IBM 350
| Company type | Division (until divestment) |
|---|---|
| Industry | Computer storage hardware |
| Founded | 1956 |
| Defunct | 2003 |
| Fate | Divested to Hitachi |
| Products | Hard disk drives, floppy disk drives |
| Parent | IBM |
IBM produced magnetic disk storage hardware from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. IBM is credited with inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), with numerous technological advancements attributed to its workforce. The fundamental mechanical architecture of hard disk drives has largely remained unchanged since the introduction of the IBM 1301, with performance benchmarks established during the 1950s still serving as a reference. Throughout the years, these devices have experienced substantial decreases in cost and physical dimensions, coupled with marked enhancements in capacity and speed.
From 1969 through the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not become a key player in producing the smaller 5.25- or 3.5-inch formats. Although IBM marketed its magnetic disk drives, 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, providing all HDDs solely as OEM products.
IBM employed various designations for its magnetic disk storage devices, including direct-access storage device (DASD), disk file, and diskette file. This article adopts the widely accepted industry terminology of hard disk drive (HDD) and floppy disk drive (FDD).
IBM 350
The IBM 350 disk storage unit, recognized as the first-ever disk drive, was launched on September 14, 1956, as part of the IBM 305 RAMAC computer system. A related model, the IBM 355, was introduced for use with the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, while production units began shipping in November 1957 to customers including United Airlines.
Engineered to support real-time business accounting operations, the IBM 350 stored five million 6-bit characters (equivalent to 3.75 MB) across fifty-two disks of diameter, utilizing a total of 100 recording surfaces rotating at 1200 revolutions per minute. It offered a data transfer speed of 8,800 characters per second and incorporated an access mechanism that positioned read/write heads to select specific disk pairs and tracks. Several enhanced versions were released throughout the late 1950s. The IBM RAMAC 305 system equipped with the IBM 350 was leased at a rate of $3,200 per month. The IBM 350 was retired from production in 1969.
The patent originating from the RAMAC project is regarded as foundational for disk drive technology. Although IBM’s Board initially canceled it due to concerns about potential disruption to their punch card business, development persisted under authorization from IBM's president.
The cabinet housing the IBM 350 measured approximately long, high, and wide. Weighing nearly one ton, transportation required forklifts and large cargo aircraft. Currie Munce, former research vice president at Hitachi Global Storage Technologies, which acquired IBM’s storage unit, noted that capacity could have exceeded five million characters; however, IBM’s marketing team was reluctant to offer higher-capacity drives commercially. Nonetheless, models with double capacity were announced in January 1959 and shipped later that year.
In recognition of its significance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, a restoration initiative led by Al Hoagland collaborated with Santa Clara University to refurbish an IBM 350 RAMAC unit. This effort transitioned to the Computer History Museum in Mountain View, California in 2005 and is currently exhibited publicly within the museum's Revolution gallery.
IBM 353
The IBM 353, implemented on the IBM 7030, bore resemblance to the IBM 1301 but offered a quicker data transfer speed. It provided storage for 2,097,152 (221) words of 64 bits each (totaling 134,217,728 bits) and achieved transfer rates of 125,000 words per second. A prototype delivered in late 1960 was the first disk drive to incorporate an individual head per surface that floated on compressed air, evolving from the IBM 350 design. Production versions utilized self-flying heads akin to those found in the IBM 1301.
IBM 355
Introduced on September 14, 1956, the IBM 355 served as an expansion to the widely used IBM 650 system. It employed the IBM 350 mechanism but featured up to three access arms instead of one, and it stored six million decimal digits plus an additional 600,000 signs. This device transferred entire tracks between its magnetic core memory and the 653 storage unit—an IBM 650 accessory that provided sixty signed 10-digit words, enough to hold a single disk track or tape record, along with other capabilities.
IBM 1405
Released in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit came in two variants: Model 1 accommodated 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. The disks rotated vertically at a speed of 1200 rpm.
Each disk surface contained 200 tracks segmented into five sectors (numbered 0–4 on the top side and 5–9 on the bottom). Each sector held between 178 and 200 characters. One to three forked access arms, each equipped with two read/write heads (one for each side), moved vertically to select among disks (0–49) and horizontally to reach specific tracks (0–199). Reading or writing a sector required approximately 10 milliseconds.
