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IBM 0681

From Alfawiki
IBM Magnetic Disk Storage Division
Company typeDivision
IndustryComputer storage hardware
Founded1956
Defunct2003
FateDivested hard disk drive division to Hitachi
Headquarters
San Jose
,
United States
ProductsHard disk drives, floppy disk drives

IBM was a pioneer in producing magnetic disk storage hardware from 1956 until 2003, when 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 numerous advancements within these fields. The core mechanical architecture of hard disk drives has largely remained unchanged since the introduction of the IBM 1301, with key performance indicators staying relatively stable since the 1950s. Over time, these devices have experienced notable decreases in cost and physical dimensions, alongside substantial enhancements in storage capacity and operational speed.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not become a leading producer of the smaller 5.25- or 3.5-inch floppy drives. Although magnetic disk drives were available from IBM early on, it was not until 1981 that the company started offering them under original equipment manufacturer (OEM) agreements. By 1996, IBM discontinued production of HDDs exclusive to its own systems, transitioning all models to OEM offerings.

IBM applied several names to its magnetic disk products, including direct-access storage device (DASD), disk file, and diskette file; however, this article utilizes the industry-standard designations hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit marked the debut of the first disk drive and was introduced by IBM on September 14, 1956, as a component of the IBM 305 RAMAC computer system. A related model, the IBM 355, was announced for use with the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, while mass production shipments began in November 1957 to United Airlines.

Created to fulfill real-time accounting requirements, the IBM 350 held five million 6-bit characters (equivalent to 3.75 MB) across fifty-two disks measuring 24 inches in diameter. These disks provided one hundred recording surfaces and tracks. Operating at a rotational speed of 1200 rpm, it achieved a data transfer rate of 8,800 characters per second. Read/write heads were moved across surfaces and tracks by an access mechanism. Several enhanced versions were introduced in the late 1950s. The IBM RAMAC 305 system with the IBM 350 was leased at $3,200 per month. Production of the IBM 350 ceased in 1969.

The patent originating from the RAMAC project is recognized as a foundational patent for disk drive technology. Despite initial cancellation by IBM's Board of Directors due to concerns about its potential impact on punch card sales, development persisted at IBM’s San Jose facility until receiving approval from IBM’s president.

The unit's enclosure measured roughly 60 inches in length, stood 68 inches tall, and was 29 inches wide. Weighing approximately one ton, it required forklift handling for transportation and was commonly shipped via large cargo aircraft. According to Currie Munce, research vice president at Hitachi Global Storage Technologies, although capacity could have been expanded beyond five million characters, IBM’s marketing team was reluctant to promote larger capacity units. Nevertheless, 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. In 2002, a restoration effort led by Al Hoagland commenced work on refurbishing an IBM 350 RAMAC in partnership with Santa Clara University. This initiative transferred to the Computer History Museum in Mountain View, California in 2005 and is currently displayed as part of the museum’s Revolution exhibit.

IBM 353

The IBM 353, utilized in 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, with a transfer rate of 125,000 words per second. A prototype delivered in late 1960 was the first disk drive to implement one head per surface that floated on compressed air, continuing the design principles established by the IBM 350 disk storage (RAMAC). Production versions adopted self-flying heads akin to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 enhanced the functionality of the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms instead of just one as in the IBM 350. This unit could store six million decimal digits along with 600,000 sign characters. Data was transferred in full tracks to and from the magnetic core memory of the 653, an optional IBM 650 storage unit containing sixty signed 10-digit words—adequate for a single disk track or tape record—along with two unrelated functionalities.

IBM 1405

Announced in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was available in two models: Model 1 offered capacity for ten million alphanumeric characters (60 million bits) across 25 disks; Model 2 doubled this capacity to twenty million characters (120 million bits) using fifty disks. The disks were arranged vertically on a shaft rotating at 1200 rpm.

