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IBM 7300

From Alfawiki
Adapted from the English Wikipedia article IBM 7300, available under CC BY-SA 4.0Updated 9 August 2025
IBM Magnetic Disk Storage Division
Company typeDivision
IndustryComputer storage devices
Founded1956
Defunct2003
FateDivested to Hitachi
ParentIBM

IBM was engaged in the production of magnetic disk storage devices from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) originated from IBM, with its workforce contributing significantly to advancements in these technologies. The core mechanical architecture of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and performance benchmarks have adhered to similar criteria since the 1950s. This category of products has experienced extraordinary decreases in cost and physical dimensions, alongside substantial improvements in storage capacity and operational speed.

From 1969 through the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not establish a strong presence in producing smaller 5.25- or 3.5-inch models. Although IBM sold its magnetic disk drives commercially, it only started distributing them under original equipment manufacturer (OEM) agreements beginning in 1981. By 1996, IBM had ceased producing hard disk drives exclusively for its own systems, shifting entirely to OEM supply.

IBM has referred to its magnetic disk drives using various terms such as direct-access storage device (DASD), disk file, and diskette file. This article employs the industry-standard terminology of hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit, recognized as the first hard disk drive, was introduced on September 14, 1956, as a component of the IBM 305 RAMAC system. A related 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 beginning shipment in November 1957 to customers including United Airlines.

Engineered to fulfill real-time accounting requirements, the IBM 350 housed fifty-two 24-inch disks with a total of 100 recording surfaces, storing five million 6-bit characters (equivalent to 3.75 MB). The disks rotated at a speed of 1,200 rpm, enabling a data transfer rate of 8,800 characters per second. Its access mechanism allowed for vertical and radial movement of heads to select specific tracks. Enhanced versions were introduced throughout the late 1950s. The RAMAC 305 system equipped with the IBM 350 was leased at a rate of $3,200 per month. Production of the IBM 350 ended in 1969.

A patent originating from the RAMAC project is considered foundational for the development of disk drives. Although initially rejected by IBM’s Board over concerns about potential disruption to their punch card business, development persisted at IBM’s San Jose facility until receiving approval from IBM’s president.

The unit measured approximately 60 inches in length, stood 68 inches tall, and was 29 inches wide, weighing around one ton—necessitating forklifts or cargo aircraft for transportation. Currie Munce of Hitachi Global Storage Technologies (the company that acquired IBM’s storage division) noted that capacity could have been expanded beyond five million characters; however, marketing hesitated due to uncertain demand. Despite this caution, double-capacity models were announced in January 1959 and shipped later that year.

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 effort led by Al Hoagland commenced in 2002 at the Magnetic Disk Heritage Center alongside Santa Clara University and subsequently moved to the Computer History Museum in Mountain View in 2005, where it is publicly exhibited as part of the Revolution display.

IBM 353

The IBM 353, designed to operate alongside the IBM 7030, resembled the IBM 1301 but offered a higher data transfer speed. It provided storage for 2,097,152 (221) 64-bit words, equivalent to 134,217,728 bits, and could move data at a rate of 125,000 words per second. A prototype delivered in late 1960 was notable for being the first disk drive to implement a dedicated head per surface that floated on a cushion of compressed air, an advancement inspired by the IBM 350 disk storage (RAMAC) design. The production versions incorporated self-levitating heads similar to those used in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 enhanced the functionality of the widely used IBM 650. It utilized the IBM 350 mechanism but featured up to three access arms rather than just one as in the IBM 350, and it stored six million decimal digits plus an additional 600,000 sign characters. This device transferred entire tracks between its magnetic core memory and the 653 storage option for the IBM 650, which contained sixty signed 10-digit words—sufficient for a single disk track or tape record—alongside two other independent features.

IBM 1405

Launched in 1961 for use with the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two variants: Model 1 accommodated 10 million alphanumeric characters (60 million bits) across 25 disks, while Model 2 doubled this capacity to 20 million characters (120 million bits) using 50 disks. The disks were arranged vertically and rotated at a speed of 1200 rpm.

