IBM 9345

IBM

Company type	Public
Industry	Computer hardware, data storage
Founded	June 16, 1911 (1911-06-16) in Endicott, New York, United States
Headquarters	Armonk, New York , United States
Products	Magnetic disk storage hardware (hard disk drives, floppy disk drives)

IBM was a pioneer in producing magnetic disk storage hardware from 1956 until 2003, when it divested its hard disk drive division to Hitachi. IBM's workforce was instrumental in inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing numerous advancements in these fields. Since the introduction of the IBM 1301, the fundamental mechanical architecture of hard disk drives has remained largely unchanged, with performance benchmarks established as early as the 1950s. IBM’s offerings are distinguished by significant reductions in cost, miniaturization, and remarkable enhancements in storage capacity and speed over the years.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not become a leading producer of the smaller 5.25-inch or 3.5-inch floppy drives. Although IBM consistently marketed magnetic disk drives, it only began supplying them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM discontinued manufacturing HDDs exclusively for its own systems and transitioned to providing all drives as OEM products.

IBM employed various designations for its magnetic disk drives, including direct-access storage device (DASD), disk file, and diskette file. For clarity, this article adopts the industry-standard 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 introduced alongside the IBM 305 RAMAC computer system on September 14, 1956. A comparable model, the IBM 355, was launched for the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, with full production units shipped starting November 1957 to United Airlines.

Engineered to facilitate real-time business accounting tasks, the IBM 350 stored five million characters of six bits each (equivalent to 3.75 MB) across fifty-two disks measuring 24 inches in diameter, utilizing a total of 100 recording surfaces. The disks rotated at a speed of 1200 rpm, enabling data transfer rates of up to 8,800 characters per second. The read/write heads moved both vertically and horizontally to access specific tracks on the disks. Multiple enhanced versions were introduced during the late 1950s. Leasing for the RAMAC 305 system equipped with the IBM 350 was priced at $3,200 per month. The product line was discontinued in 1969.

A key patent from this program, US3,503,060, is regarded as foundational technology for disk drives. Although initially rejected by IBM’s Board due to concerns about its potential adverse effects on punch card operations, development persisted at IBM’s San Jose laboratory until it received executive approval.

The physical dimensions of the IBM 350’s cabinet were approximately 60 inches in length, 68 inches in height, and 29 inches in width. Weighing close to one ton, transportation required forklifts and large aircraft. Currie Munce from Hitachi Global Storage Technologies— which later acquired IBM’s storage division— noted that although capacity might have surpassed five million characters, IBM’s marketing team was reluctant to promote larger drives. Nevertheless, double-capacity models were announced in January 1959 and delivered later that year.

In recognition of its historical significance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. A restoration initiative began in 2002 under Al Hoagland’s leadership at Santa Clara University; this project moved to the Computer History Museum in Mountain View, California in 2005 and is now publicly exhibited as part of their Revolution display.

IBM 353

The IBM 353, utilized in conjunction with the IBM 7030, resembled the IBM 1301 but offered a higher data transfer speed. It provided storage for 2,097,152 (2²¹) words of 64 bits each, totaling 134,217,728 bits, and achieved a transfer rate of 125,000 words per second. A prototype delivered in late 1960 was notable as the first disk drive to implement a dedicated read/write head per surface that floated on compressed air, following the concept established by the earlier IBM 350. Production versions adopted self-levitating heads similar to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an expansion for the widely used IBM 650. This unit employed the IBM 350 mechanism but featured up to three access arms instead of just one, allowing it to store six million decimal digits along with 600,000 sign indicators. It facilitated full-track transfers to and from the magnetic core memory of the 653—an optional IBM 650 storage device containing sixty signed ten-digit words, sufficient capacity for a single disk track or tape record—plus two additional unrelated functionalities.

