IBM 0667

IBM

Industry	Technology, Computer hardware
Founded	June 16, 1911 (1911-06-16) in Endicott, New York, United States
Fate	Divested hard disk drive operations to Hitachi in 2003
Headquarters	Armonk, New York , United States
Products	Magnetic disk storage systems (hard disk drives, floppy disk drives)
Website	www.ibm.com

IBM was a pioneer in the production of magnetic disk storage systems from 1956 until 2003, at which point it divested its hard disk drive operations to Hitachi. IBM's workforce was instrumental in inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing numerous technological advancements. The fundamental mechanical design of HDDs has largely persisted since the introduction of the IBM 1301, with performance benchmarks adhering to established standards dating back to the 1950s. Over time, the sector has experienced dramatic decreases in cost and physical dimensions, alongside substantial improvements in storage capacity and speed.

From 1969 through 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 formats. While IBM consistently marketed its magnetic disk drives, it only began providing them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had discontinued producing hard disk drives exclusive to its own hardware, shifting entirely to OEM distribution.

IBM has employed several designations for its magnetic disk products, including direct-access storage device (DASD), disk file, and diskette file; this article, however, adopts the common industry terminology hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

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

Engineered to facilitate real-time business accounting processes, the IBM 350 accommodated five million 6-bit characters (equivalent to 3.75 MB) distributed over fifty-two disks each measuring 24 inches in diameter, utilizing one hundred recording surfaces and tracks. The disks rotated at a speed of 1200 rpm, supporting a data transfer rate of 8,800 characters per second. A mechanical access system positioned read/write heads to select specific surfaces and tracks on the disks. Several enhanced versions were launched during the late 1950s. The IBM RAMAC 305 system with the 350 was leased at a rate of $3,200 monthly. This model was officially retired from service in 1969.

A key patent from this era, US Patent 3,503,060 associated with the RAMAC project, is regarded as a foundational document for disk drive technology. Although initially halted by IBM's board due to concerns over competing with its punch card division, development proceeded following approval from IBM’s president.

The physical cabinet housing the IBM 350 measured roughly 60 inches in length, stood 68 inches tall, and was 29 inches wide. Weighing approximately one ton, it required forklift assistance for relocation and was frequently transported via large cargo aircraft. Currie Munce, then research vice president at Hitachi Global Storage Technologies—successor to IBM’s storage division—noted that while capacity could have been expanded beyond five million characters, marketing hesitated due to difficulties in promoting higher-capacity models. Nevertheless, double-capacity variants were announced and shipped starting in 1959.

Acknowledging its historical importance, the RAMAC 350 Disk File was named an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, a restoration initiative led by Al Hoagland partnered with Santa Clara University to refurbish an IBM 350 RAMAC unit. In 2005, this effort transitioned to the Computer History Museum located in Mountain View, California, where it remains exhibited within the Revolution gallery.

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 a storage capacity of 2,097,152 (2²¹) 64-bit words, equivalent to 134,217,728 bits, and achieved a transfer rate of 125,000 words per second. A prototype delivered in late 1960 was notable as the first disk drive to employ one head per disk surface that floated on compressed air, similar to the earlier IBM 350 model. Production versions adopted 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 for the widely used IBM 650 system. It utilized the IBM 350 mechanism but incorporated up to three access arms rather than just one, enabling storage of six million decimal digits plus an additional 600,000 sign characters. This unit transferred entire tracks to and from the magnetic core memory of the 653, an optional IBM 650 component that held sixty signed 10-digit words—sufficient capacity for a single disk track or tape record.

IBM 1405

Announced in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two variants. Model 1 stored up to ten million alphanumeric characters (60 million bits) on a stack of 25 disks; Model 2 doubled this capacity to twenty million characters (120 million bits) using fifty disks. The disks were arranged vertically and rotated at a speed of 1200 revolutions per minute.

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

Access times varied between a minimum of about 100 milliseconds and a maximum of up to 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 offered storage for 100,000 sectors containing either two hundred characters in move mode or one hundred seventy-eight characters in load mode, which included an additional word mark bit per character; Model 1 provided half that number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was created specifically for the IBM 7070 system, with a second model announced in 1959. Nevertheless, after the introduction of the IBM 1301 on June 5, 1961, customers using the IBM 7070 and IBM 7074 favored the IBM 1301 over the IBM 7300. The technology within the IBM 7300 shared common elements with earlier 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 designed for use with mainframe computers in the IBM 7000 series as well as the IBM 1410. Each module stored twenty-eight million characters (168 million bits), or twenty-five million characters when paired with the IBM 1410, distributed over twenty-five disks featuring forty user-accessible recording surfaces with two hundred fifty tracks each. The Model 1 consisted of a single module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute and supported data transfer rates of ninety thousand characters per second.

