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IBM 0671

From Alfawiki
Adapted from the English Wikipedia article IBM 0671, 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
ProductsHard disk drives, floppy disk drives
ParentIBM

IBM manufactured magnetic disk storage equipment from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. IBM's workforce was responsible for inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing significantly to advancements in these fields. The core mechanical architecture of hard disk drives has stayed largely unchanged since the IBM 1301, with performance benchmarks rooted in standards set during the 1950s. Over time, this product range has seen dramatic decreases in cost and physical dimensions, coupled with major improvements in storage capacity and operational speed.

IBM produced 8-inch floppy disk drives from 1969 until the mid-1980s but did not become a leading manufacturer of the smaller 5.25- or 3.5-inch floppy drives. Although 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 stopped creating HDDs exclusively for its own systems, instead offering all drives as OEM components.

Throughout its history, IBM has referred to its magnetic disk drives using various terms such as direct-access storage device (DASD), disk file, and diskette file. For clarity, this article employs the widely accepted industry terms hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit, recognized as the first-ever disk drive, was launched on September 14, 1956, as an integral part of the IBM 305 RAMAC computer system. A related model, the IBM 355, was introduced alongside the IBM 650 RAMAC system. The initial prototype was delivered to Zellerbach Paper Company in June 1956, with production units dispatched beginning November 1957 to customers including United Airlines.

Engineered for real-time business accounting applications, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB) across fifty-two disks measuring 24 inches each, utilizing one hundred recording surfaces and tracks rotating at a speed of 1200 rpm. It incorporated a moving head assembly for data retrieval and achieved a transfer rate of 8,800 characters per second. The system was leased at $3,200 monthly and discontinued in 1969.

Patent US3503060, originating from the RAMAC initiative, is regarded as a foundational patent for disk drive technology. Although initially rejected by IBM's board due to concerns about its effect on punch card sales, development proceeded after approval from IBM’s president.

The physical dimensions of the IBM 350 were approximately 60 inches in length, 68 inches in height, and 29 inches in width, weighing close to one ton and requiring forklift handling for transportation. Despite having potential for greater capacity, IBM's marketing strategy was cautious about promoting larger models; nevertheless, versions with double capacity were introduced in 1959.

Acknowledging its historical importance, the RAMAC 350 was designated an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Restoration work commenced in 2002 under the leadership of Al Hoagland and Santa Clara University before transferring to the Computer History Museum, where it remains on public display.

IBM 353

The IBM 353, deployed on the IBM 7030, bore resemblance to the IBM 1301 but offered an enhanced data transfer rate. It provided storage for 2,097,152 (221) words of 64 bits each (totaling 134,217,728 bits) and could move data at a speed of 125,000 words per second. A prototype delivered in late 1960 was notable as the first disk drive employing one head per surface that flew on compressed air similar to the mechanism used in the IBM 350 disk storage (RAMAC). Production versions featured self-flying heads akin to those found on the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as a supplementary device for the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms, compared to the single arm on the IBM 350. Its storage capacity included 6 million decimal digits plus an additional 600,000 signs. Data transfer involved moving an entire track to and from the magnetic core memory of the 653, an optional unit for the IBM 650 that held sixty signed 10-digit words—sufficient to accommodate one 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 offered storage for 10 million alphanumeric characters (equivalent to 60 million bits) across 25 disks, while Model 2 doubled this capacity to 20 million characters (120 million bits) using 50 disks. The disks rotated vertically at a speed of 1200 rpm.

Each disk surface contained 200 tracks segmented into five sectors, with sector numbering from 0 to 4 on the upper side and from 5 to 9 on the lower side. Sector sizes ranged between 178 and 200 characters. The unit utilized one to three forked access arms, each equipped with two read/write heads servicing both sides of a disk. Vertical movement of these arms selected among disks numbered 0 through 49, while horizontal movement targeted tracks numbered from 0 to 199. The duration for reading or writing a sector was approximately 10 milliseconds.

