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IBM 1301

From Alfawiki
IBM Magnetic Disk Storage Division
Company typeDivision
IndustryComputer storage devices
Founded1956
Defunct2003
FateDivested to Hitachi
ProductsHard disk drives, floppy disk drives
ParentIBM

IBM was a pioneer in producing magnetic disk storage devices from 1956 until 2003, when it divested its hard disk drive division to Hitachi. The company is credited with inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), with numerous technological advancements driven by IBM engineers. The core mechanical architecture of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and performance benchmarks have adhered to consistent standards established in the 1950s. Over time, these devices have experienced dramatic reductions in cost and physical dimensions, while simultaneously achieving substantial improvements in capacity and performance.

IBM manufactured 8-inch floppy disk drives from 1969 through the mid-1980s but did not establish a significant presence in the market for smaller 5.25-inch or 3.5-inch floppy drives. While IBM sold its magnetic disk drives commercially, it only began offering them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had discontinued producing HDDs solely for its own systems, shifting entirely to OEM distribution.

Throughout its history, IBM used various designations for its magnetic disk storage products, such as direct-access storage device (DASD), disk file, and diskette file. This article adopts the widely accepted industry terminology: hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit marked the debut of the first hard disk drive and was introduced as part of the IBM 305 RAMAC system on September 14, 1956. A related model, the IBM 355, was announced for use with the IBM 650 computer. The initial prototype was delivered to Zellerbach Paper Company in June 1956, with production units commencing shipments in November 1957 to customers including United Airlines.

Engineered to support real-time accounting applications, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB) across fifty-two disks utilizing one hundred recording surfaces. The disks rotated at a speed of 1200 rpm, enabling a data transfer rate of 8,800 characters per second. A complex access system allowed read/write heads to move both vertically and horizontally to select specific surfaces and tracks on the disks. Several enhanced versions were introduced throughout the late 1950s. The IBM RAMAC 305 system bundled with the 350 was leased at a rate of $3,200 per month. Production of this model ended in 1969.

The patent originating from the RAMAC project is regarded as the foundational intellectual property for disk drive technology. Although initially rejected by IBM's Board due to concerns about cannibalizing its punch card business, development proceeded with authorization from IBM's president.

The device’s cabinet measured approximately long, high, and wide, weighed around one ton, and required forklift handling for relocation. According to Currie Munce of Hitachi Global Storage Technologies, marketing considerations constrained capacity expansion despite technical possibilities; nevertheless, double-capacity models were announced in January 1959 and shipped later that year.

In recognition of its historical significance, the RAMAC 350 Disk File was named an International Historic Landmark by The American Society of Mechanical Engineers in 1984. A restoration initiative commenced in 2002 under the leadership of Al Hoagland, partnering with Santa Clara University. This project later moved to the Computer History Museum in Mountain View, California, where the unit is demonstrated publicly.

IBM 353

The IBM 353, deployed with the IBM 7030, bore resemblance to the IBM 1301 but offered an enhanced data transfer speed. It provided a storage capacity of 2,097,152 (221) 64-bit words, equivalent to 134,217,728 bits, and achieved a transfer rate of 125,000 words per second. A prototype delivered in late 1960 was the first disk drive to implement a single head per surface that floated on compressed air, similar to the IBM 350 disk storage (RAMAC). Production units utilized self-flying heads akin to those found in the 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as a companion to the widely used IBM 650. It employed the IBM 350 mechanism but featured up to three access arms instead of one, enabling storage of 6 million decimal digits plus an additional 600,000 signs. The unit transferred entire tracks between its magnetic core memory and the 653 storage option for the IBM 650, which contained sixty signed 10-digit words—sufficient for a single track or tape record—alongside two other distinct functionalities.

IBM 1405

The IBM 1405 Disk Storage Unit was announced in 1961 for use with the IBM 1400 series business computers and came in two variants: Model 1 held 10 million alphanumeric characters (60 million bits) across 25 disks; Model 2 doubled this capacity with 20 million characters (120 million bits) on 50 disks. Disks were oriented vertically and rotated at a speed of 1200 rpm.