Each disk surface contained 200 tracks segmented into five sectors, with sectors numbered from 0 to 4 on the upper side and from 5 to 9 on the lower side. Each sector could hold between 178 and 200 characters. The unit featured one to three fork-shaped access arms equipped with two read/write heads each (one for the top and one for the bottom), which moved vertically to select among disks (0–49) and horizontally to choose tracks (0–199). The time required to read or write a sector was approximately 10 milliseconds.

Access times varied from as little as 100 milliseconds up to a maximum of about 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 included around 100,000 sectors capable of holding either 200 characters in move mode or 178 characters in load mode (the latter adding a word mark bit per character). Model 1 offered half that number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was developed specifically for the IBM 7070, with a second model announced in 1959. However, its competitiveness diminished following the release of the IBM 1301 in 1961 among users of the IBM 7070 and IBM 7074 systems. The technology within the IBM 7300 shared elements with earlier units such as the IBM 350, IBM 355, and IBM 1405.

IBM 1301

Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was aimed at supporting IBM 7000 series mainframes along with the IBM 1410. Each module held up to 28 million characters (168 million bits), or alternatively, when used with the IBM 1410, stored about 25 million characters across its set of twenty-five large disks featuring forty user-accessible recording surfaces. These disks spun at a rate of 1800 rpm and enabled data transfer speeds reaching approximately ninety thousand characters per second. Model 1 consisted of a single module while Model 2 stacked two modules vertically.

A significant innovation was its employment of individual arms and read-write heads dedicated to each disk surface that moved simultaneously in unison like a comb, drastically reducing seek times and limiting maximum access time to around one hundred eighty milliseconds. It also pioneered aerodynamically engineered heads that floated on a thin air layer above disk surfaces to improve performance.

Connection to host systems was facilitated through the IBM 7631 File Control unit, allowing compatibility with both IBM 1410 and IBM 7000 series computers or enabling sharing between two systems. Leasing fees were set at $2,100 per month for Model 1 and $3,500 per month for Model 2; purchase prices were $115,500 and $185,000 respectively. The IBM 7631 controller added an additional $1,185 monthly lease cost or $56,000 if purchased outright. All models were phased out by approximately 1970.

IBM 1302

Released in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the IBM 1301, reaching 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and a data transfer rate of 180,000 characters per second, exceeding twice the speed of its predecessor. Each module incorporated two separate access mechanisms dedicated to the inner and outer cylinder regions. A Model 2 variant doubled storage by stacking two such modules. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, with purchase prices at $252,000 and $355,500 respectively. The addition of the IBM 7631 controller incurred an extra monthly lease cost of $1,185 or a purchase price increase of $56,000. Production and support for the 1302 ceased in February 1965.

IBM 1311

The IBM 1311 Disk Storage Drive, introduced on October 11, 1962, was designed for mid-range business and scientific computer systems. Comparable in size to a top-loading washing machine, it stored up to 2 million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven different models were launched before being discontinued in the early 1970s.

Each IBM 1316 disk pack is approximately four inches tall, weighs about ten pounds, and contains six disks measuring fourteen inches in diameter. These disks provide ten recording surfaces; the outermost surfaces remain unused. A hydraulic actuator equipped with ten read/write heads accesses tracks on disks rotating at 1500 revolutions per minute. Every surface contains 100 tracks divided into twenty sectors each; every sector holds one hundred characters. The disk pack is housed within a plastic casing featuring a locking handle to facilitate straightforward insertion and removal—a design later widely adopted across the industry.

