IBM 0676

IBM Magnetic Disk Storage Division

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

IBM was a pioneer in manufacturing magnetic disk storage devices from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. IBM employees were instrumental in inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing numerous technological advancements. Since the introduction of the IBM 1301, the fundamental mechanical architecture of hard disk drives has remained largely unchanged, with performance benchmarks established during the 1950s still serving as a reference. Over time, these storage devices have experienced dramatic decreases in cost and physical dimensions, accompanied by substantial improvements in capacity and speed.

IBM manufactured 8-inch floppy disk drives from 1969 through the mid-1980s but did not become a leading producer of smaller 5.25-inch or 3.5-inch floppy drives. While IBM marketed its magnetic disk drives commercially, it only began offering them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had ceased producing hard disk drives exclusively for its own systems, instead supplying all HDDs as OEM components.

Throughout its history, IBM labeled its magnetic disk drives with various terms such as direct-access storage device (DASD), disk file, and diskette file. For clarity and consistency, this article employs the industry-standard designations hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit marked IBM’s introduction of the first disk drive, launched as part of the IBM 305 RAMAC computer system on September 14, 1956. A closely related model, the IBM 355, was announced to support the IBM 650 RAMAC system. The initial prototype was delivered to Zellerbach Paper Company in June 1956, followed by production units shipped to United Airlines in Denver beginning November 1957.

Created to fulfill real-time business accounting requirements, the IBM 350 stored five million characters encoded in six bits each (equivalent to approximately 3.75 MB). It contained fifty-two disks measuring 24 inches in diameter, providing a total of 100 recording surfaces and tracks, all rotating at a speed of 1200 revolutions per minute. Data throughput reached 8,800 characters per second. The device employed a mechanical actuator that moved read/write heads across both surfaces and tracks. Several enhanced versions were introduced throughout the late 1950s. The IBM RAMAC 305 system including the 350 was leased for $3,200 monthly. Production of this unit ended in 1969.

The US Patent numbered 3,503,060 emerging from the RAMAC project is regarded as the seminal patent for disk drive technology. Although initially rejected by IBM’s board over concerns about negatively impacting its punch card business, development was allowed to proceed with approval from IBM’s president.

The physical dimensions of the IBM 350's cabinet measured approximately 60 inches in length, stood 68 inches tall, and was 29 inches wide. Weighing close to one ton, transportation required forklifts and cargo aircraft. According to Currie Munce from Hitachi Global Storage Technologies—which acquired IBM’s storage division—the device’s capacity could have been expanded beyond five million characters; however, marketing hesitated to promote larger drives due to uncertainty about market demand. Despite this hesitation, versions with double capacity were announced in January 1959 and shipped later that year.

Acknowledging its historical importance, the RAMAC 350 Disk File was named an International Historic Landmark by The American Society of Mechanical Engineers in 1984. A restoration initiative commenced in 2002 under Al Hoagland’s leadership in partnership with Santa Clara University and was relocated to the Computer History Museum in Mountain View, California in 2005. There it remains on public display as part of the Revolution exhibition.

IBM 353

The IBM 353, implemented on the IBM 7030, bore similarity to the IBM 1301 but offered an enhanced data transfer speed. It provided storage for 2,097,152 (2²¹) 64-bit words, equivalent to 134,217,728 bits, with a transfer rate of 125,000 words each second. A prototype delivered in late 1960 was the first disk drive to employ a single head per surface that floated on compressed air, reminiscent of the IBM 350 disk storage (RAMAC). Production versions featured self-levitating heads similar to those used in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as a companion to the widely used IBM 650. It incorporated the IBM 350’s mechanism but supported up to three access arms instead of just one. The unit stored six million decimal digits along with 600,000 sign characters. Data transfer occurred in full tracks between the magnetic core memory of the 653—an optional IBM 650 component holding sixty signed 10-digit words sufficient for a single disk track or tape record—and two other unrelated functions.

IBM 1405

Announced in 1961 for the IBM 1400 business computer series, the IBM 1405 Disk Storage Unit came in two variants: Model 1 with a capacity of ten million alphanumeric characters (60 million bits) distributed over 25 disks, and Model 2 offering twenty million characters (120 million bits) across 50 disks. The disks were stacked vertically and rotated at a speed of 1200 revolutions per minute.