Access times varied between a minimum of 100 milliseconds and a maximum of about 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 contained a total of 100,000 sectors capable of holding either 200 characters in move mode or 178 characters in load mode, the latter incorporating an additional word mark bit per character. Model 1 comprised half as many sectors, totaling 50,000.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered specifically for use with the IBM 7070. Although a second model was announced in 1959, its appeal diminished following the release of the IBM 1301 on June 5, 1961, which attracted customers of both the IBM 7070 and IBM 7074 systems. The technology employed by the IBM 7300 bore resemblance to that found in 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 designed for compatibility with IBM's mainframe computers in the IBM 7000 series as well as the IBM 1410. Each module could store up to 28 million characters (168 million bits), while modules paired with the IBM 1410 held slightly less at approximately 25 million characters. Each module consisted of a stack of twenty-five disks providing forty user-accessible recording surfaces, each surface containing two hundred fifty tracks. The Model 1 configuration included one module; Model 2 incorporated two modules arranged vertically. Disks rotated at a speed of eighteen hundred rpm, enabling data transfer rates reaching ninety thousand characters per second.

A significant advancement featured in this unit was the allocation of a distinct arm and read/write head for every disk surface. These heads moved collectively in unison resembling a comb structure, thereby eliminating delays caused by repositioning heads across multiple disks. This mechanism reduced maximum access times to approximately one hundred eighty milliseconds. Additionally, the IBM 1301 pioneered the use of aerodynamically designed flying heads that hover on a thin air cushion above disk surfaces, substantially improving operational efficiency.

Connection to host systems was managed via the IBM 7631 File Control unit, which facilitated integration with both IBM 1410 and IBM 7000 series computers and allowed shared usage across two systems.

Leasing fees for the IBM 1301 Model 1 were set at $2,100 per month or $115,500 for outright purchase; Model 2 commands $3,500 monthly or $185,000 to buy. The IBM 7631 controller incurred additional charges of $1,185 monthly or $56,000 if purchased. All versions were phased out by the year 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit represented a significant advancement in recording technology, delivering four times the capacity of its predecessor, the 1301, with 117 million 6-bit characters per module. It achieved an average access time of 165 milliseconds and supported data transfer rates up to 180,000 characters per second, more than doubling the throughput of the 1301. Each storage module incorporated two separate access mechanisms dedicated to the inner and outer cylinder groups. The Model 2 variant increased capacity by stacking two modules together. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, while purchase prices stood at $252,000 and $355,500 respectively; the IBM 7631 controller added an additional $1,185 monthly or $56,000 if purchased outright. Production of the 1302 ceased in February 1965.

IBM 1311

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

Each IBM 1316 disk pack consists of six disks measuring 14 inches in diameter, providing ten usable recording surfaces (the outer surfaces remain unused). These disks rotate at a speed of 1500 revolutions per minute and contain 100 tracks per surface with 20 sectors on each track; every sector holds 100 characters. Read/write heads are hydraulically positioned across tracks for data access. The disk pack is enclosed within a plastic casing equipped with a locking handle that facilitates straightforward insertion and removal—design elements that influenced subsequent disk pack innovations.

The seven models of IBM 1311 include both master drives with integrated controllers and slave drives that connect to these masters:

  1. Master drive compatible with IBM 1440, 1460, or 1240 systems; capable of controlling up to four Model 2 slave drives. (1962–1971)
  2. Slave drive designed to work with master drive features. (1962–1975)
  3. Master drive for IBM 1620 or 1710 systems; controls up to three Model 2 drives; lacks additional special features. (1962–1971)
  4. Master drive supporting IBM 1401 systems; manages up to four Model 2 drives. (1962–1971)
  5. Master drive intended for IBM 1410, 7010, or 7740 systems; controls up to four Model 2 drives; includes standard Direct Seek functionality. (1963–1971)
  6. Presumed master drive with limited documentation available. (1968–1971)
  7. Presumed slave drive corresponding to Model 6; limited information exists. (1968–1971)

Several optional enhancements were offered to boost performance and storage capabilities:

  • Direct Seek: Removes the default requirement to return the read/write heads to track zero during seek operations.
  • Scan Disk: Facilitates rapid automatic searches for specific identifiers or conditions.
  • Seek Overlap: Permits overlapping seek operations and read/write activities across multiple drives simultaneously.
  • Track Record: Increases storage efficiency by writing one large record per track instead of multiple smaller sectors—yielding approximately up to 17.9 million bits in six-bit mode.

