IBM 5444

IBM Magnetic Disk Storage Division

Industry	Computer storage devices
Founded	1956
Defunct	2003
Fate	Divested to Hitachi
Headquarters	San Jose , United States
Products	Hard disk drives, floppy disk drives

IBM was a pioneer in producing magnetic disk storage devices from 1956 until 2003, when it divested its hard disk drive division to Hitachi. IBM's workforce was instrumental in inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing numerous advancements to these technologies. The core mechanical structure of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and key performance indicators have stayed relatively stable since the 1950s. Over time, this product category has experienced dramatic decreases in cost and physical dimensions, alongside substantial enhancements in capacity and speed.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not become a leading producer of the smaller 5.25- or 3.5-inch floppy formats. Although IBM sold magnetic disk drives directly, it only started offering them under original equipment manufacturer (OEM) agreements beginning in 1981. By 1996, IBM had discontinued producing hard disk drives specifically designed for its own systems, supplying all HDDs exclusively as OEM components.

IBM has used several terms to describe its magnetic disk storage devices, including direct-access storage device (DASD), disk file, and diskette file. For clarity and consistency, this article employs the industry-standard terminology: hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit, recognized as the first-ever disk drive, was introduced by IBM on September 14, 1956, as part of the IBM 305 RAMAC system. A comparable model, the IBM 355, was launched for the IBM 650 RAMAC system. The initial prototype was delivered to Zellerbach Paper Company in June 1956, with production units commencing shipment in November 1957 to United Airlines located in Denver.

Engineered for real-time business accounting applications, the IBM 350 could hold 5 million characters encoded in 6 bits each (approximately 3.75 MB). It consisted of fifty-two disks providing a total of 100 recording surfaces and tracks, rotating at a speed of 1200 rpm. The data transfer rate reached 8,800 characters per second. Its access mechanism allowed read/write heads to move both vertically and radially across the disks’ surfaces. Several enhanced versions were developed during the late 1950s. The RAMAC 305 system equipped with the IBM 350 was leased at a rate of $3,200 monthly. This model was retired from production in 1969.

The patent originating from the RAMAC project is regarded as the foundational intellectual property for disk drives. Initially rejected by IBM’s board over concerns about its effect on punch card sales, development persisted at IBM’s San Jose facility until gaining approval from IBM’s president.

Physically, the IBM 350’s cabinet measured approximately long by high by wide and weighed around one ton, necessitating forklifts and large cargo aircraft for transportation. According to Currie Munce of Hitachi Global Storage Technologies— which acquired IBM’s storage division—capacity could have been expanded beyond five million characters; however, IBM’s marketing team was reluctant to market higher-capacity units. Despite this caution, double-capacity models were announced and shipped starting in 1959.

In recognition of its historical significance, the RAMAC 350 Disk File was designated an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, a restoration initiative led by Al Hoagland collaborated with Santa Clara University to refurbish an IBM 350 RAMAC unit. By 2005, this effort transitioned to the Computer History Museum in Mountain View, California, where it is publicly displayed within the Revolution exhibition.

IBM 353

The IBM 353, designed for use with the IBM 7030, bore similarity to the IBM 1301 but offered an enhanced transfer speed. It provided storage for 2,097,152 (2²¹) 64-bit words, equivalent to 134,217,728 bits, and achieved a data transfer rate of 125,000 words per second. A prototype delivered in late 1960 marked the first disk drive to implement a dedicated head per surface that floated on compressed air, analogous to the IBM 350 (RAMAC). Production versions incorporated self-levitating heads similar to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an expansion for the widely used IBM 650 system. It employed the IBM 350 mechanism but featured up to three access arms instead of one, increasing its capability. The device stored 6 million decimal digits along with 600,000 sign indicators. Data was transferred in full tracks between the magnetic core memory of the 653, an optional IBM 650 unit containing sixty signed 10-digit words—adequate for a single disk track or tape record—while also supporting two additional unrelated functions.

