IBM 0669

IBM Magnetic Disk Storage Division

Company type	Division
Industry	Computer storage devices
Founded	1956
Defunct	2003
Fate	Divested to Hitachi
Products	Hard disk drives, floppy disk drives
Parent	IBM

IBM was a pioneer in producing magnetic disk storage devices from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. The company is credited with inventing both the hard disk drive (HDD) and floppy disk drive (FDD), with numerous technological advancements originating from IBM’s engineering teams. The core mechanical architecture of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and performance benchmarks established in the 1950s continue to be relevant. Over time, these storage solutions have experienced substantial reductions in cost and physical dimensions, along with notable enhancements in capacity and operational efficiency.

IBM manufactured 8-inch floppy disk drives between 1969 and the mid-1980s but did not become a leading producer of smaller 5.25- or 3.5-inch floppy drives. While IBM marketed its magnetic disk drives commercially, it only started offering them under original equipment manufacturer (OEM) agreements in 1981. By 1996, IBM had discontinued producing HDDs exclusively for its own systems and shifted entirely to OEM distribution.

Throughout its history, IBM referred to its magnetic disk drives using various names such as direct-access storage device (DASD), disk file, and diskette file; however, this article adopts the industry-standard terminology hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit holds the distinction of being the first-ever disk drive, introduced by IBM as part of the IBM 305 RAMAC computer system on September 14, 1956. A related model, the IBM 355, was launched for the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, with production units first shipped in November 1957 to United Airlines in Denver, Colorado.

Created to support real-time business accounting tasks, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB), utilizing fifty-two disks featuring a total of 100 recording surfaces and tracks spinning at a speed of 1200 rpm. It achieved a data transfer rate of 8,800 characters per second through a head positioning mechanism that moved to select specific disk pairs and tracks. Several enhanced versions were introduced throughout the late 1950s. The IBM RAMAC 305 system equipped with the 350 disk storage was leased at a rate of $3,200 per month. The IBM 350 was retired from production in 1969.

The patent originating from the RAMAC project is regarded as foundational for disk drive technology. Initially canceled by IBM’s Board over concerns about its potential impact on punch card sales, the project was later reinstated by IBM’s president following persistent development efforts at their San Jose laboratory.

Physically, the cabinet housing the IBM 350 measured approximately long, high, and wide. Weighing nearly one ton, transportation required forklifts and large cargo aircraft. According to Currie Munce of Hitachi Global Storage Technologies—which acquired IBM’s storage operations—capacity could have been expanded beyond five million characters; however, IBM’s marketing team was reluctant to promote higher-capacity units. Nonetheless, double-capacity models were announced in January 1959 and shipped within that year.

In recognition of its historical significance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. In 2002, a restoration initiative led by Al Hoagland commenced work on refurbishing an IBM 350 RAMAC in partnership with Santa Clara University. This effort transitioned in 2005 to the Computer History Museum in Mountain View, California, where the restored unit is exhibited within the Revolution gallery.

IBM 353

The IBM 353, implemented with the IBM 7030, bore similarities to the IBM 1301 but delivered a superior transfer speed. It accommodated 2,097,152 (2²¹) words of 64 bits each, totaling 134,217,728 bits, and achieved a data transfer rate of 125,000 words per second. A prototype dispatched in late 1960 was the first disk drive to employ one head per surface that floated on compressed air, reminiscent of the IBM 350 disk storage system. Production models utilized self-levitating heads similar to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 enhanced storage capacity for the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms compared to the single arm in the IBM 350. This unit could hold 6 million decimal digits along with 600,000 sign characters. It transferred entire tracks to and from the magnetic core memory within the IBM 650’s 653 option, which contained sixty signed words of ten digits each—sufficient for one disk track or tape record.

IBM 1405

Debuting in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two variants: Model 1 offered storage for 10 million alphanumeric characters (60 million bits) distributed across 25 disks, while Model 2 doubled that capacity using 50 disks. The disks rotated at a speed of 1200 rpm, with each side containing 200 tracks segmented into five sectors.

