IBM 2311

IBM

Company type	Public
Industry	Computer hardware, data storage
Founded	June 16, 1911 (1911-06-16) in Endicott, New York, United States
Defunct	2003 (2003)
Fate	Divested hard disk drive division to Hitachi
Headquarters	Armonk, New York , United States
Products	Hard disk drives, floppy disk drives, magnetic disk storage devices

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. IBM is credited with inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), with its workforce contributing numerous technological advancements in these fields. The core mechanical architecture of hard disk drives has largely remained unchanged since the introduction of the IBM 1301, with performance benchmarks still based on criteria set during the 1950s. Throughout this product line's history, there have been extraordinary reductions in cost and physical dimensions, accompanied by substantial enhancements in capacity and speed.

From 1969 through the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not establish a significant presence in producing smaller 5.25-inch or 3.5-inch drives. While IBM sold its magnetic disk drives directly, it only began offering them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had discontinued manufacturing hard disk drives exclusively for its own systems, shifting entirely to OEM distribution.

IBM referred to its magnetic disk drives using various names, including direct-access storage device (DASD), disk file, and diskette file. However, this article employs the industry-standard terms hard disk drive (HDD) and floppy disk drive (FDD) for clarity.

IBM 350

The IBM 350 disk storage unit, recognized as the very first disk drive, debuted on September 14, 1956, as an integral component of the IBM 305 RAMAC system. A related product, the IBM 355, was introduced for use with the IBM 650 system. The initial prototype was delivered to Zellerbach Paper Company in June 1956, with production models reaching customers such as United Airlines beginning November 1957.

Engineered to address real-time business accounting requirements, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB) across fifty-two disks that utilized one hundred recording surfaces. The disks rotated at a speed of 1200 rpm, enabling a data transfer rate of 8,800 characters per second. Its access mechanism involved movable heads that selected pairs of disks and specific tracks. Several enhanced versions were launched during the late 1950s. The RAMAC 305 system equipped with the IBM 350 was leased at a rate of $3,200 per month. This model remained on the market until it was discontinued in 1969.

Patent US3,503,060 stemming from the RAMAC project is acknowledged as a foundational patent for disk drive technology. Although initially rejected by IBM's Board out of concern that it might undermine punch card sales, development persisted at IBM San Jose until it received approval from IBM’s president.

The unit’s cabinet measured approximately long by high by wide and weighed around one ton, necessitating forklift handling and often requiring transportation by cargo aircraft. Currie Munce from Hitachi Global Storage Technologies—successor to IBM’s storage division—indicated that while capacity could have been expanded beyond five million characters, marketing considerations imposed limits. Versions with double capacity were announced and shipped starting in 1959.

In recognition of its significance, the RAMAC 350 Disk File was named an International Historic Landmark by The American Society of Mechanical Engineers in 1984. A restoration initiative led by Al Hoagland commenced in 2002 at the Magnetic Disk Heritage Center in partnership with Santa Clara University. Since 2005, this restored unit has been on display at the Computer History Museum located in Mountain View, California.

IBM 353

The IBM 353, designed for use with the IBM 7030, bore resemblance to the IBM 1301 but offered a higher data transfer speed. It provided storage for 2,097,152 (2²¹) 64-bit words, equating to 134,217,728 bits, and achieved a transfer rate of 125,000 words per second. A prototype delivered in late 1960 was notable for being the first disk drive to employ one read/write head per surface that floated on compressed air, similar to the IBM 350 disk storage system. Production versions utilized self-flying heads akin to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an expansion unit for the widely used IBM 650 computer. It utilized the IBM 350 mechanism but featured up to three access arms—compared to the single arm on the IBM 350—and could store six million decimal digits along with 600,000 sign characters. The device transferred entire tracks to and from the magnetic core memory of the 653, an optional IBM 650 storage unit containing sixty signed 10-digit words, sufficient for one disk track or a tape record.

IBM 1405

Announced in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two models: Model 1 offered a capacity of ten million alphanumeric characters (60 million bits) across 25 disks, while Model 2 doubled this capacity to twenty million characters (120 million bits) using fifty disks. The disks were arranged vertically and spun at a speed of 1,200 revolutions per minute.