Each disk surface held 200 tracks divided into five sectors; sectors numbered 0–4 were on the top side and sectors 5–9 on the bottom. Each sector contained between 178 and 200 characters. One to three forked access arms, each equipped with two read/write heads for both top and bottom surfaces, moved vertically to select among disks (0–49) and horizontally to select tracks (0–199). Every track comprised ten sectors. Reading or writing a sector took approximately ten milliseconds.

Access times ranged from as low as 100 milliseconds up to a maximum of 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 featured a total of 100,000 sectors holding either two hundred characters in move mode or one hundred seventy-eight characters in load mode, which included an additional word mark bit per character. Model 1 contained half as many sectors.

IBM 7300

Designed for use with the IBM 7070, the IBM 7300 Disk Storage Unit had a second model announced in 1959. Nevertheless, following the release of the IBM 1301 on June 5, 1961, customers operating IBM 7070 and IBM 7074 systems favored the newer technology. The IBM 7300 utilized technology comparable to that found in the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

The IBM 1301 Disk Storage Unit was unveiled on June 2, 1961, targeting the IBM 7000 series mainframe computers and the IBM 1410. Each module stored twenty-eight million characters (168 million bits), or twenty-five million characters when used with the IBM 1410. Modules consisted of twenty-five disks providing forty user recording surfaces and totaling two hundred fifty tracks per surface. The Model 1 configuration included a single module; Model 2 stacked two modules together. Disks rotated at a speed of eighteen hundred rpm and supported data transfer rates of ninety thousand characters per second.

A significant advancement was employing an individual arm and read/write head for every surface that moved collectively like a comb assembly. This innovation eliminated delays caused by repositioning heads between disks and reduced maximum access time to one hundred eighty milliseconds. Furthermore, heads were aerodynamically engineered to fly on a thin cushion of air above each disk surface, allowing them to operate closer and enhancing performance.

Connectivity was provided through the IBM 7631 File Control, enabling compatibility with either IBM 1410 or IBM 7000 series computers and permitting shared use between two systems.

The leasing price for IBM 1301 Model 1 was $2,100 per month or $115,500 for purchase; Model 2 cost $3,500 monthly or $185,000 to acquire. The IBM 7631 controller added $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 increased storage capacity fourfold compared to the 1301, reaching 117 million 6-bit characters per module. It featured an average access time of 165 milliseconds and data transfer speeds of 180,000 characters per second, more than doubling the performance of its predecessor. Each module was equipped with two separate access mechanisms dedicated to the inner and outer cylinders. The Model 2 variant enhanced capacity by stacking two modules together. Leasing fees for the Model 1 were set at $5,600 monthly or $252,000 for outright purchase; the Model 2 was available for lease at $7,900 per month or $355,500 to buy. Additionally, the IBM 7631 controller incurred a monthly lease cost of $1,185 or a purchase price of $56,000. The IBM 1302 was discontinued in February 1965.

IBM 1311

Introduced on October 11, 1962, the IBM 1311 Disk Storage Drive catered to mid-range business and scientific computing needs. 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 released before being phased out by the early 1970s.

The IBM 1316 disk pack measures approximately 4 inches in height and weighs around 10 pounds. It consists of six disks measuring 14 inches each, providing ten usable recording surfaces. Operating at a speed of 1500 revolutions per minute, the disks are accessed by ten read/write heads mounted on a hydraulically controlled arm. Each surface contains 100 tracks with 20 sectors per track; each sector accommodates 100 characters. A protective plastic casing surrounds the disk pack to facilitate handling and insertion.

The IBM 1311 series included seven models divided into master drives—which incorporated controllers—and slave drives that lacked controllers. Master drives could manage multiple slave units—typically up to four—depending on the host system such as the IBM 1401 or IBM 1440. These models were withdrawn from service between 1971 and 1975.

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

  • Direct Seek: Removes the need to return to track zero before moving to a new track.
  • Scan Disk: Provides fast automatic search capabilities.
  • Seek Overlap: Permits concurrent seek operations and read/write processes across multiple drives.
  • Track Record: Maximizes capacity by storing one large record per track instead of multiple sectors; this method increases total storage to roughly 18 million bits under various configurations.