Each sector stored between 178 and 200 characters. One to three fork-shaped access arms, each equipped with two read/write heads positioned on the top and bottom of a disk, moved vertically and horizontally to reach any of the up to fifty disks and their tracks. The read/write time per sector was 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. Model 2 housed around 100,000 sectors capable of operating in either "move mode" (200 characters) or "load mode" (178 characters plus a word mark bit). Model 1 contained half this number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was designed for use with the IBM 7070 and was introduced alongside a model 2 version in 1959. Nevertheless, the arrival of the IBM 1301 on June 5, 1961, made it a more attractive option for users of both the IBM 7070 and IBM 7074 systems. The technology employed in the IBM 7300 shared characteristics with that found in the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

Announced on June 2, 1961, the IBM 1301 Disk Storage Unit was aimed at the IBM 7000 series mainframe computers as well as the IBM 1410. Each module stored approximately twenty-eight million characters (twenty-five million when used with the IBM 1410), featuring twenty-five large disks with forty user recording surfaces containing two hundred fifty tracks each. The Model 1 configuration included a single module; Model 2 stacked two modules vertically. Disks revolved at a speed of eighteen hundred rpm and supported data transfer rates of ninety thousand characters per second.

A significant advancement was its implementation of an individual arm and read-write head for every surface arranged together like a comb. This innovation removed delays caused by switching heads between disks and reduced maximum access times to just one hundred eighty milliseconds. The IBM 1301 also pioneered aerodynamically designed heads that floated on a thin cushion of air close to disk surfaces, greatly enhancing performance.

Connection was facilitated through the IBM 7631 File Control unit, which enabled operation with either IBM 1410 or IBM 7000 series computers or allowed sharing between two systems.

Leasing fees for Model 1 were set at $2,100 per month or $115,500 for purchase; Model 2 cost $3,500 monthly or $185,000 outright. The IBM 7631 controller added $1,185 per month or $56,000 if bought. All versions were phased out by the year 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit significantly increased storage capacity to 117 million 6-bit characters per module, a fourfold improvement over the IBM 1301. 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 module incorporated two separate access mechanisms designed for the inner and outer cylinder zones. The Model 2 version doubled this capacity by stacking two modules together. Monthly leasing fees were set at $5,600 for Model 1 and $7,900 for Model 2, while purchase prices were $252,000 and $355,500 respectively. The addition of the IBM 7631 controller increased costs by $1,185 per month or $56,000 for outright purchase. Production of the IBM 1302 ceased in February 1965.

IBM 1311

Introduced on October 11, 1962, the IBM 1311 Disk Storage Drive was aimed at mid-range business and scientific computing environments. Roughly the size of a top-loading washing machine, it stored up to two million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven different models were released before being phased out in the early 1970s.

Each IBM 1316 Disk Pack measures approximately four inches in height and weighs about ten pounds. It contains six disks measuring fourteen inches in diameter with ten usable recording surfaces (the outermost surfaces remain unused). The disks rotate at a speed of 1500 revolutions per minute, while read/write heads mounted on hydraulic actuators move between tracks. Each surface holds 100 tracks subdivided into 20 sectors per track; each sector can store up to 100 characters. The disk pack is encased in a clear plastic shell equipped with a locking mechanism to facilitate straightforward insertion and removal.

Among the seven IBM 1311 models are master drives that include controllers capable of managing up to four (or three) Model 2 slave drives across various IBM systems such as the IBM 1401, IBM 1440, IBM 1620, and IBM 1410. These master units are larger due to additional power supplies and control circuitry.

Several optional enhancements were available to optimize business operations:

• Direct Seek—removes the need to return to track zero before initiating a seek.
• Scan Disk—enables automated rapid scanning for specific identifiers or conditions.
• Seek Overlap—allows concurrent seek operations alongside read/write processes when multiple drives operate simultaneously.
• Track Record—increases storage efficiency by recording one large record per track instead of multiple sectors; this mode supports approximately 18.7 million bits in "Load Mode."

These capabilities contributed to improved performance and storage optimization during their service life.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the IBM 1302, modified to align with S/360 DASD architecture standards. It utilizes a fixed module composed of 25 platters providing a total of 46 recording surfaces. The Model 3 configuration contains one such module, whereas Model 4 incorporates two modules. Each module features two independent access mechanisms servicing the innermost and outermost sets of 250 cylinders—referred to as access groups—each equipped with a dedicated read/write head per track. Average rotational latency is approximately 17 milliseconds with a maximum delay of up to 34 milliseconds; maximum seek time within each access group reaches up to 180 milliseconds. Tracks are sized at 4,985 bytes each, resulting in a formatted capacity of roughly 112 megabytes per module. Connection to IBM mainframe systems is managed through the IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970 alongside the IBM 2835 Storage Control, the IBM 2305 fixed-head storage device initially interfaced with System/360 models 85 and 195 via the IBM 2880 Block Multiplexor Channel.