IBM 1405

Launched in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit came in two variants: Model 1 offered storage for ten million alphanumeric characters (equivalent to 60 million bits) distributed across 25 disks; Model 2 doubled this capacity with twenty million characters (120 million bits) on fifty disks. The disks rotated vertically at a speed of 1200 revolutions per minute.

Each disk surface contained 200 tracks subdivided into five sectors; sectors numbered 0 through 4 were located on top surfaces while sectors 5 through 9 were on bottom surfaces. Sector capacity ranged between 178 and 200 characters. One to three forked access arms were equipped with two read/write heads each, enabling simultaneous operation on both sides of a disk. These arms moved vertically to select among disks (0–49) and horizontally to access tracks (0–199). The duration for reading or writing a sector was approximately ten milliseconds.

Access times varied from as low as 100 milliseconds up to a maximum of 700 milliseconds for Model 1 and extended to 800 milliseconds for Model 2. Model 2 contained one hundred thousand sectors capable of holding either two hundred characters in move mode or one hundred seventy-eight characters in load mode, which incorporated a word mark bit per character. Model 1 included fifty thousand sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered specifically for use with the IBM 7070, with a second model announced in 1959. Despite this, when the IBM 1301 became available on June 5, 1961, customers preferred the newer technology of the IBM 1301 over the IBM 7300. The design of the IBM 7300 incorporated technological elements from 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 targeted applications involving mainframe computers from the IBM 7000 series as well as the IBM 1410. Each module provided storage for twenty-eight million characters (168 million bits), or twenty-five million characters when paired with the IBM 1410. A module consisted of twenty-five large disks presenting forty user-accessible recording surfaces and two hundred fifty tracks per surface. Model 1 included a single module; Model 2 stacked two modules vertically. The disks rotated at a speed of eighteen hundred revolutions per minute and achieved data transfer rates up to ninety thousand characters per second.

A significant advancement was its design featuring an individual arm and read/write head dedicated to each disk surface; these moved collectively like a comb assembly. This arrangement minimized seek times by removing the need to reposition heads across different disks, reducing maximum access time to approximately one hundred eighty milliseconds.

The IBM 1301 was pioneering as the first disk drive employing aerodynamically engineered heads that float on a thin cushion of air above disk surfaces, allowing closer proximity and enhanced performance.

Connectivity was provided through the IBM 7631 File Control unit, which allowed operation either with a single or multiple shared systems from the IBM 1410 or IBM 7000 series lines.

Leasing charges for Model 1 were set at $2,100 monthly or $115,500 for purchase; Model 2 cost $3,500 per month or $185,000 outright. The IBM 7631 controller carried an additional monthly lease fee of $1,185 or $56,000 if purchased. All versions were discontinued by the year 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the IBM 1301, reaching 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and a data transfer rate of 180,000 characters per second, more than doubling the throughput of its predecessor. Each module incorporated two separate access mechanisms dedicated to the inner and outer cylinders. A Model 2 variant expanded capacity further by stacking two modules together. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2; purchase prices were $252,000 and $355,500 respectively. The IBM 7631 controller added an additional $1,185 monthly or a $56,000 purchase cost. The 1302 was discontinued in February 1965.

IBM 1311

The IBM 1311 Disk Storage Drive, introduced on October 11, 1962, was designed for medium-sized business and scientific computing systems. Comparable in size to a top-loading washing machine, it utilized a removable IBM 1316 disk pack capable of storing two million characters. Throughout the 1960s, seven different models were released before being phased out by the early 1970s.

Each IBM 1316 Disk Pack consists of six disks measuring 14 inches in diameter with ten recording surfaces (the outer surfaces remain unused). Ten read/write heads mounted on a single hydraulic actuator operate at a rotational speed of 1500 rpm. Each surface contains 100 tracks with 20 sectors per track; each sector holds 100 characters. The disk pack is enclosed within a plastic casing featuring a locking mechanism for straightforward removal and insertion.