A significant advancement was the implementation of an individual arm and read-write head for every surface that moved simultaneously like a comb assembly. This design eliminated delays caused by moving heads between disks and reduced maximum access time to one hundred eighty milliseconds. Additionally, it was the first disk drive to utilize aerodynamically engineered heads that floated on a thin air cushion, allowing them to operate closer to disk surfaces and thereby improving performance.

Connection was established through the IBM 7631 File Control unit, enabling compatibility with either IBM 1410 or IBM 7000 series systems or allowing sharing between two computers.

Leasing costs for Model 1 were $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 discontinued by the year 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit delivered a fourfold increase in capacity compared to the IBM 1301, reaching 117 million 6-bit characters per module. It provided an average access time of 165 milliseconds and achieved a data transfer rate of 180,000 characters per second, more than twice as fast as its predecessor. Each module incorporated two separate access mechanisms dedicated to the inner and outer cylinders. The Model 2 variant doubled storage by stacking two modules together. Leasing fees for Model 1 were set at $5,600 monthly or $252,000 for outright purchase; Model 2 was priced at $7,900 per month or $355,500 to acquire. The IBM 7631 controller added an additional $1,185 monthly lease or $56,000 purchase cost. Production of the 1302 ceased in February 1965.

IBM 1311

Announced on October 11, 1962, the IBM 1311 Disk Storage Drive was designed for medium-sized business and scientific computing systems. Comparable in size to a top-loading washing machine, it stored two million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven different models were introduced and were phased out by the early 1970s.

The IBM 1316 disk pack measures approximately four inches in height and weighs around ten pounds. It contains six disks, each 14 inches in diameter, with ten usable recording surfaces (the outer surfaces remain unused). The disks rotate at a speed of 1500 rpm and employ ten read/write heads mounted on a hydraulically actuated arm assembly. Each surface is divided into 100 tracks with twenty sectors per track; each sector holds one hundred characters. The disk pack is encased in a transparent plastic shell with a locking handle to facilitate easy insertion and removal.

The seven IBM 1311 drive models include master drives equipped with controllers and slave drives managed by those 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 designed for IBM 1620 or 1710 systems; controls up to three Model 2 drives; no special features included. (1962–1971)
4. Master drive for IBM 1401; controls up to four Model 2 drives. (1962–1971)
5. Master drive for IBM 1410, 7010, or 7740 systems; supports up to four Model 2 drives; includes standard Direct Seek capability. (1963–1971)
6. Presumed master drive introduced in 1968; discontinued in the early 1970s.
7. Presumed slave drive introduced in 1968; discontinued in the early 1970s.

Several optional enhancements were available to improve performance and capacity:

• Direct Seek: Removes the need to return to track zero before seeking a new position.
• Scan Disk: Allows rapid automatic scanning for specific identifiers or conditions.
• Seek Overlap: Enables simultaneous seek and read/write operations across multiple drives.
• Track Record: Boosts capacity by writing a single large record per track instead of multiple sectors—achieving nearly eighteen million bits depending on operating mode.

Master drives (Models 1,3,4,5) include additional power supplies and control circuitry, making them roughly one foot wider than the Model 2 slave versions.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the 1302, modified for S/360 direct access storage device architecture. It employs a fixed module containing twenty-five platters with forty-six recording surfaces. Model 3 features one such module; Model 4 contains two modules. Each module is equipped with two independent access mechanisms servicing the innermost and outermost sets of approximately 250 cylinders—referred to as access groups—each having one read/write head per track. Average rotational latency is approximately seventeen milliseconds with a maximum delay of thirty-four milliseconds; maximum seek time per group is about one hundred eighty milliseconds. Each track holds roughly four thousand nine hundred eighty-five bytes; total storage per module equals approximately one hundred twelve megabytes. Connectivity to IBM mainframes is provided via the IBM 2841 Storage Control Unit.

IBM 2305

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

The 2305 gained prominence within System/370's Virtual Storage environment, frequently utilized as a paging storage unit on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). It was also well-suited for managing high-transaction small data sets like catalogs and job queues.