Each disk surface contained 200 tracks segmented into five sectors; sectors numbered 0 through 4 were located on the top surfaces, while sectors 5 through 9 were on the bottom sides. Each sector accommodated between 178 and 200 characters. One to three forked access arms, each equipped with two read/write heads positioned on the top and bottom of a disk, moved vertically to select among disks (0–49) and horizontally to choose tracks (0–199). The time required to read or write a sector was approximately 10 milliseconds.

Access durations varied from as little as 100 milliseconds up to a maximum of 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. The latter contained about 100,000 sectors with either 200 characters in move mode or reduced to 178 characters in load mode, which incorporated a word mark bit per character. Model 1 featured half the number of sectors compared to Model 2.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered specifically for use with the IBM 7070, with IBM releasing a second model in 1959. Nevertheless, following the introduction of the IBM 1301 on June 5, 1961, many customers of both the IBM 7070 and IBM 7074 preferred the newer system. The technology in the IBM 7300 drew upon earlier designs from models such as the IBM 350, IBM 355, and IBM 1405.

IBM 1301

Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was aimed at users of the IBM 7000 series mainframe computers as well as the IBM 1410. Each module stored approximately twenty-eight million characters (168 million bits), or twenty-five million characters when paired with the IBM 1410. A module consisted of twenty-five large disks featuring forty user-accessible recording surfaces and two hundred fifty tracks per surface. The Model 1 configuration included a single module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute and transferred data at ninety thousand characters per second.

A notable advancement was the implementation of an individual arm and read-write head for every recording surface that moved collectively like a comb. This innovation removed delays caused by repositioning heads across multiple disks and reduced maximum access time to one hundred eighty milliseconds. Additionally, this was the first disk drive to utilize aerodynamically designed heads that hover on a thin cushion of air above the disk surface, improving operational efficiency.

Interface with computers was facilitated through the IBM 7631 File Control unit. Different models allowed usage by either an IBM 1410 or a member of the IBM 7000 series—or even shared operation between two systems.

Leasing rates for the IBM 1301 Model 1 were $2,100 monthly or $115,500 for outright purchase; Model 2 leased for $3,500 per month or $185,000 to buy. The IBM 7631 controller added $1,185 monthly or $56,000 if purchased outright. All variants were phased out by around 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit provided a storage capacity four times greater than that of the 1301, accommodating 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and achieved a data transfer speed of 180,000 characters per second, which was more than double the rate of the 1301. Each module was equipped with two separate access mechanisms designed for the inner and outer cylinders. The Model 2 variant increased 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. The addition of the IBM 7631 controller incurred an extra monthly lease charge of $1,185 or a purchase cost of $56,000. Production of the 1302 ceased in February 1965.

IBM 1311

The IBM 1311 Disk Storage Drive was introduced on October 11, 1962, targeting medium-sized business and scientific computer applications. It utilized a removable IBM 1316 disk pack capable of storing two million characters. Throughout the 1960s, seven different models were released before being phased out by the early 1970s.

Each IBM 1316 Disk Pack measures four inches in height, weighs approximately ten pounds, and contains six disks each measuring fourteen inches in diameter, with ten usable recording surfaces (the outer surfaces remain unused). A hydraulic actuator moves ten read/write heads to access specific tracks. The disks rotate at 1500 revolutions per minute; each surface includes 100 tracks divided into twenty sectors of one hundred characters each. The disk pack is enclosed within a plastic casing featuring a locking handle to ensure secure insertion and removal.