Master drives (Models 1,3,4,5) are equipped with 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 1302, adapted specifically for S/360 direct access storage device architecture. It contains a fixed module comprising 25 platters with recording surfaces on 46 of them. The Model 3 includes a single module whereas Model 4 incorporates two modules. Each module is equipped with two independent access mechanisms—referred to as access groups—one dedicated to the innermost set of 250 cylinders and another servicing the outermost set of 250 cylinders. Each access mechanism has one read/write head per track available. The average rotational latency is approximately 17 milliseconds with a maximum delay of up to 34 milliseconds, while the maximum seek time per access group can reach up to 180 milliseconds. Tracks hold about 4,985 bytes each, resulting in a formatted capacity around 112 megabytes per module. Connection to IBM mainframes is established through the IBM 2841 Storage Control Unit.

IBM 2305

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

The arrival of System/370 and its Virtual Storage capability increased the 2305's popularity, as it frequently functioned 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 for managing small, high-activity data sets like catalogs and job queues.

The 2305-1 model provides a storage capacity of 5.4 MB and supports data transfer rates up to 3.0 MB/s via a 2-byte channel interface, with an average access time of approximately 2.5 milliseconds. In contrast, the larger 2305-2 offers an 11.2 MB capacity at a lower transfer rate of 1.5 MB/s and an average access time of around 5 milliseconds.

Optimized for rapid and continuous access to modest-sized data volumes, the 2305’s speed and capacity make it ideal for system-resident functions including work files, job queues, indices, and frequently referenced data sets. Its quick responsiveness also makes it particularly effective as a paging device in systems handling transaction rates of 1.5 or more per second.

IBM 2311

The IBM 2311 Disk Storage Drive made its debut in 1964 alongside the 2841 Control Unit, designed primarily for the IBM System/360 but also utilized by the IBM 1130, IBM 1800, and directly connected to System/360 Models 20 and 25. It employed the IBM 1316 Disk Pack originally introduced with the IBM 1311.

The Model 1 variant connects to most IBM mainframes through the 2841 Control Unit; however, for the System/360 Model 25, this role is fulfilled by a Disk Attachment Control. Disk packs are formatted using IBM's count key data variable record length format. Meanwhile, Models 11 or 12—attached via the Model 20’s integrated control—use fixed-sector formatting, rendering disk packs incompatible between these formats.

Mechanically akin to the IBM 1311 but enhanced for higher recording density, the 2311 stores up to 7.25 megabytes on a removable six-platter IBM 1316 disk pack. It features ten read/write heads mounted on a hydraulically actuated arm with mechanical detents that ensure precise track positioning. Each platter surface contains 200 tracks plus three spare tracks reserved for defect management. The average seek time is approximately 85 milliseconds, with a data transfer rate reaching up to 156 kB/s.

Thanks to standardized electrical interfaces across System/360 models, third-party manufacturers were able to produce plug compatible disk drives, fostering competitive alternatives within IBM’s storage ecosystem.

IBM 2314 Disk Access Storage Facility Model 1

Released on April 22, 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms. Equipped with a Two Channel Switch, it could connect simultaneously to two channels. While its mechanism was similar to that of the IBM 2311, it offered significantly higher data density.

This model stored roughly 29 million characters on a removable IBM 2316 disk pack composed of eleven diameter disks (totaling twenty recording surfaces). It utilized twenty individual read/write heads mounted on a hydraulically actuated arm featuring mechanical detents for each track. Each surface contained 200 tracks. Initial access times were comparable to those of the IBM 2311; however, later improvements in hydraulic actuators led to enhanced speed performance. The data transfer rate doubled to approximately 310 kB/s.