Access times varied 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 contained a total of 100,000 sectors with either 200 characters in move mode or reduced to 178 characters in load mode, which included a word mark bit per character. Model 1 had half as many sectors at 50,000.
IBM 7300
The IBM 7300 Disk Storage Unit was created specifically for use with the IBM 7070; a second model was announced in 1959. Nevertheless, when the IBM 1301 was introduced on June 5, 1961, it became more appealing to customers using the IBM 7070 and IBM 7074 systems. The IBM 7300 shared technological features with the IBM 350, IBM 355, and IBM 1405 disk drives.
IBM 1301
Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was designed for mainframe computers in the 7000 series and also compatible with the IBM 1410. Each module stored up to twenty-eight million characters (168 million bits), or twenty-five million characters when used with the IBM 1410. Every module consisted of twenty-five large disks providing forty user-accessible recording surfaces and featured two hundred fifty tracks per surface. The Model 1 contained one module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute, transferring data at ninety thousand characters per second.
A significant advancement was having an individual arm and read/write head dedicated to each surface, moving collectively like a comb assembly. This eliminated delays caused by switching heads and reduced maximum access time to approximately one hundred eighty milliseconds by positioning heads closer to their respective tracks. The IBM 1301 was also pioneering as the first disk drive employing aerodynamically designed heads that float on a thin cushion of air above the disk surface, thereby improving performance.
Connection was established through the IBM 7631 File Control unit, enabling operation with either the IBM 1410 or systems from the IBM 7000 series or allowing sharing between two computers.
Leasing costs for the IBM 1301 Model 1 were $2,100 monthly or $115,500 for purchase; Model 2 leased at $3,500 per month or $185,000 to buy. The IBM 7631 controller added $1,185 monthly or $56,000 if purchased outright. All models were phased out by around 1970.
IBM 1302
Launched in September 1963, the IBM 1302 Disk Storage Unit delivered a fourfold increase in capacity compared to the 1301, reaching 117 million 6-bit characters per module. It achieved an average access time of 165 milliseconds and supported data transfer speeds of 180,000 characters per second, which was more than twice as fast as its predecessor. Each module was equipped with two separate access mechanisms dedicated to the inner and outer cylinders. The Model 2 configuration stacked two modules together, 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 purchase prices were $252,000 and $355,500 respectively. The IBM 7631 controller was an optional addition costing $1,185 monthly or $56,000 for outright purchase. The IBM 1302 was discontinued in February 1965.
IBM 1311
Announced on October 11, 1962, the IBM 1311 Disk Storage Drive catered to medium-sized business and scientific computing needs. It utilized removable IBM 1316 disk packs capable of storing approximately 2 million characters. Throughout the 1960s, seven different models were produced before being phased out by the early 1970s.
Each IBM 1316 disk pack measures about four inches in height, weighs close to ten pounds, and contains six disks each measuring fourteen inches in diameter with ten recording surfaces total. These disks rotate at a speed of 1500 revolutions per minute. Every surface is organized into one hundred tracks, with twenty sectors per track holding one hundred characters each. Hydraulic mechanisms move the read/write heads, which are mechanically locked into place for precise alignment on tracks. The disk pack is protected within a plastic casing featuring a locking handle to secure it firmly during operation.
The seven IBM 1311 models included master drives—housing control logic and additional power supplies—and slave drives operated under master control. Depending on the system (such as IBM 1440 or IBM 1620), master drives could manage either three or four slave units. Variations among models reflected compatibility with different systems and feature sets; all were retired by the early seventies.
Several optional enhancements improved functionality and storage efficiency:
- Direct Seek: bypasses returning to track zero before seeking a new track.
- Scan Disk: facilitates swift automatic search operations.
- Seek Overlap: permits simultaneous seeks and read/write operations across multiple drives.
- Track Record: boosts capacity by storing a single large record per track instead of multiple smaller sectors, raising total storage beyond 17 million bits.
Master drive variants (Models 1,3,4,5) are physically wider than the Model 2 slave drives due to their additional components.