Among the seven IBM 1311 models are master drives equipped with controllers and additional power supplies that can manage up to four or three Model 2 slave drives depending on the system type (e.g., IBM 1440, IBM 1620, IBM 1401). Master units support advanced functions such as Direct Seek (which bypasses returning to track zero), Scan Disk (for rapid automatic searching), Seek Overlap (allowing simultaneous seeking during read/write operations), and Track Record mode (writing one large record per track to increase storage efficiency). Utilizing Track Record mode enhances capacity to roughly 17.9 million bits in "Move Mode" and nearly 18.8 million bits in "Load Mode."

Due to the extra control components and power supplies, master drives (Models 1,3,4,5) are approximately one foot wider than Model 2 slave drives.

IBM 2302

The IBM 2302 serves as the System/360 counterpart to the IBM 1302, featuring track formatting tailored to the S/360 DASD architecture rather than that of the earlier 7000 series.

It employs a fixed module containing 25 platters with a total of 46 recording surfaces. The Model 3 includes one such module; Model 4 incorporates two modules. Each module contains two independent access mechanisms—referred to as access groups—one handling the innermost 250 cylinders and the other managing the outermost 250 cylinders. Each access mechanism provides a single read/write head per track. The average rotational latency is approximately 17 milliseconds with a maximum of 34 milliseconds; maximum seek time within an access group is up to 180 milliseconds. Each track holds about 4,985 bytes; accounting for formatting overhead and alternate tracks, each module offers around 112 megabytes of storage capacity. Connectivity to IBM mainframes is facilitated through the IBM 2841 Storage Control Unit.

IBM 2305

Introduced in 1970 alongside the IBM 2835 Storage Control Unit, the IBM 2305 fixed-head storage device initially interfaced with System/360 models such as the 360/85 and 360/195 via the IBM 2880 Block Multiplexor Channel.

With the advent of Virtual Storage in System/370 through OS/VS2, demand for the 2305 surged as it became widely employed as a paging device on systems including the IBM models 3155, 3165, 3158, 3168, 3033, 4341, and specially microcoded versions of the 3081. It was also well suited for high-transaction small data sets like catalogs and job queues.

The smaller-capacity model, the 2305-1, provides storage of approximately 5.4 megabytes with data transfer rates reaching up to three megabytes per second and an average access time of about two and a half milliseconds. The larger-capacity model, the 2305-2, offers around eleven point two megabytes at a transfer rate of one point five megabytes per second with an average access time near five milliseconds.

Engineered for rapid continuous access to small volumes of data, the IBM 2305’s combination of speed and capacity made it ideal for system-resident functions including work files, job queues, indices, and frequently accessed datasets. Its swift response time proved particularly advantageous when functioning as a paging device in heavily loaded environments processing more than one and a half transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive, launched in 1964 alongside the 2841 Control Unit, was designed to support the IBM System/360 lineup and was also compatible with the IBM 1130 and IBM 1800 systems. It connected directly to the System/360 Model 20 and Model 25. All units utilized the removable IBM 1316 Disk Pack, originally introduced with the IBM 1311.

The Model 1 connects through the 2841 Control Unit to most IBM mainframe models; for the Model 25, connection occurs via a Disk Attachment Control. Disk packs employ IBM’s count key data format, which supports variable record lengths. Versions 11 and 12, intended for the System/360 Model 20’s integrated control, utilize fixed sector formatting, and their disk packs are not interchangeable with those of other models.

While mechanically resembling the IBM 1311, the 2311 improved recording technology to achieve higher data density. It holds 7.25 megabytes on a removable disk pack consisting of six platters. The drive includes ten read/write heads mounted on a hydraulically actuated arm featuring mechanical detents for accurate track alignment. Each disk surface accommodates 200 tracks plus three additional spare tracks to replace any defective ones. The average seek time is approximately 85 milliseconds, with a data transfer rate reaching 156 kB/s.