IBM 1405

Announced in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two configurations: Model 1 held 10 million alphanumeric characters (60 million bits) across 25 disks; Model 2 doubled this capacity to 20 million characters (120 million bits) using 50 disks. The disks rotated vertically at a speed of 1200 revolutions per minute.

Each disk surface contained 200 tracks segmented into five sectors; sectors numbered 0 through 4 were on top surfaces, while sectors 5 through 9 were on bottom surfaces. Each sector accommodated between 178 and 200 characters. One to three forked access arms—each equipped with two read/write heads covering both top and bottom surfaces—moved vertically across disks (0–49) and horizontally across tracks (0–199). Every track provided ten sectors. The time required for reading or writing a sector was approximately 10 milliseconds.

Access times varied from as low as 100 milliseconds up to a maximum of around 700 milliseconds for Model 1 and up to roughly 800 milliseconds for Model 2. Model 2 contained a total of 100,000 sectors that could hold either 200 characters in move mode or alternatively, in load mode, stored 178 characters plus a word mark bit. Model 1 featured half as many sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered for use with the IBM 7070. Although IBM introduced a Model 2 version in 1959, the subsequent release of the IBM 1301 on June 5, 1961, attracted more interest from customers using the IBM 7070 and IBM 7074 systems. The technology within the IBM 7300 shared similarities with that employed in the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was designed for mainframe computers in the 7000 series as well as the IBM 1410. Each module stored approximately 28 million characters (168 million bits), or about 25 million characters when used with the IBM 1410. Modules consisted of twenty-five large disks featuring forty user-accessible recording surfaces and two hundred fifty tracks per surface. The Model 1 included one module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred rpm and transferred data at a rate of ninety thousand characters per second.

A notable advancement was the implementation of a dedicated arm and read/write head for every recording surface, which moved collectively like a comb. This arrangement eliminated delays caused by repositioning heads across multiple disks and reduced maximum access time to approximately one hundred eighty milliseconds. Additionally, the IBM 1301 pioneered aerodynamically shaped heads that floated on a thin layer of air above disk surfaces to improve performance.

The unit interfaced through the IBM 7631 File Control device, which allowed connection either individually or shared between an IBM 1410 and an IBM 7000 series computer.

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

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the 1301, reaching 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and data transfer speeds of 180,000 characters per second, more than doubling the throughput of its predecessor. Each unit incorporated two separate access mechanisms dedicated to the inner and outer cylinders. The Model 2 variant enhanced storage by stacking two modules, effectively doubling capacity. 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. An additional IBM 7631 controller was available for $1,185 monthly or $56,000 to buy. The IBM 1302 was discontinued in February 1965.

IBM 1311

The IBM 1311 Disk Storage Drive, introduced on October 11, 1962, was designed for medium-sized business and scientific computing environments. Approximately the size of a top-loading washing machine, it housed 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 4 inches in height and weighs around 10 pounds. It contains six disks measuring 14 inches in diameter, providing ten recording surfaces. A hydraulic actuator moves ten read/write heads collectively across the tracks while the disks rotate at 1500 revolutions per minute. Each surface features 100 tracks divided into 20 sectors per track; each sector accommodates 100 characters. The disk pack is encased within a clear plastic shell equipped with a locking handle for easy insertion and removal.

The seven IBM 1311 models include master drives—equipped with controllers—and slave drives lacking them. Master drives manage multiple slave units and differ based on system compatibility such as with IBM 1440, IBM 1620, or IBM 1401 systems. Variations among models exist in terms of supported features and withdrawal timelines spanning from the early to mid-1970s.

Available optional enhancements to improve performance and capacity include:

• Direct Seek: Removes the need to return to zero position before seeking.
• Scan Disk: Facilitates rapid automatic searches for specific identifiers or conditions.
• Seek Overlap: Permits simultaneous seeks alongside read/write operations across multiple drives.
• Track Record: Boosts capacity by recording one large record per track instead of multiple sectors; supports up to approximately 18.7 million bits depending on encoding.

