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IBM 2302

From Alfawiki
IBM Magnetic Disk Storage Division
IndustryComputer storage devices
Founded1956
Defunct2003
FateDivested to Hitachi
ProductsHard disk drives, floppy disk drives
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. IBM pioneered both the hard disk drive (HDD) and floppy disk drive (FDD), with numerous critical advancements in these technologies credited to its workforce. The core mechanical principles behind hard disk drives have largely persisted since the introduction of the IBM 1301, and contemporary performance benchmarks originate from standards established in the 1950s. Over time, this product category has experienced dramatic decreases in cost and physical dimensions, coupled with substantial improvements in capacity and speed.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not significantly penetrate the markets for smaller 5.25- or 3.5-inch FDD formats. Although IBM consistently marketed its magnetic disk drives, it began offering them under original equipment manufacturer (OEM) agreements only starting in 1981. By 1996, IBM had discontinued producing HDDs solely for its own systems, making all models available as OEM products.

IBM has referred to its magnetic disk drives using various terms such as direct-access storage device (DASD), disk file, and diskette file; however, this article adopts the industry-standard designations hard disk drive (HDD) and floppy disk drive (FDD) for clarity.

IBM 350

The IBM 350 disk storage unit, recognized as the first hard disk drive, was unveiled by IBM on September 14, 1956, as a 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 initial prototype was delivered to Zellerbach Paper Company in June 1956, with production units commencing shipment in November 1957 to clients including United Airlines.

Engineered for real-time business accounting applications, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB) distributed over fifty-two disks utilizing one hundred recording surfaces and tracks. The disks rotated at a speed of 1200 rpm, enabling a data transfer rate of 8,800 characters per second. Its access system moved read/write heads both vertically and radially to select tracks on the disks. Several enhanced versions were released during the late 1950s. The IBM RAMAC 305 system equipped with the 350 was leased at $3,200 monthly. Production of the IBM 350 ceased in 1969.

The patent stemming from the RAMAC initiative is regarded as foundational for disk drive technology. Although initially canceled due to apprehensions about its effect on IBM’s punch card operations, development persisted at IBM San Jose until receiving approval from IBM's president.

The physical dimensions of the IBM 350 cabinet were approximately long, high, and wide; it weighed around one ton and required forklifts and cargo aircraft for transportation. Currie Munce, then research vice president at Hitachi Global Storage Technologies (the company that acquired IBM’s storage division), noted that capacity could have surpassed five million characters, but IBM’s marketing team was reluctant to promote higher capacity drives at that time. Nevertheless, double-capacity versions 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. Beginning in 2002, a restoration initiative led by Al Hoagland collaborated with Santa Clara University to refurbish an IBM 350 RAMAC unit. This effort transitioned to the Computer History Museum, Mountain View, California in 2005, where it is publicly exhibited within the museum’s Revolution gallery.

IBM 353

The IBM 353, designed to operate alongside 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, equivalent to 134,217,728 bits, and achieved transfer rates of 125,000 words per second. A prototype delivered in late 1960 was notable as the first disk drive to implement a dedicated head per surface that floated on compressed air, similar to the earlier IBM 350 design. Production versions employed self-levitating heads comparable to those utilized in the IBM 1301.

IBM 355

Unveiled on September 14, 1956, the IBM 355 served as an enhancement to the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms instead of one, enabling storage of six million decimal digits along with 600,000 sign characters. This device transferred entire tracks to and from the magnetic core memory of the 653, an optional storage unit for the IBM 650 that held sixty signed 10-digit words—adequate capacity for a single disk track or tape record.

IBM 1405

Launched in 1961 for 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; Model 2 doubled this capacity to 20 million characters (120 million bits) using 50 disks. The disks were arranged vertically in a stack and rotated at a speed of 1,200 rpm.