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

Access times varied from as low as 100 milliseconds up to a maximum of around 700 milliseconds for Model 1 and approximately 800 milliseconds for Model 2. Model 2 accommodated around 100,000 sectors capable of holding either 200 characters in move mode or 178 characters in load mode, which included an additional word mark bit per character. Model 1 contained roughly half this number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered for use with the IBM 7070 system and featured a model announced in 1959. Nevertheless, with the arrival of the 1301 in 1961, many customers of the IBM 7070 and IBM 7074 opted for this newer alternative due to its advantages. The technology underlying the IBM 7300 shared similarities with that found 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 primarily for mainframe computers in the 7000 series as well as the IBM 1410. Each module housed twenty-five large disks providing forty user-accessible recording surfaces with a total storage capacity of twenty-eight million characters (168 million bits)—twenty-five million characters for the IBM 1410 variant. Each recording surface contained approximately two hundred fifty tracks. The Model 1 configuration included one module, whereas Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute and supported data transfers at ninety thousand characters per second.

A significant innovation was its use of individual arms and heads dedicated to each recording surface, moving collectively in a comb-like fashion. This arrangement eliminated delays caused by repositioning heads across multiple disks, reducing maximum access times to about one hundred eighty milliseconds. Furthermore, the heads were aerodynamically engineered to fly over disk surfaces supported by a thin cushion of air, enabling closer proximity and improved performance.

Connection to host systems was managed through the IBM 7631 File Control unit, which allowed operation with either an IBM 1410 or a computer from the IBM 7000 series—or even simultaneous access by both systems.

Leasing fees for Model 1 were set at $2,100 per month or $115,500 for purchase; Model 2 leased at $3,500 monthly or $185,000 to buy. The IBM 7631 controller added $1,185 monthly or $56,000 if purchased outright. All versions were phased out by around 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 a data transfer speed of 180,000 characters per second, more than doubling the throughput of its predecessor. Each unit contained two independent access mechanisms dedicated to the inner and outer cylinders. The Model 2 configuration stacked two modules to double storage capacity. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, with purchase prices at $252,000 and $355,500 respectively. The IBM 7631 controller was available for an additional $1,185 monthly or $56,000 for outright purchase. Production ceased in February 1965.

IBM 1311

Introduced on October 11, 1962, the IBM 1311 Disk Storage Drive was designed for mid-range business and scientific computing systems. Comparable in size to a top-loading washing machine, it accommodated 2 million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven different models were produced before being phased out in the early 1970s.

The IBM 1316 disk pack measures approximately 4 inches in height and weighs about 10 pounds. It comprises six disks, each measuring 14 inches in diameter, providing ten usable recording surfaces overall. Spinning at 1,500 revolutions per minute, each surface contains 100 tracks subdivided into 20 sectors; every sector holds 100 characters. The disk pack is encased in a plastic shell to facilitate handling and protect the media.

Seven variants of the IBM 1311 existed: master drives equipped with controllers and slave drives without controllers. Master units managed up to four or three slave drives depending on configuration. These models supported systems including the IBM 1440, IBM 1460, IBM 1240, IBM 1620, IBM 1710, IBM 1401, IBM 1410, IBM 7010, and IBM 7740.

Available optional enhancements comprised:

• Direct Seek: eliminates the need to return to track zero before initiating a seek.
• Scan Disk: performs automatic rapid searches for specific identifiers or conditions.
• Seek Overlap: allows concurrent seeking and read/write operations across multiple drives.
• Track Record: boosts capacity by recording one large record per track instead of multiple sectors; enabling storage of approximately 17.9 million bits in "Move Mode" and roughly 18.8 million bits in "Load Mode."