Master drive models (1,3,4,5) incorporate additional power supplies and control circuitry, resulting in a wider physical profile compared to Model 2 slave drives.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the IBM 1302, utilizing track formatting tailored specifically for S/360 DASD architecture rather than that used in the earlier 7000 series. It features a fixed module containing 25 platters with a total of 46 recording surfaces. The Model 3 includes one such module; Model 4 comprises two modules. Each module is equipped with two independent access mechanisms—one dedicated to the innermost set of 250 cylinders and another serving the outermost set of 250—referred to as access groups. Each mechanism provides one read/write head per track. Rotational latency averages at 17 milliseconds with a maximum delay reaching up to 34 milliseconds. Maximum seek time for each access group is specified at 180 milliseconds. Each track holds approximately 4,985 bytes; after formatting and incorporating alternate tracks, total capacity amounts to about 112 megabytes. The IBM 2302 connects to mainframe systems through an IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970, the IBM 2305 fixed-head storage unit, along with its companion IBM 2835 Storage Control, initially connected to the 360/85 and 360/195 systems through the IBM 2880 Block Multiplexor Channel. Its popularity grew with the advent of System/370's Virtual Storage, where it was frequently employed as a paging device on various models such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). This storage solution was particularly effective for handling small but heavily accessed data sets like catalogs and job queues.

The smaller capacity variant, the 2305-1, provided 5.4 MB of storage and delivered a data transfer rate of 3.0 MB/s via a two-byte channel interface, boasting an average access time of 2.5 milliseconds. In contrast, the larger 2305-2 model offered double the capacity at 11.2 MB but with a reduced throughput of 1.5 MB/s and an average access time of approximately 5 milliseconds.

Engineered for rapid and continuous access to relatively small volumes of data, the IBM 2305’s combination of speed and capacity made it ideal for system-resident tasks, work files, job queues, index files, and other frequently retrieved data sets. Its swift response times rendered it suitable for paging operations in environments processing more than 1.5 transactions per second under heavy load.

IBM 2311

The IBM 2311 Disk Storage Drive debuted in 1964 alongside the 2841 Control Unit, supporting the IBM System/360 series as well as compatibility with the IBM 1130, IBM 1800, System/360 Model 20, and Model 25. It utilized removable storage media known as the IBM 1316 Disk Pack, originally developed for the IBM 1311.

For most IBM mainframes, the Model 1 version of the 2311 connected via the 2841 Control Unit; however, on the System/360 Model 25, it interfaced through a Disk Attachment Control that assumed control unit responsibilities. The disk packs employed IBM’s count key data format featuring variable-length records.

Models designated as 11 and 12 were tailored for the System/360 Model 20’s integrated control unit and utilized fixed-sector formatting. Due to these differing formats, disk packs from Model 1 were not compatible with those used by Models 11 or 12.

While mechanically resembling the IBM 1311, the IBM 2311 incorporated enhanced recording technology. Each removable six-platter IBM 1316 disk pack could store up to 7.25 megabytes. The drive contained ten read/write heads mounted on a hydraulically actuated arm that was mechanically detented for precise track alignment. Each disk surface featured 200 tracks plus three additional spares reserved for defective areas. The average seek time measured approximately 85 milliseconds with a data transfer speed of around 156 kB/s.

Uniform electrical interfaces across System/360 models allowed third-party vendors to manufacture plug compatible disk drives, fostering competition within the IBM-compatible storage market.

IBM 2314 Disk Access Storage Facility Model 1

Released on April 22, 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms. Equipped with a Two Channel Switch capability, it could simultaneously connect to two separate channels. Building upon the foundation of the IBM 2311 design, this model increased both data density and total capacity by employing the taller IBM 2316 disk pack containing eleven disks—providing twenty recording surfaces—and storing roughly twenty-nine million characters.