IBM 2302
The IBM 2302 represents the System/360 adaptation of the IBM 1302, featuring track formatting tailored to S/360 Direct Access Storage Device (DASD) architecture. It employs a non-removable module consisting of twenty-five platters with forty-six recording surfaces. The Model 3 contains a single module; the Model 4 includes two modules. Each module incorporates two independent access mechanisms—termed access groups—one servicing the innermost 250 cylinders and the other handling the outermost 250 cylinders. Each access group provides one read/write head per track. Average rotational latency is approximately seventeen milliseconds with a maximum of thirty-four milliseconds; maximum seek time per access group is about one hundred eighty milliseconds. Each track holds 4,985 bytes, resulting in a total module capacity of roughly 112 megabytes. Connection to IBM mainframes is facilitated through the IBM 2841 Storage Control Unit.
IBM 2305
Introduced in 1970 alongside the IBM 2835 Storage Control, the IBM 2305 fixed-head storage device was designed to interface with System/360 models such as the 360/85 and 360/195 via the IBM 2880 Block Multiplexor Channel.
During the era of System/370 virtual storage systems, the IBM 2305 gained popularity as a paging device across various models including the IBM 3155, 3165, 3158, 3168, 3033, 4341, and even the IBM 3081 with specialized microcode support. It was also well-suited for managing high-activity small data sets like catalogs and job queues.
The smaller model, designated as the 2305-1, offers a capacity of approximately 5.4 megabytes with a data transfer rate of three megabytes per second over a two-byte channel interface and an average access time of about two and a half milliseconds. The larger variant, the 2305-2, provides nearly double capacity at eleven point two megabytes but operates at a slower transfer rate of one point five megabytes per second with an average access time of five milliseconds.
Engineered for rapid and continuous access to relatively small volumes of data, the IBM 2305’s combination of capacity and high throughput made it ideal for system-resident functions such as work files, job queues, indices, and frequently accessed datasets. Its fast response times rendered it particularly effective as a paging device in heavily loaded environments processing more than one point five transactions per second.
IBM 2311
Launched in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive was designed to support the IBM System/360 series, as well as the IBM 1130 and IBM 1800. It also connected directly to System/360 Models 20 and 25. All units utilized the removable IBM 1316 Disk Pack originally introduced with the IBM 1311.
The Model 1 typically interfaces with most IBM mainframes through the 2841 Control Unit; for Model 25 systems, a Disk Attachment Control handles this connection. The disk packs employ IBM's count key data format, which allows variable record lengths. In contrast, Models 11 and 12—attached via the Model 20’s integrated control—use a fixed sector format, rendering their disk packs incompatible with those of Model 1.
While mechanically comparable to the IBM 1311, the 2311 offers enhanced recording density, storing 7.25 megabytes on a removable six-platter disk pack. It incorporates ten read/write heads mounted on a hydraulically driven arm equipped with mechanical detents for precise track positioning. Each platter surface contains 200 tracks plus three optional spare tracks. The average seek time is approximately 85 ms, and data transfer occurs at a rate of 156 kB/s.
Uniform electrical interfaces across System/360 models allowed third-party vendors to produce plug-compatible disk drives, encouraging a competitive market for IBM-compatible storage products.
IBM 2314 Disk Access Storage Facility Model 1
Introduced in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 provided expanded storage for the System/360 and System/370 families. Featuring two-channel switching capability, it could connect simultaneously to two separate channels. Its mechanical design resembled that of the 2311 but supported higher data density.
This drive utilized a taller IBM 2316 disk pack composed of eleven platters (totaling 20 surfaces), capable of holding about 29 million characters. Twenty read/write heads mounted on a hydraulically actuated arm accessed these surfaces, each containing 200 tracks. Initial access times were comparable to those of the 2311; subsequent enhancements improved performance further. Data transfer rates doubled to reach approximately 310 kB/s.
The Model 1 was delivered as nine disk drives bundled together with a dedicated storage control unit; drives were installed in drawers for convenient disk pack handling—earning them the nickname "Pizza Ovens." Of these nine drives, eight operated online simultaneously while one remained offline as a spare. Drive system addresses could be configured by users through interchangeable plugs, enabling flexible drive management.
An optional 2844 Control Unit allowed two System/360 channels to access separate drives within the facility concurrently.
Subsequent versions of the IBM 2314 included:
IBM 2314 direct access storage facility - A series
In 1969, IBM separated the facility into distinct models supporting up to nine drives (with eight active online) connected to a 2314 Storage Control:
- 2312 Disk Storage, consisting of a single-drive unit.
- 2313 Disk Storage, comprising four drives.
- 2318 Disk Storage, featuring two drives.