The IBM 2305 gained popularity within System/370 environments running Virtual Storage (OS/VS2), frequently functioning as a paging device on systems including models such as the 3155, 3165, 3158, 3168, as well as larger models like the 3033, 4341, and specially microcoded versions of the 3081. It was also well-suited for handling high-activity small data sets like catalogs and job queues.

The smaller model, the IBM 2305-1, delivers a capacity of approximately 5.4 megabytes with data transfer rates up to three megabytes per second and an average access time of about two and a half milliseconds. The larger IBM 2305-2 offers roughly double the capacity at around eleven point two megabytes but operates at slower transfer speeds near one point five megabytes per second with an average access time of five milliseconds.

Engineered for rapid and continuous access to relatively small volumes of data, the IBM 2305's specifications make it ideal for system-resident files such as work files, job queues, indices, and frequently accessed datasets. Its swift response time also renders it highly effective as a paging device in heavily loaded computing environments processing more than one point five transactions per second.

IBM 2311

Launched in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive catered to a wide array of IBM System/360 systems and was also compatible with the IBM 1130 and IBM 1800. It could be directly connected to the IBM System/360 Model 20 and Model 25. All units utilized the removable IBM 1316 Disk Pack, which was initially introduced with the IBM 1311.

The Model 1 interfaces with most IBM mainframe systems through the 2841 Control Unit; for the System/360 Model 25, connection occurs via a Disk Attachment Control that offers comparable capabilities. The disk packs employ IBM's count key data format, which supports variable record lengths.

Models 11 and 12 of the 2311, designed for use with the System/360 Model 20’s integrated control, utilize fixed sector formatting. Due to differing formats, disk packs are not interchangeable between Model 1 and Models 11 or 12.

While mechanically similar to the IBM 1311, the 2311 incorporates advanced recording technology, enabling storage of 7.25 megabytes on a six-platter removable disk pack. It is equipped with ten read/write heads mounted on a hydraulically driven mechanism featuring mechanical detents for accurate track positioning. Each platter surface accommodates 200 tracks plus three optional spare tracks. The average seek time is approximately 85 ms, and data transfer rates reach up to 156 kB/s.

Its standardized electrical interface ensured compatibility across System/360 models and encouraged a market for third-party plug-compatible disk drives.

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 systems. Featuring a Two Channel Switch capability, it allowed simultaneous connection to two channels. Mechanically similar to the IBM 2311, this drive offered increased data density.

The IBM 2314 housed approximately 29 million characters on an IBM 2316 disk pack composed of eleven platters (20 recording surfaces). Each surface had one hydraulically actuated read/write head with mechanical detents for precise track alignment. Every surface contained 200 tracks. Subsequent versions enhanced access times beyond those initially comparable to the 2311, while doubling data transfer speeds to around 310 kB/s.

The original Model 1 configuration consisted of nine disk drives sold as a single unit along with a storage control unit: one single-drive module plus two four-drive modules, totaling nine drives. These drives were installed in drawers facilitating straightforward disk pack replacement, earning them the nickname "Pizza Ovens." Only eight drives were accessible online simultaneously; the ninth served as a spare or offline maintenance unit. Drive addresses within the system were determined by user-interchangeable plugs, enabling address reassignment by swapping plugs.

An optional IBM 2844 Control Unit permitted two System/360 channels to concurrently access separate disk drives inside the facility.

Additional variants of the IBM 2314 were introduced later:

IBM 2314 direct access storage facility - A series

In 1969, IBM separated the original 2314 facility into distinct models capable of supporting up to nine drives (eight active) connected to a 2314 Storage Control:

• 2312 Disk Storage, a single-drive unit.
• 2313 Disk Storage, comprising four drives.
• 2318 Disk Storage, containing two drives.