Master drives (Models 1, 3, 4, and 5) incorporated additional power supplies and control circuitry and were about one foot wider than the Model 2 slave drives.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the IBM 1302 within the S/360 DASD framework. It utilizes a fixed module containing 25 platters across 46 recording surfaces. The Model 3 includes a single module while Model 4 features two modules. Each module employs two separate access mechanisms servicing the innermost and outermost sets of 250 cylinders—referred to as access groups—each equipped with one read/write head per track. The average rotational latency is approximately 17 milliseconds; maximum seek time per access group reaches up to 180 milliseconds. Each track holds about 4,985 bytes, resulting in a module capacity near 112 megabytes. Connectivity to IBM mainframes is established through the IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970 alongside the IBM 2835 Storage Control Unit, the IBM 2305 fixed-head storage device initially interfaced with System/360 Models 85 and 195 via the IBM 2880 Block Multiplexor Channel. Its popularity surged with System/370's Virtual Storage implementation, frequently serving as a paging device on systems such as the IBM 3155, IBM 3165, IBM 3033, and IBM 4341. It was also well-suited for high-transaction small data sets including catalogs and job queues.

The smaller model, the IBM 2305-1, provided a capacity of 5.4 megabytes with a data transfer rate of three megabytes per second and an average access time of approximately two and a half milliseconds. The larger IBM 2305-2 offered an expanded capacity of about eleven point two megabytes at one point five megabytes per second with an average access time near five milliseconds. Its rapid response times and elevated data throughput made it ideal for system-resident files such as work files, job queues, indices, and frequently accessed datasets. The device’s swift access capabilities were particularly advantageous in heavily loaded environments requiring more than one point five transactions per second, significantly improving paging efficiency within virtual storage systems.

IBM 2311

Launched in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive was designed to support the IBM System/360 series and was also compatible with the IBM 1130 and IBM 1800 systems. It connected directly to the IBM System/360 Model 20 and Model 25. All variants utilized the removable IBM 1316 Disk Pack, which was initially developed for use with the IBM 1311.

For the Model 1 of the 2311, connection was established through the 2841 Control Unit; in contrast, the Model 25 relied on a Disk Attachment Control for this purpose. Disk packs employed IBM’s count key data system, which featured variable record lengths. However, Models 11 and 12, which worked with the Model 20 control, used fixed sector formatting, rendering disk packs incompatible between these two formatting styles.

While mechanically resembling the IBM 1311, the 2311 offered enhanced recording density. It stored approximately 7.25 megabytes on a removable disk pack composed of six platters. The mechanism included ten read/write heads actuated hydraulically, with each platter surface containing 200 tracks plus three additional spare tracks allocated for defect handling. Average seek time was about 85 ms, and data transfer rates could reach up to 156 kB/s.

Uniform electrical interfaces across System/360 models encouraged third-party vendors to manufacture plug compatible disk drives, thereby promoting a competitive market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Debuting in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms and incorporated a Two Channel Switch enabling dual-channel connectivity. Building upon the foundation of the IBM 2311, it enhanced storage capacity and data density by utilizing an eleven-platter removable IBM 2316 disk pack, which held roughly 29 million characters (calculated as 200 tracks × 20 surfaces × approximately 7294 bytes per track).

This drive featured twenty read/write heads mounted on a hydraulically actuated arm equipped with mechanical detents to ensure precise track positioning. While initial access times were similar to those of the IBM 2311, improvements in actuator technology later reduced these times. The data transfer rate was doubled compared to its predecessor, reaching about 310 kB/s.

The Model 1 was packaged as a unit containing nine disk drives alongside a storage control unit. Each drive was housed within its own drawer to facilitate easy access to disk packs. Due to their appearance, these units earned the nickname "Pizza Ovens." Although nine drives were included, only eight could be accessed by the system simultaneously; the ninth served as an offline spare for maintenance or replacement tasks. Drive system addresses were configured via user-interchangeable plugs, allowing reassignment of addresses without modifying hardware.

An optional 2844 Control Unit permitted concurrent access from two System/360 channels to different drives within the facility.

Subsequent iterations of the IBM 2314 expanded these functionalities:

IBM 2314 direct access storage facility - A series

In 1969, IBM introduced a modular approach by separating the facility into distinct models capable of supporting up to nine drives (with eight online) connected through a 2314 Storage Control:

• 2312 Disk Storage: single-drive module.
• 2313 Disk Storage: four-drive module.
• 2318 Disk Storage: two-drive module.