IBM 2319
To address competition from plug compatible manufacturers producing equivalent storage subsystems to the 2314, IBM introduced in 1970 an affordable three-drive module called the 2319. This model was derived by removing one drive from the four-drive 2313 and marketing it as the 2319 A1, offered at significantly lower rental costs. This approach reduced entry barriers for new customers while maintaining higher pricing for existing clients. The 2319-A1 connects to integrated controllers used in System/370 Models 135 and 145. Additionally, standard DASD units like the 2312 or 2318 can be attached to the 2319-A1.
The 2319 B series supports configurations of three, six, or nine drives connected to a new 2314 Model B Storage Control Unit.
IBM 3310
Launched on January 30, 1979, the IBM 3310 Direct Access Storage Device was designed specifically for IBM 4331 midrange computer systems. Each unit provided a storage capacity of 64.5 MB and utilized fixed-block architecture (FBA). This architecture was compatible exclusively with the S/370 operating systems DOS/VSE and VM, which supported FBA devices.
IBM 3330
Introduced in June 1970, the IBM 3330 Direct Access Storage Facility—codenamed Merlin—was developed for IBM System/370 and System/360/195 platforms. The initial offerings included the two-drive Model 1 and the single-drive Model 2. Each removable disk pack had a capacity of 100 MB, featured a 30 ms access time, and delivered data transfer speeds of up to 806 kB/s. A significant advancement was its built-in error correction using fire codes, which improved reliability and lowered costs by compensating for imperfections on the disk surface.
The standard setup combined a storage control unit (3830 Model 1) with anywhere from one to four drives physically connected to form strings with a maximum of eight drives. In August 1972, IBM released the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated control units from drive strings. The 3830 Model 2 functioned as a director managing multiple strings, while each string’s first unit—the 3333—included two drives plus a controller capable of handling up to three attached 3330 drives, totaling eight drives per string. Two such 3333 units could be linked to a single controller, expanding capacity to sixteen drives; an optional string switch allowed connection to two controllers.
In 1973, IBM introduced double-density (-11) variants: the 3333–11, 3330-11, and 3336–11 Disk Packs doubled storage capacity to 200 MB. Mixing single- and double-density drives within the same string was not supported. Upgrading from original models to Model-11 versions was feasible but complicated, involving drive conversions and data transfers.
Production of the IBM 3330 ceased in 1983.
IBM 3340 and 3344
While the IBM 3340 and 3344 share many characteristics, only the IBM 3340 can operate as the head of a drive string; no A model exists for the 3344, so any 3344 units must be connected to a 3340 A model serving as head.
IBM 3340
The IBM 3340 Direct Access Storage Facility, known by its codename Winchester, was introduced in March 1973 for IBM System/370. It came in three configurations: the A2 model with two drives plus a controller, and B2 (two drives) and B1 (single drive) units. The B models could be connected to an A2 unit to expand up to eight drives.
This system utilized removable data modules that integrated both head and arm assemblies; their access doors opened mechanically during loading or unloading without requiring removal of any covers. The drive offered an access time of approximately 25 ms and supported data transfer rates up to 885 kB/s. Three versions of the IBM 3348 Data Modules were available: capacities included two at 35 MB and one at 70 MB with an additional fixed-head area of 500 KB designed for quicker access. The device incorporated error correction features and was discontinued in 1984.
Engineered in San Jose under Ken Haughton's leadership, the design initially aimed at two removable modules each holding about 30 MB, inspiring the "Winchester" codename after the Winchester .30-30 rifle. Although storage capacities increased over time, this nickname remained associated with the technology.
A notable breakthrough was its economical head design that allowed read/write heads to land on and lift off from spinning disks without unloading them completely, significantly simplifying mechanics and reducing costs. This innovation—dubbed "Winchester technology"—became a foundational standard in disk drive manufacturing.
The term Winchester continued as a generic label for hard drives into the early 1990s but has since largely fallen out of use worldwide.
IBM 3344
The IBM 3344 shares similarities with the 3340 but utilizes fixed media rather than the removable 3348 data modules. Each spindle houses four logical drives, each providing storage capacity equivalent to a 3348–70 module. This model is offered exclusively in dual-drive configurations and does not include an A (head of string) variant. The 3344-B2F version is distinguished by fixed heads positioned over certain cylinders on both drives. Both the 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F unit as the head of string. Internally, the 3344 mirrors the IBM 3350, differing primarily in the control unit’s microcode.