The 2305-1 variant delivers a capacity of 5.4 MB with a data transfer rate of 3.0 MB/s and an average access time of 2.5 ms; in contrast, the larger 2305-2 offers an 11.2 MB capacity at 1.5 MB/s with a mean access time of 5 ms.

Engineered for rapid and continuous access to limited data volumes, the 2305’s speed and storage size made it ideal for system-resident tasks such as work files, job queues, indices, and frequently accessed datasets. Its swift response times rendered it particularly effective as a paging device in systems handling workloads exceeding 1.5 transactions per second.

IBM 2311

Introduced in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive served the IBM System/360 family and was also compatible with the IBM 1130, IBM 1800, and directly connected to System/360 Models 20 and 25. This drive utilized the removable IBM 1316 Disk Pack, originally launched with the IBM 1311.

The Model 1 of the 2311 connects to most IBM mainframes through the 2841 Control Unit; on the System/360 Model 25, it operates via a Disk Attachment Control providing comparable functionality. Disk packs employed IBM’s count key data format supporting variable-length records. Models 11 and 12 of the 2311 linked to Model 20’s integrated control unit and relied on fixed-sector formatting; notably, disk packs for Model 1 were not interchangeable with those used by Models 11 and 12 due to differing formats.

While mechanically akin to the IBM 1311, the 2311 enhanced recording density and accommodated a single removable six-platter IBM 1316 disk pack storing approximately 7.25 megabytes. It featured ten read/write heads mounted on a hydraulically actuated arm, each platter surface containing 200 tracks plus three spare tracks allocated for defects. The average seek time was approximately 85 ms, paired with a data transfer speed of about 156 kB/s.

Standardized electrical interfaces allowed third-party vendors to manufacture plug compatible disk drives, encouraging a competitive market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Released in April of 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 connect simultaneously to two channels. Building upon the foundation of the IBM 2311 design, it increased both data density and capacity by utilizing the taller IBM 2316 disk pack containing eleven disks (providing twenty recording surfaces), capable of storing roughly twenty-nine million characters.

This drive incorporated twenty read/write heads mounted on a hydraulically actuated arm, with each surface containing two hundred tracks. Although initial access times matched those of the IBM 2311, subsequent improvements in hydraulic actuator technology reduced seek durations. Data transfer rates were doubled to approximately 310 kB/s.

The Model 1 system was sold as a package including nine disk drives grouped under one price point along with a storage control unit—comprising one single-drive module and two four-drive modules. Each drive was housed in an individual pull-out drawer—colloquially referred to as "Pizza Ovens" because of their appearance. At any given time, only eight drives were accessible; the ninth functioned as an offline spare to facilitate maintenance without interrupting ongoing operations. Drive addresses were configurable via user-swappable plugs providing flexible setup options.

An optional IBM 2844 Control Unit enabled concurrent access from two separate System/360 channels to different drives within this facility.

Subsequent versions of the IBM 2314 expanded upon these features:

IBM 2314 Direct Access Storage System - Model Variants

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

• The 2312 Disk Storage, consisting of a single drive unit.
• The 2313 Disk Storage, comprising four drives.
• The 2318 Disk Storage, featuring two drives.

IBM 2319

To address challenges posed by plug-compatible vendors offering alternatives to the 2314 subsystem, IBM launched in 1970 the cost-effective three-drive module named 2319. This was achieved by removing one drive from the four-drive 2313 and renaming it as the 2319 A1. This approach enabled IBM to reduce leasing fees for new clients while keeping higher charges for existing customers. The 2319-A1 interfaces with integrated controllers designed for System/370 Models 135 and 145, and it also supports attachment of standard 2314 DASD units such as the 2312 or 2318. The 2319 B series expanded options with configurations of three, six, or nine drives connected to a newly designed 2314 Model B Storage Control Unit.

IBM 3310

Debuting on January 30, 1979, the IBM 3310 Direct Access Storage Device was developed specifically for IBM 4331 midrange computer systems. Each unit delivered a capacity of 64.5 MB and utilized fixed-block architecture. It was compatible with DOS/VSE and VM, which were the only S/370 operating systems supporting FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, internally codenamed Merlin, was introduced in June 1970 for IBM System/370 and System/360 Model 195 platforms. Initial offerings included a two-drive Model 1 and a single-drive Model 2. The removable disk packs provided storage of 100 MB each, with an average access time of 30 ms and data transfer speeds reaching 806 kB/s. A significant advancement was the incorporation of built-in error correction using fire codes, which improved reliability while reducing costs by allowing tolerance for minor disk surface defects.