IBM 2319

In response to competition from plug compatible manufacturers producing storage devices comparable to the 2314, IBM launched the more affordable three-drive module 2319 in 1970. This was achieved by removing one drive from the four-drive 2313 unit and marketing it as the 2319 A1, available at a significantly reduced rental cost. This strategy lowered expenses for new customers while maintaining higher fees for existing users. The 2319-A1 interfaces with integrated controllers designed for System/370 Models 135 and 145. Additionally, traditional 2314 DASD units such as the 2312 or 2318 can be connected to the 2319-A1. The 2319 B series, consisting of three-disk drive modules, supports configurations of three, six, or nine drives connected to the newly introduced 2314 Model B Storage Control Unit.

IBM 3310

Released 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 employed fixed-block architecture. It was compatible with DOS/VSE and VM operating systems running on S/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, debuted in June 1970 for IBM System/370 and System/360/195 systems. The initial offerings included a two-drive Model 1 and a single-drive Model 2. Removable disk packs contained 100 MB each (404×19×13,030 bytes). It delivered an access time of approximately 30 ms and data transfer speeds reaching 806 kB/s. A notable advancement was its built-in error correction, which enhanced reliability and lowered costs by allowing tolerance for disk surface flaws through fire codes capable of correcting error bursts up to eleven bits.

The setup began with a single storage control unit (3830 Model 1) linked to one or more 3330 drives, expandable up to four drives per string (with a maximum of eight drives). In August 1972, IBM introduced the 3830 Model 2 Storage Control and the 3333 Disk Storage and Control, which separated control units from the disk drives. The 3830 functioned as a director-type controller overseeing multiple strings; the first unit in each string (the 3333) housed two drives plus a controller and could manage up to three additional attached 3330s, allowing eight drives per string. Two such 3333 units could connect to one controller, supporting up to sixteen drives total, with optional string switches enabling connections to two controllers simultaneously.

In 1973, IBM launched double-density (-11) models: the 3333–11, the 3330-11, and higher-capacity (200 MB) disk packs designated as the 3336–11. Mixing single-density and double-density drives within a string was unsupported. Field upgrades to Model 11 involved drive conversion along with data migration.

The IBM 3330 was discontinued in 1983.

IBM 3340 and 3344

While sharing many characteristics, only the IBM 3340 can act as the head of a string; there are no A model variants of the IBM 3344, which must therefore connect through a 3340 A model serving as head of string.

IBM 3340

Launched in March 1973 for IBM System/370, the IBM 3340 Direct Access Storage Facility—known by its codename Winchester—was offered in three models: the A2 model featuring two drives plus a controller, and B series models B2 (two drives) and B1 (one drive). B units attach to an A2 controller with support for up to eight drives.

This device utilized removable data modules that combined both head and arm assemblies; during load or unload operations, the module’s access door mechanically opened or closed, eliminating the need for manual cover removal required by earlier disk packs. The system achieved a response time of approximately 25 ms and data transfer rates around 885 kB/s. Three versions of IBM’s 3348 Data Modules provided capacities of either 35 MB or 70 MB; one variant of the latter included an additional fixed-head area offering faster access to about 500 KB. Error correction was incorporated into the design before discontinuation in 1984.

Developed under Ken Haughton in San Jose, this design initially targeted two removable modules each holding about 30 MB—hence its "Winchester" codename inspired by the Winchester .30-30 rifle. Despite later capacity increases, this nickname persisted.

A significant innovation was its economical head design that allowed heads to land on and lift off spinning media without unloading them completely, simplifying actuator mechanisms and reducing costs. This "Winchester technology" became an industry-standard approach influencing hard disk drive designs well into the early 1990s when the term was widely used before gradually falling out of common usage worldwide.