Seven models of the IBM 1311 existed: master drives equipped with controllers and slave drives without them. Master drives could manage multiple slave drives across various IBM systems:

  1. Master drive compatible with IBM 1440, 1460, or 1240 computers; capable of controlling up to four Model 2 slave drives. Released October 1962; discontinued February 1971.
  2. Slave drive matching master drive functionality. Released October 1962; discontinued January 1975.
  3. Master drive intended for IBM 1620 or 1710 systems; controls up to three Model 2 slave drives; lacks special features. Released October 1962; discontinued May 1971.
  4. Master drive designed for IBM 1401 systems; controls as many as four Model 2 slave drives. Released October 1962; discontinued February 1971.
  5. Master drive for IBM 1410, 7010, or 7740 systems; controls up to four Model 2 slave drives; incorporates standard Direct Seek capability. Released January 1963; discontinued May 1971.
  6. & #7 Models presumed to be master and slave variants introduced in March 1968; withdrawn February 1971.

Several optional enhancements were available to improve functionality and storage efficiency:

  • Direct Seek: Removes the requirement to return to track zero before moving to another track.
  • Scan Disk: Enables automated rapid searching for specific identifiers or conditions.
  • Seek Overlap: Permits concurrent seeking operations alongside reading or writing across multiple drives.
  • Track Record: Increases storage by writing a single large record per track instead of multiple sectors—achieving approximately 17.9 million bits in "Move Mode" or around 18.8 million bits in "Load Mode."

Master drives (Models 1, 3, 4, 5) feature additional power supplies and control circuitry, resulting in a width roughly one foot greater than that of Model 2 slave drives.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the IBM 1302 but uses track formatting tailored for S/360 DASD architecture rather than the earlier IBM 7000 series.

This unit employs a non-removable module comprising twenty-five platters with forty-six recording surfaces. The Model 3 configuration contains one such module; Model 4 includes two modules. Each module is equipped with two independent access mechanisms—one dedicated to the innermost set of 250 cylinders and another for the outermost set of 250 cylinders—each referred to as an access group. Every access mechanism provides one read/write head per track. The average rotational latency measures approximately seventeen milliseconds with a maximum delay of thirty-four milliseconds; maximum seek time per access group is around one hundred eighty milliseconds. Tracks are sized at nearly five thousand bytes (4,985 bytes); after accounting for formatting overhead and alternate tracks, total module capacity reaches approximately one hundred twelve megabytes. Connectivity to IBM mainframes is achieved via the IBM 2841 Storage Control Unit.

IBM 2305

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

During the System/370 period, particularly for Virtual Storage (OS/VS2), the 2305 frequently served as a paging device on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). It was also well-suited to managing high-traffic small data sets like catalogs and job queues.

The smaller 2305-1 model provides a capacity of 5.4 MB, operating at a data transfer speed of 3.0 MB/s via a two-byte channel interface, with an average access latency of 2.5 milliseconds. Its larger counterpart, the 2305-2, offers an 11.2 MB capacity at a reduced rate of 1.5 MB/s and an average access time of 5 ms.

Optimized for rapid and continuous access to limited data volumes, the 2305's balance of speed and capacity made it ideal for system-resident tasks such as work files, job queues, indices, and frequently accessed data sets. Its swift response times were particularly advantageous in heavily loaded environments requiring paging device throughput exceeding 1.5 transactions per second.

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 the IBM 1130 and IBM 1800 systems. It also connected directly to System/360 Model 20 and Model 25 units. All drives utilized removable IBM 1316 Disk Packs, which were initially introduced with the IBM 1311.

For most IBM mainframes, the Model 1 version of the 2311 links through the 2841 Control Unit; in contrast, on the System/360 Model 25, it connects via a Disk Attachment Control that performs similar functions. The disk packs employ IBM's count key data variable-length record format.

Models 11 and 12, designed specifically for the integrated control of System/360 Model 20 machines, use fixed-sector formatting. Due to these format differences, disk packs are not interchangeable between Model 1 and Models 11 or 12.

Although mechanically akin to the IBM 1311, the 2311 incorporates enhanced recording technology and stores up to 7.25 megabytes on a six-platter removable disk pack. It features ten read/write heads mounted on a hydraulically actuated arm equipped with mechanical detents for precise track alignment. Each platter surface contains 200 tracks plus three spare tracks allocated for defect management. The average seek time is approximately 85 milliseconds with a data transfer rate of around 156 kB/s.

