IBM 0663

IBM Magnetic Disk Storage Division

Company type	Division (former)
Industry	Computer storage
Founded	1956
Defunct	2003
Fate	Divested hard disk drive division to Hitachi
Products	Hard disk drives, floppy disk drives, magnetic disk storage units
Parent	IBM

IBM was engaged in the production of magnetic disk storage units from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. IBM's workforce was instrumental in pioneering both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing numerous advancements to these technologies. The core mechanical architecture of hard disk drives has largely remained unchanged since the introduction of the IBM 1301, with performance benchmarks adhering to established standards dating back to the 1950s. Over time, this category of products has experienced dramatic reductions in physical size and cost, coupled with substantial improvements in storage capacity and operational efficiency.

From 1969 until the mid-1980s, IBM produced 8-inch floppy disk drives but did not become a significant manufacturer of the smaller 5.25- or 3.5-inch variants. While IBM sold its magnetic disk drives directly, it only began offering them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had discontinued manufacturing hard disk drives exclusively for its own systems, transitioning entirely to OEM distribution for all HDDs.

IBM has applied different terminology for its magnetic disk storage devices over time, including direct-access storage device (DASD), disk file, and diskette file. For consistency, 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 holds the distinction of being the first commercially available disk drive, launched as a component of the IBM 305 RAMAC computer system on September 14, 1956. A related model, the IBM 355, was introduced for the IBM 650 RAMAC system. The initial prototype was delivered to Zellerbach Paper Company in June 1956, with production units sent to United Airlines beginning in November 1957.

Engineered to support real-time business accounting tasks, the IBM 350 offered storage for five million 6-bit characters (approximately 3.75 MB) distributed across fifty-two disks measuring 24 inches each. These disks featured a total of 100 recording surfaces and tracks. Operating at a rotation speed of 1200 rpm, it achieved a data transfer rate of 8,800 characters per second. The device’s access mechanism utilized moving heads to select specific disk pairs and tracks. Several enhanced versions were introduced throughout the late 1950s. The RAMAC 305 system paired with the IBM 350 was leased at a rate of $3,200 per month. This model remained in production until its retirement in 1969.

The patent US3503060 emerging from the RAMAC project is recognized as foundational in disk drive technology. Although initially rejected by IBM’s board due to concerns about its potential impact on punch card sales, development proceeded after receiving authorization from IBM’s president.

The physical dimensions of the cabinet were substantial: measuring 60 inches in length, 68 inches in height, and 29 inches in width. Weighing roughly one ton, transportation required forklifts and cargo aircraft. A research vice president at Hitachi Global Storage Technologies later remarked that capacity could have been increased beyond five million characters; however, marketing apprehensions about selling larger drives limited such expansion. Despite this, models with double the original capacity were announced in January 1959 and delivered later that year.

In recognition of its engineering significance, the RAMAC 350 Disk File was designated an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, restoration efforts led by Al Hoagland took place at the Magnetic Disk Heritage Center in partnership with Santa Clara University. By 2005, this restored unit was relocated to the Computer History Museum, where it is publicly showcased within the Revolution exhibition.

IBM 353

The IBM 353, utilized 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 supported data transfers at a rate of 125,000 words per second. A prototype delivered in late 1960 was notable as the first disk drive to employ a single head per surface that operated on a cushion of compressed air, similar to the IBM 350 disk storage (RAMAC). Production versions incorporated self-flying heads comparable to those found in the IBM 1301.

IBM 355

Unveiled on September 14, 1956, the IBM 355 expanded the functionality of the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms, compared to just one on the IBM 350. This unit could hold 6 million decimal digits plus an additional 600,000 sign indicators. It facilitated full-track transfers between magnetic core memory in the 653—an optional storage unit for the IBM 650 containing sixty signed 10-digit words suitable for a single disk track or tape record—and included two other unrelated capabilities.

IBM 1405

Launched in 1961 for use with the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit came in two variations: Model 1 offered storage for 10 million alphanumeric characters (60 million bits) across 25 disks; Model 2 doubled this capacity with 20 million characters (120 million bits) over 50 disks. These disks were arranged vertically and rotated at a speed of 1200 revolutions per minute.