Master drive models (1, 3, 4, and 5) feature extra power supplies and control circuitry, making them approximately one foot wider than Model 2 slave drives.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the 1302, with track formatting tailored to S/360 DASD standards rather than those of the IBM 7000 series. It utilizes a fixed module containing 25 platters and provides recording across 46 surfaces. The Model 3 includes one such module; Model 4 incorporates two modules. Each module contains two independent access mechanisms—referred to as access groups—one dedicated to the innermost set of 250 cylinders and another for the outermost set of 250 cylinders. Each access group is equipped with one read/write head per track. The average rotational latency is approximately 17 milliseconds with a maximum delay of up to 34 milliseconds. The maximum seek time for each access group is around 180 milliseconds. Tracks hold up to 4,985 bytes; after formatting and including alternate tracks, total module capacity reaches about 112 megabytes. Connection to IBM mainframes is established through an IBM 2841 Storage Control Unit.

IBM 2305

Announced in 1970, the IBM 2305 fixed-head storage device, paired with the IBM 2835 Storage Control, initially interfaced with the 360/85 and 360/195 systems through the IBM 2880 Block Multiplexor Channel. The 2305 saw significant demand following the introduction of Virtual Storage on the System/370, frequently functioning as a paging storage for systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). It was also well-suited for managing high-transaction small data sets including catalogs and job queues.

The 2305-1 model delivers a storage capacity of 5.4 MB with a transfer speed of 3.0 MB/s over a two-byte channel interface and an average access latency of 2.5 milliseconds. In contrast, the larger 2305-2 provides 11.2 MB capacity at a transfer rate of 1.5 MB/s and an average seek time of 5 milliseconds.

Engineered for rapid and continuous access to relatively small volumes of data, the 2305’s combination of capacity and swift data throughput made it ideal for system-resident functions such as work files, job queues, indices, and frequently accessed datasets. Its quick response times rendered it especially effective as a paging device in systems experiencing heavy workloads exceeding 1.5 transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive debuted in 1964 alongside the 2841 Control Unit, serving the IBM System/360 series while also supporting the IBM 1130, IBM 1800, and direct attachment to System/360 Models 20 and 25. This drive employed the removable IBM 1316 Disk Pack, originally designed for the IBM 1311.

While most IBM mainframes connected to the Model 1 via the 2841 Control Unit, the System/360 Model 25 utilized a Disk Attachment Control offering comparable functionality. Disk packs were formatted using IBM’s count key data variable record length system. However, Models 11 and 12—used with the System/360 Model 20’s integrated control—employed fixed-sector formatting; disk packs were not interchangeable between these two formatting types.

Though mechanically akin to the IBM 1311, the 2311 incorporated improved recording technology and stored up to 7.25 megabytes on a six-platter removable disk pack. It featured ten read/write heads mounted on a hydraulically actuated arm with mechanical detents to ensure precise track alignment. Each platter surface contained 200 tracks plus three spare tracks reserved for defect management. The average seek time was approximately 85 ms, with a data transfer rate reaching up to 156 kB/s.

Uniform electrical interfaces across the System/360 lineup allowed third-party vendors to manufacture plug-compatible disk drives, fostering competition in the IBM ecosystem.

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 environments. Equipped with an optional Two Channel Switch feature, it could connect simultaneously to two channels. While its drive mechanism was similar to that of the IBM 2311, it offered increased data density.

The IBM 2314 housed over twenty-nine million characters on a removable IBM 2316 disk pack comprising eleven disks of diameter (totaling twenty recording surfaces). It utilized twenty read/write heads mounted on a hydraulically actuated arm with mechanical detents for accurate track positioning. Each surface contained two hundred tracks. Subsequent models enhanced access times beyond those of the original IBM 2311 design while doubling data transfer rates to approximately 310 kB/s.