The uniform electrical interface across System/360 models facilitated third-party manufacturers’ production of plug compatible disk drives, encouraging a competitive market for IBM-compatible storage hardware.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 systems. Its Two Channel Switch capability allowed simultaneous connection to two channels. While its disk mechanism was similar to that of the IBM 2311, it featured increased data density.

This drive stored roughly 29 million characters on a removable IBM 2316 disk pack that expanded from six to eleven disks per pack, yielding twenty recording surfaces. Each disk measured in diameter. Twenty separate read/write heads were hydraulically actuated with mechanical detents ensuring accurate track positioning; each surface contained about 200 tracks. Initial access times paralleled those of the IBM 2311 but improved in later versions due to actuator refinements. Data transfer speeds doubled to approximately 310 kB/s.

The original Model 1 package included nine drives bundled under one price point; it shipped with a storage control unit, one single-drive module, and two four-drive modules totaling nine drives. These drives were installed in pull-out drawers to facilitate easy disk pack changes and earned the nickname "Pizza Ovens." Although nine drives were included, only eight could be active simultaneously; the ninth served as an offline spare to allow maintenance without disrupting operations. Drive system addresses were configured using user-swappable plugs enabling rapid reassignment or spare designation.

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

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

IBM 2314 Direct Access Storage System - Series Overview

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

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

IBM 2319

To rival plug-compatible competitors offering storage subsystems comparable to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. This model was developed by reducing one drive from the four-drive 2313 design, rebranded as the 2319 A1, and marketed at a significantly lower rental fee to attract new clientele while maintaining premium pricing for existing users. The 2319-A1 interfaces with integrated controllers tailored 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 accommodates 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 designed for IBM 4331 midrange computer systems. Each drive provided a capacity of 64.5 MB and utilized fixed-block architecture. It supported DOS/VSE and VM operating systems running on System/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, was introduced in June 1970 to support IBM System/370 and System/360/195 systems. The initial offerings included the two-drive Model 1 and single-drive Model 2 units. Removable disk packs had a capacity of 100 MB each (404×19×13,030 bytes), with an access time of approximately 30 milliseconds and a data transfer rate of 806 kB/s. A notable advancement was the incorporation of fire code error correction, which improved reliability by allowing tolerance for disk surface defects and thereby reduced overall costs.

Originally, the system consisted of one storage control unit (3830 Model 1) physically attached to a single 3330 drive, with expandability up to four control units in a chain supporting as many as eight drives. In August 1972, IBM released the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which decoupled control units from disk drives. The upgraded 3830 functioned as a director-style controller capable of managing multiple chains; each chain began with a first unit (the 3333) that combined a controller with two drives and could oversee up to three additional attached 3330 drives for a total of eight drives per chain. Two such 3333 units could be linked to one controller, enabling support for up to sixteen drives; an optional string switch permitted connection to two controllers simultaneously.

In 1973, IBM announced double-density (-11) variants—namely the 3333–11, 3330-11, and 3336–11 Disk Packs—that doubled storage capacity to 200 MB (808×19×13,030 bytes). Mixing standard and double-density drives within the same chain was not supported. Field upgrades from standard models to Model-11 versions were offered but necessitated converting drives and migrating all data completely.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

While IBM's 3340 and 3344 models share many features, only the IBM 3340 is capable of acting as the head unit in a chain configuration. There are no A model variants for the IBM 3344; consequently, any IBM 3344 device must be connected under a head-of-string IBM 3340 A model unit.

IBM 3340

Introduced in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility was internally known as Winchester. The product line included three variants: the 3340-A2, which combined two drives with a controller, alongside the B2 model (two drives) and the B1 model (single drive). Up to eight B-units could be linked to a single A2 controller.

This system utilized removable data modules that housed both the head and arm assemblies. The module featured an access door that opened during the mechanical load and unload process to engage with the drive, eliminating the need to remove protective covers when inserting the module. It delivered an average access time of 25 milliseconds and supported data transfer speeds of 885 kB/s. Three IBM 3348 Data Module variants were available, offering capacities of 35 MB, 70 MB, and a 70 MB version equipped with fixed heads providing 500 KB of faster-access storage. The IBM 3340 incorporated built-in error correction capabilities and was phased out in 1984.