IBM 3344

The IBM 3344 closely parallels the 3340 model but distinguishes itself by employing fixed media rather than the removable 3348 data modules. Each spindle accommodates four logical drives, matching the storage capacity of a 3348–70. This model is exclusively available as a dual-drive configuration, with no variant designated as A (head of string). The 3344-B2F variant differs from the 3344-B2 by incorporating fixed heads over certain cylinders on both drives. Both versions necessitate a 3340-A2 or 3340-A2F unit to serve as the head of string. Internally, the IBM 3344 shares hardware similarities with the IBM 3350; the only variations are found within the control unit microcode.

IBM 3350

The IBM 3350 Direct Access Storage Facility, codenamed Madrid, debuted in 1975 alongside the IBM System/370. It introduced sealed, non-removable head-disk assemblies (HDAs) that integrated both heads and arms into a single unit. Each HDA contained 555 cylinders and 30 heads, with each track holding 19,069 bytes, resulting in an approximate capacity of 317 MB per disk. This sealed HDA design set a new standard for IBM DASD devices going forward.

The product line included models A2, A2F, B2, B2F, C2, and C2F—each consisting of two HDAs. Units labeled A2 and A2F featured an electronic board enabling connection to storage control units (controllers or head-of-string devices). These units could be combined into strings with configurations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC-. Typically, the A2 unit was equipped with a string switch allowing dual connections to storage controllers like the 3830 Model 2 or ISC within CPUs such as the 3148. This setup permitted simultaneous I/O operations directed at separate HDAs. Subsequent controllers like the 3880 preserved backward compatibility with these units. The C2 model incorporated a secondary controller acting as a backup path but offered limited connectivity options.

Units marked with "x2F" (for example, A2F) included fixed head sections spanning the first five cylinders on both HDAs, effectively eliminating seek time within these regions. This fixed-head area was generally allocated for frequently accessed data such as HASP or JES2 checkpoint files to enhance spool device performance. Additionally, it was utilized for swap data in TSO and system swaps within OS/360 successors and MVS environments, thereby optimizing context switching efficiency between users or batch jobs.

The IBM 3350 series was phased out in September 1994.

IBM 3370

Released in January 1979, the IBM 3370 Direct Access Storage Device served midrange systems including the IBM 4331, 4341, and System/38. It featured seven fixed disks measuring fourteen inches each and provided a total storage capacity of 571 MB per unit. Notably, it was the first hard disk drive to implement thin-film head technology developed during the late 1960s at IBM’s Thomas J. Watson Research Center. The device operated on fixed-block architecture and supported DOS/VSE and VM operating systems running on S/370 platforms.

IBM 3375

The IBM 3375, designed as a complementary device to the 3370, employed count key data architecture required by OS/360 and its successor operating systems.

IBM 3380

Introduced on June 11, 1980, the IBM 3380 Direct Access Storage Device utilized film head technology and initially offered a capacity of 2.52 GB per unit—comprising two hard disk assemblies each accessed by dual actuators holding approximately 630 MB. It achieved a data transfer rate of 3 MB/s with an average access time of around sixteen milliseconds. At launch, pricing ranged between $81,000 and $142,200. However, initial deliveries were postponed until October 1981 due to tribology challenges involving interaction between heads and media.

Typically configured with one A-unit and up to three B-units, each IBM 3380 contained four devices per unit for a maximum of sixteen devices per string. These were commonly connected to IBM’s 3880 storage control units featuring dual paths that enabled simultaneous I/O operations targeting different hard disk assemblies.

In February of 1985, IBM introduced Extended Capability Models (3380 E) offering double density with a total capacity of 5.04 GB per unit—two actuators managing approximately 1.26 GB each across two disk assemblies.

The triple-capacity 3380 K, announced in August 1987, provided storage of up to 7.562 GB per unit (two actuators handling roughly 1.89 GB each). Both K and J models supported an optional four-path mode which doubled device count to thirty-two per string when connected via IBM’s 3990 storage control unit; this configuration allowed four simultaneous I/O streams.

The IBM 3380 family encompassed twelve models: six A-units acting as string heads with integrated controller logic connecting to storage control units; five B-units attached to A- or C-units; and one C-unit designed for direct connection to an IBM channel.

Production continued until May of 1996, marking an impressive fifteen-year lifecycle for this disk drive series from IBM.