The original configuration connected one storage control unit (3830 Model 1) to a chain of up to four drives (with a maximum of eight drives per chain). In August 1972, IBM introduced the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control units from drive chains. The 3830 Model 2 functioned as a director-style controller overseeing multiple chains; within each chain, the initial unit—the 3333—combined a controller with two drives and could manage up to three additional attached 3330 drives, totaling eight drives per chain. Two such chains could be linked to one control unit, allowing up to sixteen drives per controller.

In 1973, IBM released double-density (-11) versions—the 3333–11, 3330-11, and 3336–11 Disk Packs—that doubled capacity to 200 MB. Mixing single-density and double-density drives within a single chain was unsupported. Upgrading from standard models to Model-11 versions in the field was feasible but complex, involving hardware conversions and data transfers.

The IBM 3330 was discontinued in 1983.

IBM 3340 and IBM 3344

While the IBM 3340 and IBM 3344 share many characteristics, only the IBM 3340 can serve as the head of a drive chain; no A model exists for the IBM 3344, which must connect to an IBM 3340 A model acting as the chain's head unit.

IBM 3340

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

This system utilized removable data modules containing both the head and arm assembly; during mechanical load or unload operations, the module’s access door opened to engage with the drive, avoiding the need to remove covers as required by earlier disk pack designs. It delivered a 25 ms access time alongside data transfer speeds of 885 kB/s. The IBM 3348 Data Modules came in three versions: one with a 35 MB capacity and two with 70 MB each—one of which included 500 KB of fixed heads for faster access. Featuring built-in error correction, the 3340 was eventually discontinued in 1984.

Engineered in San Jose under Ken Haughton’s leadership, the initial concept centered on two removable 30 MB modules—hence the "Winchester" nickname inspired by the Winchester .30-30 rifle. Despite subsequent capacity increases, this moniker persisted.

A significant advancement was its economical head design that eliminated the need to unload heads from the media. This "Winchester technology" permitted heads to land on and lift off from spinning disks, greatly simplifying and reducing costs associated with head and arm mechanisms. This innovation became a foundational standard within disk drive manufacturing.

The term Winchester or Winnie remained widely used to describe hard drives into the early 1990s but has since largely disappeared worldwide.

IBM 3344

The IBM 3344 shares similarities with the 3340 but employs fixed media rather than removable 3348 data modules. Each spindle accommodates four logical drives, each possessing storage capacity equivalent to a 70 MB 3348 module. Available exclusively as dual-drive models, the 3344 lacks an A (head of string) variant. The 3344-B2F model includes fixed heads over certain cylinders on both drives. Both the 3344-B2 and B2F require connection to a 3340-A2 or A2F unit serving as head of string. Internally, the IBM 3344 mirrors the IBM 3350; distinctions exist only in the microcode of its control unit.

IBM 3350

Introduced in 1975 for IBM System/370, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. Its sealed, non-removable head-disk assemblies (HDAs), which integrate both head and arm components, provide storage capacity of approximately 317.5 million bytes distributed over 555 cylinders and 30 heads per HDA. This sealed HDA configuration became IBM’s standard approach for DASD thereafter.

Available models—A2, A2F, B2, B2F, C2, and C2F—all contained two HDAs. The A2 and A2F versions incorporated an extra electronic board enabling connection to a control unit (serving as controller or head-of-string). Installations were arranged in strings beginning with an A2 or A2F unit, followed by up to three B2 units or combinations including C2 units. The A2 unit typically featured a string switch allowing simultaneous I/O operations via connections to two storage control units. Compatible controllers included the Model 2 of IBM 3830, ISC units within CPUs such as the 3148/3158/3168, and later backward-compatible models like the IBM 3880. The C2 model housed a spare controller for redundancy but offered fewer connectivity options compared to A units.

Permissible IBM 3350 string configurations included -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

Models designated with "x2F" (e.g., A2F) incorporated fixed head regions spanning the first five cylinders on both HDAs, effectively eliminating seek time within these zones. This feature enhanced performance for frequently accessed data such as HASP or JES2 checkpoint areas and improved system swap data handling in TSO environments—facilitating more efficient context switching.

The IBM 3350 series was officially retired from the market in September 1994.