IBM 2319

In 1970, IBM launched the affordable three-drive 2319 series to rival plug compatible manufacturers offering 2314-equivalent storage. This was achieved by removing one drive from the four-drive 2313 unit, rebranding it as the 2319 A1, and providing it at a notably lower rental cost. This approach reduced expenses for new customers while preserving higher rates for existing clients. The 2319-A1 connects exclusively to System/370 Models 135 and 145 integrated controllers. Traditional 2314 DASD devices such as the 2312 or 2318 can be linked to the 2319-A1. The 2319 B series accommodates configurations of three, six, or nine drives connected to the updated 2314 Model B Storage Control Unit.

IBM 3310

Released on January 30, 1979, the IBM 3310 Direct Access Storage Device was designed specifically for IBM 4331 midrange computer systems. Each drive provided a capacity of 64.5 MB and utilized fixed-block architecture (FBA). It was compatible with DOS/VSE and VM, the only S/370 operating systems that supported FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, known internally as Merlin, debuted in June 1970 targeting IBM System/370 and System/360/195 platforms. The initial lineup featured a two-drive Model 1 and a single-drive Model 2. Each removable disk pack stored 100 MB, with an access time of 30 ms and a data transfer rate of 806 kB/s. A significant advancement was the inclusion of integrated error correction using fire codes, which improved reliability and lowered costs by allowing tolerance for imperfections on the disk surface.

Originally, one storage control unit (3830 Model 1) was connected to a single 3330 drive, with up to three additional drives physically linked in a chain—permitting a maximum of eight drives per string.

In August 1972, IBM introduced the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated control units from drive strings. The upgraded 3830 functioned as a director-type controller capable of managing multiple strings. The initial unit in each string, the 3333, combined a controller with two drives and could support up to three attached 3330 drives for a total of eight drives per string. The 3830 Model 2 supported two such strings (up to sixteen drives), with optional string switches enabling connections to two distinct controllers.

In 1973, IBM launched double-density (-11) variants: the models 3333–11, 3330-11, and larger-capacity 3336–11 Disk Packs holding up to 200 MB. Mixing single- and double-density drives within one string was not permitted. Field upgrades from original models to Model-11 versions required drive conversions and complete data migration.

The IBM 3330 was discontinued in 1983.

IBM 3340 and 3344

While the IBM 3340 and IBM 3344 share many similarities, only the IBM 3340 can act as the head of a string; there are no A model versions of the IBM 3344, which must connect to an IBM 3340 A model serving as head of string.

IBM 3340

The IBM 3340 Direct Access Storage Facility, nicknamed Winchester, was introduced in March 1973 for IBM System/370 systems. It came in three configurations: the 3340-A2 featuring two drives with an integrated controller, and B2 (two drives) and B1 (single drive) units that connect to the A2 model—supporting up to eight drives per string.

This device utilized removable data modules that included both head and arm assemblies; a mechanical load/unload mechanism opened or closed the module’s access door to engage it with the drive mechanism. Unlike previous disk packs, no cover removal was necessary during insertion. The system delivered a 25 ms access time along with a data transfer rate of 885 kB/s. Three versions of the IBM 3348 Data Module were available: one with a capacity of 35 MB and two with capacities of 70 MB—one of which provided an additional fast-access area of approximately 500 KB accessible via fixed heads. The IBM 3340 incorporated error correction technology and was retired in 1984.

Developed in San Jose under Ken Haughton’s leadership, its initial design focused on two removable modules each holding about 30 MB. This design inspired its Winchester codename after the Winchester .30-30 rifle cartridge. Despite later increases in capacity, the nickname persisted.

A major breakthrough was its economical head design allowing heads to land on and take off from spinning media without unloading—a feature known as "Winchester technology." This innovation reduced mechanical complexity and manufacturing costs substantially, setting an industry benchmark. The term Winchester or Winnie remained commonly used for hard drives into the early ’90s but has since declined worldwide usage.

IBM 3344

The IBM 3344 shares similarities with the 3340 but distinguishes itself by utilizing fixed media rather than the removable 3348 data modules. Each spindle accommodates four logical drives, each matching the storage capacity of a 3348–70. This model is exclusively available in dual-drive configurations and does not include an A (head of string) variant. The 3344-B2F differs from the 3344-B2 by featuring fixed heads over select cylinders on both drives. Both models require a 3340-A2 or 3340-A2F unit as the head of string. Internally, the IBM 3344 mirrors the IBM 3350, differing solely in the microcode embedded within its control unit.

