midrange systems, the IBM 3370 incorporated seven fixed 14-inch platters, delivering a storage capacity of 571 MB. It marked the industry's first hard disk drive to implement thin-film head technology, developed at the Thomas J. Watson Research Center. The 3370 utilized a fixed-block architecture and was compatible with DOS/VSE and VM operating systems on S/370 platforms.

IBM 3375

The IBM 3375 served as a counterpart device featuring count key data architecture, designed to operate with OS/360 and its subsequent versions.

IBM 3380

Released on June 11, 1980, the IBM 3380 adopted thin-film head technology and provided a storage capacity of 2.52 GB per unit, achieved through two hard disk assemblies each equipped with two actuators accessing 630 MB. It supported a data transfer rate of 3 MB/s and had an average access time of approximately 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges involving the interaction between heads and media, shipments commenced in October 1981.

The typical setup comprised one A unit accompanied by up to three B units; each 3380 contained four devices, enabling up to sixteen devices per string. Usually attached to a 3880 storage control unit with dual paths, it allowed concurrent I/O operations targeting separate HDAs.

In February 1985, IBM introduced the Extended Capability Models (3380 E) featuring double density with a capacity of 5.04 GB per unit (two actuators at 1.26 GB each). Later in August 1987, the triple-capacity Model K offered 7.562 GB per unit (two actuators at 1.89 GB each), including an optional four-path mode supporting up to thirty-two devices per string when connected to a 3990 storage control unit.

The IBM 3380 series included twelve models: six A-units functioning as string heads with controller logic interfacing with storage control units; five B-units connecting to A- or C-units; and one C-unit providing direct channel connection. Production concluded in May 1996 after an extensive fifteen-year lifecycle.

IBM 3390

Introduced in November 1989, the IBM 3390 Direct Access Storage Device family offered storage capacities reaching up to 22 gigabytes distributed across multiple drives. System pricing varied from $90,000 to $795,000 depending on configuration and capacity.

A typical 3390 string consisted of a central A unit housing four or eight devices, optionally flanked by one or two B units accommodating up to twelve devices each. Operating in four-path mode connected to a 3990 storage control unit, the system could support an additional 3390 string for a total of up to sixty-four devices per subsystem.

Hard Disk Assemblies (HDAs) featured two actuator-head units combined with platters. Model 1 delivered a pre-format capacity of 1.89 GB; Model 2 increased this to 3.78 GB per HDA; Model 3 (released in 1991) boosted capacity by fifty percent to reach 5.67 GB per HDA; and Model 9 (introduced in 1993) tripled the capacity to approximately 11.3 GB per HDA.

Departing from earlier DASD designs that employed large AC motors with belt drives, the IBM 3390 HDAs utilized enclosed DC motors for direct drive. The Model 9 represented IBM’s final Single Large Expensive Disk (SLED) drive offering.

IBM 9345

The IBM 9345 hard disk drive was launched in November 1990 as a Request Price Quotation (RPQ) for IBM’s SuperComputing Systems Extensions (SCSE). Developed at IBM’s San Jose laboratory under the codename Sawmill, this full-height 5¼-inch HDD contained up to eight platters measuring 130 mm each and reached a maximum capacity of 1.5 GB. Significantly, it was the pioneer HDD employing Magnetoresistive (MR) head technology.

IBM 9340

In October 1991, IBM launched the 9345 DASD as a member of the 9340 channel-attached count key data (CKD) DASD subsystem series designed for IBM mainframes, including the ES/9000 processor lineup. The 9345 Model 1 was equipped with two 1.0 GB hard disk drives, whereas Model 2 contained two 1.5 GB drives.

From a functional perspective, the 9340/9345 closely resembled the 3990/3390 devices; however, it did not include the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length compared to the 3390.