IBM 3370

In January 1979, IBM introduced the IBM 3370 Direct Access Storage Device designed for IBM 4331, 4341, and System/38 midrange computer systems. This model incorporated seven fixed 14-inch platters, delivering a storage capacity of 571 MB per unit. Notably, the 3370 was the pioneer hard disk drive to incorporate thin-film head technology, which originated from research at the Thomas J. Watson Research Center during the late 1960s. It utilized fixed-block architecture (FBA) and was compatible with DOS/VSE and VM operating systems running on S/370 platforms.

IBM 3375

The IBM 3375 served as a companion to the 3370, employing count key data (CKD) architecture necessary for operating systems such as OS/360 and its successors.

IBM 3380

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

The standard IBM 3380 setup included one A unit accompanied by up to three B units; each unit contained four devices, enabling a maximum of sixteen devices per string. Typically connected through a 3880 storage control unit featuring dual paths, this configuration allowed two concurrent I/O operations targeting distinct hard disk assemblies.

In February 1985, IBM released the Extended Capability Model (3380 E) with double density, doubling capacity to 5.04 GB per unit—comprising two actuators of 1.26 GB each on two assemblies. Later, in August 1987, the triple-capacity Model K became available, offering a total of 7.562 GB per unit with two actuators of 1.89 GB each. Models J and K supported four-path operation when connected to a 3990 storage control unit, allowing up to thirty-two devices per string and enabling four simultaneous I/O processes.

The IBM 3380 series included twelve distinct models: six A-units functioning as string heads with controller logic interfacing with IBM storage control units; five B-units designed to connect to either A or C units; and one C-unit capable of direct connection to IBM channels.

Manufacture of the IBM 3380 continued until May 1996, culminating in an impressive fifteen-year production span—an unusually extended lifecycle for disk drives within the industry.

IBM 3390

Launched in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities reaching up to 22 gigabytes across multiple drives. Pricing varied widely from $90,000 to $795,000 depending on configuration and capacity levels.

A typical IBM 3390 string comprises a central A unit containing four or eight devices, optionally flanked by one or two B units that can hold up to twelve devices each. Operating in four-path mode, the system connects via a 3990 storage control unit that supports an additional second string of IBM 3390 drives—allowing up to sixty-four devices within a single subsystem.

Each Hard Disk Assembly (HDA) contains two actuator-head units along with platters: Model 1 offers a capacity of 1.89 GB per HDA; Model 2 doubles this to 3.78 GB per HDA. The Model 3 (introduced in 1991) increased capacity by fifty percent to reach 5.67 GB per HDA, while Model 9 (released in 1993) tripled it further to achieve 11.3 GB per HDA.

Departing from earlier DASD designs that employed large alternating current motors with belt drives, the IBM 3390 HDAs utilized enclosed direct current motors for direct drive operation. The Model 9 marked IBM’s final implementation of a Single Large Expensive Disk (SLED) drive design.

IBM 9345

The IBM 9345 hard disk drive was launched in November 1990 as a Request Price Quotation (RPQ) for IBM’s SuperComputing Systems Extensions (SCSE). Created at IBM's San Jose facility under the project name Sawmill, this full-height 5¼-inch HDD supported up to eight 130 mm platters, delivering a maximum storage capacity of 1.5 GB. Notably, it was the pioneering HDD to utilize magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM released the 9345 DASD within the 9340 series, a channel-attached count key data (CKD) DASD subsystem designed for IBM mainframes such as the ES/9000 lineup. The Model 1 of the 9345 consisted of two 1.0 GB drives, whereas Model 2 housed two 1.5 GB drives.

From a functional perspective, the 9340/9345 series resembled the 3990/3390 models but differed by lacking the non-volatile RAM cache found in the 3990 and offered a shorter maximum block length compared to the 3390.

The operating system’s Input/Output Supervisor (IOS) identified these devices through a specialized initializer named IECCINIT, which handled multiple DASD variants. During system initialization, the OS detected that the 9340 did not include non-volatile cache and that the 9345 had a lower track capacity, assigning device types distinct from those of the 3990/3390 accordingly.