Developed under Ken Haughton’s leadership in San Jose, the original concept centered on two removable 30 MB modules. This design inspired the Winchester codename, referencing the Winchester .30-30 rifle. Despite increases in storage capacity over time, the nickname remained.

A significant technological breakthrough was its economical head design that allowed read/write heads to land and lift off directly from spinning disks without unloading. This "Winchester technology" simplified head and arm mechanics while reducing costs, eventually becoming an industry benchmark. Although the term Winchester was widely used for hard drives through the early 1990s, it has since become less common.

IBM 3344

The IBM 3344 shares similarities with the 3340 but distinguishes itself by employing fixed media instead of removable IBM 3348 data modules. Each spindle contains four logical drives, each matching the capacity of a single 3348–70 module. Available exclusively in dual-drive configurations, it lacks an A-series (head-of-string) model. The 3344-B2F variant features fixed heads positioned over certain cylinders on both drives. Both 3344-B2 and 3344-B2F require connection to a 3340-A2 or 3340-A2F unit acting as head-of-string. Internally, the IBM 3344 mirrors the IBM 3350’s architecture, differing primarily in microcode embedded within its control unit.

IBM 3350

Launched in 1975 for IBM System/370 systems, the IBM 3350 Direct Access Storage Facility bore the code name Madrid. Its sealed head-disk assemblies (HDAs), which integrated both head and arm components into a single unit, established a design precedent for subsequent IBM DASD products. The disk configuration comprised 555 cylinders, each with 30 heads, and tracks containing 19,069 bytes—resulting in roughly 317 MB of storage per HDA.

The product line included models A2, A2F, B2, B2F, C2, and C2F, each housing two HDAs. Models A2 and A2F incorporated an additional electronic board facilitating connection to control units—often called controllers or head-of-string units. These units were arranged in strings typically headed by an A2 or A2F model followed by up to three B2 units or combinations including C2 units. The A2 model generally featured a string switch allowing dual attachment to storage control units such as the IBM 3830 Model 2 or Integrated Storage Control within IBM CPUs like the 3148. Later controllers like the IBM 3880 maintained compatibility with these configurations. The C2 unit contained a secondary controller providing a backup communication path when the primary controller was offline; however, its connectivity options were limited.

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

Models designated with "x2F" (for example, A2F) contained two HDAs featuring fixed-head zones spanning the first five cylinders. This design eliminated seek delays within this area and enhanced performance for frequently accessed data such as HASP or JES2 checkpoint files and TSO swap space—thereby improving system responsiveness during context switches.

The IBM 3350 series was officially discontinued in September 1994.

IBM 3370

Released in January 1979, the IBM 3370 Direct Access Storage Device was designed to support IBM 4331, 4341, and System/38 midrange systems. It consisted of seven fixed 14-inch platters, delivering a storage capacity of 571 MB per unit. Notably, it was the first hard disk drive to incorporate thin-film head technology developed at the Thomas J. Watson Research Center. The 3370 utilized a fixed-block architecture and was compatible with DOS/VSE and VM operating systems, the only S/370 environments that supported FBA devices.

IBM 3375

The IBM 3375 served as a complementary model, employing count key data architecture required by OS/360 and its subsequent operating systems.

IBM 3380

Debuting on June 11, 1980, the IBM 3380 Direct Access Storage Device featured thin-film head technology with a total capacity of 2.52 GB per unit, composed of two hard disk assemblies each containing two independent actuators accessing 630 MB. It delivered data transfer speeds of up to 3 MB/s and had an average access time of approximately 16 milliseconds. Initial pricing ranged between $81,000 and $142,200; however, shipments were postponed until October 1981 due to tribology challenges affecting the interaction between heads and media.

A typical configuration included one A unit combined with up to three B units; each IBM 3380 housed four devices, enabling configurations of up to 16 devices per string. These strings were generally connected to a 3880 storage control unit capable of managing two concurrent I/O operations directed at different hard disk assemblies.