Each disk surface contained 200 tracks segmented into five sectors, with sectors numbered from 0–4 on the upper side and from 5–9 on the lower side. Sector capacity ranged between 178 and 200 characters. One to three forked access arms, each equipped with two read/write heads positioned on top and bottom surfaces, moved both vertically and horizontally under electronic control to access any of the disks (numbered 0–49) and tracks (numbered 0–199). Reading or writing a sector required approximately 10 milliseconds.

Access times varied between 100 milliseconds and a maximum of about 700 milliseconds for Model 1 or up to 800 milliseconds for Model 2. The latter model contained roughly 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 comprised approximately half as many sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered for integration with the IBM 7070. Although IBM announced a second model in 1959, the subsequent release of the IBM 1301 on June 5, 1961, offered an appealing alternative for users of both the IBM 7070 and IBM 7074 systems. The technology underpinning the IBM 7300 shared characteristics with that found in the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

Announced on June 2, 1961, the IBM 1301 Disk Storage Unit targeted users of mainframe computers in the IBM 7000 series as well as the IBM 1410. Each module could store up to twenty-eight million characters (168 million bits), while the capacity for the IBM 1410 variant was slightly lower at twenty-five million characters. Modules consisted of twenty-five large disks providing forty user-accessible recording surfaces with each surface containing two hundred fifty tracks. Model 1 included one module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred rpm and transferred data at ninety thousand characters per second.

A significant advancement was the implementation of an individual arm and read/write head dedicated to each surface, moving collectively like a comb. This configuration eliminated delays caused by relocating heads between disks and reduced maximum access times to approximately one hundred eighty milliseconds. The heads were aerodynamically engineered to hover on a thin cushion of air above disk surfaces, allowing closer spacing and enhanced performance.

Connection was facilitated through the IBM 7631 File Control unit, enabling compatibility with IBM 1410 or IBM 7000 series machines or allowing shared use between two computers.

Pricing reflected its advanced technology: Model 1 was available for lease at $2,100 per month or purchase at $115,500; Model 2 could be leased for $3,500 monthly or bought for $185,000. The IBM 7631 controller carried an additional cost of $1,185 monthly or $56,000 if purchased outright. All models were discontinued by 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the IBM 1301, accommodating 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, which was more than double that of its predecessor. Each module incorporated two separate access mechanisms to service the inner and outer cylinders. The Model 2 version doubled storage by stacking two modules together. Leasing fees were set at $5,600 monthly for Model 1 and $7,900 monthly for Model 2, with purchase prices of $252,000 and $355,500 respectively. The addition of the IBM 7631 controller increased costs by $1,185 per month or $56,000 for outright purchase. Production of the IBM 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. It utilized a removable IBM 1316 disk pack that held six 14-inch disks with ten recording surfaces spinning at 1,500 revolutions per minute. Each surface contained 100 tracks, each track divided into 20 sectors, with each sector storing 100 characters. The disk pack was encased in a plastic shell to facilitate handling and protect the media.

Throughout the 1960s, seven different models were introduced before being phased out by the early 1970s. The initial drive connected to the system as a "master drive," which housed the controller and could manage several Model 2 "slave drives." Master drives varied depending on system compatibility and could control between three and four slave units.

Available optional features included:

  • Direct Seek: Removed the need to return to track zero before seeking.
  • Scan Disk: Allowed for automatic high-speed search operations.
  • Seek Overlap: Enabled simultaneous seek and read/write operations across multiple drives.
  • Track Record: Enhanced storage capacity by writing one large record per track instead of multiple sectors, increasing total storage to approximately 18 million bits.

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

IBM 2302

The IBM 2302 represents the System/360 adaptation of the IBM 1302, tailored for S/360 DASD configurations. It features a fixed module containing 25 platters with a total of 46 recording surfaces. The Model 3 includes a single module while the Model 4 contains two modules. Each module is equipped with two independent access mechanisms servicing the innermost and outermost sets of 250 cylinders—designated as access groups—with one read/write head allocated per track. Rotational latency averages at 17 milliseconds with a maximum delay of up to 34 milliseconds; maximum seek time within each access group is approximately 180 milliseconds. Each track holds about 4,985 bytes; formatted capacity totals around 112 megabytes. Connection to IBM mainframe systems 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 such as the 360/85 and 360/195 via the IBM 2880 Block Multiplexor Channel.