Each side of a disk contained 200 tracks subdivided into five sectors; sectors numbered 0 through 4 were located on the top side and sectors 5 through 9 on the bottom. Each sector held between 178 and 200 characters. Between one and three fork-shaped access arms, each equipped with two read/write heads (one for each disk side), moved vertically to select disks numbered from 0 to 49 and horizontally to access tracks from 0 to 199. Reading or writing a sector required approximately 10 milliseconds.

Access times varied from as low as 100 milliseconds up to around 700 milliseconds for Model 1 and reached up to 800 milliseconds for Model 2. Model 2 contained about 100,000 sectors that could hold either 200 characters in move mode or 178 characters in load mode, which added a word mark bit per character. Model 1 had half the number of sectors compared to Model 2.

IBM 7300

The IBM 7300 Disk Storage Unit was developed specifically for use with the IBM 7070. Although IBM introduced a model 2 version in 1959, with the arrival of the IBM 1301 on June 5, 1961, customers of both the IBM 7070 and IBM 7074 tended to prefer the newer IBM 1301 over the IBM 7300. The technology underlying the IBM 7300 shared elements with earlier units 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 for integration with IBM’s mainframe systems and the IBM 1410. Each module stored up to approximately twenty-eight million characters (168 million bits), although this was reduced to twenty-five million characters when used with the IBM 1410. A module consisted of twenty-five large disks providing forty usable recording surfaces and two hundred fifty tracks per surface. 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, enabling data transfer rates of ninety thousand characters per second.

A significant advancement was its use of individual arms and read-write heads dedicated to each disk surface that moved simultaneously like a comb assembly. This eliminated delays associated with repositioning heads between disks and reduced maximum access times down to approximately one hundred eighty milliseconds. Additionally, it was pioneering in employing aerodynamically engineered heads that floated on a thin air cushion above disk surfaces, enhancing reliability and performance.

The system connected through an IBM 7631 File Control unit, allowing operation either with an IBM 1410 or IBM 7000 series computer or sharing access between two machines.

Leasing fees for Model 1 were set at $2,100 monthly or $115,500 for outright purchase; Model 2 was available at $3,500 per month lease or $185,000 purchase price. The IBM 7631 controller carried additional costs of $1,185 per month or $56,000 if purchased. All versions were phased out by the year 1970.

IBM 1302

Unveiled in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the 1301, reaching 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and achieved data transfer speeds of 180,000 characters per second, more than twice as fast as its predecessor. Each module was equipped with two separate access mechanisms dedicated to the inner and outer cylinder groups. The Model 2 configuration stacked two such modules, effectively doubling the storage capacity. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, while outright purchase prices stood at $252,000 and $355,500 respectively. The IBM 7631 controller added an additional monthly lease charge of $1,185 or a purchase cost of $56,000. Production of the 1302 ceased in February 1965.

IBM 1311

Introduced on October 11, 1962, the IBM 1311 Disk Storage Drive was designed for medium-sized business and scientific computing environments. It utilized a removable IBM 1316 disk pack capable of storing two million characters. Throughout the 1960s, seven distinct models were released before being phased out by the early 1970s.

The IBM 1316 Disk Pack measures approximately four inches in height, weighs near ten pounds, and consists of six 14-inch disks providing ten active recording surfaces—the outermost surfaces remain unused. Ten read/write heads are hydraulically positioned across the tracks while the disks rotate at 1,500 revolutions per minute. Each surface contains 100 tracks divided into 20 sectors per track, each sector holding about 100 characters. The disk pack is enclosed within a transparent plastic casing featuring a locking handle to facilitate insertion and removal.

The seven IBM 1311 variants include master drives equipped with controllers that manage multiple Model 2 slave drives. These master units supported systems such as the IBM 1440, IBM 1460, IBM 1401, IBM 1410, and IBM 7010, with the ability to control up to four slave drives. Certain models incorporated Direct Seek as a standard feature; others offered optional enhancements like Scan Disk, Seek Overlap, and Track Record to boost performance and storage efficiency.

Key features include:

• Direct Seek: Removes the necessity to return to track zero before initiating a seek operation.
• Scan Disk: Facilitates automatic rapid searches for specific identifiers or conditions.
• Seek Overlap: Permits overlapping seek operations during simultaneous read/write activities on multiple drives.
• Track Record: Improves capacity by recording a single large record per track instead of multiple sectors—achieving approximately 17.9 million bits in "Move Mode" and nearly 18.8 million bits in "Load Mode."