In February 1985, IBM released the Extended Capability Models (3380 E) featuring double-density storage with a capacity of 5.04 GB per unit (two actuators at 1.26 GB each). Later, in August 1987, the Model K offered triple the initial capacity at 7.562 GB per unit (two actuators at 1.89 GB each) and introduced an optional four-path mode that supported up to 32 devices per string with four simultaneous I/O operations through a 3990 storage control unit.

The IBM 3380 series included twelve variants: six A-units (acting as string heads with integrated controller logic interfacing with IBM storage control units), five B-units (connecting to A- or C-units), and one C-unit (which connected directly to an IBM channel).

Manufacturing continued until May 1996, marking a significant fifteen-year production span for this enterprise-level storage device.

IBM 3390

Introduced in November 1989, the IBM 3390 Direct Access Storage Device family provided storage capacities reaching up to 22 gigabytes across multiple drives. Prices varied from $90,000 to $795,000 depending on the specific configuration and capacity.

A typical IBM 3390 setup consisted of a central A unit containing four or eight devices, optionally accompanied by one or two B units holding as many as twelve devices each. Operating in four-path mode, these configurations connected to a 3990 storage control unit capable of supporting an additional 3390 string for a total of up to sixty-four devices per subsystem.

Hard Disk Assemblies (HDAs) featured two actuator-head units along with platters: Model 1 offered an unformatted capacity of 1.89 GB; Model 2 doubled this to 3.78 GB; Model 3, announced in 1991, increased capacity further to 5.67 GB; and Model 9 in 1993 expanded it significantly to 11.3 GB per HDA.

In contrast to earlier DASD models that employed belt-driven AC motors, the IBM 3390 HDAs utilized directly driven DC motors enclosed within the drive assembly. The Model 9 represented IBM’s last Single Large Expensive Disk (SLED) drive offering.

IBM 9345

Released in November 1990 as a Request Price Quotation (RPQ) for IBM's SuperComputing Systems Extensions (SCSE), the IBM 9345 hard disk drive was engineered at IBM's San Jose facility under the project name Sawmill. This full-height 5¼-inch drive housed up to eight 130 mm platters, delivering a maximum storage capacity of 1.5 GB. Notably, it was the pioneer HDD to incorporate Magnetoresistive (MR) read/write heads.

IBM 9340

The IBM 9340 DASD was introduced in October 1991 as part of the 9340 channel-attached count key data (CKD) DASD subsystem lineup designed for IBM mainframes, including the ES/9000 series processors. The Model 1 variant contained two hard drives each with a capacity of 1.0 GB, while Model 2 featured two drives with 1.5 GB each.

In terms of operation, the 9340/9345 series paralleled the functionality of the 3990/3390 models but differed by lacking the non-volatile RAM cache found in the 3990 and offering a shorter maximum block length compared to the 3390.

The OS Input/Output Supervisor (IOS) identified these devices through a specialized initializer named IECCINIT, which also handled other DASD types. Upon initialization, the operating system detected that the 9340 did not include non-volatile cache and that the 9345 had fewer tracks per surface, resulting in these devices being assigned unique device types distinct from those of the 3990/3390 family.

9330 Family of Disk Drives

  1. The 9331 Diskette Unit models 1 and 11 incorporated one 8-inch floppy disk drive; models 2 and 12 contained a single 5-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 employed either IBM 0664 or IBM 0681 HDDs depending on specific model configurations.
  4. The 9334 Disk Expansion Unit connected between one and four SCSI hard drives to RS/6000 systems.
  5. The 9335 Direct Access Storage Subsystem featured IBM's proprietary "Kestrel" hard drive with an 850 MB capacity, comprising three 14-inch platters and dual rotary actuators that allowed simultaneous access to multiple surfaces; it was announced in October 1986 as part of the IBM 9370 system, with no known OEM variants.
  6. The IBM 0681-based Disk Unit was designated as the 9336 model (codenamed Redwing).
  7. The Disk Array Subsystem, model 9337, incorporated either IBM's 0662 (Spitfire) or 0663 (Corsair) hard disk drives.