During the System/370 era supporting Virtual Storage (OS/VS2), the IBM 2305 became a popular choice as a paging device on systems including the models 3155, 3165, 3158, 3168, as well as larger machines like the 3033, 4341, and specially microcoded versions of the 3081. It was also well-suited for high-activity small data sets such as catalogs and job queues.

The smaller capacity model, the IBM 2305-1, provided storage of approximately 5.4 megabytes with a data transfer rate reaching up to three megabytes per second over a two-byte channel interface and an average access time of about 2.5 milliseconds. The larger IBM 2305-2 offered roughly double that capacity at around 11.2 megabytes but operated at a slower transfer rate of approximately 1.5 megabytes per second with an average access time near five milliseconds.

Engineered for rapid continuous access to relatively small volumes of data, the IBM 2305 was ideal for system-resident files such as work files, job queues, indices, and frequently accessed datasets. Its swift response times made it particularly effective as a paging device in heavily loaded environments processing more than one and a half transactions per second.

IBM 2311

Launched in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive was engineered primarily for the IBM System/360, while also compatible with the IBM 1130 and IBM 1800 systems. It interfaces directly with the IBM System/360 Model 20 and Model 25. All units utilize the removable IBM 1316 Disk Pack, which debuted with the IBM 1311.

The Model 1 of the 2311 connects to most IBM mainframe systems through the 2841 Control Unit. For the System/360 Model 25, connection is established via a Disk Attachment Control that provides equivalent functionality. The disk packs employ IBM's count key data format, supporting variable record lengths.

Models 11 and 12 are designed to attach to the System/360 Model 20’s built-in control, using a fixed sector format instead. Disk packs between Model 1 and Models 11 or 12 are not interchangeable.

Though mechanically akin to the IBM 1311, the 2311 offers enhanced recording density, storing approximately 7.25 megabytes on a six-platter removable IBM 1316 disk pack. It incorporates ten read/write heads mounted on a hydraulically actuated arm, with each surface containing 200 tracks plus three optional spare tracks. The average seek time is about 85 milliseconds, and data transfer occurs at a rate of 156 kB/s.

Standardized electrical interfaces across System/360 models allowed third-party vendors to manufacture compatible disk drives, which contributed to the growth of a plug-compatible hardware ecosystem.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 was compatible with both System/360 and System/370 families, featuring a Two Channel Switch that enabled dual-channel access. Its disk mechanism resembled that of the 2311 but provided greater storage density.

This drive accommodated over 29 million characters on a removable IBM 2316 disk pack composed of eleven disks (totaling twenty recording surfaces). It utilized twenty read/write heads mounted on a hydraulically actuated arm equipped with mechanical detents for precise track positioning. Each surface contained 200 tracks. Improvements in actuator design led to faster access times compared to earlier models, effectively doubling data transfer speeds to approximately 310 kB/s.

The initial Model 1 configuration included nine disk drives sold as a single unit, comprising a storage control unit, one single-drive module, and two four-drive modules. Each drive was housed within its own drawer for convenient disk pack handling, earning these units the nickname "Pizza Ovens." While only eight drives could be accessed concurrently, the ninth functioned as an offline spare to facilitate maintenance without interrupting system operations. Drive addresses were user-configurable through swappable plugs, allowing physical address changes by replacing the plug.

An optional 2844 Control Unit allowed two System/360 channels to simultaneously access separate drives within the storage facility.