Master drive models (1,3,4,5) incorporate additional power supplies and control circuitry; they are roughly one foot wider than Model 2 slave drives.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the IBM 1302 but features track formatting compatible with S/360 DASD architecture rather than that of the earlier 7000 series.

This unit employs a fixed module containing 25 platters with a total of 46 recording surfaces. The Model 3 configuration includes one such module; Model 4 contains two modules. Each module is fitted with two independent access mechanisms—termed access groups—one dedicated to the innermost 250 cylinders and another to the outermost 250 cylinders. Each access group provides one read/write head per track. Rotational latency averages around 17 milliseconds with a maximum delay of up to 34 milliseconds; maximum seek time within each access group is approximately 180 milliseconds. Individual track size measures about 4,985 bytes; after accounting for formatting and alternate tracks, total module capacity reaches roughly 112 megabytes. The IBM 2302 interfaces with mainframe systems through the IBM 2841 Storage Control Unit.

IBM 2305

Announced in 1970, the IBM 2305 fixed-head storage drive, 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 introduction of Virtual Storage on the System/370, demand for the 2305 increased significantly. It was frequently deployed as a paging device on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter utilizing specialized microcode). Additionally, it was well suited for managing high-activity small data sets like catalogs and job queues.

The 2305-1 model provides a storage capacity of 5.4 MB, delivering data at a rate of 3.0 MB per second over a two-byte channel interface, with an average access time of approximately 2.5 milliseconds. In contrast, the larger 2305-2 variant offers 11.2 MB capacity but operates at a reduced data transfer speed of 1.5 MB per second and an average access time of about 5 milliseconds.

Engineered for rapid and continuous access to relatively small volumes of data, the 2305’s combination of speed and capacity made it ideal for system-resident functions such as work files, job queues, indices, and frequently accessed datasets. Its swift response time proved advantageous in environments with heavy loads requiring transaction rates exceeding 1.5 per second, further enhancing its suitability as a paging device.

IBM 2311

The IBM 2311 Disk Storage Drive was launched in 1964 alongside the 2841 Control Unit, serving not only the IBM System/360 series but also the IBM 1130 and IBM 1800 systems. It also provided direct connectivity to System/360 Models 20 and 25. All drives utilized the IBM 1316 Disk Pack, which had been originally introduced with the IBM 1311.

The Model 1 version of the 2311 connects to most IBM mainframes via the 2841 Control Unit; for System/360 Model 25 systems, a Disk Attachment Control performs this role. The disk packs employ IBM’s count key data variable record length format. In contrast, Models 11 and 12—attached to Model 20’s integrated control—use fixed sector formatting. Notably, disk packs are not interchangeable between Model 1 and Models 11 or 12.

While mechanically resembling the IBM 1311, the 2311 featured enhanced recording density. It stored up to 7.25 megabytes on a removable six-platter IBM 1316 disk pack. The drive contained ten read/write heads mounted on a hydraulically actuated mechanism with mechanical detents for precise track positioning. Each surface held 200 tracks plus three spare tracks allocated for defect management. The average seek time was approximately 85 milliseconds with a data transfer rate reaching up to 156 kilobytes per second.

A standardized electrical interface across the System/360 lineup allowed third-party vendors to manufacture plug compatible disk drives, encouraging competition within the IBM-compatible storage market.

IBM 2314 Disk Access Storage Facility Model 1

Introduced in April of 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms and featured a Two Channel Switch enabling dual-channel connections. Its disk mechanism was similar to that of the IBM 2311 but provided increased data density.

This model stored roughly twenty-nine million characters on a removable IBM 2316 disk pack consisting of eleven disks measuring fourteen inches in diameter. The pack offered twenty recording surfaces with two hundred tracks each. The actuator assembly held twenty read/write heads hydraulically positioned with mechanical detents to ensure accurate track alignment. Initial access times were comparable to those of the IBM 2311 but were later improved through actuator enhancements. Data transfer rates were doubled to approximately 310 kilobytes per second.

The Model 1 configuration grouped nine drives into a single unit that included both a storage control unit and drive modules. Drives were housed in drawers facilitating easy access to disk packs; this design led operators to nickname them "Pizza Ovens." Although only eight drives could be accessed simultaneously, one drive remained offline as a spare to allow maintenance without interrupting ongoing operations. System addresses could be customized by users through interchangeable plugs, permitting flexible drive reassignment.