Each disk surface included 200 tracks segmented into five sectors; sectors numbered 0–4 were on the top side and sectors 5–9 on the bottom, each sector accommodating either 178 or 200 characters. One to three forked access arms were equipped with two read/write heads apiece for both top and bottom surfaces. Vertical movement selected among disks (0–49), while horizontal movement positioned the heads over tracks (0–199), with ten sectors per track. Reading or writing a sector took approximately 10 milliseconds.

Access times varied from as low as 100 milliseconds up to a maximum of roughly 700 milliseconds for Model 1 and up to about 800 milliseconds for Model 2. Model 2 contained around 100,000 sectors capable of holding either 200 characters in move mode or 178 characters in load mode, which incorporated an additional word mark bit per character. Model 1 featured approximately half that number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered for compatibility with the IBM 7070, with a second model announced in 1959. Despite this, following the introduction of the IBM 1301 on June 5, 1961, many customers of the IBM 7070 and IBM 7074 preferred the newer system. The IBM 7300 shared technological elements with earlier devices such as the IBM 350, IBM 355, and IBM 1405.

IBM 1301

Announced on June 2, 1961, the IBM 1301 Disk Storage Unit was designed primarily for the IBM 7000 series mainframes and also supported the IBM 1410. Each module stored up to 28 million characters (168 million bits), except for the version used with the IBM 1410 which held approximately 25 million characters. A module comprised twenty-five large disks providing forty user-accessible recording surfaces, each containing two hundred fifty tracks. The Model 1 configuration included a single module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute and data transfer rates reached ninety thousand characters per second.

One major advancement was providing each surface with its own dedicated arm and read/write head assembly that moved simultaneously like a comb. This design significantly reduced seek times and limited maximum access time to approximately one hundred eighty milliseconds. The heads were aerodynamically engineered to fly on a thin cushion of air above each disk surface, allowing them to operate closer to the media and thereby enhancing performance.

Connection to host systems was managed through the IBM 7631 File Control unit, enabling operation with either an IBM 1410 or an IBM 7000 series computer—or even sharing between two systems.

Leasing costs for the IBM 1301 Model 1 were $2,100 monthly or $115,500 for purchase; Model 2 rental was $3,500 per month or $185,000 to acquire. The IBM 7631 controller added $1,185 monthly or $56,000 if purchased outright. All models were phased out by around 1970.

IBM 1302

Introduced in September 1963, the IBM 1302 Disk Storage Unit significantly enhanced recording capabilities, offering four times the storage capacity of its predecessor, the 1301, with a total of 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and supported data transfer rates of 180,000 characters per second, more than doubling the speed of the 1301. Each module incorporated two separate access mechanisms designed for the inner and outer sets of 250 cylinders. The Model 2 configuration stacked two modules to achieve twice the storage capacity. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, while purchase prices were $252,000 and $355,500 respectively. The addition of the IBM 7631 controller incurred an extra monthly lease cost of $1,185 or a purchase price of $56,000. Production of the 1302 ceased in February 1965.

IBM 1311

Announced on October 11, 1962, the IBM 1311 Disk Storage Drive was designed to serve medium-sized business and scientific computer systems. Comparable in size to a top-loading washing machine, it stored up to 2 million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven distinct models were introduced before being phased out by the early 1970s.

The IBM 1316 disk pack stood approximately 4 inches tall, weighed around 10 pounds, and contained six disks each measuring 14 inches in diameter with ten usable recording surfaces (the outer surfaces remained unused). Data was accessed by ten read/write heads that moved hydraulically across tracks while disks rotated at a speed of 1500 revolutions per minute. Each surface was divided into 100 tracks with 20 sectors per track; every sector held 100 characters. Encased within a plastic shell featuring a locking handle, the disk pack was easily inserted and removed—a design approach that became standard for future disk packs.

The seven models included master drives equipped with controllers capable of managing multiple Model 2 slave drives. Key configurations encompassed:

  1. Master drives for IBM 1440/1460/1240 systems controlling up to four slave units.
  2. Slave drives compatible with master drive functionalities.
  3. Master drives for IBM 1620/1710 systems managing up to three slaves.
  4. Master drives for IBM 1401 systems supporting up to four slaves.
  5. Master drives for IBM 1410/7010/7740 systems featuring standard Direct Seek capability.