9330 family of disk drives

1. The 9331 Diskette Unit models 1 and 11 contained a single 8-inch floppy disk drive; models 2 and 12 were equipped with one 5-inch floppy disk drive.
2. The 9332 Direct Access Storage Device incorporated the IBM 0667 hard disk drive.
3. The 9333 High Performance Disk Drive Subsystem utilized either IBM 0664 or IBM 0681 HDDs depending on specific models.
4. The 9334 Disk Expansion Unit provided connectivity for one to four SCSI hard drives to RS/6000 systems.
5. The 9335 Direct Access Storage Subsystem featured an IBM Hursley-designed "Kestrel" hard disk—a rack-mountable unit with three large (14-inch) disks totaling an 850 MB capacity, employing dual rotary actuators to access multiple surfaces. This system debuted alongside the October 1986 IBM 9370 Information System. No original equipment manufacturer (OEM) versions are documented.
6. The 9336 Disk Unit was based on the IBM 0681 HDD, also known as Redwing.
7. The 9337 Disk Array Subsystem integrated IBM’s IBM 0662 (Spitfire) or IBM 0663 (Corsair) hard disk drives.

IBM 2310

Introduced in 1964 with the IBM 1800 and subsequently in 1965 with the IBM 1130, the IBM 2310 Removable Cartridge Drive stored up to 512,000 sixteen-bit words (equivalent to approximately one million bytes) on an IBM 2315 cartridge. This cartridge contained a single oxide-coated aluminum platter encased in plastic with openings allowing access for two read/write heads via an arm mechanism.

IBM 5444

The IBM 5444, which debuted in September 1969 as part of System/3 and developed at IBM’s Hursley laboratory in England under the codename Dolphin, utilized the IBM 5440 disk cartridge featuring one fourteen-inch platter. It was available in three variations:

• Model 1: included one fixed and one removable disk, each having one hundred tracks per surface; cartridge capacity was approximately 1.23 MB
• Model 2: featured one fixed and one removable disk, each with two hundred tracks per surface; storage capacity reached about 2.46 MB
• Model 3: contained only one removable disk with two hundred tracks per surface; capacity matched that of Model 2 at roughly 2.46 MB

IBM 62GV

Launched in May 1974, the IBM 62GV was created at IBM's Hursley facility under the project name Gulliver. Initially, it provided a storage capacity of 5 MB, which was later expanded in subsequent versions to 10 MB (62TM) and 14 MB. This model utilized a Swinging Arm actuator mechanism paired with a single 14-inch platter. The actuator design, developed at Hursley, became one of IBM's most widely licensed electromechanical innovations, adopted broadly across the industry throughout the 1980s and remaining a standard nearly four decades later. Approximately 177,000 units of the IBM 62GV were sold, making it the first hard disk drive to surpass 100,000 units in sales.

OEM and Small Systems HDDs

This section details HDDs manufactured by IBM that were supplied as OEM solutions or designed for IBM's smaller computing platforms such as System/3, System/32, /34, /36, and AS/400. Drives are organized by their OEM model numbers along with their initial shipment dates.

IBM 0680

Introduced in 1979, the 0680 was utilized across many IBM small systems and lower-tier System/370 models as the 3310 direct access storage device. Officially announced as the OEM version 0680 in September 1981, it was engineered at IBM’s Hursley laboratory in the UK under the codename Piccolo. The drive offered up to 65MB capacity through six 8-inch (210 mm) platters equipped with an enhanced rotary actuator.

A higher-capacity variant known as the 62SW was released in June 1984; however, its market penetration was limited due to pricing that closely matched the IBM 62GV.

IBM 0676

The 0676 made its debut in November 1982 as part of the 5247 Disk Storage Unit for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the designation 21ED, this model featured an 8-inch HDD configuration with initial storage options of either 15 or 30MB using two or four platters sized at 210 mm each. In 1983, it was incorporated into the System/36’s 5360 System Unit. By 1984, its capacity was doubled by increasing track density per platter surface and it was integrated into the System/36’s upgraded 5362 Unit.

IBM 0665

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

IBM 0667

The 0667 became available starting August 1986. Created at IBM Rochester under the codename "Grant," it was a full-height ESDI-compatible hard drive measuring 5¼ inches with up to four platters of 130 mm diameter and a maximum capacity of 70MB. This drive was offered as an option on select PC RT models (6150, 6151, and 6152) as well as within System/36 Model Units (5363 and 5364).

IBM 0669

Shipped in 1987, the 0669 was developed at IBM Rochester under the project name "Grant-Prime." It was a full-height hard drive sized at five inches featuring up to four platters measuring 130 mm each and delivering storage capacities reaching up to 115 MB. This HDD served internally within both the System/36’s 5363 Unit and Series 1’s 4956 System Units.