The Model 1 system came as a package of nine disk drives sold at a single price point, including a storage control unit, one single-drive module, and two four-drive modules. Drives were installed in drawers facilitating easy disk pack removal and earned the nickname "Pizza Ovens" due to their visual resemblance. Although nine drives were present, only eight could be accessed concurrently; one served as a hot spare or was reserved for offline maintenance tasks. Drive system addresses were configured by swapping user-accessible plugs, enabling flexible assignment including designation of spare units.

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

Subsequent versions of the IBM 2314 further expanded its features:

IBM 2314 Direct Access Storage System - Variants

In 1969, IBM segmented the storage system into distinct models capable of supporting up to nine drives (with eight active simultaneously) connected to a 2314 Storage Control. These included:

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

IBM 2319

To compete with plug-compatible vendors offering alternatives equivalent to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. This model was developed by removing one drive from the four-drive 2313 configuration, rebranding it as the 2319 A1, and pricing it significantly lower on rental terms. This approach reduced expenses for new customers while keeping existing customers' rental fees high. The 2319-A1 connects exclusively to integrated controllers designed for System/370 Models 135 and 145. Traditional 2314 DASD units such as the 2312 or 2318 can also be linked to the 2319-A1. The 2319 B series supports configurations of three, six, or nine drives connected to an updated 2314 Model B Storage Control Unit.

IBM 3310

Introduced on January 30, 1979, the IBM 3310 Direct Access Storage Device was aimed at IBM 4331 midrange computer systems. Each drive provided a storage capacity of 64.5 MB. Utilizing fixed-block architecture, the 3310 was compatible solely with DOS/VSE and VM operating systems running on S/370 hardware.

IBM 3330

The IBM 3330 Direct Access Storage Facility, internally known as Merlin, debuted in June 1970 for IBM System/370 and System/360 Model 195 platforms. Initially offered in two variants—a two-drive Model 1 and a single-drive Model 2—it employed removable disk packs each holding 100 MB. Its access time was rated at 30 ms with data transfer speeds reaching 806 kB/s. Notably, it incorporated built-in error correction utilizing fire codes, which enhanced dependability and lowered costs by allowing for minor disk surface imperfections.

The original configuration paired one storage control unit (3830 Model 1) with up to four drives attached in a chain of as many as eight drives total. By August 1972, IBM introduced the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control units from drive strings. The upgraded 3830 functioned as a director-type controller overseeing multiple drive strings. The initial unit in each string, the 3333, combined a controller with two drives and could manage up to three additional connected 3330 units, totaling eight drives per string. Two such 3333 units could be linked to one 3830 Model 2 controller, enabling support for up to sixteen drives per controller; optional string switches allowed connections to multiple controllers.

In 1973, IBM announced double-density (-11) models—3333–11, 3330-11, and 3336–11—that featured disk packs with capacities up to 200 MB. Mixing standard- and double-density drives within a single string was unsupported. Although field upgrades from original Models to Model-11 versions were possible, they were complex procedures requiring conversion of drives and complete data migration.

The IBM 3330 product line was discontinued in 1983.

IBM 3340 and IBM 3344

While sharing many characteristics, the IBM 3340 and 3344 differ in that only the 3340 can act as the head of a drive string; the 3344 must be connected downstream to a 3340 A model serving as the head unit.

IBM 3340

The IBM 3340 Direct Access Storage Facility, internally known as Winchester, debuted in March 1973 for IBM System/370 systems. It was available in three configurations: the 3340-A2 (which included two drives and a controller), the 3340-B2 (two drives only), and the 3340-B1 (a single drive). Up to eight B-units could be connected to one A2 unit.

This system utilized removable data modules that housed both the head and arm assembly, featuring a mechanically operated access door during loading and unloading. This design eliminated the previous necessity of removing disk pack covers. The device offered an access time of 25 milliseconds and a data transfer rate of 885 kilobytes per second. Three module variants were marketed: one with a 35 MB capacity and two with 70 MB, one of which included a 500 KB fixed-head area for faster data retrieval. The IBM 3340 incorporated error correction capabilities and was discontinued in 1984.