The drive featured twenty read/write heads mounted on a hydraulically actuated arm with mechanical detents for accurate track positioning. Initial access times were comparable to those of the IBM 2311 but improved in subsequent versions due to enhancements in actuator technology. Data transfer rates doubled relative to its predecessor, reaching approximately 310 kB/s.

The original Model 1 configuration was sold as a package consisting of nine drives bundled together along with separate control units and modules. Drives were installed in drawer-like mounts allowing convenient disk pack handling; this design earned them the nickname "Pizza Ovens." Although nine drives were included in each system, only eight could be accessed simultaneously—the ninth served either as an online spare or could be taken offline for maintenance. Users could configure drive system addresses flexibly by swapping plugs on connectors.

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

Further variations of the IBM 2314 were introduced later:

IBM 2314 Direct Access Storage Facility - Model Variants

In 1969, IBM segmented the 2314 storage system into distinct models, each supporting up to nine drives (eight active simultaneously) connected to a 2314 Storage Control:

• 2312 Disk Storage, consisting of a single-drive unit.
• 2313 Disk Storage, comprising a four-drive configuration.
• 2318 Disk Storage, featuring a two-drive setup.

IBM 2319

To compete against plug-compatible manufacturers offering alternatives to the 2314 storage, IBM launched the cost-effective three-drive 2319 series in 1970 by removing one drive from the four-drive 2313 and renaming it as the 2319 A1. This approach enabled reduced rental fees for new clients while preserving higher charges for existing users. The 2319-A1 model exclusively connects to System/370 Models 135 and 145 integrated controllers, whereas standard 2314 DASD units such as the 2312 or 2318 remain compatible for attachment. The 2319 B series supports configurations of three, six, or nine drives linked to a newly introduced 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 storage capacity of 64.5 MB and utilized fixed-block architecture (FBA), compatible with DOS/VSE and VM operating environments running on System/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, internally known as Merlin, debuted in June 1970 targeting IBM System/370 and System/360 Model 195 machines. Initial offerings included a two-drive Model 1 and a single-drive Model 2. Removable disk packs held up to 100 MB each, featuring a 30 ms average access time and a data transfer rate of approximately 806 kB/s. A significant advancement was the incorporation of built-in error correction using fire codes, which improved reliability and lowered costs by allowing tolerance for disk surface flaws.

Originally, one storage control unit (the 3830 Model 1) connected directly to up to four drives in a chain (maximum eight drives). By August 1972, IBM introduced the separate 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, transforming the controller into a director capable of managing multiple drive chains. The lead unit in each chain—the 3333—combined controller functions with two drives and could manage up to three additional attached 3330 drives, supporting eight drives per chain. The enhanced 3830 Model 2 could link two such chains (up to sixteen drives), with optional string switches permitting connections to two storage controllers simultaneously.

In 1973, IBM announced double-density (-11) variants: the 3333–11, 3330-11, and 3336–11 disk packs, which doubled storage capacity to 200 MB. Mixing single-density and double-density drives within the same chain was unsupported; although field upgrades were feasible, they required substantial conversion work and data migration efforts.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

While the IBM 3340 and IBM 3344 share many characteristics, only the IBM 3340 can function as the head of a drive chain; no A model exists for the IBM 3344, which must connect through an IBM 3340 A model acting as head of string.

IBM 3340

The IBM 3340 Direct Access Storage Facility, codenamed Winchester, was introduced in March 1973 for IBM System/370 systems. It was offered in three configurations: the A2 model (two drives with controller), B2 (two drives), and B1 (single drive). B models attach to an A2 controller unit, supporting up to eight drives per controller assembly.

This system employed removable data modules that housed both head and arm assemblies; during load/unload operations, the module's access door opened without requiring removal of covers as with earlier disk packs. It delivered a typical access time of approximately 25 ms and supported data transfer rates near 885 kB/s. Three types of IBM 3348 Data Modules were available: one with a capacity of around 35 MB and two versions with approximately 70 MB each—one of which included an additional fixed-head area providing faster access over roughly 500 KB. The design incorporated error correction features and was phased out in 1984.