Among its advanced features were:

  • Direct Seek: Allowed direct positioning without returning to track zero first.
  • Scan Disk: Facilitated swift automatic search operations.
  • Seek Overlap: Enabled concurrent seeks and read/write operations across multiple drives.
  • Track Record: Enhanced storage efficiency by recording a single large record per track instead of multiple sectors, increasing total capacity up to approximately 18.7 million bits under specific conditions.

Master drives (Models 1,3,4,5) were roughly one foot wider than Model 2 slave drives due to additional power supplies and control circuitry.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the IBM 1302 but employs track formatting tailored to S/360 DASD architecture rather than that used in the IBM 7000 series. It contains a fixed module consisting of 25 platters with recording possible on 46 surfaces. The Model 3 includes one such module, while the Model 4 incorporates two modules. Each module is equipped with two independent access mechanisms—referred to as access groups—which cover the innermost and outermost sets of 250 cylinders respectively. Each access group provides one read/write head per track. Average rotational latency is approximately 17 milliseconds with a maximum delay of up to 34 milliseconds; maximum seek time per access group is around 180 milliseconds. Tracks hold about 4,985 bytes each; when factoring in formatting and alternate tracks, total module capacity reaches roughly 112 megabytes. Connection to IBM mainframe systems is facilitated through the IBM 2841 Storage Control Unit.

IBM 2305

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

With the advent of System/370's Virtual Storage features, the 2305 became increasingly popular, often deployed as a paging storage unit on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). It was also favored for managing small but frequently accessed data sets like catalogs and job queues.

The smaller variant, the 2305-1, provides a capacity of 5.4 MB and achieves a data transfer rate of 3.0 MB/s via a two-byte channel interface, boasting an average access latency of 2.5 milliseconds. In contrast, the larger 2305-2 model offers an 11.2 MB capacity with a data rate of 1.5 MB/s and an average access time of approximately 5 milliseconds.

Engineered to deliver rapid and continuous access to modest data volumes, the IBM 2305's speed and storage size make it well-suited for hosting system-resident functions, work files, job queues, indices, and other frequently utilized datasets. Its swift response time makes it particularly effective as a paging device in high-throughput environments exceeding 1.5 transactions per second.

IBM 2311

Introduced in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive was compatible with IBM System/360, IBM 1130, and IBM 1800 systems. It also connected directly to the IBM System/360 Model 20 and Model 25. All units operated using removable IBM 1316 Disk Packs, originally developed for the IBM 1311.

The Model 1 version connects to most IBM mainframes through the 2841 Control Unit; however, for the System/360 Model 25, connection is established via a Disk Attachment Control functioning as a control unit. The disk packs employ IBM's count key data variable-length record format.

Models 11 and 12 integrate with the System/360 Model 20’s built-in control using a fixed-sector format. Due to differences in formatting, disk packs are not interchangeable between Model 1 drives and Models 11 or 12.

While mechanically akin to the IBM 1311, the IBM 2311 enhanced recording density to store up to 7.25 megabytes on a removable six-platter disk pack. It features ten read/write heads mounted on a hydraulically actuated arm; each platter surface contains 200 tracks plus three optional spares. The average seek time measures approximately 85 milliseconds with a data transfer speed of around 156 kB/s.

Uniform electrical interface standards across the System/360 series allowed third-party vendors to manufacture plug compatible disk drives, fostering a competitive marketplace for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965 for the System/360 and System/370 platforms, the IBM 2314 featured a Two Channel Switch capability that permitted simultaneous connection to two channels. Its mechanical design was similar to that of the IBM 2311 but offered significantly higher data density.

The drive accommodated roughly 29 million characters on an IBM 2316 disk pack that expanded from six to eleven disks (providing twenty recording surfaces). The actuator held twenty individual read/write heads hydraulically positioned over each surface’s approximately 200 tracks. Subsequent models improved average access times beyond those of the original IBM 2311 while doubling data transfer rates to about 310 kB/s.

The Model 1 configuration included nine disk drives sold as a single unit alongside a separate storage control unit. These drives were mounted in drawer-like enclosures for straightforward disk pack handling, earning them the nickname "Pizza Ovens." Only eight drives operated concurrently; the ninth served as an offline spare to facilitate maintenance without interrupting ongoing operations. Drive system addresses could be reassigned flexibly using user-swappable plugs, including designation of spare drives.