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

Later models expanded upon these foundational capabilities:

IBM 2314 Direct Access Storage System - Variants

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

• The 2312 Disk Storage, which comprised a single-drive unit.
• The 2313 Disk Storage, featuring four drives.
• The 2318 Disk Storage, containing two drives.

IBM 2319

To address competition from plug-compatible manufacturers producing storage devices comparable to the 2314, IBM launched the cost-effective three-drive 2319 series in 1970. The 2319-A1 model was created by removing one module from the four-drive 2313 and rebranding it, enabling significantly lower rental fees for new clients while maintaining elevated pricing for existing customers. This model interfaces with integrated controllers designed for System/370 Models 135 and 145. Additionally, standard 2314 DASD units such as the 2312 or 2318 can be connected to the 2319-A1. The 2319 B series supports configurations of three, six, or nine drives linked to a newly developed 2314 Model B Storage Control Unit.

IBM 3310

Released on January 30, 1979, the IBM 3310 Direct Access Storage Device was aimed at IBM 4331 midrange computer systems. Each drive provided a capacity of 64.5 MB and operated using fixed-block architecture (FBA). It was compatible with DOS/VSE and VM operating systems running on S/370 platforms.

IBM 3330

The IBM 3330 Direct Access Storage Facility, internally known as Merlin, debuted in June 1970 targeting IBM System/370 and System/360/195 platforms. It initially offered two models: the two-drive Model 1 and the single-drive Model 2. Each removable disk pack stored 100 MB, featured a 30 ms access latency, and supported data transfer speeds of up to 806 kB/s. A notable advancement was its built-in error correction employing fire codes, which improved dependability and lowered costs by allowing tolerance for disk surface flaws.

The original configuration consisted of one storage control unit (3830 Model 1) attached to a single 3330 drive, with the ability to connect up to three additional drives in a chained arrangement—forming groups of as many as eight drives.

In August 1972, IBM rolled out the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which decoupled control units from drive chains. The enhanced 3830 functioned as a director-type controller capable of managing multiple drive strings. The initial unit in each string—the 3333—combined controller functionality with two drives and could support up to three additional attached 3330 drives (maximum eight drives per string). The Model 2 controller could link two such units, allowing management of up to sixteen drives per storage control system; furthermore, the optional string switch on the 3333 enabled connection to two controllers.

In 1973, IBM introduced double-density (-11) variants: the models 3333–11, 3330-11, and the larger-capacity 3336–11 Disk Packs with storage up to 200 MB. Mixing single- and double-density drives within a string was not permitted. Field upgrades from standard models to Model-11 versions were feasible but intricate, involving drive conversions and data transfer processes.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

While the IBM 3340 and IBM 3344 share many characteristics, only the IBM 3340 can act as the head of a drive string; there are no A model variants of the IBM 3344. Consequently, an IBM 3344 must connect to an IBM 3340 A model serving as the lead unit in the string.

IBM 3340

The IBM 3340 Direct Access Storage Facility, known by the codename Winchester, was launched in March 1973 for the IBM System/370 platform. It came in three configurations: the 3340-A2 featuring two drives and a controller, along with the B2 model having two drives, and the B1 model with a single drive. Up to eight B-units could be connected to an A2 controller.

This system utilized removable data modules that housed the head and arm assemblies. A mechanical load/unload mechanism operated an access door to engage or disengage the module with the drive, thereby removing the necessity to open covers during insertion. The average access time was 25 milliseconds, complemented by data transfer speeds of 885 kB/s. The IBM 3348 Data Modules were available in three variants offering capacities of 35 MB, 70 MB, and a 70 MB version that included a 500 KB fixed-head section for accelerated access. Incorporating error correction, the 3340 was discontinued in 1984.

Designed under Ken Haughton’s leadership in San Jose, the initial concept focused on two removable modules each with 30 MB capacity. The "Winchester" nickname was inspired by the Winchester .30-30 rifle, reflecting this original 30/30 storage configuration; although storage sizes later expanded, the codename persisted.

A significant breakthrough was its economical head design which allowed heads to land on and lift off from spinning disks without unloading. This innovation simplified the head and arm mechanism while reducing costs. This "Winchester technology" subsequently became a benchmark standard within disk drive manufacturing.