Developed at IBM's San Jose facility under Ken Haughton’s leadership, this product initially focused on two removable modules each holding about 30 MB—hence its Winchester codename referencing the .30-30 rifle cartridge. Although capacities increased later on, the nickname persisted.

A notable technological breakthrough was its economical head design that enabled heads to land on and lift off from spinning disk surfaces without unloading mechanisms. This "Winchester technology" simplified head and arm assembly complexity while reducing manufacturing costs, establishing an industry standard for hard disk drive production.

The term Winchester or its abbreviation Winnie remained widely used when referring to hard drives into the early 1990s but has since largely fallen out of use worldwide.

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 offering storage equivalent to a 3348–70. This model is exclusively available in dual drive configurations, with no option for an A (head of string) variant. The 3344-B2F version incorporates fixed heads over certain cylinders on both drives. Both the 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F unit to serve as the head of string. Internally, the IBM 3344 mirrors the IBM 3350; the only differences reside in the microcode of the control unit.

IBM 3350

The IBM 3350 Direct Access Storage Facility, codenamed Madrid, was introduced in 1975 for use with IBM System/370 systems. It featured sealed, non-removable head-disk assemblies (HDAs) that combined the head and arm assembly into a single unit, establishing a design precedent for subsequent IBM DASD products. Its disk geometry comprised 555 cylinders, 30 heads, and tracks containing 19,069 bytes each, resulting in a storage capacity near 317 MB per HDA.

Models A2, A2F, B2, B2F, C2, and C2F each housed two HDAs. The A2 and A2F models included an extra electronic board that facilitated connection to the control unit and often functioned as the head-of-string controller. Storage units were arranged in strings beginning with an A2 or A2F device, followed by up to three B2 units or combinations involving C2 units. The A2 model typically incorporated a string switch allowing dual connections to storage control units, enabling concurrent I/O operations directed at different HDAs. Compatible storage control units encompassed the 3830 Model 2 and Integrated Storage Control (ISC) across various CPU models; later controllers such as the 3880 maintained backward compatibility. The C2 model contained a secondary controller that could act as a backup if the primary controller in the A unit failed, though it offered limited connectivity options.

Variants labeled "x2F" included fixed head zones over the initial five cylinders on both HDAs, effectively eliminating seek time within this area. This feature was designed to optimize access to frequently used regions such as HASP or JES checkpoint data by minimizing head movement on spool devices. Additionally, it supported TSO swap data and system swap data for OS/360 successors, improving context switching efficiency among TSO users or batch processes.

The IBM 3350 series was discontinued in September 1994.

IBM 3370

Released in January 1979, the IBM 3370 Direct Access Storage Device was aimed at IBM midrange systems including the 4331, 4341, and System/38. It comprised seven fixed 14-inch disks with a total capacity of 571 MB per unit. Notably pioneering thin-film head technology—developed at IBM’s Thomas J. Watson Research Center during the late 1960s—the 3370 employed fixed-block architecture and supported DOS/VSE and VM operating systems on S/370 platforms.

IBM 3375

The IBM 3375 served as a complement to the 3370 by implementing count key data architecture essential for OS/360 and its subsequent operating systems.

IBM 3380

Debuting on June 11, 1980, the IBM 3380 featured a capacity of 2.52 GB per unit using film head technology. Each unit contained two hard disk assemblies equipped with two independent actuators accessing approximately 630 MB each. It delivered a data transfer rate of 3 MB per second and averaged an access time of about 16 milliseconds. Initial prices ranged between $81,000 and $142,200. Due to tribology challenges between heads and media surfaces, shipments commenced in October 1981.

Configurations generally consisted of one A unit paired with up to three B units; each IBM 3380 housed four devices allowing strings up to sixteen devices connected via a 3880 storage control unit capable of handling two simultaneous I/O operations targeting distinct HDAs.