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

Subsequent versions of the IBM 2314 expanded upon these foundational features:

IBM 2314 Direct Access Storage System - Model Variants

In 1969, IBM segmented the storage 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, equipped with four drives.
  • 2318 Disk Storage, containing two drives.

IBM 2319

To address competition from plug-compatible vendors producing equivalents to the 2314 storage subsystems, IBM launched in 1970 an economical three-drive module named the 2319. This was achieved by removing one drive from the four-drive 2313 unit and rebranding it as the 2319 A1, which was offered at a notably lower rental cost. This approach allowed new clients to benefit from reduced rental fees, while existing customers continued under previous pricing arrangements. The 2319-A1 connects to integrated controllers designed for System/370 Models 135 and 145. Additionally, traditional 2314 DASD units such as the 2312 or 2318 can be linked to the 2319-A1. The 2319 B series expanded the offering with three-drive modules capable of supporting configurations of three, six, or nine drives attached to a newly introduced 2314 Model B Storage Control Unit.

IBM 3310

The IBM 3310 Direct Access Storage Device was introduced on January 30, 1979, targeting IBM 4331 midrange computer systems. Each drive provided a storage capacity of 64.5 MB. Utilizing fixed-block architecture, the 3310 was compatible exclusively with S/370 operating systems DOS/VSE and VM that supported FBA devices.

IBM 3330

Launched in June 1970 under the codename Merlin, the IBM 3330 Direct Access Storage Facility was designed for IBM System/370 and System/360/195 platforms. It was initially available as a two-drive Model 1 and a single-drive Model 2, employing removable disk packs with a capacity of 100 MB (404×19×13,030 bytes). The device featured a rapid access time of 30 ms and a data transfer speed of 806 kB/s. A notable innovation was the integration of error correction, which enhanced dependability and lowered costs by enabling tolerance for minor disk surface flaws through fire codes capable of correcting error bursts up to eleven bits in length.

The original configuration consisted of one storage control unit (3830 Model 1) physically attached to a single 3330 drive, with the option to bolt together up to three additional units in sequence, permitting strings of up to eight drives.

In August 1972, IBM unveiled the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which decoupled control functions from the drive string. The upgraded 3830 functioned as a director-type controller overseeing multiple strings. The leading unit in each string, the 3333, combined controller capabilities with two drives and could manage up to three connected 3330 drives for an eight-drive maximum per string. The 3830 Model 2 supported connection of two such strings (up to sixteen drives), with optional string switches enabling attachment to two separate controllers.

In 1973, IBM announced double-density (-11) versions: the models named 3333–11, 3330-11, and the higher-capacity 3336–11 Disk Packs offering up to 200 MB (808×19×13,030 bytes). Mixing standard and double-density drives within a single string was not permitted. Field upgrades from original models to Model-11 versions were possible but involved drive conversion processes and data migration efforts.

The IBM 3330 was discontinued in 1983.

IBM 3340 and 3344

While the IBM 3340 and 3344 share many characteristics, only the 3340 functions as the head of string; there are no A model variants of the 3344, which must be connected to a 3340 A model serving as the head of string.

IBM 3340

Introduced in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility, also known by its codename Winchester, launched with three variants: the 3340-A2 featuring two drives and a controller, and the B2 (two drives) and B1 (single drive) models. The B-series units could be connected to an A2 controller, supporting up to eight drives in a chain.

This system utilized removable data modules that incorporated both the head and arm assembly; during mechanical load and unload operations, an access door on each module opened to engage with the drive mechanism, eliminating the need to remove any cover when inserting modules. It achieved an average access time of 25 milliseconds and data transfer speeds reaching 885 kB/s. The IBM 3348 Data Modules came in three configurations offering capacities of 35 MB, 70 MB, and a specialized 70 MB version equipped with fixed heads for accelerated access. The 3340 also integrated error correction capabilities before being discontinued in 1984.

Designed in San Jose under Ken Haughton's leadership, the initial concept centered on two removable modules each holding approximately 30 MB—hence the Winchester nickname referencing the famous .30-30 rifle. Although storage capacity increased later on, this nickname persisted.