IBM 3390

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

A typical 3390 configuration consists of a primary A unit containing either four or eight drives, accompanied by up to two B units, each housing as many as 12 drives. This setup functions in a four-path mode and connects to a 3990 storage control unit, which can manage an additional 3390 string, resulting in a total of up to 64 devices.

Each Hard Disk Assembly (HDA) includes two actuator-head assemblies and platters. The Model 1 HDAs offered an unformatted capacity of 1.89 GB, Model 2 increased this to 3.78 GB, Model 3 (introduced in 1991) expanded it further to 5.67 GB, and Model 9 (released in 1993) doubled the capacity to 11.3 GB per HDA.

In contrast to earlier DASD models that employed AC motors with belt drives, the 3390 HDAs utilize direct-drive DC motors housed within the enclosure. The Model 9 represented IBM's final iteration of the Single Large Expensive Disk (SLED) drive.

IBM 9345

The IBM 9345 hard disk drive became available in November 1990 as a Request Price Quotation (RPQ) option under IBM’s SuperComputing Systems Extensions (SCSE). Developed at IBM’s San Jose laboratory under the codename Sawmill, this full-height 5¼-inch HDD contained up to eight 130 mm platters and provided a maximum capacity of 1.5 GB. It was notable for being the first HDD equipped with Magnetoresistive (MR) read/write heads.

IBM 9340

IBM introduced the 9340 DASD in October 1991 as part of the channel-attached CKD DASD subsystem family designed for IBM mainframes such as the ES/9000 series. The 9345 Model 1 included two HDDs each with a capacity of 1.0 GB, whereas Model 2 featured two HDDs with capacities of 1.5 GB each.

Operationally, the 9340/9345 line resembled the capabilities of the 3990/3390 series but did not incorporate the non-volatile RAM cache present in the 3990 nor did it support as long a maximum block length as the 3390. The OS Input/Output Supervisor (IOS) identified these devices through the IECCINIT initializer, which detected the absence of non-volatile cache and adjusted device type classifications accordingly.

9330 family of disk drives

1. The 9331 Diskette Units included versions equipped with either one 8-inch or one 5¼-inch floppy disk drive.
2. The 9332 Direct Access Storage Device utilized the IBM 0667 hard disk drive.
3. The 9333 High Performance Disk Drive Subsystem incorporated either IBM 0664 or IBM 0681 hard drives depending on specific models.
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 the IBM "Kestrel" hard drive developed at IBM Hursley in the UK—an 850 MB device containing three 14-inch platters with dual rotary actuators capable of accessing multiple surfaces simultaneously. This rack-mountable unit debuted alongside the October 1986 IBM 9370 Information System. No known OEM variants exist.
6. The 9336 Disk Unit employed the IBM 0681 hard disk drive (Redwing).
7. The 9337 Disk Array Subsystem utilized either IBM’s 0662 (Spitfire) or 0663 (Corsair) hard disk drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive was introduced in conjunction with the IBM 1800 in 1964 and later with the IBM 1130 in 1965, likely becoming available toward late that year. It stored up to 512,000 sixteen-bit words (equivalent to 1,024,000 bytes) on an IBM 2315 cartridge, which consisted of a single fourteen-inch oxide-coated aluminum platter enclosed within a plastic shell featuring openings for both the read/write arm and two read/write heads.

IBM 5444

Introduced in September 1969 as a component of the System/3 lineup, the IBM 5444 was engineered at IBM's Hursley facility in England, carrying the project name Dolphin. This model utilized the 5440 disk cartridge, which housed a single 14-inch platter. The series comprised three variants:

• Model 1: featured one fixed and one removable disk, each offering 100 tracks per surface, with a cartridge storage capacity of 1.23 MB
• Model 2: included one fixed and one removable disk, each with 200 tracks per surface, delivering a cartridge capacity of 2.46 MB
• Model 3: contained a single removable disk with 200 tracks per surface, providing a cartridge capacity of 2.46 MB

IBM 62GV

The IBM 62GV, unveiled in May 1974 from IBM’s Hursley laboratory under the codename Gulliver, initially provided a storage capacity of 5 MB. Subsequent versions expanded this to 10 MB (designated as 62TM) and later to 14 MB. It incorporated a Swinging Arm actuator paired with one 14-inch disk—a mechanism developed at Hursley that became IBM’s most widely licensed electro-mechanical innovation. This actuator design, along with its filtration system, saw extensive adoption across hard disk drives throughout the 1980s and continues to influence HDD architecture nearly forty years on. Approximately 177,000 units of the IBM 62GV were produced, marking it as the first hard drive to surpass sales of 100,000 units.