The seven IBM 1311 models consisted of master drives incorporating controllers and slave drives managed by these masters:

1. Master drive for IBM 1440, 1460, or 1240 systems capable of controlling up to four Model 2 drives (1962–1971)
2. Slave drive compatible with master features (1962–1975)
3. Master drive for IBM 1620 or 1710 systems controlling up to three Model 2 drives without special features (1962–1971)
4. Master drive designed for IBM 1401 systems managing up to four Model 2 drives (1962–1971)
5. Master drive for IBM 1410, 7010, or 7740 systems controlling up to four Model 2 drives; includes standard Direct Seek functionality (1963–1971)
6. Presumed master drive introduced in 1968 and withdrawn by early 1971
7. Presumed slave drive introduced in 1968 and withdrawn by early 1971

Several optional enhancements were available to improve performance and storage capacity:

• Direct Seek: Removes the need to return to track zero before seeking a target track.
• Scan Disk: Provides rapid automatic scanning for specific identifiers or conditions.
• Seek Overlap: Permits overlapping seek operations with simultaneous reads or writes across multiple drives.
• Track Record: Increases capacity by writing a single large record per track instead of multiple sectors, raising total storage to roughly 17.9 million bits in six-bit mode and nearly 18.8 million bits when using seven-bit mode.

Master drives (Models 1,3,4,5) are equipped with additional power supplies and control logic circuits and are approximately one foot wider than the Model 2 slave drives.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the IBM 1302 but is formatted specifically for System/360 DASD architecture rather than that of the IBM 7000 series. It contains a fixed module consisting of twenty-five platters with forty-six recording surfaces. The Model 3 includes a single module; Model 4 incorporates two modules. Each module is fitted with two independent access mechanisms—referred to as access groups—which handle the innermost and outermost sets of 250 cylinders respectively; each group has one read/write head per track. Rotational latency averages around seventeen milliseconds with a maximum delay of thirty-four milliseconds; maximum seek time within each access group reaches up to one hundred eighty milliseconds. Each track holds approximately 4,985 bytes, resulting in a total formatted capacity of about one hundred twelve megabytes per module. Connection to IBM mainframes is established through the IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970, the IBM 2305 fixed-head storage device, paired with the IBM 2835 Storage Control, was initially developed for use with the System/360 Model 85 and 195, utilizing the IBM 2880 Block Multiplexor Channel. Its popularity increased with the advent of System/370's Virtual Storage, where it was frequently employed as a paging device on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). Additionally, it was well-suited for managing small but highly active data sets like catalogs and job queues.

The 2305-1 model provides a storage capacity of 5.4 MB, delivering a data transfer rate of 3.0 MB/s and an average access time of 2.5 milliseconds. The larger variant, the 2305-2, offers 11.2 MB capacity with a transfer speed of 1.5 MB/s and an average access latency of 5 milliseconds. This balance of storage size and rapid data throughput made it ideal for system-resident functions such as work files, job queues, indices, and frequently accessed datasets. Its swift response time was particularly advantageous when used as a paging device in high-demand environments processing more than 1.5 transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive was launched in 1964 alongside the 2841 Control Unit to serve the IBM System/360 series as well as the IBM 1130 and IBM 1800 systems. It also connected directly to the IBM System/360 Model 20 and Model 25. All models utilized the removable IBM 1316 Disk Pack, initially designed for the IBM 1311.

The Model 1 connects via the 2841 Control Unit, whereas the System/360 Model 25 employs a Disk Attachment Control that offers similar capabilities. Disk packs utilize IBM’s count key data format, which supports variable record lengths.

Models 11 and 12, integrated with the control system of Model 20, write disk packs using a fixed-sector format; these packs are not compatible with those used by Model 1 systems.

Although mechanically akin to the IBM 1311, the IBM 2311 incorporates enhanced recording technology. It stores up to 7.25 megabytes on a removable disk pack containing six platters. The drive is equipped with ten read/write heads mounted on a hydraulically actuated mechanism that positions them over more than 200 tracks per surface, plus three additional spare tracks for defect management. It delivers an average seek time of approximately 85 milliseconds and a data transfer rate of around 156 kB/s.

Standardized electrical interfaces ensured interoperability across diverse IBM platforms, which encouraged third-party manufacturers to produce plug compatible disk drives compatible with IBM systems.

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 families. Its Two Channel Switch capability permitted simultaneous connection to two separate channels. While its disk mechanism resembled that of the IBM 2311, it featured improved recording density.