IBM 2310

Introduced initially with the IBM 1800 in 1964 and subsequently with the IBM 1130 in 1965—likely shipping first alongside the latter—the IBM 2310 Removable Cartridge Drive stored data on an IBM 2315 cartridge containing a single oxide-coated aluminum platter enclosed within a plastic shell. This cartridge had openings to accommodate the read/write arm and two heads, offering storage for approximately 512,000 sixteen-bit words (equivalent to about one million bytes).

IBM 5444

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

  • Model 1: One fixed and one removable platter, each featuring one hundred tracks per surface; cartridge capacity totaled approximately 1.23 MB
  • Model 2: One fixed plus one removable platter with two hundred tracks per surface each; capacity increased to around 2.46 MB
  • Model 3: A single removable platter offering two hundred tracks per surface; storage capacity also about 2.46 MB

IBM 62GV

The IBM 62GV, introduced starting May of 1974 and developed at IBM Hursley under project name Gulliver, initially provided five megabytes of storage on a single fourteen-inch platter operated by a Swinging Arm actuator. Subsequent versions included a ten-megabyte model (62TM) and another with fourteen megabytes capacity. This Swinging Arm actuator design—originated at Hursley—became IBM’s most widely licensed electromechanical invention, gaining extensive adoption throughout the industry from the early eighties onward and remaining in production nearly four decades later with over ten billion units manufactured globally. Approximately one hundred seventy-seven thousand units of the IBM 62GV were sold, marking it as the first hard disk drive to surpass sales of one hundred thousand units.

OEM and Small Systems Hard Drives

This segment details hard disk drives produced by IBM, provided as OEM components and for IBM’s smaller systems such as the System/3, System/32, /34, /36, and AS/400. The drives are identified by their OEM model numbers and arranged according to their initial shipment dates.

IBM 0680

Introduced in 1979, the 0680 was widely deployed across IBM small systems and the lower tiers of the System/370, marketed as the 3310 direct access storage device. The OEM variant was officially announced in September 1981 under the 0680 designation. Created at IBM’s Hursley laboratory in the UK under the project name Piccolo, it provided up to 65MB capacity through six 8-inch (210 mm) platters and featured an enhanced rotary actuator mechanism.

A double-capacity model known as the 62SW was released in June 1984; however, its market penetration was limited because its cost per megabyte was comparable to that of the 62GV.

IBM 0676

The 0676 debuted in November 1982 as a 5247 Disk Storage Unit designed for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the internal code 21ED, this 8-inch hard drive initially offered storage options of either 15 or 30 MB using two or four platters sized at 210 mm. In 1983, it became part of the S/36’s 5360 System Unit. By 1984, its capacity was doubled by increasing track density per surface and it was incorporated into the System/36’s 5362 System Unit.

IBM 0665

Released in October 1985 within the PC AT (5170) system unit, the 0665 was developed at IBM Rochester under the codename "Pixie." This hard drive measured 5 inches and came with capacities of 20, 30, and 44 MB.

IBM 0667

The 0667 arrived on the market in August 1986. Created at IBM Rochester under the project name "Grant," it was a full-height, ESDI interface, 5-inch hard drive capable of holding up to four platters each measuring 130 mm. This model was available as an option on select PC RT models (6150, 6151, and 6152) and within System/36 Model System Units (5363, 5364).

IBM 0669

Launched in 1987, the 0669 was developed at IBM Rochester, Minnesota with the codename "Grant-Prime." It featured a full-height form factor with a maximum capacity of 115 MB distributed across four platters sized at 130 mm. This drive served as the internal storage solution for both the System/36 5363 and Series 1 (4956) System Units.

IBM 0671

Also introduced in 1987, the 0671—known internally as "Lee"—was an ESDI full-height, five-inch hard disk with capacities reaching up to 316 MB using as many as eight platters of 130 mm diameter. It represented IBM’s first implementation of thin metal film recording technology. In 1988, this model was incorporated into the IBM AS/400’s 9404 System Unit supporting configurations with two or three drives.