In February 1985, IBM released double-density Extended Capability Models (3380 E) offering doubled capacity at 5.04 GB per unit (two actuators storing about 1.26 GB each). The triple-capacity Model K arrived in August 1987 with a total of approximately 7.562 GB per unit (two actuators at roughly 1.89 GB). This model supported an optional four-path mode enabling up to thirty-two devices per string when connected to a 3990 storage control unit—permitting four concurrent I/O operations.

The IBM 3380 family consisted of twelve models: six A-units acting as string heads with controller logic interfacing with IBM storage control units; five B-units connecting to either A- or C-units; and one C-unit providing direct channel connectivity.

Production continued until May 1996, marking an impressive fifteen-year lifespan for the IBM 3380 disk drive series.

IBM 3390

Launched in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities up to 22 gigabytes distributed across multiple disk drives. Depending on the selected configuration and storage size, system prices varied between $90,000 and $795,000.

A typical 3390 configuration consists of a primary A unit housing four or eight drives, which may be accompanied by one or two B units each containing up to twelve drives. This setup functions in a four-path mode connected to a 3990 storage control unit, which is capable of supporting an additional 3390 string, allowing for a total of up to 64 devices.

Each Hard Disk Assembly (HDA) includes two actuator-head mechanisms and several platters. Model 1 HDAs offered a formatted capacity of 1.89 GB, Model 2 doubled this to 3.78 GB, while Model 3—introduced in 1991—increased capacity by 50% to reach 5.67 GB. The Model 9, released in 1993, further expanded storage to 11.3 GB per HDA, tripling the original capacity.

Differing from earlier DASD designs that utilized large AC motors with belt drives, the 3390 HDAs incorporated DC motors that directly drive the platters within the enclosure. Notably, the Model 9 represented IBM's final implementation of the Single Large Expensive Disk (SLED) technology.

IBM 9345

Released as an RPQ option in November 1990 for IBM's SCSE (SuperComputing Systems Extensions), the IBM 9345 hard disk drive was developed at IBM’s San Jose laboratory under the codename Sawmill. It featured a full-height 5¼-inch form factor with up to eight disks measuring 130 mm each, delivering a maximum capacity of 1.5 GB. This model was distinguished as the first HDD to incorporate magnetoresistive (MR) read/write heads.

IBM 9340

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

From an operational perspective, the 9340/9345 paralleled the functionality of the 3990/3390 systems but differed by lacking non-volatile RAM cache present in the 3990 and by supporting shorter maximum block lengths than the 3390. The Input/Output Supervisor (IOS) component of the operating system identified device characteristics through the IECCINIT initialization routine, which accounted for both the absence of non-volatile cache in the 9340 and reduced track size in the 9345 when assigning device types.

9330 family of disk drives

1. The 9331 Diskette Unit models 1 and 11 were equipped with one 8-inch floppy disk drive; models 2 and 12 included one 5-inch floppy disk drive.
2. The 9332 Direct Access Storage Device utilized IBM’s model 0667 hard disk drive.
3. The 9333 High Performance Disk Drive Subsystem employed either IBM’s model 0664 or model 0681 hard drives 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 featured an IBM-designed "Kestrel" hard drive with a capacity of approximately 850 MB, comprising three large (14-inch) disks and dual rotary actuators enabling access to multiple surfaces. Announced alongside the IBM 9370 Information System in October 1986, it was designed for rack mounting and had no known OEM variants.
6. The 9336 Disk Unit incorporated IBM’s model 0681 hard disk drive, also known as Redwing.
7. The 9337 Disk Array Subsystem integrated either IBM’s model 0662 (Spitfire) or model 0663 (Corsair) hard disk drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive debuted in 1964 alongside the IBM 1800 system and was subsequently introduced with the IBM 1130 in 1965, with initial shipments likely commencing late that year. This device stored approximately half a million sixteen-bit words (equivalent to about one million bytes) on an IBM 2315 cartridge. The cartridge itself contained a single aluminum disk coated with oxide material enclosed within a plastic casing featuring openings for both the read/write arm and dual heads.