Developed in San Jose under Ken Haughton’s leadership, the original concept involved two removable modules of approximately 30 MB each, inspiring the "Winchester" codename after the Winchester .30-30 rifle. Despite later increases in storage capacities, the nickname endured.

A major advancement was the economical head design enabling heads to land on and lift off from spinning disks without unloading, significantly simplifying the head and arm mechanics while lowering manufacturing costs. This "Winchester technology" set an industry benchmark for disk drive architecture.

The term Winchester continued to be used as a generic label for hard drives into the early 1990s but has since fallen out of widespread usage globally.

IBM 3344

The IBM 3344 shares similarities with the 3340 but employs fixed media rather than removable 3348 data modules. Each spindle supports four logical drives, each matching the capacity of a 3348–70 module. The model is exclusively available in dual-drive configurations, lacking an A-unit (head of string) variant. The 3344-B2F differs from the 3344-B2 by incorporating fixed heads over certain cylinders on both drives. Both models require a 3340-A2 or 3340-A2F unit to serve as head of string. Internally, the IBM 3344 is identical to the IBM 3350; differences are confined to control unit microcode variations.

IBM 3350

The IBM 3350 Direct Access Storage Facility, known by its code name Madrid, was introduced in 1975 for use with IBM System/370 platforms. Featuring sealed, non-removable head-disk assemblies (HDAs) that integrated head and arm components, it established a design standard for subsequent IBM DASD products. Its disk geometry consisted of 555 cylinders, 30 heads, and approximately 19,069 bytes per track, delivering roughly 317 MB of storage per HDA.

Available models included A2, A2F, B2, B2F, C2, and C2F—all containing two HDAs. The A2 and A2F models incorporated an additional electronic board facilitating connection to the control unit; these often functioned as controllers or head-of-string units. Units were organized into strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. The A2 model typically featured a string switch allowing concurrent I/O operations to different HDAs through two storage control units such as the Model 3830 or integrated storage controllers embedded in CPUs like the IBM 3148 and later models (e.g., the IBM 3880), which maintained backward compatibility.

The C2 model contained a secondary controller providing a backup access path for itself and other units but offered fewer connection options compared to the string switch found in A units. Valid IBM 3350 string configurations included -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC- arrangements.

Models with an "x2F" suffix (such as A2F) featured fixed-head zones covering the first five cylinders on both HDAs, effectively eliminating seek time within this region. This enhancement targeted high-access areas like HASP or JES2 checkpoint files to reduce head movement on spool devices. It also supported TSO swap data along with system swap data for OS/360 successors (MVT, SVS) and MVS by improving context switching efficiency between users or batch jobs.

The IBM 3350 line was officially retired from service in September 1994.

IBM 3370

Debuting in January 1979 for IBM 4331, 4341, and System/38 midrange systems, the IBM 3370 Direct Access Storage Device incorporated seven fixed 14-inch platters, providing a storage capacity of 571 MB. It marked the first hard disk drive to implement 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 running on S/370 platforms.

IBM 3375

The IBM 3375 served as a counterpart to the 3370, employing count key data architecture essential for operation under OS/360 and its subsequent versions.

IBM 3380

Unveiled on June 11, 1980, the IBM 3380 featured film head technology and offered a unit capacity of 2.52 GB, achieved through two hard disk assemblies each equipped with two independent actuators accessing 630 MB. It supported data transfer speeds of up to 3 MB/s with an average access latency of 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges affecting head-media interaction, deliveries commenced in October 1981.

The typical setup consisted of one A unit coupled with up to three B units; each IBM 3380 contained four devices, enabling configurations with up to sixteen devices per string. These drives were usually attached to IBM 3880 storage control units featuring dual-path connectivity, allowing two concurrent I/O operations directed at separate hard disk assemblies.