Subsequent models expanded upon these features:

IBM 2314 direct access storage facility - A series

In 1969, IBM separated the facility into distinct models capable of supporting up to nine drives (with eight online) connected to a 2314 Storage Control:

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

IBM 2319

In response to competition from plug-compatible manufacturers producing storage devices equivalent to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. This was achieved by removing one drive module from the four-drive 2313 and rebranding it as the 2319 A1, which was offered at a significantly lower rental cost. This approach allowed IBM to attract new customers with reduced pricing while preserving higher rental fees for existing clients. The 2319-A1 connects exclusively to integrated controllers designed for System/370 Models 135 and 145. Additionally, traditional 2314 DASD units such as the 2312 or 2318 could interface with the 2319-A1. The 2319 B series introduced three-drive modules capable of supporting configurations of three, six, or nine drives when attached to the new 2314 Model B Storage Control Unit.

IBM 3310

Unveiled 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 operated using 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, known by its codename Merlin, was introduced in June 1970 for IBM System/370 and System/360/195 systems. Initially available as the two-drive Model 1 and single-drive Model 2 variants, it featured removable disk packs with a capacity of 100 MB each. The device offered a 30 ms access time and data transfer speeds up to 806 kB/s. It was among the first to implement error correction using fire codes, improving reliability by accommodating disk surface defects and lowering operational costs.

The original configuration included one storage control unit (3830 Model 1) physically attached to a single 3330 drive, allowing up to three additional drives to be connected in an eight-drive chain. In August 1972, IBM released the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control units from storage drives. The upgraded 3830 functioned as a director-type controller managing multiple drive strings. The initial unit in each string, the 3333, combined a controller with two drives and could manage up to three connected 3330 drives (totaling eight drives). The enhanced 3830 Model 2 supported two such strings via connection to two 3333 units, enabling control over sixteen drives per controller; optional string switches on the 3333 allowed dual-controller operation.

In 1973, IBM introduced double-density (-11) models: the 3333–11, 3330-11, and higher-capacity 3336–11 Disk Packs offering up to 200 MB of storage. Mixing standard- and double-density drives within a single string was unsupported. Upgrading existing systems to double density necessitated drive conversion and complete data migration.

The IBM 3330 line was discontinued in 1983.

IBM 3340 and 3344

While sharing many features, only the IBM 3340 could act as the head of a drive string; there were no A model variants of the IBM 3344, which required connection to a 3340 A model serving as head of string.

IBM 3340

Introduced in March 1973 for IBM System/370, the IBM 3340 Direct Access Storage Facility bore the codename Winchester. The initial lineup included three models: the A2 featuring two drives plus a controller, and two B models—the B2 with two drives and B1 with a single drive. B models connected to an A2 unit in configurations supporting up to eight drives.

This system utilized removable data modules that incorporated both head and arm assemblies; during mechanical load/unload operations, an access door opened to connect these modules without requiring cover removal upon insertion. It delivered a rapid access time of 25 milliseconds and data transfer rates reaching 885 kB/s. Three versions of the IBM 3348 Data Module were marketed: one with a capacity of 35 MB and two with capacities of 70 MB—the latter including a variant equipped with fixed heads offering faster access speeds. The design incorporated error correction capabilities and remained in production until its withdrawal in 1984.

Developed at IBM's San Jose facility under Ken Haughton's leadership, this design originally centered on two removable modules each holding approximately 30 MB—hence its Winchester codename inspired by the Winchester .30-30 rifle cartridge. Although storage sizes increased over time, the nickname endured.

A significant advancement was its economical head design that enabled heads to land on and lift off from spinning disks without unloading, substantially reducing both complexity and cost associated with head/arm mechanisms. This innovation, known as "Winchester technology," became widely adopted across the industry.

The terms Winchester or Winnie remained popular references for hard disk drives through the early 1990s but have since fallen out of common usage.