IBM 5444

Introduced in September 1969 as a component of System/3, the IBM 5444 was engineered at IBM’s Hursley facility in England, operating under the project name Dolphin. It utilized the 5440 disk cartridge, which contained a single 14-inch platter. The product line included three variants:

• Model 1: featured one fixed and one removable disk, each supporting 100 tracks per surface, resulting in a cartridge storage capacity of 1.23 MB
• Model 2: included one fixed and one removable disk, each with 200 tracks per surface, offering 2.46 MB capacity
• Model 3: consisted solely of one removable disk with 200 tracks per surface, providing 2.46 MB capacity

IBM 62GV

Released in May 1974, the IBM 62GV was developed at IBM’s Hursley laboratory under the codename Gulliver and initially delivered a storage capacity of 5 MB. Subsequent versions expanded capacities to include the 62TM at 10 MB and a later model with 14 MB. This drive incorporated a Swinging Arm actuator paired with a single 14-inch platter. The actuator mechanism, created at Hursley, became IBM’s most widely licensed electro-mechanical innovation and was broadly adopted across the HDD industry throughout the 1980s and beyond. Approximately 177,000 units were produced during its lifecycle, making it the first hard drive to surpass shipments of 100,000 units.

OEM and Small Systems HDDs

This section details IBM-produced hard drives marketed as OEM products or designed for IBM’s smaller systems such as System/3, System/32, /34, /36, and AS/400. Drives are identified by their OEM model numbers and arranged by their initial shipment dates.

IBM 0680

First delivered in 1979 for use with most IBM small systems and entry-level System/370 models as the 3310 direct access storage device, the drive was officially announced under the OEM designation 0680 in September 1981. Developed at IBM’s Hursley site in the UK under the codename Piccolo, it offered an initial maximum capacity of up to 65 MB via six 8-inch (210 mm) platters combined with an enhanced rotary actuator.

A higher-capacity version known as the 62SW was introduced in June 1984 but experienced limited market penetration due to its cost per megabyte being comparable to that of the earlier 62GV model.

IBM 0676

The 0676 appeared in November 1982 as the 5247 Disk Storage Unit tailored for the IBM System/23 Datamaster. Originating from IBM Rochester, Minnesota under the project name 21ED, this was an 8-inch hard drive initially available with either two or four platters delivering capacities of 15 or 30 MB. In 1983, it was integrated into the S/36 via the 5360 System Unit. By 1984, its capacity was doubled through increased track density per platter surface and it was incorporated into the S/36's upgraded 5362 System Unit.

IBM 0665

Launched in October 1985 within the PC AT (5170) system chassis, the 0665 was developed at IBM Rochester under the codename "Pixie." This model featured a compact form factor using a 5¼-inch hard disk with storage options of 20, 30, or 44 MB.

IBM 0667

The 0667, introduced in August 1986 and developed at IBM Rochester under the codename "Grant," was a full-height ESDI hard drive sized at 5¼ inches. It supported up to four platters measuring 130 mm and offered a maximum capacity of 70 MB. This drive was utilized in selected PC RT models (6150, 6151, and 6152) as well as System/36 Model System Units (5363 and 5364).

IBM 0669

Released in 1987 and also developed at IBM Rochester under the codename "Grant-Prime," the 0669 was a full-height hard drive measuring approximately five inches. It supported up to four platters sized at 130 mm each and delivered storage capacities reaching up to115 MB. This unit served as the internal hard disk for System/36 model units (5363) and Series/1 (4956) system units.

IBM 0671

Introduced in 1987, the 0671 was developed under the codename "Lee" at IBM Rochester. It was a full-height 5-inch hard disk drive featuring ESDI technology, capable of storing up to 316 MB across as many as eight 130 mm platters. This model marked IBM's initial implementation of thin metal film recording surfaces. In 1988, it was incorporated into the IBM AS/400 9404 System Unit, supporting configurations with two or three drives.