A significant advancement was the introduction of a cost-effective head design that allowed heads to land on and lift off from spinning disk surfaces without unloading, substantially simplifying and reducing expenses related to the head and arm assembly. This innovation, known as "Winchester technology," set a new industry benchmark in disk drive engineering.

The terms Winchester or Winnie were widely used to refer to hard disk drives into the early 1990s but have since declined in global usage.

IBM 3344

The IBM 3344 closely resembles the 3340 but distinguishes itself by employing fixed media instead of removable 3348 data modules. Each spindle accommodates four logical drives, each matching the capacity of a single 3348–70 module. Available exclusively as dual-drive models, the 3344 lacks an A (head-of-string) variant. The model 3344-B2F differs from the standard 3344-B2 by incorporating fixed heads over selected cylinders on both drives. Both require attachment to a 3340-A2 or 3340-A2F unit acting as head of string. Internally, the architecture of the IBM 3344 aligns with that of the IBM 3350, differing primarily in control unit microcode.

IBM 3350

Launched in 1975 for IBM System/370, the IBM 3350, codenamed Madrid, introduced sealed head-disk assemblies (HDAs) containing integrated head and arm components that were non-removable. Its disk structure comprised 555 cylinders, each with 30 heads and tracks holding approximately 19,069 bytes, resulting in roughly 317 MB storage per HDA. The adoption of sealed HDAs became standard practice for IBM DASD devices thereafter.

The product line included models A2, A2F, B2, B2F, C2, and C2F, each housing two HDAs. Models A2 and A2F featured an extra electronic board facilitating connection to control units—often referred to as controllers or heads-of-string. Storage units were arranged in strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations involving C2 units. Typically, the A2 model incorporated a string switch allowing linkage to two separate storage control units for concurrent I/O operations across different HDAs. Compatible control units encompassed the Model 2 of the IBM 3830, Integrated Storage Control (ISC) embedded within CPUs such as the IBM 3148, as well as later backward-compatible controllers like the IBM 3880. The C2 unit contained a spare controller reserved for failover if an A unit's controller malfunctioned but offered limited connectivity options.

Valid string configurations for IBM 3350 included arrangements such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

Models with an "x2F" suffix (for example, A2F) incorporated fixed-head regions covering the first five cylinders on each HDA, effectively reducing seek time to zero within these zones. This feature was commonly utilized to store frequently accessed checkpoint data for spooling systems like HASP or JES2 to minimize mechanical head movement. Additionally, it supported swap data storage for TSO environments and system swap areas under operating systems such as MVT, SVS, and MVS—enhancing efficiency during context switches.

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

IBM 3370

In January 1979, IBM launched the IBM 3370 Direct Access Storage Device, designed for use with IBM 4331, 4341, and System/38 midrange systems. This unit incorporated seven fixed 14-inch platters, delivering a storage capacity of 571 MB per device. Notably, it was the pioneer in utilizing thin-film head technology, a development originating from the Thomas J. Watson Research Center during the late 1960s. The 3370 employed a fixed-block architecture and was compatible with DOS/VSE and VM operating systems on S/370 mainframe platforms.

IBM 3375

The IBM 3375 served as a complementary storage device based on count key data architecture, essential for operating systems such as OS/360 and its successors.

IBM 3380

Debuting on June 11, 1980, the IBM 3380 Direct Access Storage Device utilized film head technology and offered a capacity of 2.52 GB per unit. This configuration consisted of two hard disk assemblies with dual actuators, each accessing 630 MB. It achieved a data transfer rate of 3 MB/s and had an average access time of 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges affecting the interaction between heads and media, shipments were delayed until October 1981.

A typical setup included one A unit accompanied by up to three B units; each IBM 3380 contained four devices, allowing for a maximum of sixteen devices per string. These units were commonly connected to a 3880 storage control unit featuring dual-path connectivity, supporting two concurrent I/O operations directed at separate hard disk assemblies.

In February 1985, IBM introduced the Extended Capability Models (3380 E), which doubled storage capacity to 5.04 GB per unit by employing two actuators of 1.26 GB each across two disk assemblies.