IBM 3350
Introduced in 1975 for the IBM System/370, the IBM 3350 Direct Access Storage Facility, codenamed Madrid, featured sealed, non-removable head-disk assemblies (HDAs) integrating both head and arm components. This design set a precedent for subsequent IBM DASD products. Its disk geometry consisted of 555 cylinders, 30 heads, and 19,069 bytes per track, yielding approximately 317 MB of storage per HDA.
The models A2, A2F, B2, B2F, C2, and C2F each contained two HDAs. The A2 and A2F models incorporated an additional electronics board that enabled connection to the control unit; these served as controllers or head-of-string devices. Configurations were arranged in strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. The A2 model typically included a string switch allowing dual connections to storage control units such as the 3830 Model 2 or Integrated Storage Control (ISC) found in CPUs like the 3148 and later models including the 3880, which maintained backward compatibility.
The C2 model featured a secondary controller designed as a backup path in case of failure of the A unit's controller; however, it supported fewer connections and could not perform simultaneous I/O operations like the A unit.
Permissible IBM 3350 configurations included strings such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.
Models designated with "x2F" (for example, A2F) incorporated fixed heads over the first five cylinders on each HDA to eliminate seek time within this region. This enhancement was aimed at frequently accessed areas like HASP or JES2 checkpoint data to reduce head movement on spool devices. It also improved support for TSO swap data and system swap data on MVT, SVS, and MVS operating systems by optimizing context switch efficiency without requiring contiguous memory pages.
The IBM 3350 series was discontinued in September 1994.
IBM 3370
Debuted in January 1979 for use with IBM 4331, 4341, and System/38 midrange systems, the IBM 3370 Direct Access Storage Device comprised seven fixed 14-inch disks providing a total capacity of 571 MB per unit. It was notable for being the first hard disk drive to utilize thin-film head technology developed at IBM’s Thomas J. Watson Research Center during the late 1960s. The device employed fixed-block architecture and was compatible with DOS/VSE and VM operating systems.
IBM 3375
The IBM 3375 served as a counterpart employing count key data architecture required by OS/360 and its successor operating systems.
IBM 3380
Released on June 11, 1980, the IBM 3380 Direct Access Storage Device used thin-film head technology and offered a capacity of approximately 2.52 gigabytes per unit (comprising two hard disk assemblies with two actuators each accessing around 630 MB). It delivered data transfer rates up to 3 MB/s with an average access time near 16 milliseconds. Initial pricing ranged from $81,000 to $142,200. Due to tribological challenges between heads and media surfaces, shipments commenced in October 1981.
Standard configurations supported one A unit plus up to three B units, expanding device strings from earlier models to accommodate as many as sixteen devices. These units were commonly connected to IBM 3880 storage control units featuring dual paths that enabled two simultaneous I/O operations targeting separate HDAs.
In February 1985, IBM introduced double-density Extended Capability Models (3380 E) doubling capacity to about 5.04 GB per unit (two actuators at roughly 1.26 GB each). Later in August 1987, a triple-capacity model labeled the 3380 K was launched offering approximately 7.562 GB per unit (two actuators at about 1.89 GB each). Models J and K supported four-path operation when connected to a 3990 storage control unit, allowing up to thirty-two devices on a string with four concurrent I/O operations.
The IBM 3380 family consisted of twelve models: six A-units serving as string heads with controller logic linking them to storage control units; five B-units connecting through A- or C-units; and one C-unit designed for direct connection to an IBM channel.
Production continued until May 1996, marking a fifteen-year production span for this disk drive series.
IBM 3390
Introduced in November 1989, the IBM 3390 series of Direct Access Storage Devices provided storage capacities reaching up to 22 gigabytes distributed across multiple disk units. Depending on the selected configuration and storage size, pricing varied from $90,000 to $795,000.
A typical 3390 configuration consists of a primary A unit containing either four or eight drives, which can be complemented by one or two B units, each supporting up to 12 drives. This setup operates in a four-path mode connected to a 3990 storage controller, which is capable of managing an additional 3390 string, allowing for a total of 64 drives.
The Hard Disk Assemblies (HDAs) incorporate two actuator-head assemblies and platters. Model 1 delivers a raw capacity of 1.89 GB per HDA, while Model 2 doubles this to 3.78 GB. The Model 3, released in 1991, increased capacity by 50% to 5.67 GB per HDA, and the Model 9 from 1993 tripled it further to reach 11.3 GB per HDA.