The Model 1 was sold as a package including nine disk drives under one price point; separately shipped components included a storage control unit, one single-drive module, and two four-drive modules summing to nine drives total. Drives were installed in drawers allowing straightforward disk pack access and earned the nickname "Pizza Ovens" due to their visual resemblance. Although nine drives were physically present, only eight could be accessed by the system at any given time—the ninth served as an offline spare enabling maintenance without interrupting operations. Drive system addresses were configured via user-swappable plugs, permitting flexible reassignment including designation of spares.

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

Subsequent variations of the IBM 2314 were introduced later:

IBM 2314 Direct Access Storage Facility - Model Series

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

  • 2312 Disk Storage, featuring a single-drive configuration.
  • 2313 Disk Storage, comprising four drives.
  • 2318 Disk Storage, housing two drives.

IBM 2319

To address competition from plug compatible manufacturers producing storage subsystems comparable to the 2314, IBM launched the 2319 in 1970—a cost-effective three-drive module. This was achieved by removing one drive from the four-drive 2313 unit, rebranding it as the 2319 A1, and offering it at a significantly lower rental fee. This approach reduced initial costs for new customers while retaining higher charges for existing clients. The 2319-A1 connects to integrated controllers designed for System/370 Models 135 and 145; it also supports conventional 2314 DASD models such as the 2312 or 2318. The 2319 B series expanded options by accommodating three, six, or nine drives linked to an updated 2314 Model B Storage Control Unit.

IBM 3310

On January 30, 1979, IBM introduced the IBM 3310 Direct Access Storage Device aimed at IBM 4331 midrange computer systems. Each unit provided a storage capacity of 64.5 MB and utilized fixed-block architecture, primarily supporting DOS/VSE and VM operating systems running on S/370 hardware.

IBM 3330

Launched in June 1970 for use with IBM System/370 and System/360/195 platforms, the IBM 3330—code-named Merlin—offered removable disk packs with a capacity of 100 MB each. It featured an access time of 30 ms and data transfer speeds reaching 806 kB/s. A significant advancement was its integrated error correction using fire codes, which improved dependability and lowered costs by accommodating minor disk surface flaws.

Initial setups consisted of one storage control unit (3830 Model 1) connected to up to four interlinked 3330 drives (with a maximum of eight drives per string). In August 1972, IBM unveiled the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control units from drive strings. This design permitted one or multiple strings managed by a director-style controller (3830 Model 2), with each 3333 unit containing two drives capable of controlling up to three attached 3330s—allowing capacity expansion up to sixteen drives per control unit through dual connections and optional string switches.

In 1973, double-density (-11) variants were introduced—3333–11, 3330-11, and 3336–11—with disk packs doubling their capacity to 200 MB. Mixing single-density and double-density drives within the same string was not supported; upgrading required converting drives and migrating all data completely.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

While the IBM 3340 and IBM 3344 shared many characteristics, only the IBM 3340 could function as the head of a string; the IBM 3344 had to be attached to a model A version of the IBM 3340 acting as the string leader.

IBM 3340

The IBM 3340 Direct Access Storage Facility, known by its code name Winchester, debuted in March 1973 for IBM System/370. It was offered in three configurations: the 3340-A2 with two drives plus controller, and B2 (two drives) and B1 (one drive) models that connected to an A2 unit supporting up to eight drives.

This model used removable data modules containing both head and arm assemblies; a mechanical load/unload mechanism opened or closed an access door on the module to engage it with the drive. Unlike earlier disk packs, no removal of covers was necessary during installation. The drive delivered a typical access time of 25 ms with data transfer rates of approximately 885 kB/s. Three types of IBM 3348 Data Modules were available: one offering a capacity of 35 MB, and two providing capacities of 70 MB—one including an additional fixed-head storage of about 500 KB for rapid access. The IBM 3340 incorporated error correction features and was withdrawn from production in 1984.

Developed in San Jose under Ken Haughton's guidance, its original design targeted two removable modules each with approximately 30 MB capacity—hence the nickname Winchester, inspired by the Winchester .30-30 rifle model. Although storage sizes increased over time, this name persisted.

A notable breakthrough was its economical head design that eliminated the need to unload heads from media surfaces. This "Winchester technology" allowed heads to land directly on spinning disks and lift off without unloading mechanisms, simplifying head and arm construction while reducing costs. This approach set a new industry standard.