The designation Winchester or Winnie endured into the early 1990s as a colloquial term for hard disk drives but has since declined in global usage.

IBM 3344

The IBM 3344 shares similarities with the 3340 but replaces removable IBM 3348 data modules with fixed media. Each spindle supports four logical drives, each matching the capacity of a single 3348–70 module. This model is exclusively offered in dual-drive configurations and lacks an A (head-of-string) variant. The 3344-B2F differs from the standard B2 by incorporating fixed heads over certain cylinders on both drives. Both versions depend on a 3340-A2 or 3340-A2F unit to serve as head of string. Internally, the IBM 3344 is identical to the IBM 3350; distinctions lie solely within the control unit microcode.

IBM 3350

Introduced in 1975 for IBM System/370, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. It featured sealed head-disk assemblies (HDAs) that were non-removable and integrated both the heads and arm assemblies—a design that set a precedent for subsequent IBM DASD products. Its disk geometry comprised 555 cylinders, 30 heads per cylinder, and tracks containing 19,069 bytes each, resulting in roughly 317 MB of storage per HDA.

The product line included models A2, A2F, B2, B2F, C2, and C2F, each housing two HDAs. Models A2 and A2F contained an additional electronic board enabling connection to a control unit; these units functioned as controllers or heads of string. Installation typically began with an A2 or A2F unit followed by up to three B2 units or combinations such as two B2s and one C2 unit. The A2 model generally featured a string switch allowing it to connect simultaneously to two storage control units for concurrent I/O operations. Compatible control units encompassed the 3830 Model 2, Integrated Storage Controller (ISC) within CPUs like the 3148/3158/3168, as well as later backward-compatible models such as the 3880.

The C2 unit also contained a controller that provided an alternate path for itself and other units but could only link to one storage control unit at a time; it served as a standby controller should the primary A unit’s controller fail. Valid IBM 3350 string configurations included -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC- arrangements.

Models designated with "x2F" (for example, A2F) featured fixed-head regions spanning the first five cylinders on both HDAs. This design eliminated seek time within that area and was commonly reserved for frequently accessed checkpoint files such as HASP or JES2 spools. This arrangement enhanced performance by reducing head movement on spool devices and supported swap data for TSO environments as well as system swap operations under MVT, SVS, or MVS operating systems—thereby improving context-switch efficiency between users or batch jobs.

The IBM 3350 series was officially withdrawn from service in September 1994.

IBM 3370

Released in January 1979, the IBM 3370 Direct Access Storage Device was designed to support IBM 4331, 4341, and System/38 midrange systems. Each unit contained seven fixed 14-inch platters, delivering a total storage capacity of 571 MB. It marked the first use of thin-film head technology in hard disk drives, a development originating from the Thomas J. Watson Research Center during the late 1960s. The 3370 utilized a fixed-block architecture and was compatible with DOS/VSE and VM—S/370 operating systems that supported FBA devices.

IBM 3375

The IBM 3375 served as a complementary model employing count key data (CKD) architecture, designed for compatibility with OS/360 and its subsequent operating systems.

IBM 3380

Debuting on June 11, 1980, the IBM 3380 incorporated thin-film head technology to achieve a storage capacity of 2.52 GB per unit, composed of two hard disk assemblies each equipped with dual actuators accessing 630 MB. It featured a data transfer rate of 3 MB per second and an average access time of 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges between the heads and media surfaces, shipments were delayed until October 1981.

Standard setups consisted of one A unit accompanied by up to three B units; each 3380 housed four devices, allowing configurations of up to sixteen devices in a string. Typically connected through a 3880 storage control unit with dual pathways, it supported two concurrent I/O operations targeting separate hard disk assemblies.

In February 1985, IBM released the Extended Capability Models (3380 E) featuring double-density technology with a capacity of 5.04 GB per unit (two actuators at 1.26 GB each). This was followed by the triple-capacity 3380 K model in August 1987, offering 7.562 GB per unit with two actuators at 1.89 GB each. Both Models J and K could optionally operate in four-path mode, enabling strings of up to thirty-two devices and supporting four simultaneous I/O operations via a 3990 storage control unit.