IBM 3344

The IBM 3344 is similar in design to the 3340 but distinguishes itself by utilizing fixed media rather than the removable 3348 data modules. Each spindle accommodates four logical drives, each with a capacity equivalent to a 3348–70 module. This model is exclusively offered in dual-drive configurations and does not include an A (head of string) variant. The 3344-B2F version incorporates fixed heads positioned over specific cylinders on both drives. Both the 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F unit to serve as the head of string. Internally, the architecture of the 3344 mirrors that of the IBM 3350, with the only difference being the microcode programmed into its control unit.

IBM 3350

Released in 1975 for use with IBM System/370 systems, the IBM 3350 Direct Access Storage Facility, codenamed Madrid, introduced sealed head-disk assemblies (HDAs) that combined heads and arms into a single sealed unit—setting a new standard for IBM DASD products. Its disk layout comprised 555 cylinders, 30 heads, and tracks holding 19,069 bytes each, resulting in an approximate capacity of 317 MB per HDA.

The product line included models A2, A2F, B2, B2F, C2, and C2F, all consisting of two HDAs per unit. Models A2 and A2F contained an additional electronic board enabling connection to storage control units (also called controllers or head-of-string units). These units were arranged in strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations involving C2 units. The A2 model typically featured a string switch that permitted concurrent I/O operations to two separate HDAs via two storage control units such as the 3830 Model 2 or ISC integrated into CPUs like the 3148, 3158, or 3168. Later controllers like the IBM 3880 retained backward compatibility with these configurations.

The C2 model included its own controller acting as a secondary access path for itself and other units; however, this controller operated only when the primary A unit's controller was powered down due to malfunction. Valid string arrangements included -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

"x2F" variants (for example, A2F) were equipped with fixed-head regions spanning the first five cylinders of each HDA. This design eliminated seek time within those cylinders and enhanced performance for frequently accessed data areas such as HASP or JES2 checkpoint regions and TSO swap spaces under OS/360 successors and MVS environments—significantly improving context switching between users or batch jobs.

The IBM 3350 series was discontinued in September 1994.

IBM 3370

Introduced in January 1979 for IBM midrange systems including the 4331, 4341, and System/38, the IBM 3370 Direct Access Storage Device featured seven fixed disks measuring 14 inches each with a total capacity of 571 MB per unit. It was notable as the first hard disk drive to incorporate thin-film head technology developed at IBM’s Thomas J. Watson Research Center. The device utilized fixed-block architecture and was compatible with DOS/VSE and VM operating systems running on S/370 platforms.

IBM 3375

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

IBM 3380

Unveiled on June 11, 1980, the IBM 3380 leveraged thin-film head technology to deliver a unit capacity of 2.52 GB—comprising two hard disk assemblies each with two independent actuators accessing approximately 630 MB per actuator. It offered a data transfer rate of up to 3 MB/s and an average access time of about 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges affecting interactions between heads and media surfaces, shipments commenced in October 1981.

A typical configuration consisted of one A unit plus up to three B units; each IBM 3380 housed four devices total, allowing strings containing as many as sixteen devices. These were generally connected via IBM 3880 storage control units supporting dual paths to enable simultaneous I/O operations targeting different HDAs.

In February 1985, IBM introduced Extended Capability Models (3380 E) featuring double-density technology that doubled capacity to approximately 5.04 GB per unit (two actuators each holding around 1.26 GB). The triple-capacity model known as the 3380 K debuted in August 1987 with a capacity of roughly 7.562 GB per unit (two actuators at about 1.89 GB each) and supported an optional four-path mode which allowed up to thirty-two devices in a string through a IBM 3990 storage control unit—enabling four concurrent I/O operations.

The IBM 3380 family consisted of twelve models: six A-units functioning as heads of string with integrated string controller logic connecting directly to IBM storage control units; five B-units designed to connect to either A or C units; and one C-unit capable of connecting directly to IBM channels.

Production continued until May 1996, marking an impressive fifteen-year lifespan that exceeded that of most disk drives available during that period.

IBM 3390

Launched in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities up to 22 gigabytes distributed over multiple drives. Pricing for these systems varied between $90,000 and $795,000, depending on the chosen configuration and storage size.