In contrast to earlier DASD models that utilized AC motors driving the HDAs through belts, the 3390 integrated a DC motor within the enclosure itself. Notably, the Model 9 represented IBM's final iteration of the Single Large Expensive Disk (SLED) design.
IBM 9345
Unveiled in November 1990 as a Request for 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. Featuring a full-height 5¼-inch form factor with up to eight 130 mm platters, it offered capacities as high as 1.5 GB. This drive was pioneering in its use of Magnetoresistive (MR) heads, marking a key technological breakthrough.
IBM 9340
Released in October 1991, the IBM 9345 was part of the broader 9340 channel-attached count key data (CKD) DASD subsystem family designed for IBM mainframes such as the ES/9000 series. The Model 1 configuration included two HDDs each with a capacity of 1.0 GB, while Model 2 doubled this to two drives of 1.5 GB each.
From an operational standpoint, the capabilities of the 9340/9345 closely matched those of the earlier 3990/3390 systems but lacked certain features: specifically, they did not include non-volatile RAM cache like the 3990 and supported shorter maximum block lengths compared to the 3390. The operating system’s Input/Output Supervisor (IOS) identified these devices using a specialized initializer called IECCINIT, which accounted for the absence of non-volatile cache in the 9340 and reduced track size in the 9345 by assigning appropriate device types.
9330 family of disk drives
- The 9331 Diskette Unit comprised models equipped with either a single 8-inch or a single 5¼-inch floppy disk drive.
- The 9332 Direct Access Storage Device utilized the IBM 0667 hard disk drive.
- The 9333 High Performance Disk Drive Subsystem incorporated IBM’s 0664 or IBM 0681 HDDs depending on specific models.
- The 9334 Disk Expansion Unit connected between one and four SCSI hard disk drives to RS/6000 systems.
- The 9335 Direct Access Storage Subsystem featured an IBM "Kestrel" hard disk developed at IBM Hursley in the UK — an 850 MB unit containing three large (14-inch) disks with dual rotary actuators enabling access to multiple surfaces. This rack-mountable device was introduced alongside the October 1986 announcement of the IBM 9370 Information System and had no known original equipment manufacturer equivalents.
- The 9336 Disk Unit employed the IBM Redwing (0681) hard disk drive.
- The 9337 Disk Array Subsystem made use of IBM’s Spitfire (0662) or Corsair (0663) HDD models.
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, with initial shipments likely commencing late that year with the latter system. It stored a total of 512,000 sixteen-bit words (equivalent to approximately one million bytes) on an IBM 2315 cartridge. This cartridge contained a single oxide-coated aluminum platter enclosed within a plastic casing featuring openings for both the read/write arm and two read/write heads.
IBM 5444
Introduced in September 1969 as part of the System/3 lineup, the IBM 5444 was engineered at IBM's Hursley facility in England and carried the internal code name Dolphin. This model utilized the 5440 disk cartridge, which housed a single 14-inch disk. The product range included three variants:
- Model 1: featured one fixed disk plus one removable disk, each offering 100 tracks per surface, with a cartridge storage capacity of 1.23 MB
- Model 2: contained one fixed and one removable disk, each providing 200 tracks per surface, yielding a cartridge capacity of 2.46 MB
- Model 3: equipped with a single removable disk featuring 200 tracks per surface and a cartridge capacity of 2.46 MB
IBM 62GV
Released in May 1974, the IBM 62GV was developed at the Hursley laboratory in the UK under the codename Gulliver. Its initial storage capacity was 5 MB, later expanded to 10 MB (62TM) and eventually to 14 MB in subsequent models. It incorporated a Swinging Arm actuator mechanism with a single 14-inch disk. This actuator design, conceived at Hursley, became IBM's most widely licensed electromechanical innovation and was broadly adopted across the industry during the 1980s. Remarkably, it remained in use for nearly four decades, appearing in over ten billion devices globally. Approximately 177,000 units of the IBM 62GV were shipped, marking it as the first hard drive to surpass 100,000 units sold.
OEM and Small Systems HDDs
This segment focuses on HDDs produced by IBM intended for OEM distribution as well as integration into IBM’s smaller systems such as System/3, System/32, /34, /36, and AS/400 platforms. Drives are identified by their OEM model numbers and organized according to their initial shipment dates.