The OS Input/Output Supervisor (IOS) identified this equipment through a specialized initializer named IECCINIT, which also handled other DASD varieties. During system initialization, the OS detected the absence of non-volatile cache in the 9340 and noted that the 9345 had a diminished track capacity, resulting in its classification under a device type separate from the 3990/3390.

9330 family of disk drives

1. The 9331 Diskette Unit models 1 and 11 incorporated one 8-inch floppy disk drive; models 2 and 12 featured one 5-inch floppy disk drive.
2. The 9332 Direct Access Storage Device utilized the IBM 0667 hard disk drive.
3. The 9333 High Performance Disk Drive Subsystem employed IBM 0664 or IBM 0681 hard drives depending on the specific model.
4. The 9334 Disk Expansion Unit connected between one and four SCSI hard drives to RS/6000 systems.
5. The 9335 Direct Access Storage Subsystem incorporated an IBM-developed "Kestrel" hard drive—an 850 MB unit containing three 14-inch platters and dual rotary actuators, each accessing three surfaces with two heads per surface. This rack-mountable system was announced in October 1986 as part of the IBM 9370 Information System. No original equipment manufacturer versions are documented.
6. The 9336 Disk Unit used the IBM 0681 hard disk drive (Redwing).
7. The 9337 Disk Array Subsystem employed IBM 0662 (Spitfire) or IBM 0663 (Corsair) hard disk drives.

IBM 2310

Introduced in 1964 alongside the IBM 1800 and subsequently with the IBM 1130 in 1965—likely first shipping with the latter in late ’65—the IBM 2310 Removable Cartridge Drive stored data on an IBM 2315 cartridge holding 512,000 sixteen-bit words (equivalent to 1,024,000 bytes). This cartridge contained a single oxide-coated aluminum platter encased in plastic with openings for the read/write arm and dual heads.

IBM 5444

Released in September 1969 as part of System/3 and developed at IBM's Hursley facility in England under the codename Dolphin, the IBM 5444 utilized a single-disk cartridge called the 5440 featuring one fourteen-inch platter. It was available in three models:

• Model 1: included one fixed and one removable disk, each offering 100 tracks per surface; cartridge capacity was approximately 1.23 MB
• Model 2: comprised one fixed and one removable disk, each containing 200 tracks per surface; cartridge capacity reached about 2.46 MB
• Model 3: consisted solely of one removable disk with 200 tracks per surface; cartridge capacity also around 2.46 MB

IBM 62GV

The IBM 62GV, introduced in May of 1974 and developed at IBM’s Hursley laboratory under the codename Gulliver, initially offered a storage capacity of five megabytes. Subsequent iterations included versions with ten megabytes (62TM) and fourteen megabytes. This device featured a Swinging Arm actuator paired with a single fourteen-inch platter. This actuator design, created at Hursley, became IBM’s most widely licensed electro-mechanical innovation and has been universally adopted across hard disk drives since the early ’80s. Approximately 177,000 units of the IBM 62GV were produced, marking it as the first hard disk drive to surpass sales of one hundred thousand units.

OEM and Small Systems HDDs

This segment covers IBM-produced hard disk drives supplied as OEM components and for IBM’s smaller computer systems such as the System/3, System/32, /34, /36, and AS/400. The drives are organized by their OEM model numbers and dates of release.

IBM 0680

Initially introduced in 1979, the 0680 was deployed across many IBM small systems and entry-level System/370 units as the 3310 direct access storage device. Officially announced as the 0680 OEM variant in September 1981, it was engineered at IBM’s Hursley facility in the UK under the project name Piccolo. This model comprised six 8-inch (210 mm) platters, delivering a starting capacity of up to 65MB, and incorporated an enhanced rotary actuator mechanism.

A higher-capacity iteration, the 62SW, became available in June 1984 but experienced limited market traction due to its cost per megabyte being comparable to that of the 62GV model.