The IBM 3380 series comprised twelve distinct models: six A-units (which led the string and contained controller logic for storage control unit connections), five B-units (designed for attachment to A or C units), and one C-unit (capable of direct connection to an IBM channel).

Production of the IBM 3380 concluded in May 1996 after fifteen years on the market, marking it as one of the longest-lived disk drive product lines.

IBM 3390

Introduced in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities up to twenty-two gigabytes distributed across multiple drives. System pricing varied from $90,000 to $795,000 depending on configuration and capacity.

A typical IBM 3390 configuration featured a central A unit containing four or eight devices, optionally accompanied by one or two B units housing up to twelve devices each. Operating in four-path mode, these units connected to a 3990 storage control unit capable of supporting a second string for a total maximum of sixty-four devices per subsystem.

Each Hard Disk Assembly (HDA) included two actuator-head assemblies along with platters. Model 1 HDAs offered capacities of 1.89 GB; Model 2 increased this to 3.78 GB per HDA. An upgrade in 1991 introduced Model 3 HDAs with capacities reaching 5.67 GB each, while Model 9 in 1993 further expanded capacity to 11.3 GB per HDA.

Distinct from earlier DASD models that employed belt-driven AC motors, the IBM 3390 HDAs utilized direct-drive DC motors enclosed within the assembly. The Model 9 represented IBM’s last implementation of Single Large Expensive Disk (SLED) technology.

IBM 9345

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

IBM 9340

In October 1991, IBM launched the 9345 Direct Access Storage Device (DASD) as part of the IBM 9340 family—a channel-attached count key data (CKD) DASD subsystem designed for IBM mainframes, including the ES/9000 series processors. The Model 1 of the 9345 DASD contained two HDDs each with 1.0 GB capacity, while Model 2 comprised two drives with 1.5 GB each.

From a functional perspective, the 9340/9345 devices were similar to the IBM 3990/3390 series; however, they did not include the non-volatile RAM cache found in the 3990 and supported shorter maximum block lengths compared to the 3390.

The operating system's Input/Output Supervisor (IOS) identified these devices through a specialized initializer called IECCINIT, which also managed other DASD types. During initialization, the OS detected that the 9340 lacked non-volatile cache and that the 9345 had fewer tracks per surface, resulting in their classification under device types distinct from those assigned to the 3990/3390 series.

9330 family of disk drives

1. Models 1 and 11 of the 9331 Diskette Unit contained a single 8-inch floppy disk drive; models 2 and 12 were equipped with one 5¼-inch floppy disk drive.
2. The IBM 0667 hard disk drive powered the 9332 Direct Access Storage Device.
3. The high-performance disk drives in the 9333 subsystem utilized either IBM 0664 or IBM 0681 HDDs depending on the specific model.
4. The 9334 Disk Expansion Unit connected one to four SCSI hard drives to RS/6000 systems.
5. The 9335 Direct Access Storage Subsystem featured an IBM-designed "Kestrel" HDD—an 850 MB drive consisting of three large 14-inch platters and dual rotary actuators. Each actuator accessed three surfaces with two heads per surface. This rack-mountable device debuted alongside the IBM 9370 Information System in October 1986. No original equipment manufacturer (OEM) versions are known.
6. The IBM 0681 HDD (also known as Redwing) was employed in the 9336 Disk Unit.
7. The disk array subsystem designated as the 9337 incorporated either IBM's 0662 (Spitfire) or 0663 (Corsair) hard drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive was introduced in conjunction with the IBM 1800 in 1964 and later with the IBM 1130 in 1965, with initial shipments likely starting in late 1965 alongside the IBM 1130. It stored up to 512,000 words of sixteen bits each (equivalent to approximately one million bytes) on an IBM 2315 cartridge. This cartridge housed a single aluminum disk coated with oxide, enclosed within a plastic shell featuring openings for both the read/write arm and its two heads.