In February 1985, IBM introduced the double-density Extended Capability (3380 E) models, doubling capacity to 5.04 GB per unit by utilizing two actuators with 1.26 GB each. Later, in August 1987, the triple-capacity Model K expanded storage to 7.562 GB per unit with two actuators at 1.89 GB each and offered an optional four-path mode. This enhancement allowed up to thirty-two devices per string via a 3990 storage control unit and supported four simultaneous I/O processes.

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

Production of the IBM 3380 concluded in May 1996 following a fifteen-year market presence, distinguishing it as one of the longest-lasting enterprise storage products.

IBM 3390

Launched in November 1989, the IBM 3390 Direct Access Storage Device series provided capacities reaching up to 22 gigabytes distributed across multiple drives. System pricing varied from $90,000 to $795,000 depending on configuration and total storage.

A typical IBM 3390 string comprised a central A unit containing four or eight devices, optionally supplemented by one or two B units housing up to twelve devices each. Operating in four-path mode via a connection to a 3990 storage control unit, the system could support an additional string for a maximum of sixty-four devices within a single subsystem.

Each Hard Disk Assembly (HDA) included two actuator-head units along with platters. The Model 1 HDA delivered an unformatted capacity of 1.89 GB; Model 2 doubled this to 3.78 GB per HDA. Released in September 1991, Model 3 increased capacity further to 5.67 GB per HDA, while Model 9, introduced in May 1993, expanded it significantly to 11.3 GB per HDA.

Distinct from previous DASD designs that relied on large AC motors and belts, the IBM 3390 HDAs incorporated directly driven DC motors housed within the enclosure.

The Model 9 represented IBM’s final offering in the Single Large Expensive Disk (SLED) category.

IBM 9345

Introduced in November 1990 as a Request for 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 HDD supported up to eight 130 mm platters, delivering a maximum storage capacity of 1.5 GB. It was pioneering as the first hard drive to incorporate Magnetoresistive (MR) read/write heads.

IBM 9340

The IBM 9345 DASD debuted in October 1991 within the 9340 series of channel-attached count key data (CKD) DASD subsystems tailored for IBM mainframes, notably including the ES/9000 processor line. The Model 1 configuration consisted of two 1.0 GB drives, whereas Model 2 comprised two drives each with 1.5 GB capacity.

In terms of functionality, the 9340/9345 series mirrored the capabilities of the 3990/3390 models but omitted the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length compared to the 3390.

Device recognition by the operating system’s Input/Output Supervisor (IOS) was managed through a dedicated initializer named IECCINIT. This routine detected the absence of non-volatile cache in the 9340 and identified the reduced track capacity characteristic of the 9345, assigning appropriate device types accordingly.

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 were equipped with one 5¼-inch floppy disk drive.
  2. The 9332 Direct Access Storage Device utilized the IBM 0667 hard disk drive.
  3. The 9333 High Performance Disk Drive Subsystem employed either IBM 0664 or IBM 0681 HDDs depending on specific model variants.
  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 an IBM-designed "Kestrel" hard disk drive with an 850 MB capacity, containing three 14-inch platters and dual rotary actuators enabling access to multiple surfaces. Announced in October 1986 alongside the IBM 9370 Information System, this rack-mountable unit did not have any known OEM equivalents.
  6. The 9336 Disk Unit was built around the IBM 0681 HDD, also known as Redwing.
  7. The 9337 Disk Array Subsystem incorporated IBM’s 0662 (Spitfire) or 0663 (Corsair) hard drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive was launched in 1964 alongside the IBM 1800 and subsequently introduced with the IBM 1130 in 1965, likely shipping initially with the latter late that year. It stored a total of 512,000 sixteen-bit words (equivalent to 1,024,000 bytes) on an IBM 2315 cartridge that contained a single oxide-coated aluminum platter encased within a plastic shell featuring openings for both the read/write arm and two heads.