IBM 0671

Also introduced in 1987, the 0671—known internally as "Lee"—was an ESDI full-height five-inch hard drive supporting up to eight platters of size 130 mm and offering capacities as high as 316 MB. This model represented IBM’s initial implementation of thin metal film recording technology on disk surfaces. By 1988, it found application within the IBM AS/400 9404 System Unit where configurations supported two or three drives.

IBM 0661

Introduced in 1989 as model 371, the 0661 was developed under the "Lightning" project at IBM facilities in Rochester and Hursley, UK. This SCSI hard drive featured a capacity of 320 MB, utilizing up to eight 95 mm platters with 14 read/write heads. In 1990, it was succeeded by a 400 MB "Turbo" variant. The 0661 became a standard component in various IBM systems, including the AS/400 System Unit Model CXX.

IBM 0681

Released in April 1990 from IBM Hursley and codenamed Redwing, the 0681 marked the final hard disk drive developed at that location. It was a full-height 5-inch HDD with a maximum capacity of 857 MB, employing twelve 130 mm platters. Notably, it was the first IBM drive to incorporate PRML data decoding technology. This model powered the 9333 Disk Drive Subsystem launched in early 1992, which later expanded to include a higher-capacity 1.07 GB version by May of the same year.

IBM 0663

The 0663, known as "Corsair," debuted in late 1991 as a compact 3-inch hard disk drive with a half-height form factor (1.6 inches tall). It provided up to 1 GB storage distributed over eight 95 mm platters. Offered on select PS/2 and RS/6000 systems, this was IBM's inaugural OEM drive equipped with Magnetoresistance (MR) head technology.

IBM 0664

Launched in November 1992 and developed under the codename "Allicat" at IBM Rochester, Minnesota, the 0664 was a full-height (3.25-inch) 5-inch HDD that combined two 3-inch drives into one unit. It delivered up to 2.013 GB capacity across eight 95 mm platters.

IBM 0662

Introduced in June 1993 and codenamed "Spitfire" at IBM Rochester, the 0662 was a full-height (1-inch tall) 3-inch hard disk drive offering a capacity of 1.05 GB using three platters or five surfaces. It served as the internal storage device for both the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was a pioneer in floppy disk technology, launching an 8-inch floppy disk drive (FDD) in 1971 primarily as a read-only program loading device. Its first read/write floppy drive appeared in 1973 alongside the introduction of the 3740 Data Entry System. Although IBM established early standards for these large-format drives, it refrained from marketing them independently, allowing industry standards for the format to develop organically.

At one point, IBM was the largest consumer of OEM-supplied 5-inch floppy drives. Its preference for two-sided drives with a track density of 48 tracks per inch helped set this configuration as an industry benchmark. Despite plans to manufacture such drives internally and explore smaller formats, IBM discontinued these initiatives by 1985. Earlier efforts to market its proprietary 4-inch DemiDiskette as an OEM product in 1983 did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three new hard disk drive families: the Travelstar series featuring compact 2-inch drives for notebook computers; the Deskstar line comprising 3-inch desktop drives; and the Ultrastar series consisting of high-performance 3-inch drives aimed at advanced computing systems.

IBM's first HDD compared to its final HDDs

The following table contrasts IBM’s inaugural hard disk drive—the RAMAC 350—with its last three OEM models from the "Star" series, illustrating remarkable advancements in capacity and efficiency alongside significant reductions in size and cost over a span of nearly five decades.

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)	~2374 (~8100 BTUs/hour), varying up to ~5500 VA depending on model	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 list 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 Beyond HDDs and FDDs

Within certain IBM operating systems, both HDDs and FDDs are categorized under DASDs (direct access storage devices). Additional technologies classified as DASDs include:

IBM 7320 Drum

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

IBM 2301 Drum

The IBM 2301, a magnetic drum storage device, was released in the late 1960s.

IBM 2303 Drum

Launched in 1964, the IBM 2303 is another magnetic drum-based storage device.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell employs short magnetic tape strips for data storage. It accommodates ten removable cells, each with a capacity of 40 MB, providing an aggregate of 400 MB.

IBM 3850 Mass Storage System

The IBM 3850 Mass Storage System, introduced in 1974, functions as a tape cartridge library that stages data onto IBM 3330 or 3350 disk drives, offering virtual drive access to the host 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 Eventful Evolution of Disk Drives
• IBM 1311 Disk Storage Drive
• IBM 2314 Direct Access Storage