The term Winchester remained commonly associated with hard disk drives into the early '90s but gradually fell out of regular use thereafter.

IBM 3344

The IBM 3344 is similar in design to the 3340 but utilizes fixed media instead of the removable 3348 data modules. Each spindle supports four logical drives, each providing storage capacity equivalent to a 3348–70 module. The 3344 is exclusively offered as a dual-drive system and does not include an A (head of string) variant. The 3344-B2F model incorporates fixed heads over certain cylinders on both drives. Both the 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F unit to serve as the head of string. Internally, the IBM 3344 shares its architecture with the IBM 3350, differing only in the control unit's microcode.

IBM 3350

Introduced in 1975 for use with IBM System/370, the IBM 3350 featured sealed head-disk assemblies (HDAs) that combined heads and arms into a non-removable, enclosed unit. The disk geometry consisted of 555 cylinders, 30 heads, and tracks holding 19,069 bytes each, resulting in an approximate capacity of 317 MB per HDA. This sealed HDA design became standard across IBM DASD products thereafter.

Configurations included models A2, A2F, B2, B2F, C2, and C2F, each containing two HDAs. Models A2 and A2F incorporated an additional electronic board to interface with the control unit; these units were commonly termed controllers or head-of-string devices. Typical arrangements involved one A2 or A2F followed by up to three B2 units or a combination of two B2s and one C2 unit. The A2 model featured a string switch enabling connection to two storage control units simultaneously, thereby supporting concurrent I/O operations targeting separate HDAs. Compatible storage control units included the IBM 3830 Model 2, Integrated Storage Controllers (ISC) such as those found in the IBM 3148, and later backward-compatible devices like the IBM 3880. The C2 unit also contained a controller that provided an alternate path for itself and other devices but was restricted to connection with a single control unit; it primarily served as a backup if the A unit's controller failed. Valid IBM 3350 string configurations included combinations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

Units designated with "x2F" (for example, A2F) incorporated fixed head regions spanning the first five cylinders on both HDAs, effectively eliminating seek time within this zone. This fixed-head area was typically allocated for high-access data such as HASP or JES2 checkpoint files to reduce head movement on spool devices. It also supported swap areas utilized by TSO and system swap under MVT, SVS, and MVS operating systems—enhancing context switching efficiency between TSO users or batch jobs.

The IBM 3350 series was discontinued in September 1994.

IBM 3370

Released in January 1979 for systems including the IBM 4331, 4341, and System/38 midrange computers, the IBM 3370 comprised seven fixed 14-inch disks delivering a total capacity of 571 MB per unit. It was notable for being the first hard disk drive to implement thin-film head technology developed at IBM’s Thomas J. Watson Research Center. The device employed fixed-block architecture and was supported by VSE and VM operating systems running on S/370 platforms.

IBM 3375

The IBM 3375 complemented the capabilities of the 3370 by utilizing count key data architecture required for operating systems such as OS/360 and its successors.

IBM 3380

Unveiled on June 11, 1980, the IBM 3380 Direct Access Storage Device utilized film head technology and provided a capacity of approximately 2.52 GB per unit (comprising two hard disk assemblies each equipped with two actuators accessing about 630 MB). It delivered data transfer rates up to 3 MB/s with an average access time near 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribology challenges involving head-media interaction, shipments commenced in October 1981.

The device configuration allowed one A unit plus up to three B units; each IBM 3380 contained four devices allowing strings of up to sixteen drives. These were typically connected to IBM 3880 storage controllers featuring dual paths that permitted simultaneous I/O operations directed at different HDAs.

In February 1985, IBM introduced double-density Extended Capability Models (3380 E) offering capacities of up to 5.04 GB per unit (two actuators each storing roughly 1.26 GB). The triple-capacity Model K followed in August 1987 with a capacity of approximately 7.562 GB per unit (two actuators holding about 1.89 GB each). Models J and K provided optional four-path connectivity supporting up to thirty-two devices per string when attached to IBM 3990 controllers; this allowed four concurrent I/O operations.