IBM 5444

Released in September 1969 as part of System/3, the IBM 5444 was developed at IBM’s Hursley laboratory in England under the codename Dolphin. It utilized a single-disk cartridge designated as the IBM 5440 containing one fourteen-inch platter. Three distinct models were available:

  • Model 1: included one fixed disk plus one removable disk, each providing 100 tracks per surface; cartridge capacity was approximately 1.23 MB
  • Model 2: featured one fixed and one removable disk, each with double that track density at 200 tracks per surface; cartridge capacity reached about 2.46 MB
  • Model 3: comprised solely one removable disk with a track density of 200 tracks per surface; cartridge capacity also around 2.46 MB

IBM 62GV

The IBM 62GV, which began shipping in May of 1974 from IBM’s Hursley laboratory in the United Kingdom under the project name Gulliver, initially offered a storage size of five megabytes. Subsequent versions expanded capacity to ten megabytes (62TM) and later fourteen megabytes. It employed a Swinging Arm actuator mechanism paired with a single fourteen-inch platter. This actuator design became IBM’s most widely licensed electro-mechanical innovation, extensively adopted throughout hard disk drives during the decade of the eighties and remaining in use today with cumulative production exceeding ten billion units. Approximately 177,000 units of the IBM 62GV were shipped, marking it as the first HDD model to surpass sales of one hundred thousand units.

OEM and Small Systems Hard Drives

This segment outlines HDDs produced by IBM, distributed as OEM components and designed for IBM small-scale systems such as the System/3, System/32, /34, /36, and AS/400. The drives are cataloged by their OEM model designations and organized according to their initial shipment dates.

IBM 0680

Introduced in 1979, the 0680 was utilized across many IBM small systems and entry-level System/370 models, branded as the 3310 direct access storage device. Officially announced as the 0680 OEM variant in September 1981, this drive was engineered at IBM’s Hursley laboratory in the UK under the project name Piccolo. It incorporated six 8-inch (210 mm) platters along with an enhanced rotary actuator, delivering a starting capacity up to 65MB.

A higher-capacity iteration, known as the 62SW, became available in June 1984 but experienced modest market penetration due to pricing that closely matched the 62GV model.

IBM 0676

The 0676 made its debut in November 1982 as part of the 5247 Disk Storage Unit tailored for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the internal code 21ED, this HDD featured eight-inch platters and initially offered storage options of either 15 or 30 MB through configurations of two or four 210 mm disks. By 1983, it was incorporated within the S/36's 5360 System Unit. In 1984, its capacity was doubled by increasing track density per platter surface, subsequently being utilized in the System/36’s 5362 System Unit.

IBM 0665

The 0665 was introduced in October 1985 within the PC AT (5170) chassis. Created under the codename "Pixie" at IBM Rochester, this model was a 5¼-inch hard disk drive available in capacities of 20, 30, and 44 MB.

IBM 0667

Released in August 1986, the 0667 was developed at IBM Rochester with the project name "Grant." This full-height ESDI HDD measured 5¼ inches and supported up to four 130 mm platters with a total capacity of approximately 70 MB. It was employed in select PC RT models (6150, 6151, 6152) as well as System/36 Model System Units (5363, 5364).

IBM 0669

The 0669, launched in 1987 and created at IBM Rochester under the codename "Grant-Prime," was a full-height five-inch HDD featuring up to four 130 mm disks that delivered a maximum capacity of around 115 MB. It served internally within System/36’s 5363 and Series/1’s 4956 System Units.

IBM 0671

Also introduced in 1987, the 0671 was developed at IBM Rochester under the name "Lee." This full-height five-inch ESDI hard drive provided storage up to approximately 316 MB across eight platters measuring 130 mm each. Notably, it was IBM’s first disk utilizing a thin metal film recording surface. By 1988, it had been integrated into the IBM AS/400 9404 System Unit configuration supporting two or three drives.