This drive utilized an eleven-platter removable IBM 2316 disk pack—larger than its predecessor’s six-platter design—offering twenty recording surfaces with two hundred tracks each and storing roughly twenty-nine million characters. Twenty read/write heads were hydraulically actuated and mechanically locked in position per track. While access times were comparable to early IBM 2311 models initially, actuator improvements in later versions enhanced performance. Data transfer rates were doubled to approximately 310 kB/s.

The original Model 1 package included nine disk drives sold together but shipped separately from a storage control unit consisting of one single-drive module and two four-drive modules. Drives were installed in drawers for convenient disk pack handling and earned the nickname "Pizza Ovens" due to their distinctive appearance. At any given moment, only eight drives were accessible; the ninth served as a spare or could be serviced offline by technicians. Drive system addresses were configured using user-replaceable plugs that allowed address reassignment simply by swapping plugs.

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

Later iterations of the IBM 2314 expanded upon these foundational features:

IBM 2314 direct access storage system - Series overview

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

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

IBM 2319

To address competition from plug-compatible vendors offering storage subsystems comparable to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. This series was developed by removing one drive from the four-drive 2313 model, rebranding it as the 2319 A1, and providing it at a significantly reduced rental fee—thereby lowering expenses for new customers while maintaining existing customer pricing. The 2319-A1 connects to integrated controllers tailored for System/370 Models 135 and 145. Additionally, traditional 2314 DASD units like the 2312 or 2318 are compatible with the 2319-A1. The 2319 B series accommodates three, six, or nine drives linked to a newly introduced 2314 Model B Storage Control Unit.

IBM 3310

Launched on January 30, 1979, the IBM 3310 Direct Access Storage Device was aimed at IBM 4331 midrange computer systems. Each unit provided a storage capacity of 64.5 MB and utilized fixed-block architecture (FBA), supporting DOS/VSE and VM operating systems on S/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, code-named Merlin, debuted in June 1970 for IBM System/370 and System/360/195 systems. Initially available as a two-drive Model 1 and a single-drive Model 2, it featured removable disk packs with a capacity of 100 MB each. With an access time of approximately 30 ms and data transfer speeds reaching 806 kB/s, it incorporated fire code error correction technology to enhance reliability and reduce operational costs.

The original configuration included a storage control unit (3830 Model 1) mounted alongside a single 3330 drive, with expandability up to four drives per string (a maximum of eight drives). In August 1972, IBM introduced the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated control units from the disk drives. The upgraded 3830 functioned as a director-type controller managing multiple strings; the first device in each string—the 3333—contained two drives plus an integrated controller and could support up to three additional attached 3330 drives (allowing up to eight drives per string). Two such 3333 units could be connected to a single controller, enabling up to sixteen drives per controller; optional string switches permitted connection to two controllers simultaneously.

In 1973, IBM released double density (-11) variants: the models 3333–11, 3330-11, and the larger-capacity disk packs labeled as 3336–11 offering up to 200 MB of storage. Mixing single density and double density drives within the same string was not supported. While field upgrades from single to double density were feasible, they required extensive drive modifications and data migration.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

Though sharing many characteristics, the IBM 3340 and IBM 3344 differ in that only the IBM 3340 can serve as the head of a string. There are no A model versions of the IBM 3344; thus, any IBM 3344 must connect under an IBM 3340 A model acting as string leader.

IBM 3340

Introduced 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 and a controller, alongside the B2 model with two drives, and the B1 model with a single drive. Up to eight B-units could be connected to an 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 would open to interface with the drive, eliminating the need to remove covers as was required with earlier disk packs. It offered an access time of 25 milliseconds and a data transfer speed of 885 kilobytes per second. Three types of IBM 3348 Data Modules were available: one with 35 MB capacity and two variants holding 70 MB each, one of which incorporated 500 KB accessible via fixed heads for quicker retrieval. The IBM 3340 supported error correction and was discontinued in 1984.

Developed under Ken Haughton in San Jose, the initial design centered around two removable 30 MB modules. The "Winchester" nickname originated from this 30/30 capacity setup, drawing inspiration from the Winchester .30-30 rifle. Although storage capacities increased later on, the codename remained in use.