IBM 3350

Introduced in 1975 for IBM System/370 systems, the IBM 3350 Direct Access Storage Facility—codenamed Madrid—was among the early implementations of sealed, non-removable head-disk assemblies (HDAs). These HDAs integrate the head and arm assemblies into a sealed unit, setting a precedent for subsequent IBM DASD products. Each HDA contains 555 cylinders, 30 heads, and stores 19,069 bytes per track, culminating in roughly 317.5 MB of storage capacity.

Models designated A2, A2F, B2, B2F, C2, and C2F each house two HDAs. The A2 and A2F models are equipped with an additional electronics board that allows them to connect to storage control units (controllers), commonly serving as head-of-string devices. These models are arranged in strings with configurations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC-. Typically, A2 units include string switches enabling concurrent I/O operations to different HDAs through dual storage control units like the 3830 Model 2 or Integrated Storage Control (ISC) embedded in IBM CPUs (3148, 3158, 3168). Later controllers such as the 3880 maintain compatibility with these arrangements. The C2 model contains a backup controller designed for use if the primary controller on the A unit fails, although it offers limited connectivity options.

The suffix "x2F" (for example, A2F) identifies HDAs featuring fixed head areas spanning the first five cylinders. This design eliminates seek delays within these regions and targets frequently accessed data zones such as HASP or JES2 checkpoint files to reduce head movement on spool devices. Furthermore, it supports TSO swap data and system swap data for OS/360 successors like MVT, SVS, and MVS by efficiently managing non-contiguous memory pages during user or batch job context switches.

The IBM 3350 series was discontinued in September 1994.

IBM 3370

Released in January 1979 for IBM midrange systems including the 4331, 4341, and System/38 computers, the IBM 3370 Direct Access Storage Device featured seven fixed disks measuring fourteen inches each and offered a total capacity of 571 MB. It was pioneering as the first hard disk drive to employ thin-film head technology developed at IBM's Thomas J. Watson Research Center. The device used fixed-block architecture and was compatible with DOS/VSE and VM operating systems.

IBM 3375

The IBM 3375 model utilized count key data architecture to support OS/360 and its successor operating systems.

IBM 3380

Unveiled on June 11, 1980, the IBM 3380 incorporated film head technology and delivered approximately 2.52 GB per unit—comprising two hard disk assemblies each equipped with two actuators accessing about 630 MB each. It achieved a data transfer rate of three megabytes per second with an average access time of sixteen milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges between heads and media surfaces, shipments commenced in October 1981.

Configured typically with one A unit alongside up to three B units—each containing four devices—a string could support as many as sixteen devices. These were commonly connected via a 3880 storage control unit featuring dual paths that allowed two simultaneous I/O operations directed at different HDAs.

In February 1985, IBM released double-density Extended Capability Models (3380 E) offering doubled capacity at approximately 5.04 GB per unit—two actuators of around 1.26 GB each across two assemblies. By August 1987, the triple-capacity Model K provided about 7.562 GB per unit with two actuators holding roughly 1.89 GB each. Models J and K introduced optional four-path operation through the use of a 3990 storage control unit, enabling up to four concurrent I/O processes across a maximum of thirty-two devices within a string.

The IBM 3380 family consisted of twelve distinct models: six A-units serving as string heads with integrated controller logic for connection to IBM storage control units; five B-units designed to connect to A- or C-units; and one C-unit capable of direct connection to an IBM channel.

Production continued until May 1996, marking an impressive fifteen-year tenure that outlasted most disk drives from its generation.

IBM 3390

Introduced in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities up to 22 gigabytes distributed over multiple drives. Depending on the system's configuration and size, prices varied from $90,000 to $795,000.

A typical 3390 setup consists of a primary A unit containing either four or eight drives, which can be optionally accompanied by one or two B units, each supporting up to 12 drives. This system functions solely in four-path mode and connects to a 3990 storage control unit, which is capable of managing a second 3390 setup, allowing for a maximum of 64 devices within a subsystem.

Each Hard Disk Assembly (HDA) contains two actuator-head assemblies along with platters. The Model 1 HDAs offered an unformatted capacity of 1.89 GB; Model 2 doubled this to 3.78 GB. Released in September 1991, the Model 3 increased capacity by 50% to 5.67 GB per HDA, while the Model 9, introduced in May 1993, tripled storage to 11.3 GB per HDA.