IBM 0680
The IBM 0680 was introduced in 1979 and deployed across numerous IBM small systems and entry-level System/370 models as the 3310 direct access storage device. Officially announced as the OEM version in September 1981, it originated from development efforts at IBM Hursley under the codename Piccolo. The unit comprised six 8-inch (210 mm) disks and initially supported up to 65 MB of storage using an enhanced rotary actuator.
A higher-capacity version known as the 62SW debuted in June 1984 but experienced limited market penetration due to pricing that was similar to that of the IBM 62GV.
IBM 0676
First appearing in November 1982, the 0676 served as a Disk Storage Unit (5247) for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the designation 21ED, this model featured an 8-inch HDD with initial capacities of either 15 or 30 MB depending on whether it contained two or four disks. In 1983, it was integrated into the System/36’s 5360 System Unit. By increasing tracks per surface in 1984, its capacity doubled and it was subsequently incorporated into the System/36’s enhanced 5362 System Unit.
IBM 0665
Launched in October of 1985 within the PC AT (5170) system unit, the IBM 0665 was developed under the codename "Pixie" at IBM Rochester. This drive was a 5¼-inch HDD offering storage options of 20, 30, or 44 MB.
IBM 0667
The 0667 model began shipping in August 1986. Created at IBM Rochester under the codename "Grant," it was a full-height ESDI hard drive measuring 5¼ inches with up to four disks sized at 130 mm each and delivering a maximum capacity of 70 MB. It was utilized in select PC RT systems (6150, 6151, and 6152) as well as within System/36 Model System Units (5363 and 5364).
IBM 0669
Released in 1987, the 0669 originated from development efforts at IBM Rochester under the codename "Grant-Prime." This full-height hard drive measured five inches and could accommodate up to four disks of 130 mm diameter for a total capacity reaching up to 115 MB. It functioned as the internal storage device for both System/36’s 5363 and Series/1’s (4956) system units.
IBM 0671
Introduced in 1987, the 0671 was developed at IBM Rochester under the codename "Lee." This full-height 5-inch HDD featured ESDI technology, offering capacities up to 316 MB across as many as eight 130 mm platters. It represented IBM's initial implementation of a thin metal film recording layer and was incorporated into the IBM AS/400 9404 System Unit in 1988, accommodating configurations of two or three drives.
IBM 0661
The 0661, originally released in 1989 as model 371, was created at IBM Rochester and Hursley with the codename "Lightning." It was a SCSI hard drive with a capacity of 320 MB, utilizing up to eight 95 mm platters and featuring 14 heads. A subsequent "Turbo" variant with 400 MB capacity appeared in 1990. This model became a standard component in several IBM systems, including the AS/400 System Unit Model CXX.
IBM 0681
Launched in April 1990 from IBM Hursley, UK, the 0681—developed under the codename Redwing—was the final HDD engineered at that location. It was a full-height 5-inch drive capable of holding up to 857 MB with as many as twelve 130 mm platters. Notably, it was the first IBM HDD to incorporate PRML data decoding technology. This drive powered the 9333 Disk Drive Subsystem introduced in early 1992, with an enhanced version featuring 1.07 GB capacity added in May of the same year.
IBM 0663
Released toward the end of 1991, the 0663—known internally as "Corsair"—was a compact half-height (1.6-inch) HDD measuring 3 inches in diameter. It offered up to 1 GB storage using eight 95 mm platters. Available on select PS/2 and RS/6000 models, this was IBM’s first OEM HDD equipped with Magnetoresistance (MR) heads.
IBM 0664
The 0664 became available in November 1992 and was developed under the codename "Allicat" at IBM Rochester, Minnesota. This full-height (3.25-inch high) 5-inch drive combined two separate 3-inch devices, delivering a total capacity of up to 2.013 GB using as many as eight 95 mm platters.
IBM 0662
Shipped in June 1993 and developed as "Spitfire" at IBM Rochester, the 0662 was a full-height (1-inch high) HDD with a diameter of 3 inches. It provided storage of approximately 1.05 GB distributed over three platters or five surfaces. This model was utilized internally within both the 9336 Disk Unit and the 9337 Disk Array.