A major breakthrough was its economical head design that did not require unloading from the disk surface. This "Winchester technology" enabled heads to land on and lift off from spinning disks, greatly simplifying and reducing the cost of the head/arm mechanism. This approach subsequently became an industry standard in hard drive manufacturing.

The term Winchester or Winnie was commonly used to refer to hard drives well into the early 1990s but has since largely disappeared from widespread terminology.

IBM 3344

The IBM 3344 shares similarities with the 3340 but employs fixed media instead of removable 3348 data modules. Each spindle supports four logical drives, each equivalent in capacity to a 3348–70 module. Unlike the 3340 series, it does not have an A (head of string) model and is only offered as a dual-drive configuration. The 3344-B2F differs from the 3344-B2 by having fixed heads over select cylinders on both drives. Both variants require connection to a 3340-A2 or 3340-A2F acting as head of string. Internally, the IBM 3344 matches the IBM 3350; distinctions arise solely from differences in control unit microcode.

IBM 3350

Launched in 1975 for IBM System/370, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. It featured sealed head-disk assemblies (HDAs) that combined heads and arms within a non-removable casing. Each HDA provided storage of approximately 317,498,850 bytes distributed over 555 cylinders and utilizing 30 heads. This sealed HDA design became IBM’s standard for DASD devices thereafter.

The available models—A2, A2F, B2, B2F, C2, and C2F—each housed two HDAs. Models A2 and A2F incorporated an additional electronics board enabling connection to control units often referred to as controllers or head-of-string units. These devices were installed in strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. Typically, A2 units featured a string switch allowing linkage to two separate storage control units, thereby enabling concurrent I/O operations on different HDAs. Compatible control units included the 3830 Model 2, Integrated Storage Controller (ISC) used in CPUs such as the IBM 3148/3158/3168 series, as well as later backward-compatible controllers like the IBM 3880. The C2 model also contained a controller providing an alternate path primarily serving as a backup should the A unit’s controller fail; however, it had more limited connectivity compared to A units. Valid string arrangements included configurations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

Models designated with "x2F" featured fixed head zones covering the first five cylinders on both HDAs, effectively eliminating seek time within this region. This area was typically reserved for frequently accessed checkpoint data (e.g., HASP or JES2), enhancing spool device efficiency by reducing head movement. Additionally, it accommodated swap data for TSO and system functions (MVT, SVS, MVS), improving context switching performance between users or batch jobs.

The IBM 3350 series was retired from service in September 1994.

IBM 3370

Launched in January 1979, the IBM 3370 Direct Access Storage Device was designed for IBM 4331, 4341, and System/38 midrange systems. It incorporated seven fixed 14-inch platters, delivering a storage capacity of 571 MB per unit. Notably, it was the 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 running on S/370 platforms.

IBM 3375

Serving as a complement to the 3370, the IBM 3375 employed count key data architecture, which was critical for supporting OS/360 and its subsequent versions.

IBM 3380

Debuted on June 11, 1980, the IBM 3380 Direct Access Storage Device featured thin-film head technology and offered a capacity of 2.52 GB per unit. Each unit consisted of two hard disk assemblies with two actuators each, providing access to 630 MB per actuator. The device achieved data transfer speeds up to 3 MB/s and an average access time of approximately 16 milliseconds. Initial pricing ranged from $81,000 to $142,200. Due to tribological challenges between heads and media surfaces, shipments commenced in October 1981.

The configuration options included one A unit plus as many as three B units; each 3380 housed four devices, allowing device strings up to sixteen units in length. These were commonly connected to a 3880 storage control unit featuring dual paths, enabling simultaneous I/O operations directed at different HDAs.

In February 1985, IBM released the Extended Capability Model (3380 E) with double density, doubling capacity to 5.04 GB per unit by employing two actuators of 1.26 GB each. Later, in August 1987, the Model K was introduced with triple the original capacity—7.562 GB per unit—featuring two actuators of 1.89 GB each. Models J and K supported an optional four-path mode that doubled device string length to thirty-two units when attached to a 3990 storage control unit, facilitating four concurrent I/O processes.

The IBM 3380 family consisted of twelve different models: six A-units (which housed string heads and 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).

Manufacturing continued until May 1996, resulting in a remarkable production span of fifteen years—significantly longer than most disk drives from that period.