The IBM 3380 family included twelve distinct models: six A-units functioning as string heads with controller logic interfacing with IBM storage units; five B-units connected downstream from A- or C-units; and one C-unit directly connected to channels. Production continued until May 1996, marking an impressive fifteen-year lifespan for this disk drive series.

IBM 3390

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

A typical 3390 setup consists of a central A unit housing four or eight drives, optionally accompanied by one or two B units that can each hold up to 12 drives. It functions in a four-path mode and connects to a 3990 storage control unit, which supports attaching a second 3390 string, allowing up to 64 devices in the overall subsystem.

The Hard Disk Assemblies (HDAs) include two actuator-head assemblies and platters. Model 1 HDAs offer a formatted capacity of 1.89 GB; Model 2 doubles this to 3.78 GB. Introduced in September 1991, Model 3 increased per-HDA capacity by 50% to 5.67 GB, while the Model 9, revealed in May 1993, tripled it further to 11.3 GB per HDA.

Unlike preceding DASD models that relied on large AC motors with belt drives, the 3390 HDAs utilize DC motors directly mounted inside the enclosure.

The Model 9 marked IBM's final iteration of the Single Large Expensive Disk (SLED) drive.

IBM 9345

Introduced as a Request Price Quotation (RPQ) in November 1990 under IBM’s SuperComputing Systems Extensions (SCSE), the IBM 9345 hard disk drive was developed at IBM’s San Jose facility with the codename Sawmill. This full-height 5¼-inch form factor device housed eight 130 mm disks and offered up to 1.5 GB capacity. Notably, it was the first HDD to integrate Magnetoresistive (MR) head technology.

IBM 9340

In October 1991, IBM unveiled the 9345 DASD as part of the IBM 9340 channel-attached CKD DASD subsystem family targeting IBM mainframes such as the ES/9000 series. The Model 1 configuration included two HDDs with 1.0 GB each, whereas Model 2 featured two HDDs at 1.5 GB each.

While functionally similar to the combination of the IBM 3990 storage control unit and IBM 3390 drives, the 9340/9345 lacked the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length compared to the 3390.

The operating system's Input/Output Supervisor (IOS) identified this hardware through a specialized initializer named IECCINIT, which accounted for its absence of non-volatile caching and reduced track capacity by assigning it a device type distinct from that of the 3990/3390.

9330 family of disk drives

  1. The 9331 Diskette Unit models 1 and 11 incorporated one single-sided 8-inch floppy disk drive; models 2 and 12 featured one single-sided 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 contained either IBM 0664 or IBM 0681 hard disk drives depending on the specific model.
  4. The 9334 Disk Expansion Unit enabled connection of one to four SCSI hard disk drives to RS/6000 systems.
  5. The 9335 Direct Access Storage Subsystem employed the "Kestrel" hard disk drive developed at IBM Hursley in the UK—this model offered an 850 MB capacity with three large (14-inch) disks and dual rotary actuators accessing multiple surfaces. Introduced alongside the October 1986 IBM 9370 Information System, it was designed for rack mounting and had no OEM counterpart.
  6. The 9336 Disk Unit used the IBM Redwing (0681) hard disk drive.
  7. The 9337 Disk Array Subsystem incorporated either IBM Spitfire (0662) or Corsair (0663) hard disk drives.

IBM 2310

Announced initially in conjunction with the IBM 1800 in 1964 and later with the IBM 1130 in 1965—most likely first shipping with the latter in late that year—the IBM 2310 Removable Cartridge Drive stored up to approximately one million bytes (512,000 sixteen-bit words) on an IBM 2315 cartridge. This cartridge contained a single oxide-coated aluminum platter enclosed within a plastic shell featuring openings for both the read/write arm and its dual heads.