In contrast to prior DASD units that utilized large AC motors with belt drives, the 3390 HDAs incorporated directly driven DC motors housed within the enclosure. Notably, the Model 9 represented IBM’s final iteration of Single Large Expensive Disk (SLED) technology.

IBM 9345

The IBM 9345 hard disk drive was launched in November 1990 as a Request Price Quotation (RPQ) option tailored for IBM's SuperComputing Systems Extensions (SCSE). Developed at IBM’s San Jose facility under the codename Sawmill, it featured a full-height 5¼-inch form factor housing eight 130 mm platters and offered up to 1.5 GB of storage. This model was pioneering in its adoption of magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM released the 9345 DASD as part of the broader IBM 9340 family—a channel-attached count key data (CKD) DASD subsystem designed for IBM mainframes such as the ES/9000 series. The Model 1 configuration included two HDDs each with a capacity of 1.0 GB, while Model 2 contained two HDDs with 1.5 GB each.

While functionally similar to the IBM 3990/3390 systems, the 9340/9345 lacked certain features: it did not include the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length than the 3390.

Device characteristics were identified by the operating system’s Input/Output Supervisor (IOS) through a specialized initializer called IECCINIT, which also handled other DASD types. During initialization, the OS recognized that the 9340 lacked non-volatile cache and noted the reduced track capacity on the 9345, assigning device types accordingly.

9330 family of disk drives

1. Models 1 and 11 of the 9331 Diskette Unit incorporated a single 8-inch floppy disk drive; models 2 and 12 featured one 5-inch floppy disk drive.
2. The 9332 Direct Access Storage Device utilized an IBM-manufactured HDD designated as model 0667.
3. The 9333 High Performance Disk Drive Subsystem employed either IBM model 0664 or model 0681 HDDs depending on specific configurations.
4. The 9334 Disk Expansion Unit connected between one and four SCSI hard disk drives to RS/6000 systems.
5. The 9335 Direct Access Storage Subsystem was equipped with an IBM-designed "Kestrel" hard drive—an 850 MB unit featuring three large (14-inch) disks and dual rotary actuators accessing multiple platter surfaces. Announced in October 1986 alongside the IBM 9370 Information System, this rack-mountable subsystem had no known OEM equivalents.
6. The 9336 Disk Unit incorporated the IBM model 0681 hard drive (codenamed Redwing).
7. The 9337 Disk Array Subsystem used either IBM model 0662 (Spitfire) or model 0663 (Corsair) hard drives.

IBM 2310

Introduced in 1964 alongside the IBM 1800 and subsequently with the IBM 1130 in 1965, the IBM 2310 Removable Cartridge Drive likely began shipping with the 1130 in late 1965. It stored 512,000 words of 16 bits each (equivalent to 1,024,000 bytes) on an IBM 2315 cartridge. This cartridge contained a single aluminum disk coated with oxide, enclosed within a plastic casing that allowed access for the read/write arm and housed two read/write heads.

IBM 5444

Released in September 1969 as part of the System/3 lineup, the IBM 5444 was engineered at IBM’s Hursley facility in England and developed under the codename Dolphin. It utilized the 5440 disk cartridge, which contained one 14-inch disk. The product was available in three configurations:

• Model 1: featured one fixed disk and one removable disk, each boasting 100 tracks per surface; total cartridge storage was 1.23 MB
• Model 2: included one fixed and one removable disk with 200 tracks per surface; capacity increased to 2.46 MB
• Model 3: consisted of a single removable disk with 200 tracks per surface; also provided 2.46 MB of storage

IBM 62GV

The IBM 62GV began shipping in May 1974. Developed at IBM’s Hursley laboratory under the codename Gulliver, it initially offered a storage capacity of 5 MB, which was later expanded to 10 MB and then to 14 MB in its subsequent versions known as the 62TM. This drive incorporated a Swinging Arm actuator paired with a single 14-inch disk—a design innovation from Hursley that became IBM’s most widely licensed electromechanical invention. The actuator and filtration technology introduced here became industry standards throughout the 1980s and continue to influence HDD designs nearly four decades later. Approximately 177,000 units of the IBM 62GV were produced during its lifecycle, marking it as the first hard drive to surpass shipments of over 100,000 units.