A typical 3390 configuration consists of a central A unit, optionally paired with one or two B units. The A unit accommodates either four or eight drives, whereas each B unit can hold up to twelve drives. Operating in a four-path mode, the 3390 connects to a 3990 storage control unit, which is capable of managing an additional 3390 string, allowing a subsystem to support as many as 64 devices.

Hard Disk Assemblies (HDAs) incorporate two actuator-head assemblies and platters. Model 1 HDAs offer a raw capacity of 1.89 GB, Model 2 doubles this to 3.78 GB, Model 3 (introduced in 1991) increases it further to 5.67 GB, and Model 9 (released in 1993) expands capacity to 11.3 GB per HDA.

Differing from previous DASD models that utilized large AC motors with belt drives, the 3390 HDAs employ directly driven DC motors housed inside the enclosure. The Model 9 marked IBM’s final iteration of the Single Large Expensive Disk (SLED) drive design.

IBM 9345

Introduced in November 1990 as a Request for Price Quotation (RPQ) for IBM’s SuperComputing Systems Extensions (SCSE), the IBM 9345 was developed at IBM’s San Jose facility under the codename Sawmill. This full-height 5¼-inch hard disk drive featured up to eight 130 mm platters and delivered a maximum capacity of 1.5 GB. It was pioneering in its use of Magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM released the 9345 DASD as part of the broader 9340 channel-attached count key data (CKD) DASD subsystem lineup tailored for IBM mainframes such as the ES/9000 series. The Model 1 version contained two HDDs each with a capacity of 1.0 GB, while Model 2 incorporated two HDDs at 1.5 GB apiece.

While functionally similar to the earlier 3990/3390 series, the 9340/9345 lacked some features such as the non-volatile RAM cache found in the 3990 and had a reduced maximum block length compared to the 3390. The operating system’s Input/Output Supervisor (IOS) detected these devices through the IECCINIT initializer, which adjusted device type assignments based on differences in cache availability and track size.

9330 family of disk drives

  1. The 9331 Diskette Unit models 1 and 11 housed one 8-inch floppy disk drive; models 2 and 12 contained one 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 hard disks depending on the specific model.
  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 the "Kestrel" hard disk drive engineered at IBM Hursley in the UK—this was an 850 MB device incorporating three fourteen-inch platters and dual rotary actuators enabling access to six surfaces. The rack-mountable unit debuted alongside the October 1986 IBM 9370 Information System. No known OEM variants exist.
  6. The 9336 Disk Unit made use of the IBM 0681 hard disk drive, known as Redwing.
  7. The 9337 Disk Array Subsystem employed either IBM’s 0662 (Spitfire) or 0663 (Corsair) hard disk drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive was announced in conjunction with the IBM 1800 in 1964 and subsequently with the IBM 1130 in 1965, likely beginning shipments with the latter system by late that year. It stored up to 512,000 sixteen-bit words (equivalent to approximately one megabyte) on an IBM 2315 cartridge. This cartridge contained a single oxide-coated aluminum platter encased within a plastic shell featuring openings for both the read/write arm and its dual heads.

IBM 5444

Unveiled in September 1969 as a component of the System/3 lineup, the IBM 5444 was engineered at IBM's Hursley facility in England under the project name Dolphin. This device utilized the 5440 disk cartridge, which housed a single 14-inch platter. The product line consisted of three variants:

  • Model 1: incorporated one fixed and one removable disk, each featuring 100 tracks per surface; cartridge storage capacity was 1.23 MB
  • Model 2: included one fixed and one removable disk, each with 200 tracks per surface; cartridge capacity reached 2.46 MB
  • Model 3: contained a single removable disk with 200 tracks per surface; cartridge capacity also amounted to 2.46 MB

IBM 62GV

The IBM 62GV made its debut in May 1974, developed at IBM’s Hursley laboratory under the codename Gulliver. Initially, it provided a storage capacity of 5 MB. Subsequent versions expanded this to include 10 MB (62TM) and 14 MB models. The drive employed a Swinging Arm actuator mechanism paired with a single 14-inch disk. This actuator design, conceived at Hursley, became IBM’s most widely licensed electro-mechanical innovation and was adopted broadly across the industry throughout the 1980s and beyond. With total shipments reaching 177,000 units, the IBM 62GV was the first hard disk drive to surpass the milestone of 100,000 units sold.