IBM 3390

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

A typical 3390 string comprised a central A unit containing four or eight devices, optionally accompanied by one or two B units with up to twelve devices each. Operating in four-path mode when connected to a 3990 storage control unit, this setup could support a second string for a total of up to sixty-four devices within a subsystem.

Each Hard Disk Assembly (HDA) included two actuator-head units along with platters; Model 1 HDAs delivered an unformatted capacity of 1.89 GB, Model 2 doubled this to 3.78 GB, Model 3 (released in September 1991) expanded it further to 5.67 GB, and Model 9 (announced in May 1993) increased capacity again to 11.3 GB per HDA.

Unlike prior DASD models that relied on large AC motors driving platters via belts, the IBM 3390 HDAs utilized direct-drive DC motors integrated inside the enclosure. The Model 9 represented IBM’s final release of a Single Large Expensive Disk (SLED) drive.

IBM 9345

Released in November 1990 as a Request for Price Quotation (RPQ) for IBM's SuperComputing Systems Extensions (SCSE), the IBM 9345 hard disk drive was developed at IBM's San Jose laboratory under the project name Sawmill. This full-height 5¼-inch drive utilized eight 130 mm platters to offer storage capacities up to 1.5 GB. Notably, it was the pioneer in incorporating magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM launched the 9345 DASD within the 9340 family of channel-attached count key data (CKD) direct access storage devices designed for IBM mainframes, including the ES/9000 line. The 9345 Model 1 housed two HDDs with 1.0 GB each, whereas Model 2 contained two drives with 1.5 GB capacity each.

From an operational standpoint, the 9340/9345 series paralleled the functionality of the 3990/3390 models but did not include the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length than the 3390.

The device was recognized by the operating system’s Input/Output Supervisor (IOS) through a dedicated initializer named IECCINIT, which also handled other DASD types. During initialization, IOS detected that the 9340 lacked non-volatile cache and that the 9345 had diminished track capacity, leading to its classification under a unique device type distinct from that of the 3990/3390.

9330 family of disk drives

1. Models 1 and 11 of the 9331 Diskette Unit featured a single 8-inch floppy disk drive; models 2 and 12 were equipped with one 5-inch floppy disk drive.
2. The IBM 0667 hard disk drive powered the 9332 Direct Access Storage Device.
3. The IBM 0664 or IBM 0681 HDDs were employed in various configurations of the 9333 High Performance Disk Drive Subsystem.
4. The 9334 Disk Expansion Unit allowed connection of one to four SCSI hard disk drives to RS/6000 systems.
5. The IBM-developed "Kestrel" HDD, with an 850 MB capacity utilizing three 14-inch platters and dual rotary actuators accessing multiple surfaces, was featured in the rack-mountable 9335 Direct Access Storage Subsystem. Announced in October 1986 alongside the IBM 9370 Information System, it has no known OEM adaptations.
6. The IBM 0681 HDD (Redwing) was used in the 9336 Disk Unit.
7. The IBM 0662 (Spitfire) or IBM 0663 (Corsair) hard drives were integrated into the 9337 Disk Array Subsystem.

IBM 2310

Introduced initially with the IBM 1800 in 1964 and later with the IBM 1130 in late 1965, the IBM 2310 Removable Cartridge Drive stored data on an IBM 2315 cartridge containing a single oxide-coated aluminum platter housed within a plastic casing featuring openings for both read/write heads and arm access. It held up to 512,000 words of sixteen bits each, equivalent to approximately one million bytes.

IBM 5444

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

• Model 1: one fixed and one removable disk with each surface containing one hundred tracks; cartridge capacity of approximately 1.23 MB
• Model 2: one fixed and one removable disk featuring two hundred tracks per surface; cartridge capacity around 2.46 MB
• Model 3: only one removable disk with two hundred tracks per surface; cartridge capacity about 2.46 MB

IBM 62GV

First shipped in May of 1974 from IBM’s Hursley laboratory in the United Kingdom under the project name Gulliver, the IBM 62GV initially offered a five-megabyte storage capacity. Subsequent versions included models with ten megabytes (62TM) and fourteen megabytes. This unit employed a Swinging Arm actuator paired with a single fourteen-inch platter—a design innovation from Hursley that became IBM’s most licensed electromechanical invention. This actuator mechanism along with its filtration system saw widespread adoption throughout hard drives during the eighties and continues as an industry standard nearly four decades later. Approximately one hundred seventy-seven thousand units were produced, marking it as the first hard disk drive to surpass one hundred thousand units shipped.