IBM 0661

The 0661 made its debut in 1989 as model number 371. Developed collaboratively under the codename "Lightning" at IBM Rochester and Hursley (UK), this SCSI hard drive offered a maximum capacity of 320 MB utilizing up to eight platters measuring 95 mm each (with a total of fourteen read/write heads). A higher-performance "Turbo" variant with a capacity of 400 MB followed in 1990. It became a commonly used drive across prominent IBM platforms including the AS/400 System Unit Model CXX.

IBM 0681

Shipped from IBM Hursley in April 1990 under the project name Redwing—the final HDD developed at that location—the 0681 provided up to an impressive capacity of 857 MB as a full-height five-inch drive featuring up to twelve platters sized at 130 mm. It introduced PRML (Partial Response Maximum Likelihood) data decoding technology. This model powered the launch of the 9333 Disk Drive Subsystem in early 1992. By May of that year, a higher-density version offering up to 1.07 GB was added to this subsystem lineup.

IBM 0663

Introduced in late 1991, the 0663, codenamed "Corsair," was a compact 3-inch hard disk drive featuring a half-height (1.6-inch) profile. It provided storage capacities up to 1 GB utilizing eight 95 mm platters. This model was available on select PS/2 and RS/6000 systems and marked the first OEM drive to incorporate Magnetoresistance (MR) head technology.

IBM 0664

Released in November 1992, the 0664—developed under the "Allicat" project at IBM Rochester, Minnesota—was a full-height 5-inch HDD measuring 3.25 inches in height. It essentially combined two 3-inch drives, offering a maximum capacity of 2.013 GB across eight 95 mm disks.

IBM 0662

The 0662 became available in June 1993. Known internally as "Spitfire" at IBM Rochester, this full-height (1-inch tall) 3-inch HDD delivered 1.05 GB of storage on three platters or five disk surfaces. It served as the internal drive for both the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was a pioneer in floppy disk technology, debuting the 8-inch floppy disk drive in 1971 initially as a read-only program loader and introducing its first read/write version in 1973 with the 3740 Data Entry System. While IBM established early standards for 8-inch FDDs, it refrained from selling these drives independently, allowing the broader industry to evolve on its own.

At one point, IBM was the largest original equipment manufacturer consumer of 5-inch floppy drives. Its preference for double-sided drives with 48 tracks per inch contributed to this becoming an industry benchmark. Although IBM planned to produce these and smaller floppy formats internally, it discontinued all such initiatives by 1985. Notably, its 1983 effort to OEM the smaller 4-inch DemiDiskette was unsuccessful.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three distinct hard drive families: the Travelstar series featuring 2-inch drives designed for laptops; the Deskstar line with 3-inch drives intended for desktop computers; and the Ultrastar series comprising high-performance 3-inch drives for demanding applications.

IBM's first HDD versus its last HDDs

The comparison table below contrasts IBM’s inaugural hard disk drive, the RAMAC 350, against the final models from its "Star" series of OEM HDDs. This illustrates substantial advancements including drastic reductions in physical size and cost alongside significant gains in capacity and efficiency.

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


DASD devices distinct from HDDs or FDDs

In certain IBM operating systems, hard disk drives (HDDs) and floppy disk drives (FDDs) are grouped under the category of DASDs (direct access storage devices). Additional types of DASD technologies encompass:

IBM 7320 drum

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

IBM 2301 drum

The IBM 2301 is a magnetic drum storage unit that debuted in the late 1960s.

IBM 2303 drum

Released in 1964, the IBM 2303 is another example of a magnetic drum storage device.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell utilizes short magnetic tape strips for data storage. It comprises ten detachable cells, each with a capacity of 40 MB, accumulating to a total of 400 MB.

IBM 3850 Mass Storage System

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

See also

External links

Related profiles

PPunched cardDDeskstarTTravelstarMMicrodrive
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