OEM and Small Systems HDDs

This section details hard disk drives manufactured by IBM that were provided as OEM products or intended for IBM’s smaller systems such as System/3, System/32, /34, /36, and AS/400. Drives are identified by their OEM model numbers and organized according to their initial shipment dates.

IBM 0680

Introduced in 1979 for deployment across many IBM small systems and entry-level System/370 units as the 3310 direct access storage device, the drive was formally announced as the OEM model 0680 in September 1981. Developed at IBM’s Hursley laboratory in the UK under the codename Piccolo, it featured six 8-inch (210 mm) platters with an initial maximum capacity of up to 65 MB and incorporated an enhanced rotary actuator.

A higher-capacity version known as the 62SW was launched in June 1984 but experienced limited market success due to its cost per megabyte being comparable to that of the larger-capacity IBM 62GV.

IBM 0676

The 0676 was released in November 1982 as part of the IBM System/23 Datamaster’s Disk Storage Unit (model 5247). Developed at IBM Rochester in Minnesota under the designation 21ED, this hard drive utilized an 8-inch form factor and offered initial capacities of either 15 or 30 MB through configurations of two or four disks. In 1983, it was incorporated into the System/36’s 5360 System Unit. The drive’s capacity doubled in 1984 by increasing track density per surface and was subsequently integrated into the System/36’s updated 5362 System Unit.

IBM 0665

Launched in October 1985 within the PC AT (5170) system unit, the 0665 was developed at IBM Rochester under the codename "Pixie." This hard disk drive measured 5¼ inches and provided storage options of 20, 30, and 44 MB.

IBM 0667

Introduced in August 1986, the 0667 was created at IBM Rochester with the project name "Grant." It was a full-height ESDI hard drive sized at 5¼ inches, capable of housing up to four disks measuring 130 mm each and offering a maximum capacity of 70 MB. This model was utilized in selected PC RT systems (6150, 6151, and 6152) as well as System/36 Model System Units (5363 and 5364).

IBM 0669

The 0669, shipped in 1987 and developed at IBM Rochester under the codename "Grant-Prime," was a full-height hard drive with a five-inch form factor. It supported up to four disks of size 130 mm each and reached storage capacities up to approximately115 MB. This unit served as the internal hard disk for both System/36 model units (5363) and Series/1 model units (4956).

IBM 0671

Introduced in 1987, the 0671 was developed under the codename "Lee" at IBM Rochester. This full-height 5-inch HDD utilized ESDI technology, offering storage capacities up to 316 MB across as many as eight 130 mm platters. It was notable for being IBM's inaugural drive to implement thin metal film recording surfaces. By 1988, it was incorporated into the IBM AS/400 9404 System Unit, supporting configurations of two or three drives.

IBM 0661

The 0661, launched in 1989 and initially designated as model 371, originated from the "Lightning" project at IBM Rochester and Hursley, UK. This SCSI hard disk drive provided 320 MB capacity using up to eight 95 mm platters with 14 heads. A subsequent "Turbo" variant with 400 MB capacity appeared in 1990. The drive became a standard component in several key IBM systems, including the AS/400 System Unit Model CXX.

IBM 0681

Released in April 1990 and developed at IBM Hursley under the codename Redwing, the 0681 represented the final HDD created by that facility. It was a full-height 5-inch drive offering up to 857 MB storage via as many as twelve 130 mm disks and was the first IBM HDD to incorporate PRML data decoding technology. This model powered the 9333 Disk Drive Subsystem launched in early 1992, with an upgraded higher-density version of 1.07 GB introduced in May of the same year.