The Model K followed in August 1987, tripling capacity to 7.562 GB per unit through two actuators of 1.89 GB each. Both Models J and K provided an optional four-path mode that enabled up to thirty-two devices per string when linked to a 3990 storage control unit, facilitating four simultaneous I/O processes.

The IBM 3380 family encompassed twelve models: six A-units acting as string leaders with integrated controller logic interfacing with IBM storage control units; five B-units that connected to either A- or C-units; and one C-unit designed for direct connection to an IBM channel.

Production of the IBM 3380 series continued until May 1996, marking an impressive fifteen-year period in service.

IBM 3390

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

A typical IBM 3390 string consists of a central A unit containing four or eight devices, optionally flanked by one or two B units supporting up to twelve devices each. Operating in four-path mode, it connects to a 3990 storage control unit that can manage a second string of IBM 3390 devices, allowing for a maximum of sixty-four devices within a subsystem.

Each Hard Disk Assembly (HDA) includes two actuator-head units along with platters. The Model 1 HDA offered an unformatted capacity of 1.89 GB; Model 2 doubled this to 3.78 GB per HDA. Announced in September 1991, Model 3 increased capacity by fifty percent to reach 5.67 GB per HDA. The Model 9 followed in May 1993, tripling the previous capacity to achieve 11.3 GB per HDA.

Departing from earlier DASD designs that relied on large AC motors with belt drives, the IBM 3390 HDAs utilized enclosed DC motors for direct drive operation. The Model 9 represented IBM's final iteration of Single Large Expensive Disk (SLED) technology.

IBM 9345

The IBM 9345 hard disk drive was introduced in November 1990 as a Request Price Quotation (RPQ) option for IBM's SuperComputing Systems Extensions (SCSE). Created at IBM's San Jose facility under the codename Sawmill, it offered capacities up to 1.5 GB within a full-height 5¼-inch form factor, utilizing as many as eight 130 mm platters. This model was notable for being the first HDD to use Magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM launched the 9345 DASD as a member of the 9340 channel-attached count key data (CKD) DASD subsystem series designed for IBM mainframes such as the ES/9000 lineup. The 9345 Model 1 included two 1.0 GB hard drives, whereas Model 2 contained two drives each with 1.5 GB capacity.

From a functional standpoint, the 9340/9345 series was similar to the 3990/3390 models; however, it lacked the non-volatile RAM cache found on the 3990 and supported a shorter maximum block length than the 3390.

The operating system's Input/Output Supervisor (IOS) recognized this device through a specialized initializer named IECCINIT, which also handled other DASD varieties. During initialization, the OS detected the absence of non-volatile cache in the 9340 and noted the reduced track capacity of the 9345, resulting in these devices being assigned unique device types distinct from those of the 3990/3390.

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 incorporated the IBM 0667 hard disk drive.
  3. The 9333 High Performance Disk Drive Subsystem utilized either IBM 0664 or IBM 0681 HDDs depending on 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 an IBM-designed "Kestrel" hard disk drive with an 850 MB capacity, comprising three 14-inch platters and dual rotary actuators enabling access to multiple surfaces; it was rack-mountable and debuted alongside the October 1986 IBM 9370 Information System. No original equipment manufacturer versions are documented.
  6. The 9336 Disk Unit employed the IBM 0681 HDD (Redwing).
  7. The 9337 Disk Array Subsystem incorporated either IBM 0662 (Spitfire) or IBM 0663 (Corsair) hard drives.

IBM 2310

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

IBM 5444

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

  • Model 1: included one fixed and one removable disk, each offering one hundred tracks per surface, with a cartridge capacity of approximately 1.23 MB
  • Model 2: comprised one fixed and one removable disk, each containing two hundred tracks per surface, yielding a cartridge capacity near 2.46 MB
  • Model 3: featured a single removable disk with two hundred tracks per surface and a cartridge capacity of about 2.46 MB

IBM 62GV

The 62GV, which began shipping in May of 1974 and was developed at IBM’s Hursley UK laboratory under the codename Gulliver, initially provided storage capacity of five megabytes. Subsequent versions (62TM) expanded capacity first to ten megabytes and later to fourteen megabytes. This design incorporated a Swinging Arm actuator paired with a single fourteen-inch platter and became IBM’s most widely licensed electromechanical innovation. Its actuator mechanism along with its filtration system were extensively adopted across hard disk drives throughout the decade of the eighties and continue to be industry standards nearly four decades later. With total production surpassing one hundred seventy-seven thousand units, the IBM 62GV was also notable for being the first hard drive to exceed shipments of one hundred thousand units.