IBM 5444

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

  • Model 1: featured one fixed and one removable disk, each with 100 tracks per surface; cartridge capacity totaled 1.23 MB
  • Model 2: included one fixed and one removable disk, each offering 200 tracks per surface; cartridge capacity was 2.46 MB
  • Model 3: consisted of a single removable disk with 200 tracks per surface; cartridge capacity measured 2.46 MB

IBM 62GV

The IBM 62GV debuted in May 1974, developed at IBM’s Hursley laboratory under the codename Gulliver, initially delivering a storage capacity of 5 MB. Subsequent iterations expanded capacity to 10 MB (62TM) and later to 14 MB. Its design incorporated a Swinging Arm actuator paired with a single 14-inch disk. This actuator mechanism, created at Hursley, became IBM’s most widely licensed electromechanical innovation, extensively adopted by hard drives throughout the 1980s and persisting as an industry standard for nearly forty years. With shipments reaching 177,000 units, the IBM 62GV was the first hard drive to surpass the milestone of 100,000 units sold.

OEM and Small Systems HDDs

This segment details IBM-produced hard drives marketed as OEM products and intended for integration with 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 by their initial shipment dates to customers.

IBM 0680

From 1979 onward, the IBM 0680 was deployed on most IBM small systems and entry-level System/370 machines under the designation 3310 direct access storage. Officially announced as the OEM model 0680 in September 1981, it originated from development efforts at IBM’s Hursley lab in the UK under the codename Piccolo. The device comprised six 8-inch (210 mm) platters and initially offered up to 65 MB of storage with an enhanced rotary actuator mechanism.

A higher-capacity variant designated as the 62SW was introduced in June 1984 but experienced limited market penetration due to its cost per megabyte aligning closely with that of the IBM 62GV.

IBM 0676

The 0676 made its first appearance in November 1982 as part of the IBM System/23 Datamaster’s Disk Storage Unit (model 5247). Developed at IBM Rochester, Minnesota under project name 21ED, this unit featured an 8-inch hard drive with initial capacities of either 15 or 30 MB achieved through two or four platters measuring 210 mm each. By 1983, it was integrated into the System/36’s 5360 System Unit. In 1984, its capacity doubled by increasing track density per surface and it was subsequently incorporated into the System/36’s upgraded 5362 System Unit.

IBM 0665

Released in October 1985 within the PC AT (5170) system chassis, the IBM 0665 was developed under the codename "Pixie" at IBM Rochester. This model utilized a 5¼-inch form factor hard drive available in capacities of 20, 30, and 44 MB.

IBM 0667

Starting shipments in August of 1986, the 0667 was created at IBM Rochester under codename "Grant." It was a full-height ESDI hard drive sized at 5¼ inches that could accommodate up to four platters of 130 mm diameter, providing a maximum capacity of up to 70 MB. This drive was offered as an option for certain PC RT models (6150, 6151, and 6152) as well as within System/36 Model System Units (5363 and 5364).

IBM 0669

Introduced in 1987 and developed at IBM Rochester under the codename "Grant-Prime," the 0669 was a full-height hard drive measuring five inches and capable of storing up to115 MB across four platters each sized at130 mm. It functioned as the internal storage device for both the System/36 model5363 and Series1 model4956 system units.

IBM 0671

Introduced in 1987, the 0671—codenamed "Lee" and developed at IBM Rochester—was an ESDI full-height 5-inch hard drive featuring up to 316 MB storage across eight 130 mm platters. It represented IBM's inaugural implementation of thin metal film recording surfaces and was incorporated into the IBM AS/400 9404 System Unit in 1988, supporting configurations of two or three drives.

IBM 0661

The 0661 appeared in 1989 as model 371. Created under the "Lightning" project at IBM Rochester and Hursley, UK, it was a SCSI hard disk drive providing up to 320 MB capacity on eight 95 mm platters with 14 heads. A subsequent "Turbo" variant with 400 MB was introduced in 1990. This model was widely adopted as standard storage in various IBM systems, such as the AS/400 System Unit Model CXX.

IBM 0681

Released in April 1990 from IBM Hursley, UK, the 0681 was developed under the "Redwing" codename—marking the final HDD product from that facility. This full-height 5-inch unit delivered up to 857 MB using twelve 130 mm disks and introduced PRML data decoding technology. It was utilized in the 9333 Disk Drive Subsystem beginning early 1992, with a higher capacity version of 1.07 GB launched in May of that year.