IBM 0663

The late-1991 arrival of the 0663, known as "Corsair," marked a shift toward compactness with its half-height (1.6-inch) form factor and a 3-inch disk size. It delivered up to 1 GB of storage using eight 95 mm platters. Selected PS/2 and RS/6000 models featured this drive, which was also IBM’s first OEM disk incorporating Magnetoresistance (MR) heads.

IBM 0664

Debuting in November 1992 and developed under the "Allicat" codename at IBM Rochester, Minnesota, the 0664 combined two 3-inch drives into a single full-height (3.25-inch high) 5-inch HDD. It provided a maximum capacity of 2.013 GB utilizing up to eight 95 mm platters.

IBM 0662

Introduced in June 1993 and internally known as "Spitfire," the 0662 was a full-height (1-inch high) HDD with a compact 3-inch form factor. It offered a capacity of 1.05 GB distributed over three disks or five recording surfaces and served as the internal hard drive for both the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology by launching an 8-inch floppy disk drive in 1971 as a read-only device designed for program loading, followed by its first read/write version in 1973 with the introduction of the 3740 Data Entry System. Although IBM established early standards for these large-format drives, it refrained from selling them separately, allowing industry development to proceed independently.

At one time, IBM held the position as the largest original equipment manufacturer buyer of 5-inch floppy disk drives, choosing a two-sided model with a track density of 48 tracks per inch that eventually became an industry benchmark. Despite intentions to manufacture these and smaller drives internally, IBM halted such plans in 1985. An earlier attempt in 1983 to OEM a smaller, four-inch DemiDiskette also did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three distinct hard disk drive product lines: the Travelstar series featuring compact 2-inch drives aimed at notebook computers; the Deskstar line consisting of larger 3-inch desktop drives; and the Ultrastar series with high-performance-focused 3-inch drives designed for demanding applications.

IBM's first HDD versus its last HDDs

The following table contrasts IBM’s initial hard drive—the RAMAC 350—with its final three models from the "Star" series of OEM HDDs. The comparison underscores substantial advancements over nearly five decades, including significant reductions in physical size and cost paired with dramatic improvements in storage capacity and performance metrics.

Parameter (units) RAMAC 350 Ultrastar 146Z10 Deskstar 180GXP Travelstar 80GN Maximum Improvement Over 46 Years
Announcement Date Sep 1956 Jul 2002 Oct 2002 Nov 2002
Storage Capacity (gigabytes) 0.004 146 180 80 48,000
Physical Dimensions (inches) 60×68×29 4×1×5.75 4×1×5.75 2.75×0.38×3.95
Physical Dimensions (millimeters) 1500×1700×700 102×25×146 102×25×146 70×9.5×100
Volume (cubic inches) 118,320 23 23 4 29,161
Volume (liters) 1,939 0.4 0.4 0.1
Weight (pounds) 2,140 1.7 1.4 0.2 1,244
Weight (kilograms) 971 0.8 0.64 0.095
Power Consumption (watts) "8100 BTUs/hour (~2374 watts), 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
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"
Volume Density (gigabytes per cubic inch) "0.00000003" 6 8 20
Volume Density (megabytes per cubic centimeter) "0.000002" 388 478 1,203
Average 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

IBM groups hard disk drives (HDDs) and floppy disk drives (FDDs) under the category of DASDs (direct access storage devices). Additional types of DASD technologies include:

IBM 7320 Drum

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

IBM 2301 Drum

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

IBM 2303 Drum

The IBM 2303, which debuted in 1964, also belongs to the magnetic drum storage category.

IBM 2321 Data Cell

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

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System is a tape cartridge library that manages data staging onto IBM 3330 or 3350 disk drives, thereby offering virtual disk volumes to the host system.

See also

External links

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