OEM and Small Systems Hard Drives

This segment details IBM-produced hard disk drives marketed as OEM items and designed for IBM small-scale systems, including the System/3, System/32, /34, /36, and AS/400 series. Drives are cataloged by their OEM model designations and arranged according to the date they were first delivered to customers.

IBM 0680

Initially introduced in 1979, the 0680 was deployed across many IBM small systems and entry-level System/370 models as the 3310 direct access storage device. Officially announced in September 1981 as the 0680 OEM variant, it was engineered at IBM’s Hursley laboratory in the UK under the project name Piccolo. The drive featured a starting capacity of up to 65MB, utilizing six 8-inch (210 mm) platters combined with an enhanced rotary actuator mechanism.

A higher capacity iteration, known as the 62SW, became available in June 1984 but experienced modest market traction due to pricing comparable to that of the 62GV model.

IBM 0676

The 0676 was introduced in November 1982 as a 5247 Disk Storage Unit tailored for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the internal designation 21ED, it was an 8-inch hard drive offering initial storage options of either 15 or 30 MB through configurations of two or four 210 mm platters. By 1983, this drive was incorporated into the S/36’s 5360 System Unit. Its capacity was doubled in 1984 by increasing track density per platter surface, which facilitated its deployment within the S/36’s 5362 System Unit.

IBM 0665

Released in October 1985, the 0665 appeared within the PC AT (5170) system enclosure. Created under the codename "Pixie" at IBM Rochester, this 5¼-inch hard drive provided storage capacities of 20, 30, and 44 MB.

IBM 0667

Starting shipment in August 1986, the 0667 was developed at IBM Rochester with the project name "Grant." This full-height ESDI hard drive measured 5¼ inches and delivered a capacity of up to 70 MB distributed over as many as four 130 mm platters. It was offered as an optional component for select PC RT models (6150, 6151, 6152) and also for System/36 Model System Units (5363, 5364).

IBM 0669

The 0669, unveiled in 1987 and designed at IBM Rochester under the codename "Grant-Prime," was a full-height hard drive sized at 5 inches. It supported storage up to 115 MB across four 130 mm disks. This model served as the internal hard drive for both the System/36 Model 5363 and Series/1 Model 4956 System Units.

IBM 0671

Also introduced in 1987, the 0671 originated from IBM Rochester's development team under the codename "Lee." This full-height, ESDI-compliant hard disk measured five inches and provided up to 316 MB capacity utilizing as many as eight 130 mm platters. Notably, it was IBM’s inaugural HDD to employ a thin metal film recording surface. In 1988, this drive was incorporated into the IBM AS/400 Model 9404 System Unit configurations supporting two or three drives.

IBM 0661

The 0661, identified as model 371 upon release in 1989, was co-developed by teams at IBM Rochester and Hursley, UK under the codename "Lightning." This SCSI hard disk featured eight disks measuring 95 mm each with a total of fourteen heads and initially offered a capacity of around 320 MB. An upgraded "Turbo" variant launched in 1990 increased storage capability to approximately 400 MB. This model became a standard component across multiple IBM platforms including certain AS/400 System Unit Model CXX versions.

IBM 0681

Introduced in April of 1990 from IBM’s Hursley facility under the codename Redwing—the final HDD developed there—the 0681 delivered up to an estimated capacity of 857 MB using twelve platters measuring 130 mm each in a full-height five-inch form factor. It was also notable for being the first IBM hard disk to incorporate PRML (Partial Response Maximum Likelihood) data decoding technology. This drive was integrated into the newly released early-1992 IBM Model 9333 Disk Drive Subsystem. A subsequent higher-density version offering around 1.07 GB capacity became available in May of that year.

IBM 0663

Introduced in late 1991 under the codename "Corsair," the 0663 was a compact 3-inch hard disk drive resembling a half-height 5-inch unit with a height of 1.6 inches. It offered a maximum storage capacity of 1 GB across eight 95 mm platters. This model was incorporated into select PS/2 and RS/6000 systems and marked the industry's first OEM HDD to utilize Magnetoresistive (MR) read heads.