IBM 5444

Announced in September of 1969 as part of System/3, the IBM 5444 was developed at IBM's Hursley facility in England under the codename Dolphin. It used a disk cartridge known as the IBM 5440, which contained one fourteen-inch platter. Three variants were made available:

• Model 1: included one fixed and one removable disk, each featuring one hundred tracks per surface; cartridge capacity reached approximately 1.23 MB
• Model 2: incorporated one fixed plus one removable disk, both having two hundred tracks per surface; cartridge capacity doubled to around 2.46 MB
• Model 3: consisted solely of one removable disk with two hundred tracks per surface; capacity matched Model 2 at about 2.46 MB

IBM 62GV

Introduced in May 1974 from IBM's Hursley laboratory in the UK, the IBM 62GV—initially codenamed Gulliver—offered a storage capacity of 5 MB. Subsequent variants expanded this capacity to 10 MB (62TM) and later 14 MB. The device utilized a Swinging Arm actuator mechanism paired with a single 14-inch disk. This actuator design, developed at Hursley, became IBM's most widely licensed electromechanical innovation, seeing broad adoption across the industry throughout the 1980s and remaining in production nearly four decades later with over 10 billion units manufactured. Approximately 177,000 units of the IBM 62GV were shipped, making it the first hard disk drive to surpass 100,000 units sold.

OEM and Small Systems HDDs

This section covers HDDs produced by IBM for OEM applications and for their smaller system lines such as System/3, System/32, /34, /36, and AS/400. Drives are referenced by their OEM model numbers and organized according to the date of initial customer shipment.

IBM 0680

First delivered in 1979 across many IBM small systems and entry-level System/370 models as the 3310 direct access storage device, the 0680 was officially announced as an OEM product in September 1981. Developed at IBM's Hursley lab under the codename Piccolo, it provided up to 65 MB capacity through six 8-inch (210 mm) disks equipped with an enhanced rotary actuator.

A higher-capacity variant named 62SW was released in June 1984; however, its sales were limited due to pricing comparable to that of the 62GV model.

IBM 0676

Unveiled in November 1982 as part of the 5247 Disk Storage Unit for the IBM System/23 Datamaster, the 0676 was developed at IBM Rochester, Minnesota under the internal code 21ED. This 8-inch HDD offered capacities of either 15 or 30 MB via two or four 210 mm disks. In 1983, it was incorporated into the System/36’s 5360 System Unit. The following year, capacity was doubled by increasing tracks per surface, enabling its use within the System/36’s upgraded 5362 System Unit.

IBM 0665

Released in October 1985 alongside the PC AT (5170) system unit, the 0665 was developed at IBM Rochester under the codename "Pixie." This drive featured a 5¼-inch form factor with storage options of 20, 30, and 44 MB.

IBM 0667

The 0667 began shipping in August 1986. Created at IBM Rochester with the codename "Grant," this full-height ESDI HDD measured 5¼ inches and supported up to four disks sized at 130 mm each with a total capacity of up to 70 MB. It was available as an option for select PC RT models (6150, 6151, and 6152) as well as System/36 Model System Units (5363 and 5364).

IBM 0669

Introduced in 1987 and developed at IBM Rochester under "Grant-Prime," the 0669 was a full-height HDD with a five-inch form factor. It accommodated up to four disks measuring 130 mm each and offered a maximum capacity of 115 MB. This drive served as the internal hard disk for both the System/36’s 5363 and Series/1’s 4956 System Units.

IBM 0671

Also launched in 1987 and developed under the codename "Lee" at IBM Rochester, the 0671 was an ESDI full-height five-inch HDD providing up to 316 MB capacity across eight disks of 130 mm diameter. It represented IBM’s initial implementation of thin metal film recording surfaces. In 1988, this model was integrated into the AS/400’s 9404 System Unit architecture supporting configurations of two or three drives.

IBM 0661

First appearing in shipments from 1989 as model number 371, the 0661—nicknamed "Lightning"—was a SCSI HDD offering up to 320 MB storage using as many as eight disks sized at 95 mm each (with a total of fourteen heads). Development took place jointly at IBM Rochester and Hursley labs. A higher-performance "Turbo" variant reaching capacities of up to 400 MB followed in 1990. This drive became standard equipment on key IBM systems including certain AS/400 System Unit Model CXX configurations.

IBM 0681

Introduced in April 1990, the 0681 was IBM Hursley’s last hard disk drive offering, developed under the project name "Redwing." This model provided a maximum storage capacity of 857 MB across twelve 130 mm platters and was notable for being the pioneer in utilizing PRML data decoding technology. It served as the core component for the 9333 Disk Drive Subsystem starting in early 1992, with an upgraded variant boasting 1.07 GB capacity released in May of the same year.