IBM 0661

Released in 1989 as model 371, the 0661—originally called "Lightning" and developed at IBM Rochester and Hursley, UK—was a SCSI HDD offering 320 MB capacity with up to eight 95 mm platters (14 heads). A year later, a "Turbo" variant with 400 MB capacity became available. By 1990, this drive was adopted as standard equipment in multiple IBM systems, including the AS/400 System Unit Model CXX.

IBM 0681

The 0681 debuted in April 1990 and was developed at IBM Hursley under the codename Redwing—the final hard drive produced by that facility. It delivered up to 857 MB storage as a full-height 5-inch HDD utilizing up to twelve 130 mm platters and was IBM’s first to employ PRML data decoding technology. This drive powered the 9333 Disk Drive Subsystem introduced in early 1992, with a higher-capacity 1.07 GB version added by May of that year.

IBM 0663

Known as "Corsair," the 0663 shipped in late 1991 as a compact half-height (1.6-inch) 3-inch HDD offering up to 1 GB capacity on eight 95 mm platters. It was included in select PS/2 and RS/6000 systems and represented IBM’s first OEM hard disk utilizing Magnetoresistance (MR) heads.

IBM 0664

The 0664, launched in November 1992 and developed under the codename "Allicat" at IBM Rochester, was a full-height (3.25-inch) 5-inch HDD that combined two 3-inch drives, providing up to 2.013 GB capacity distributed over eight 95 mm platters.

IBM 0662

Introduced in June 1993 with the codename "Spitfire" at IBM Rochester, the 0662 was a full-height (1-inch) 3-inch HDD delivering 1.05 GB storage on three platters or five surfaces. It served as the internal drive for the IBM 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was a pioneer in floppy disk drive technology, launching its first read-only 8-inch drive in 1971 followed by its initial read/write model in 1973 with the release of the 3740 Data Entry System. Although IBM established early standards for the 8-inch floppy drives, it did not market these drives separately, allowing industry-wide standards to develop independently.

IBM historically stood as the largest original equipment manufacturer (OEM) buyer of 5-inch floppy disk drives and advocated for the two-sided, 48 tracks-per-inch format as an industry benchmark. Despite preparing to manufacture this and smaller formats internally, IBM discontinued these efforts by 1985. Its attempt in 1983 to OEM the smaller 4-inch DemiDiskette format did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM Storage Systems unveiled three families of hard disk drives: Travelstar, featuring compact 2-inch drives designed for notebook computers; Deskstar, consisting of larger 3-inch drives aimed at desktop PCs; and Ultrastar, also using a 3-inch form factor but optimized for high-performance enterprise systems.

IBM's first HDD versus its last HDDs

The table below contrasts IBM's inaugural hard disk drive—the RAMAC 350—with its final three models from the "Star" series, underscoring remarkable advancements such as drastic reductions in physical size and cost alongside substantial gains in storage capacity and performance metrics.

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 (gigabytes)	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 (millimeters)	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)	Approx.2374	16	10.3	1.85	1,283×
Power efficiency (megabytes per 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 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 rotational 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

DASD Devices Distinct from HDDs and FDDs

Within certain IBM operating systems, hard disk drives (HDDs) and floppy disk drives (FDDs) are categorized under the broader term DASDs (direct access storage devices). Additional technologies classified as DASDs encompass:

IBM 7320 Drum

Introduced in 1962, the IBM 7320 represents a magnetic drum storage apparatus.

IBM 2301 Drum

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

IBM 2303 Drum

The IBM 2303, brought to market in 1964, also utilizes magnetic drum technology for data storage.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell employs short strips of magnetic tape to retain information. It contains ten detachable cells, each with a capacity of 40 MB, culminating in a total storage size of 400 MB.

IBM 3850 Mass Storage System

The IBM 3850 Mass Storage System, unveiled in 1974, functions as a tape cartridge library that stages data onto IBM 3330 or 3350 disk drives, effectively simulating virtual disk drives for the system.

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: Disk Drive Article Links
• 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 Documentation
• IBM 2314 Direct Access Storage Materials