IBM 0676

The 0676 debuted in November 1982 as a 5247 Disk Storage Unit designed for the IBM System/23 Datamaster. Created at IBM Rochester, Minnesota under the designation 21ED, it featured an 8-inch HDD configuration with initial storage options of either 15 or 30 MB, utilizing two or four 210 mm platters. In 1983, this drive was incorporated into the System/36’s 5360 System Unit. Its capacity was doubled in 1984 through an increase in tracks per surface and subsequently used within the System/36’s 5362 System Unit.

IBM 0665

Released in October 1985 within the PC AT (5170) system unit, the 0665 was developed at IBM Rochester under the codename "Pixie." This model was a 5¼-inch hard disk offering capacities of 20, 30, and 44 MB.

IBM 0667

The 0667 became available in August 1986. Developed at IBM Rochester with the code name "Grant," it was a full-height ESDI HDD sized at 5¼ inches, capable of holding up to four 130 mm platters for a maximum of 70 MB. It was supplied for select PC RT models (6150, 6151, 6152) as well as System/36 Model System Units (5363, 5364).

IBM 0669

Introduced in 1987 and developed at IBM Rochester under the project name "Grant-Prime," the 0669 was a full-height 5-inch HDD featuring four 130 mm disks that supported up to 115 MB of storage. This drive was utilized internally within System/36 model 5363 and Series 1 model 4956 system units.

IBM 0671

Also launched in 1987 from IBM Rochester with the codename "Lee," the 0671 was a full-height ESDI HDD sized at five inches. It offered a maximum capacity of up to 316 MB spread over eight 130 mm platters. Notably, it represented IBM’s initial adoption of thin metal film recording technology. By 1988, this drive was integrated into the IBM AS/400 model 9404 System Unit, which supported configurations with two or three drives.

IBM 0661

The 0661, released in 1989 as model number 371, was created under the codename "Lightning" at both IBM Rochester and Hursley, UK. This SCSI HDD provided up to 320 MB using eight disks measuring 95 mm each (with fourteen heads), followed by an enhanced "Turbo" version delivering up to 400 MB introduced in 1990. It became a common storage device across multiple IBM platforms including the AS/400 System Unit Model CXX.

IBM 0681

Launched in April of 1990, the 0681 represented the final hard drive product developed at IBM Hursley under the codename Redwing. This full-height five-inch HDD offered capacities reaching up to 857 MB across twelve platters sized at 130 mm and introduced PRML data decoding technology. It formed part of the 9333 Disk Drive Subsystem which began shipping in early 1992, with an upgraded high-density variant providing up to 1.07 GB released in May of that year.

IBM 0663

Introduced in late 1991 under the project name "Corsair," the 0663 was a compact 3-inch hard disk drive with a half-height (1.6-inch) profile. It provided storage capacity up to 1 GB utilizing eight 95 mm platters. This drive was incorporated into specific PS/2 and RS/6000 models and marked IBM's initial OEM HDD to utilize Magnetoresistance (MR) head technology.

IBM 0664

Released in November 1992, the 0664 was developed at IBM Rochester, Minnesota, under the codename "Allicat." This full-height 5-inch hard disk (measuring 3.25 inches in height) essentially combined two 3-inch drives into one unit, delivering a maximum capacity of 2.013 GB across as many as eight 95 mm platters.

IBM 0662

The 0662, codenamed "Spitfire" and launched in June 1993 from IBM Rochester, was a full-height (1-inch thick) 3-inch HDD. It offered 1.05 GB of storage distributed over three platters or five platter surfaces and was utilized internally within the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was a pioneer in floppy disk technology, debuting the 8-inch floppy disk drive in 1971 as a read-only device for program loading. By 1973, IBM introduced its first read/write floppy disk drive integrated into the 3740 Data Entry System. Although IBM established early standards for the 8-inch floppy format, it refrained from selling these drives independently, allowing the broader industry to develop without direct IBM competition.