IBM 0663

Launched towards the end of 1991 and internally referred to as "Corsair," the 0663 was a compact 3-inch hard drive featuring a half-height (1.6-inch) form factor. It delivered up to 1 GB storage via eight 95 mm disks and was incorporated into select PS/2 and RS/6000 systems. This model marked IBM’s inaugural use of Magnetoresistance (MR) heads in an OEM disk drive.

IBM 0664

The 0664 became available in November 1992, developed at IBM’s Rochester facility under the codename "Allicat." It was a full-height 5-inch hard disk (measuring 3.25 inches tall) that effectively combined two 3-inch drives, offering a maximum capacity of 2.013 GB across up to eight 95 mm disks.

IBM 0662

Released in June 1993 and known internally as "Spitfire," the 0662 was a full-height (1 inch tall) 3-inch HDD developed at IBM Rochester. It provided a storage capacity of 1.05 GB distributed over three disks or five disk surfaces and was utilized within IBM’s internal products such as the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was instrumental in pioneering floppy disk technology, initially introducing the 8-inch floppy disk drive in 1971 as a read-only device for program loading. The company followed this with its first read/write version in 1973, integrated into the 3740 Data Entry System. Although IBM established early standards for the 8-inch drives, it never marketed them separately, allowing other industry players to drive their evolution.

At one point, IBM stood as the largest original equipment manufacturer (OEM) buyer of 5-inch floppy drives, adopting a two-sided model with a track density of 48 tracks per inch that eventually became an industry benchmark. Despite having plans to produce these drives and smaller variants internally, IBM discontinued such initiatives by 1985. Additionally, its effort to OEM a smaller 4-inch DemiDiskette in 1983 did not achieve commercial success.

"Star" series of HDDs

On October 17, 1994, IBM’s Storage Systems division introduced three families of hard drives: Travelstar, consisting of compact 2-inch drives designed for notebook computers; Deskstar, featuring 3-inch drives intended for desktop PCs; and Ultrastar, also utilizing a 3-inch form factor but optimized for high-performance computing environments.

IBM's first HDD versus its last HDDs

The table below contrasts IBM’s original hard disk drive, the RAMAC 350, with its three latest models from the "Star" series of OEM HDDs. This comparison illustrates dramatic improvements over time in cost efficiency and physical size, alongside substantial enhancements 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 consumption (watts)	8100 BTUs/hour (~2374 watts), up to 5500 VA depending on model	16	10.3	1.85	1,283
Power efficiency (megabytes/watt)	0.0016	9,125	17,476	43,243	27,375,856
List price (Template:US$)	$34,500 ($234,000 adjusted to 2002 dollars)	1,200	360	420
Cost per megabyte (Template:US$)	$9,200 ($68,000 adjusted to 2002 dollars)	0.0082	0.0020	0.0053
Areal density (megabits/in²)	0.002	26,263	46,300	70,000	35,000,000
Areal density (kilobits/mm²)	0.003	40,708	71,765	108,500
Volume density (gigabytes/in³)	0.00000003	6	8	20	622,100,131
Volume density (megabytes/cm³)	0.000002	388	478	1,203
Latency (milliseconds)	25	3	4	7	8
Average seek time (milliseconds)	600	5.9	10.2	12	102
Data transfer rate (megabytes/second)	0.001	103	29.4	43.75	11,719

DASD Devices Beyond HDDs and FDDs

In certain IBM operating systems, hard disk drives (HDDs) and floppy disk drives (FDDs) are categorized under DASDs (direct access storage devices). This classification also encompasses a range of other storage technologies, including:

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 magnetic drum storage device.

IBM 2303 Drum

The IBM 2303, released in 1964, is part of IBM’s magnetic drum storage lineup.

IBM 2321 Data Cell

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

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System functions as a tape cartridge library. It stages data onto IBM 3330 or 3350 disk drives and provides virtual disk drive access to the system.

See also

• History of the floppy disk
• History of hard disk drives
• List of IBM products

External links

• IBM Archive: Basic Storage Information
• IBM Archive: Disk Drive Articles Index
• Magnetic Disk Heritage Center
• A Quarter Century of Disk File Innovation, IBM Journal of Research and Development, 1981
• EE Times: Disk Drives' Eventful Evolution
• IBM 1311 Disk Storage Drive Documentation
• IBM 2314 Direct Access Storage Materials