OEM and Small Systems HDDs

This segment addresses HDDs manufactured by IBM for OEM distribution and for integration into IBM’s smaller systems such as the System/3, System/32, /34, /36, and AS/400. Drives are categorized by their OEM model numbers and ordered by their initial shipment dates to customers.

IBM 0680

First delivered in 1979 across many IBM small systems and entry-level System/370 models as the 3310 direct access storage device, the drive was announced under the OEM designation 0680 in September 1981. Developed at IBM’s Hursley laboratory in the UK under the codename Piccolo, it consisted of six 8-inch (210 mm) platters offering up to 65 MB of storage capacity along with an enhanced rotary actuator.

A variant with doubled storage capacity, known as the 62SW, was released in June 1984; however, it experienced limited market penetration due to its pricing per megabyte being comparable to that of the 62GV.

IBM 0676

The 0676 debuted in November 1982 as part of the IBM System/23 Datamaster’s storage solution named the 5247 Disk Storage Unit. Created at IBM Rochester in Minnesota under the internal code 21ED, this was an eight-inch hard drive initially available with either two or four platters (210 mm), offering capacities of either 15 or 30 MB. In 1983, it was integrated into the System/36’s 5360 System Unit. By increasing tracks per surface in 1984, its capacity doubled and it became part of the System/36’s upgraded storage unit, the 5362.

IBM 0665

The 0665 made its first appearance in October 1985 within the PC AT (5170) system chassis. Developed at IBM Rochester under the codename "Pixie," this model was a five-and-a-quarter-inch hard drive available in capacities of 20 MB, 30 MB, and 44 MB.

IBM 0667

Released in August 1986, the 0667 was developed at IBM Rochester with the project name "Grant." It was a full-height five-and-a-quarter-inch ESDI hard disk drive capable of holding up to four platters measuring 130 mm each and offering a total capacity of up to 70 MB. This drive was employed in select PC RT models (6150, 6151, and 6152) as well as System/36 Model System Units (5363 and 5364).

IBM 0669

The 0669, introduced in 1987 from IBM Rochester under the codename "Grant-Prime," was a full-height five-inch hard disk drive supporting up to four platters sized at 130 mm each and delivering storage up to approximately 115 MB. It functioned as the internal hard drive for both the System/36 Model 5363 and Series/1 Model 4956 system units.

IBM 0671

Introduced in 1987 from IBM Rochester under the project name "Lee," the 0671 was a full-height 5-inch ESDI hard drive offering up to 316 MB of storage with as many as eight 130 mm platters. This model represented IBM's initial implementation of thin metal film recording surfaces and was incorporated into the IBM AS/400 9404 System Unit in 1988, accommodating configurations of two or three drives.

IBM 0661

The 0661 made its debut in 1989 as the model 371. Developed collaboratively at IBM Rochester and Hursley (UK) under the codename "Lightning," it was a 320 MB SCSI hard disk utilizing up to eight 95 mm platters (14 heads). A subsequent "Turbo" variant with 400 MB capacity was released in 1990. This drive became a standard component in key IBM platforms, including the AS/400 System Unit Model CXX.

IBM 0681

Launched in April 1990 from IBM Hursley with the codename Redwing, the 0681 was the final hard drive developed at the Hursley site. It offered a maximum capacity of 857 MB within a full-height 5-inch enclosure, using up to twelve 130 mm platters. Notably, it was the first IBM drive to utilize PRML (Partial Response Maximum Likelihood) data decoding technology. Integrated into the 9333 Disk Drive Subsystem released from early 1992, an enhanced density version providing 1.07 GB became available in May 1992.