OEM and Small Systems Hard Drives

This segment details IBM-produced hard disk drives marketed as OEM components and for IBM's smaller system lines such as the System/3, System/32, /34, /36, and AS/400. Drives are cataloged by their OEM model identifiers and organized by the date of their initial customer delivery.

IBM 0680

Introduced in 1979, the 0680 served as the 3310 direct access storage on many IBM small systems and entry-level System/370 models. 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 incorporated six 8-inch (210 mm) platters, delivering a starting capacity of up to 65MB along with an enhanced rotary actuator mechanism.

A higher-capacity version, designated 62SW, was launched in June 1984 but experienced limited sales due to its comparable cost per megabyte to the existing 62GV model.

IBM 0676

The 0676 made its debut in November 1982 as part of the 5247 Disk Storage Unit tailored for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the designation 21ED, this 8-inch HDD initially offered storage options of either 15 or 30 MB utilizing two or four platters. In 1983, it was integrated into the S/36’s 5360 System Unit. By 1984, its capacity doubled through increased track density per platter surface and it was subsequently employed in the S/36’s 5362 System Unit.

IBM 0665

Launched in October 1985 within the PC AT (5170) chassis, the 0665 was developed at IBM Rochester under the codename "Pixie." This 5-inch hard drive came with storage capacities of 20, 30, and 44 MB.

IBM 0667

Beginning shipment in August 1986, the 0667 was created at IBM Rochester with the project name "Grant." It was a full-height ESDI interface 5-inch HDD containing up to four platters measuring 130 mm each and offering a maximum capacity of 70 MB. This drive was utilized in select PC RT models (6150, 6151, 6152) as well as System/36 Model System Units (5363, 5364).

IBM 0669

Developed at IBM Rochester under the codename "Grant-Prime," the 0669 arrived in 1987 as a full-height 5-inch hard disk drive capable of storing up to 115 MB across four platters of 130 mm diameter. It was internally deployed within System/36’s 5363 and Series/1’s 4956 System Units.

IBM 0671

Also released in 1987 from IBM Rochester with the codename "Lee," the 0671 was a full-height ESDI HDD featuring eight platters of 130 mm each and providing storage up to 316 MB. It represented IBM’s inaugural implementation of a thin metal film recording surface. In 1988, this drive was incorporated into the IBM AS/400 model 9404 System Unit, supporting configurations with two or three drives.

IBM 0661

The 0661, first introduced in 1989 as model number 371, was a SCSI hard disk developed under the codename "Lightning" at both IBM Rochester and Hursley, UK. It housed up to eight platters measuring 95 mm with fourteen read/write heads. A subsequent "Turbo" version offering a capacity of 400 MB appeared in 1990. This drive became a standard component across multiple IBM platforms including AS/400 System Unit Model CXX.

IBM 0681

Debuting in April 1990, the 0681 originated from IBM Hursley’s UK lab under the project title Redwing and marked that facility’s final HDD release. This full-height, five-inch drive featured twelve platters of 130 mm size and delivered capacities reaching up to 857 MB. It was notable as the first hard drive to implement PRML data decoding technology and powered the launch of the 9333 Disk Drive Subsystem in early 1992. An enhanced version with a capacity of approximately 1.07 GB was added to this subsystem lineup by May of that year.

IBM 0663

The 0663, unveiled in late 1991 and internally known as "Corsair," was a compact 3-inch hard disk drive featuring a half-height (1.6-inch) form factor. It provided storage capacity up to 1 GB across eight 95 mm platters. This model was offered on select PS/2 and RS/6000 systems and marked IBM’s initial OEM HDD to incorporate Magnetoresistive (MR) read heads.