OEM and Small Systems HDDs

This section details IBM-manufactured hard drives offered as OEM solutions and for use within IBM small systems such as System/3, System/32, /34, /36, and AS/400 models. Drives are organized by their OEM model numbers and listed according to their initial shipment dates.

IBM 0680

First introduced in 1979 across most IBM small systems and entry-level System/370 models as the direct access storage unit labeled the 3310, the 0680 was formally announced as an OEM product in September 1981. Created at IBM’s Hursley facility in the United Kingdom under the codename Piccolo, this drive comprised six disks measuring eight inches (210 mm) each and initially delivered up to 65 MB of storage capacity supported by an enhanced rotary actuator design.

A higher-capacity version known as the 62SW debuted in June 1984 but experienced limited market penetration due to pricing comparable to that of the earlier IBM 62GV.

IBM 0676

Launched in November of 1982 as part of the IBM System/23 Datamaster’s Disk Storage Unit (model number 5247), the 0676 was developed at IBM Rochester, Minnesota under the designation 21ED. This eight-inch hard drive initially offered either 15 MB or 30 MB capacities distributed over two or four disks. In 1983, it was incorporated into the System/36’s model 5360 System Unit. By increasing track density per surface in 1984, its capacity doubled before being integrated into the System/36’s updated model, the 5362 System Unit.

IBM 0665

The 0665 made its debut in October of 1985 within the PC AT (5170) system unit. Developed at IBM Rochester under the codename "Pixie," this hard drive featured a form factor of five-and-a-quarter inches and came with storage options of 20 MB, 30 MB, and up to 44 MB.

IBM 0667

The 0667 began shipping in August 1986. Created at IBM Rochester under the project name "Grant," this full-height ESDI 5¼-inch hard disk drive provided up to 70 MB of storage spread over four 130 mm platters. It was offered as an optional component for certain PC RT models (6150, 6151, 6152) as well as System/36 Model System Units (5363, 5364).

IBM 0669

Introduced in 1987, the 0669 was developed at IBM Rochester, Minnesota, under the codename "Grant-Prime." This full-height 5-inch HDD delivered capacities up to 115 MB across four 130 mm disks. It functioned as the internal hard drive for the System/36 5363 and Series 1 4956 System Units.

IBM 0671

Also released in 1987, the 0671—codenamed "Lee" at IBM Rochester—was a full-height 5-inch ESDI HDD supporting up to 316 MB on as many as eight 130 mm disks. This model marked IBM’s initial use of thin metal film recording technology. In 1988, it was integrated into the IBM AS/400 9404 System Unit, which housed two or three of these drives.

IBM 0661

The 0661, launched in 1989 as model 371, was developed under the name "Lightning" at IBM Rochester and Hursley, UK. It was a SCSI HDD with a capacity of 320 MB utilizing up to eight 95 mm disks and featuring fourteen heads. A subsequent "Turbo" variant appeared in 1990, boosting capacity to 400 MB. This drive became standard equipment in prominent IBM systems such as the AS/400 System Unit Model CXX.

IBM 0681

Released in April 1990, the 0681 was the final hard drive developed at IBM Hursley, designated with the codename Redwing. This full-height 5-inch HDD offered up to 857 MB storage on twelve 130 mm platters and was pioneering in adopting PRML data decoding technology. The drive powered the 9333 Disk Drive Subsystem introduced in early 1992. Later that year, a higher-density version with a capacity of 1.07 GB was made available in May.

IBM 0663

The 0663, known as "Corsair," debuted in late 1991 as a compact half-height (1.6-inch) form factor HDD measuring 3 inches. It provided up to 1 GB across eight 95 mm disks and was featured in select PS/2 and RS/6000 systems. Notably, this was IBM’s first OEM hard drive to incorporate Magnetoresistive (MR) head technology.

IBM 0664

Shipping in November 1992, the 0664—developed under the codename "Allicat" at IBM Rochester, Minnesota—was a full-height (3.25 inches tall) 5-inch HDD that combined two separate 3-inch drives. It offered storage capacities reaching up to approximately 2.013 GB on as many as eight 95 mm disks.

IBM 0662

The 0662 arrived in June 1993 from IBM Rochester with the project name "Spitfire." This full-height (1-inch tall) HDD utilized a smaller three-disk or five-surface design within a 3-inch form factor to deliver up to 1.05 GB of storage. It served as the internal disk for both the 9336 Disk Unit and the larger-capacity 9337 Disk Array.