IBM 0663

The 0663, introduced in late 1991 and codenamed "Corsair," was a compact hard disk featuring a half-height (1.6-inch) profile and measuring 3 inches in diameter. It delivered up to 1 GB of storage across eight 95 mm platters. This drive was offered on select PS/2 and RS/6000 models and distinguished itself as the first OEM disk drive equipped with Magnetoresistance (MR) heads.

IBM 0664

Released in November 1992 and developed under the codename "Allicat" at IBM Rochester, Minnesota, the 0664 was a full-height (3.25-inch high) 5-inch hard drive combining two separate 3-inch drives. It provided a capacity of up to 2.013 GB using as many as eight 95 mm platters.

IBM 0662

The 0662, shipped in June 1993 and developed at IBM Rochester under the codename "Spitfire," was a full-height (1-inch high) hard disk with a diameter of 3 inches. It delivered storage capacity of 1.05 GB distributed over three platters or five surfaces. This model saw internal use within the IBM 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology by introducing an 8-inch floppy disk drive (FDD) in 1971 as a read-only program load device, followed by its first read/write FDD in 1973 integrated into the 3740 Data Entry System. Although IBM established early standards for the 8-inch floppy format, it never sold standalone drives, allowing other industry players to lead further development outside IBM.

At one point, IBM was the largest original equipment manufacturer buyer of 5-inch floppy drives, and its preference for two-sided models with a density of 48 tracks per inch helped set this format as an industry benchmark. Despite plans to produce these drives along with smaller sizes, all manufacturing initiatives were halted by 1985. Additionally, IBM's attempt in 1983 to OEM a smaller four-inch DemiDiskette did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three families of hard drives: the Travelstar line featuring compact 2-inch drives designed for notebooks; the Deskstar series with 3-inch drives aimed at desktop computers; and the Ultrastar range of high-performance 3-inch drives targeting demanding system applications.

IBM's first HDD versus its last HDDs

The following table presents a comparison between IBM's inaugural hard disk drive, the RAMAC 350, and the final three models from its "Star" series of OEM HDDs. It underscores significant advancements in storage capacity and performance, coupled with substantial reductions in physical dimensions and cost.

Parameter (units)	RAMAC 350	Ultrastar 146Z10	Deskstar 180GXP	Travelstar 80GN	46-year improvement (maximum)
Release date	Sep 1956	Jul 2002	Oct 2002	Nov 2002
Storage capacity (gigabytes)	0.004	146	180	80	48,000
Size (inches)	60×68×29	4×1×5.75	4×1×5.75	2.75×0.38×3.95
Size (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)	Approximately 2374 watts (8100 BTUs/hour), with up to 5500 VA depending on model variation	16	10.3	1.85	1,283
Power efficiency (megabytes per watt)	0.0016	9,125	17,476	43,243	27,375,856
Manufacturer's suggested 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
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 Beyond HDDs and 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 the following:

IBM Model 7320 Drum

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

IBM Model 2301 Drum

The IBM 2301 is another magnetic drum storage device that became available during the late 1960s.

IBM Model 2303 Drum

The IBM 2303 magnetic drum device was released in the year 1964.

IBM Model 2321 Data Cell

Unveiled in 1964, the IBM 2321 Data Cell utilizes short strips of magnetic tape for data retention and contains ten removable cells, each holding approximately forty megabytes for a total capacity of four hundred megabytes.

IBM Model 3850 Mass Storage System

Launched in the mid-1970s (1974), the IBM 3850 Mass Storage System employed a tape cartridge library system that staged data onto IBM's disk drives such as the IBM 3330 or IBM 3350 while presenting virtualized disk drives to the host system.

See also

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

External links

• IBM Historical Archive: Fundamental Storage Information
• IBM Historical Archive: Collection of Disk Drive Articles
• Magnetic Disk Heritage Center
• A Quarter Century of Disk File Innovation, IBM Journal of Research and Development, published in1981
• EE Times: The Dynamic Evolution of Disk Drives
• IBM Model1311 Disk Storage Drive
• IBM Series2314 Direct Access Storage