At one stage, IBM ranked as the largest OEM buyer of 5-inch floppy drives worldwide; its preference for two-sided models with a density of 48 tracks per inch contributed significantly to this becoming an industry benchmark. Despite initiating development on smaller form factors, IBM discontinued these projects in 1985. Moreover, its 1983 attempt to market the 4-inch DemiDisk as an OEM product did not achieve commercial success.

Star series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three families of hard disk drives: the Travelstar line featuring 2-inch drives designed for laptops, the Deskstar series with 3-inch drives aimed at desktop computers, and the Ultrastar lineup of high-performance 3-inch drives intended for demanding systems.

Comparison: IBM's inaugural HDD versus its final HDD models

The following table contrasts IBM’s first hard disk drive, the RAMAC 350, with its last three OEM HDD offerings from the "Star" series. The comparison underscores substantial advancements in cost efficiency and physical size alongside remarkable enhancements in capacity and operational performance.

DASD Devices Beyond HDDs and FDDs

Within certain IBM operating systems, both hard disk drives (HDDs) and floppy disk drives (FDDs) are categorized as DASDs (direct access storage devices). Additional forms of DASD technology encompass the following:

IBM 7320 Drum

The IBM 7320 represents a magnetic drum storage apparatus that was introduced in 1962.

IBM 2301 Drum

Introduced in the late 1960s, the IBM 2301 is a magnetic drum-based storage device.

IBM 2303 Drum

The IBM 2303, which debuted in 1964, is another variant of magnetic drum storage technology.

IBM 2321 Data Cell

Unveiled in 1964, the IBM 2321 Data Cell utilizes short strips of magnetic tape for data storage. It comprises ten detachable cells, each with a capacity of 40 MB, amounting to a total of 400 MB.

IBM 3850 Mass Storage System

Launched in 1974, the IBM 3850 Mass Storage System is a tape cartridge library that stages data onto IBM 3330 or 3350 disk drives. These drives are then presented to the system as virtual storage units.

See also

• History of the floppy disk
• History of hard disk drives
• List of IBM products

External links

• IBM Archive: Basic Storage Information
• IBM Archive: Articles on Disk Drives
• Magnetic Disk Heritage Center
• A Quarter Century of Disk File Innovation, IBM Journal of Research and Development, 1981
• EE Times: The Evolution of Disk Drives
• IBM 1311 Disk Storage Drive
• IBM 2314 Direct Access Storage

Parameter (units)	RAMAC 350	Ultrastar 146Z10	Deskstar 180GXP	Travelstar 80GN	Improvement over 46 years (maximum)
Announcement date	Sep 1956	Jul 2002	Oct 2002	Nov 2002
Storage capacity (GB)	0.004	146	180	80	48,000-fold
Physical dimensions (inches)	60×68×29	4×1×5.75	4×1×5.75	2.75×0.38×3.95
Physical dimensions (mm)	1500×1700×700	102×25×146	102×25×146	70×9.5×100
Volume (cubic inches)	118,320	23	23	4	29,161-fold reduction
Volume (liters)	1,939	0.4	0.4	0.1
Weight (pounds)	2,140	1.7	1.4	0.2	1,244-fold decrease
Weight (kilograms)	971	0.8	0.64	0.095
Power consumption (watts)	~2374 watts (~8100 BTUs/hour), varying up to ~5500 VA by model	16	10.3	1.85	Approximately 1,283 times less power usage per unit capacity
Power efficiency (megabytes per watt)	0.0016	9,125	17,476	43,243	27 million-fold increase
Areal density (megabits per square inch)	0.002	26,263	46,300	70,000
Areal density (kilobits per square millimeter)	0.003	40,708	71,765	108,500
Volumetric density (gigabytes per cubic inch)	0.00000003	6	8	20
Volumetric density (megabytes per cubic centimeter)	0.000002	388	478	1,203
Average latency (milliseconds)	25	3	4	7
Average seek time (milliseconds)	600	5.9	10.2	12
Data transfer rate (megabytes per second)	0.001	103	29.4	43.75