IBM 0661

The 0661 appeared in 1989 as model number 371. Created under the codename "Lightning" at both IBM Rochester and Hursley in the UK, it was a SCSI HDD offering a capacity of up to 320 MB using eight platters sized at 95 mm with fourteen heads. A subsequent "Turbo" variant providing up to 400 MB was released in 1990. This drive became a standard component across various IBM platforms including the AS/400 System Unit Model CXX.

IBM 0681

Introduced in April 1990 from IBM Hursley’s laboratory under the project name "Redwing," this full-height five-inch HDD represented Hursley’s final contribution to IBM’s hard drive lineup. It delivered capacities reaching up to approximately 857 MB through twelve platters measuring 130 mm each and incorporated PRML data decoding technology. The drive powered the launch of the 9333 Disk Drive Subsystem in early 1992, with an enhanced density version offering about 1.07 GB becoming available by May of that year.

IBM 0663

Introduced in late 1991 under the codename "Corsair," the 0663 was a compact 3-inch hard disk drive with a half-height (1.6-inch) form factor. It provided up to 1 GB of storage across eight 95 mm platters. This model was incorporated into certain PS/2 and RS/6000 systems and marked IBM's first use of Magnetoresistance (MR) heads in an OEM disk drive.

IBM 0664

Unveiled in November 1992 and developed at IBM Rochester, Minnesota, under the project name "Allicat," the 0664 was a full-height 5-inch hard disk drive with a height of 3.25 inches. It combined two 3-inch drives to achieve a maximum capacity of 2.013 GB using up to eight 95 mm platters.

IBM 0662

Released in June 1993 and known internally as "Spitfire" at IBM Rochester, the 0662 was a full-height (1-inch) 3-inch hard disk drive offering 1.05 GB of storage distributed over three platters or five surfaces. It functioned 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 loading device, followed by its first read/write version in 1973 integrated into the 3740 Data Entry System. While IBM played a key role in establishing early standards for 8-inch floppy drives, it did not sell these drives independently, enabling the broader market to develop on its own.

At one point, IBM was the largest original equipment manufacturer (OEM) buyer of 5-inch floppy drives. Its selection of two-sided units with 48 tracks per inch contributed significantly to this format becoming an industry norm. Although IBM had plans to produce these and smaller floppy formats internally, all such initiatives were halted by 1985. A notable effort in 1983 to OEM a smaller 4-inch DemiDiskette did not come to fruition.

"Star" series of HDDs

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

IBM's first HDD compared to its final HDD models

The following table contrasts IBM's inaugural hard disk drive, the RAMAC 350, with its last three OEM HDDs from the "Star" series. This comparison underscores remarkable reductions in physical size and cost alongside substantial enhancements in capacity and operational efficiency over a span of nearly five decades.

Parameter (units) RAMAC 350 Ultrastar 146Z10 Deskstar 180GXP Travelstar 80GN Improvement over 46 years (maximum)
Announcement date Sep 1956 Jul 2002 Oct 2002 Nov 2002
Storage capacity (GB) 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) Approximately 2374 watts (8100 BTUs/hour), up to 5500 VA depending on configuration 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 in terms of year-2002 dollars) $0.0082 $0.0020 $0.0053
Data density (megabits per square inch) 0.002 26,263 46,300 70,000
Data 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 distinct from HDDs and FDDs

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

IBM 7320 drum

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

IBM 2301 drum

Launched in the late 1960s, the IBM 2301 is another type of magnetic drum device.

IBM 2303 drum

Dating back to 1964, the IBM 2303 is a magnetic drum storage apparatus.

IBM 2321 Data Cell

Revealed in 1964, the IBM 2321 Data Cell employs short strips of magnetic tape for data storage. It accommodates ten detachable cells, each with a capacity of 40 MB, resulting in a total storage of 400 MB.

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System is a tape cartridge library designed to stage data onto IBM 3330 or 3350 disk drives. To the operating system, it appears as virtualized 3330 drives.

See also

External links

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