IBM 0664

Introduced in November 1992 under the development codename "Allicat" at IBM Rochester, Minnesota, the 0664 was a full-height 5-inch hard drive (measuring 3.25 inches tall) that combined two 3-inch drives into a single unit. It supported a maximum capacity of 2.013 GB using up to eight 95 mm platters.

IBM 0662

Released in June 1993 and developed as "Spitfire" at IBM Rochester, the 0662 was a full-height (1 inch high) 3-inch HDD offering 1.05 GB of storage spread over three disks or five recording surfaces. This drive served as the internal hard disk for the IBM 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered the floppy disk drive technology, debuting the 8-inch FDD in 1971 initially as a read-only program loading device, followed by its first read/write variant in 1973 with the introduction of the 3740 Data Entry System. While IBM established early standards for the 8-inch floppy drives, it did not market them separately, allowing other companies to advance the industry independently.

As a significant original equipment manufacturer (OEM) consumer of 5-inch floppy drives, IBM’s preference for two-sided models with a track density of 48 tracks per inch helped cement this configuration as an industry benchmark. Although IBM prepared to produce these and smaller-sized drives internally, these plans were discontinued by 1985. An attempt in 1983 to OEM its proprietary 4-inch DemiDiskette did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM Storage Systems revealed three new families of hard disk drives: the Travelstar line of compact 2-inch drives designed for notebook computers; the Deskstar series featuring 3-inch drives aimed at desktop PCs; and the Ultrastar range of high-performance 3-inch drives intended for enterprise systems.

IBM's first HDD versus its last HDDs

The following table contrasts IBM’s inaugural hard disk drive, the RAMAC 350, with the final trio of models from its "Star" series of OEM HDDs. It illustrates significant advancements such as drastic reductions in physical size and cost, alongside substantial enhancements in storage capacity and operational efficiency.

Parameter (units)	RAMAC 350	Ultrastar 146Z10	Deskstar 180GXP	Travelstar 80GN	Maximum improvement over 46 years
Announcement date	Sep 1956	Jul 2002	Oct 2002	Nov 2002
Storage capacity (GB)	0.004	146	180	80	48,000
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
Volume (liters)	1,939	0.4	0.4	0.1
Weight (pounds)	2,140	1.7	1.4	0.2	1,244
Weight (kilograms)	971	0.8	0.64	0.095
Power consumption (watts)	~2374 (8100 BTUs/hour), up to 5500 VA depending on model	16	10.3	1.85	1,283
Power efficiency (megabytes/watt)	0.0016	9,125	17,476	43,243	27,375,856
Retail price (Template:US$)	\$34,500 (\$234,000 adjusted to 2002 dollars)	\$1,200	\$360	\$420
Cost per megabyte (Template:US$)	\$9,200 (\$68,000 adjusted to 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
Volumetric density (gigabytes/in³)	0.00000003	6	8	20
Volumetric density (megabytes/cm³)	0.000002	388	478	1,203
Average latency (ms)	25	3	4	7
Average seek time (ms)	600	5.9	10.2	12
Data transfer rate (MB/s)	0.001	103	29.4	43.75

DASD Devices Beyond HDDs and FDDs

In certain IBM operating systems, both hard disk drives (HDDs) and floppy disk drives (FDDs) fall under the classification of DASDs (direct access storage devices). This category also encompasses several other storage technologies, such as:

IBM 7320 Drum

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

IBM 2301 Drum

Launched in the late 1960s, the IBM 2301 is another example of a magnetic drum storage device.

IBM 2303 Drum

The IBM 2303, released in 1964, is also a magnetic drum-based storage apparatus.

IBM 2321 Data Cell

Presented in 1964, the IBM 2321 Data Cell utilizes short magnetic tape strips for data storage. It accommodates ten detachable cells, each with a capacity of 40 MB, resulting in an aggregate of 400 MB.

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System functions as a tape cartridge library. It stages data onto IBM 3330 or 3350 disk drives, which are then presented to the system as virtual disk drives.

See also

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

External links

• IBM Archive: Basic information on storage
• IBM Archive: Collection 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 history of disk drives
• IBM 1311 Disk Storage Drive
• IBM 2314 Direct Access Storage