Floppy disk drive
IBM was instrumental in pioneering floppy disk drives, introducing the first read-only program load version of an 8-inch FDD in 1971 and releasing its initial read/write model in 1973 alongside the 3740 Data Entry System. Although IBM established early standards for the 8-inch floppy disk drives, it refrained from marketing them separately, enabling industry-wide development to evolve independently.
At one time, IBM stood as the largest OEM consumer of 5-inch floppy disk drives. Its adoption of two-sided drives operating at a density of 48 tracks per inch contributed significantly to this becoming an industry norm. Despite extensive efforts to produce these drives and smaller variants internally, IBM ceased all such manufacturing endeavors by 1985. Additionally, its attempt in 1983 to OEM a smaller, 4-inch DemiDiskette was unsuccessful.
"Star" series of HDDs
On October 17, 1994, IBM’s Storage Systems division unveiled three distinct families of hard disk drives: Travelstar models featuring compact 2-inch platters designed for notebook computers; Deskstar drives with a standard size of 3 inches aimed at desktop applications; and Ultrastar units also sized at 3 inches but tailored for high-performance computing environments.
IBM's first HDD versus its last HDDs
The following table contrasts IBM’s inaugural hard disk drive—the RAMAC 350—with three later models from its "Star" series of OEM HDDs. The comparison highlights substantial advancements over nearly five decades, illustrating dramatic reductions in physical size and cost alongside significant gains in storage capacity and operational efficiency.
| Parameter (units) | RAMAC 350 | Ultrastar 146Z10 | Deskstar 180GXP | Travelstar 80GN | Improvement over 46 years (maximum) |
|---|---|---|---|---|---|
| Announced | Sep 1956 | Jul 2002 | Oct 2002 | Nov 2002 | |
| Capacity (gigabytes) | 0.004 | 146 | 180 | 80 | 48,000 |
| Dimensions (inches) | 60×68×29 | 4×1×5.75 | 4×1×5.75 | 2.75×0.38×3.95 | |
| Dimensions (mm) | 1500×1700×700 | 102×25×146 | 102×25×146 | 70×9.5×100 | |
| Volume (in³) | 118,320 | 23 | 23 | 4 | 29,161 |
| Volume (litres) | 1,939 | 0.4 | 0.4 | 0.1 | |
| Weight (lbs) | 2,140 | 1.7 | 1.4 | 0.2 | 1,244 |
| Weight (kg) | 971 | 0.8 | 0.64 | 0.095 | |
| Power (watts) | 8100 BTUs/hour (2374 watts), up to 5500 VA depending on model | 16 | 10.3 | 1.85 | 1,283 |
| Power density (megabytes/watt) | 0.0016 | 9,125 | 17,476 | 43,243 | 27,375,856 |
| List price (Template:US$) | \$34,500 (\$234,000 adjusted to 2002 dollars) | \$1,200 | \$360 | \$420 | |
| Price per megabyte (Template:US$) | \$9,200 (\$68,000 adjusted to 2002 dollars) | \$0.0082 | \$0.0020 | \$0.0053 | |
| Density (megabits/in²) | 0.002 | 26,263 | 46,300 | 70,000 | 35,000,000 |
| Density (kilobits/mm²) | 0.003 | 40,708 | 71,765 | 108,500 | |
| Volume density (gigabytes/in³) | 0.00000003 | 6 | 8 | 20 | |
| Volume density (megabytes/cm³) | 0.000002 | 388 | 478 | 1,203 | |
| Latency (ms) | 25 | 3 | 4 | 7 | |
| Average seek time (ms) | 600 | 5.9 | 10.2 | 12 | |
| Data rate (megabytes/s) | 0.001 | 103 | 29.4 | 43.75 |
DASD Devices Beyond HDDs and FDDs
Within certain IBM operating systems, hard disk drives (HDDs) and floppy disk drives (FDDs) are categorized as DASDs (direct access storage devices). Additional technologies classified under DASD include:
IBM 7320 Drum
The IBM 7320 represents a magnetic drum storage system that was first introduced in 1962.
IBM 2301 Drum
The IBM 2301 is a magnetic drum device that debuted in the late 1960s.
IBM 2303 Drum
Released in 1964, the IBM 2303 is another example of a magnetic drum storage apparatus.
IBM 2321 Data Cell
Announced in 1964, the IBM 2321 Data Cell utilizes short strips of magnetic tape for data storage. It accommodates ten detachable cells, each with a capacity of 40 MB, amounting to a total 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, which are then presented to the system as virtual disks.