Floppy disk drive

IBM was a pioneer in floppy disk technology, launching its first floppy disk drive with an 8-inch format in 1971 initially as a read-only program loading device. The company shipped its first read/write capable model in 1973 alongside the introduction of the 3740 Data Entry System. Although IBM established early standards for the industry’s adoption of the 8-inch FDDs, it never marketed these drives independently, allowing external manufacturers to advance development freely.

At one stage, IBM stood as the largest original equipment manufacturer buyer of the then-standardized two-sided, high-density (48 tracks per inch) five-inch floppy disk drives. Despite preparing to produce these and smaller-sized drives internally, IBM halted all such plans by mid-1985. Additionally, its effort begun in 1983 to OEM a smaller four-inch DemiDiskette failed to reach market success.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three distinct hard drive product lines: the Travelstar 2-inch series designed for laptops, the Deskstar 3-inch lineup aimed at desktop computers, and the Ultrastar 3-inch range intended for high-performance computing environments.

IBM's earliest HDD compared to its final HDD models

The following table contrasts IBM's inaugural hard disk drive, the RAMAC 350, with the last three models from its "Star" series of OEM HDDs. It illustrates remarkable advancements in capacity and speed alongside substantial decreases in both cost and physical dimensions.

Parameter (units)	RAMAC 350	Ultrastar 146Z10	Deskstar 180GXP	Travelstar 80GN	46-year improvement (maximum)
Announced	Sep 1956	Jul 2002	Oct 2002	Nov 2002
Capacity (gigabytes)	0.004	146	180	80	48,000
Dimensions (inches)	60×68×29	4×1×5.75	4×1×5.75	2.75×0.38×3.95
Dimensions (mm)	1500×1700×700	102×25×146	102×25×146	70×9.5×100
Volume (in³)	118,320	23	23	4	29,161
Volume (litres)	1,939	0.4	0.4	0.1
Weight (lbs)	2,140	1.7	1.4	0.2	1,244
Weight (kg)	971	0.8	0.64	0.095
Power (watts)	Approximately 2374 watts (~8100 BTUs/hour), with up to 5500 VA depending on the model	16	10.3	1.85	1,283
Power density (megabytes/watt)	0.0016	9,125	17,476	43,243	27,375,856
List price (Template:US$)	$34,500 ($234,000 adjusted to 2002 dollars)	$1200	$360	$420
Price per megabyte (Template:US$)	$9,200 ($68,000 in terms of 2002 dollars)	$0.0082	$0.0020	$0.0053
Areal density (megabits/in²)	0.002	26,263	46,300	70,000
Areal density (kilobits/mm²)	0.003	40,708	71,765	108,500
Volume density (gigabytes/in³)	0.00000003	6	8	20
Volume density (megabytes/cm³)	0.000002	388	478	1,203
Average rotational latency (ms)	25	3	4	7
Average seek time (ms)	600	5.9	10.2	12
Data transfer rate (megabytes/s)	0.001	103	29.4	43.75

DASD devices distinct from HDDs or FDDs

Within certain IBM operating systems, both hard disk drives and floppy disk drives are categorized as DASDs (direct access storage devices). Additional DASD technologies encompass:

IBM 7320 drum

The IBM 7320 is a magnetic drum storage unit that IBM introduced in the year 1962.

IBM 2301 drum

The IBM 2301 represents a magnetic drum storage device brought to market in the late 1960s.

IBM 2303 drum

The IBM 2303 is another magnetic drum storage product released in the year 1964.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell utilizes short strips of magnetic tape for data storage and accommodates ten detachable cells each holding forty megabytes—resulting in a total capacity of four hundred megabytes.

IBM 3850 Mass Storage System

First introduced in 1974, the IBM 3850 Mass Storage System is a tape cartridge library solution that stages data onto IBM's disk drives such as the IBM 3330 or IBM 3350 while presenting virtual disk drives to host systems.

See also

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

External links

• IBM Archive: Fundamental storage information resources
• IBM Archive: Directory of disk drive articles
• Magnetic Disk Heritage Center
• A Quarter Century of Disk File Innovation, IBM Journal of Research and Development, 1981
• EE Times: The dynamic evolution of disk drives
• IBM 1311 Disk Storage Drive
• IBM 2314 Direct Access Storage