IBM 0664

Released in November 1992, the 0664—developed at IBM Rochester, Minnesota, and known internally as "Allicat"—was a full-height (3.25-inch) 5-inch hard drive. It effectively combined two 3-inch drives and provided up to 2.013 GB of storage on as many as eight 95 mm platters.

IBM 0662

The 0662 arrived in June 1993, developed under the project name "Spitfire" at IBM Rochester. This full-height (1-inch) 3-inch HDD delivered a capacity of 1.05 GB using three disks or five recording surfaces. It was utilized as the internal storage device for both the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology by introducing the first 8-inch floppy disk drive in 1971, initially designed solely for program loading purposes. By 1973, IBM had launched its inaugural read/write floppy disk drive integrated within the 3740 Data Entry System. Although IBM set foundational standards for 8-inch floppy drives, it refrained from selling these drives independently, allowing the broader market to evolve without direct IBM competition.

At one point, IBM was the largest original equipment manufacturer (OEM) buyer of 5-inch floppy disk drives. Its adoption of double-sided drives with a density of 48 tracks per inch helped establish this format as an industry benchmark. Despite plans to produce smaller form factors, IBM discontinued these initiatives in 1985. Notably, its attempt in 1983 to OEM a 4-inch DemiDiskette did not succeed.

"Star" series of HDDs

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

IBM's first HDD versus its last HDDs

The following table contrasts IBM's original hard drive, the RAMAC 350, with its final three "Star" series OEM models, showcasing significant advancements in cost efficiency, size reduction, capacity growth, and performance enhancements over nearly five decades.

Parameter (units) RAMAC 350 Ultrastar 146Z10 Deskstar 180GXP Travelstar 80GN Maximum improvement over 46 years
Announcement date Sep 1956 Jul 2002 Oct 2002 Nov 2002
Storage capacity (GB) 0.004 146 180 80 48,000 times
Physical dimensions (inches) 60×68×29 4×1×5.75 4×1×5.75 2.75×0.38×3.95
Physical dimensions (mm) 1500×1700×700 102×25×146 102×25×146 70×9.5×100
Volume (cubic inches) 118,320 23 23 4 29,161 times smaller
Volume (liters) 1,939 0.4 0.4 0.1
Weight (pounds) 2,140 1.7 1.4 0.2 1,244 times lighter
Weight (kilograms) 971 0.8 0.64 0.095
Power consumption (watts) ~2374 (~8100 BTUs/hour), up to ~5500 VA depending on configuration 16 10.3 1.85 1,283 times more efficient
Power efficiency (MB per watt) 0.0016 9,125 17,476 43,243 27 million-fold increase
List price (Template:US$) \$34,500 (\$234,000 adjusted to 2002 dollars) \$1,200 \$360 \$420
Cost per megabyte (Template:US$) \$9,200 (\$68,000 adjusted to 2002 dollars) \$0.0082 \$0.0020 \$0.0053
Areal density (megabits per square inch) 0.002 26,263 46,300 70,000
Areal density (kilobits per square millimeter) 0.003 40,708 71,765 108,500
Volumetric density (gigabytes per cubic inch) 0.00000003 6 8 20 Over six hundred million times greater
Volumetric density (megabytes per cubic centimeter) 0.000002 388 478 1,203
Average rotational latency (milliseconds) 25 3 4 7 Substantial reduction in latency
Average seek time (milliseconds) 600 5.9 10.2 12 Up to a hundred-fold improvement
Data transfer rate (megabytes per second) 0.001 103 29.4 43.75 Thousands-fold increase

DASD Devices Beyond HDDs and FDDs

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

IBM 7320 Drum

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

IBM 2301 Drum

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

IBM 2303 Drum

The IBM 2303, brought to market in 1964, also utilizes magnetic drum technology for data storage.

IBM 2321 Data Cell

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

IBM 3850 Mass Storage System

Released in 1974, the IBM 3850 Mass Storage System is a tape cartridge library solution that stages data onto IBM 3330 or 3350 disk drives, allowing them to be accessed as virtual disk drives.

See also

External links

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