IBM 0663

Launched late in 1991 under the codename "Corsair," the 0663 was a compact half-height (1.6-inch) 3-inch hard disk drive offering up to 1 GB across eight 95 mm platters. It appeared in select PS/2 and RS/6000 systems and was notable as IBM’s first OEM disk drive featuring Magnetoresistance (MR) Heads.

IBM 0664

The 0664, released in November 1992 and developed as "Allicat" at IBM Rochester, Minnesota, was a full-height (3.25-inch) 5-inch hard drive that combined two separate 3-inch units. It provided storage capacities reaching up to 2.013 GB utilizing eight 95 mm disks.

IBM 0662

Shipping in June 1993, the 0662, known as "Spitfire" during development at IBM Rochester, was a full-height (1-inch) 3-inch HDD delivering a capacity of 1.05 GB across three platters or five surfaces. This drive served internally within the IBM 9336 Disk Unit and the larger-scale 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology by launching the first read-only 8-inch floppy disk drive in 1971, followed by its initial read/write FDD in 1973 as part of the 3740 Data Entry System. Although IBM established early standards for the 8-inch FDD format, it did not market these drives independently, thereby allowing other manufacturers to shape the market.

At one point, IBM was the largest OEM buyer of 5-inch floppy drives worldwide, with its preference for two-sided units featuring a density of 48 tracks per inch contributing significantly to this becoming an industry standard format. Despite intentions to produce these and smaller floppy drives internally, all manufacturing initiatives were discontinued by 1985. Additionally, IBM's attempt in 1983 to OEM a smaller 4-inch DemiDisk did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three families of hard disk drives: the Travelstar series for notebook computers featuring compact 2-inch drives; the Deskstar line targeting desktop applications with larger 3-inch drives; and the Ultrastar series designed for high-performance environments utilizing robust 3-inch form factors.

IBM's first HDD versus its last HDDs

The following table contrasts IBM's inaugural hard disk—the RAMAC 350—with its final trio of "Star" series OEM HDDs, illustrating remarkable advancements including drastic reductions in physical size and cost alongside substantial improvements in storage capacity and operational performance.

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 (watts) 8100 BTUs/hour (2374 watts), up to5500 VA depending on model 16 10.3 1.85 1,283
Power density (megabytes/watt) 0.0016 9,125 17,476 43,243 27,375,856
List price (Template:US$) \$34,500 (\$234,000 adjusted to2002 dollars) \$1200 \$360 \$420
Price per megabyte (Template:US$) \$9,200 (\$68,000 adjusted to2002 dollars) \$0.0082 \$0.0020 \$0.0053 4,600,000 (\$34 million adjusted to2002 dollars)
Density (megabits/in²) 0.002 26,263 46,300 70,000 35 million
Density (kilobits/mm²) 0.003 40,708 71,765 108,500
Volume density (gigabytes/in³) 0.00000003 6 8 20 622 million
Volume density (megabytes/cm³) 0.000002 388 478 1,203
Latency (ms) 25 3 4 7 8
Average seek time (ms) 600 5.9 10.2 12 102
Data transfer rate (megabytes/s) 0.001 103 29.4 43.75 11,719


DASD Devices Beyond HDDs and FDDs

Within certain IBM operating systems, hard disk drives (HDDs) and floppy disk drives (FDDs) are categorized under the umbrella of DASDs (direct access storage devices). Additional forms of DASD technology encompass:

IBM 7320 Drum

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

IBM 2301 Drum

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

IBM 2303 Drum

The IBM 2303, released in 1964, also utilizes magnetic drum technology for data storage.

IBM 2321 Data Cell

Debuted in 1964, the IBM 2321 Data Cell employs short strips of magnetic tape for data retention. It features ten removable cells, each providing 40 MB, resulting in an aggregate capacity of 400 MB.

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System is a tape cartridge library that stages information onto IBM 3330 or 3350 disk drives. This system presents these drives as virtual devices to the host system.

See also

External links

Related profiles

IIBM 1311IIBM 0661IIBM 353IIBM 355
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