Standardized electrical interfaces across the System/360 series allowed third-party manufacturers to produce plug compatible disk drives, promoting a competitive market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 was compatible with both System/360 and System/370 systems. It featured a Two Channel Switch that enabled simultaneous connection to two channels. Building upon the design of the 2311, it provided greater data density and storage capacity.

This model employed a taller removable IBM 2316 disk pack containing eleven platters (20 recording surfaces), capable of storing roughly 29 million characters. Twenty read/write heads operated on a hydraulically controlled mechanism with mechanical detents for precise track positioning. Initial access times were comparable to those of the 2311, though subsequent enhancements improved performance. The data transfer rate was doubled to approximately 310 kB/s.

The original Model 1 package included nine drives under a single price point: one storage control unit, one single-drive module, and two four-drive modules. Each drive was installed in its own drawer to facilitate easy disk pack handling, earning them the nickname "Pizza Ovens." Only eight drives could be accessed online simultaneously; the ninth served as an offline spare allowing maintenance without interrupting operations. System addresses for each drive were configured via user-swappable plugs, enabling flexible system reconfiguration.

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

Subsequent versions of the IBM 2314 expanded on this architecture:

IBM 2314 direct access storage facility - A series

In 1969, IBM separated the facility into distinct models supporting up to nine drives (with eight online) connected through a 2314 Storage Control:

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

IBM 2319

In response to competition from plug-compatible vendors producing storage subsystems comparable to the 2314, IBM introduced the affordable three-drive 2319 series in 1970. This series was developed by removing one drive from the four-drive 2313 module, rebranding the resulting unit as the 2319 A1, and offering it at a significantly lower rental cost. This approach enabled new clients to benefit from reduced pricing while existing customers continued paying higher rates. The 2319-A1 connects exclusively to integrated controllers designed for System/370 Models 135 and 145. It also supports conventional 2314 DASD devices such as the 2312 or 2318. Additionally, the 2319 B series of three-drive modules accommodates configurations of three, six, or nine drives linked to a newly introduced 2314 Model B Storage Control Unit.

IBM 3310

On January 30, 1979, IBM unveiled the IBM 3310 Direct Access Storage Device targeted at IBM 4331 midrange computer systems. Each unit provided a storage capacity of 64.5 MB. The 3310 employed fixed-block architecture and was compatible with DOS/VSE and VM, which were the only S/370 operating systems supporting FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, debuted in June 1970 for IBM System/370 and IBM System 360/195 platforms. Initial offerings included a two-drive Model 1 and a single-drive Model 2. Each removable disk pack held approximately 100 MB (404×19×13,030 bytes), featured a 30 ms access time, and delivered data transfer speeds of up to 806 kB/s. A notable innovation was built-in error correction employing fire codes, which improved reliability and lowered costs by allowing minor surface defects on disks.

The standard setup consisted of one storage control unit (3830 Model 1) connected to between one and four drives physically linked together in a "string," with support for up to eight drives per string.

In August 1972, IBM released the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated control functions from storage units. The upgraded 3830 served as a director-type controller capable of managing multiple strings. The initial device in a string, the 3333, combined controller functions with two drives and could oversee up to three additional attached 3330 drives, allowing eight drives per string. Two such 3333 units could be linked to one 3830 Model 2 controller, enabling management of as many as sixteen drives per controller; optionally, the 3333 included a string switch for dual-controller connection.

In 1973, IBM announced double-density (-11) variants—the 3333–11, 3330-11, and 3336–11—that doubled disk pack capacity to approximately 200 MB (808×19×13,030 bytes). Mixing original single-density and double-density drives within a single string was not supported. Upgrades from original models to Model-11 versions were feasible but required drive conversions and complete data migration.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and 3344

While the IBM 3340 and IBM 3344 share many characteristics, only the IBM 3340 is capable of serving as the head of a drive string; there are no A model variants for the IBM 3344. Consequently, a 3344 must be connected behind an IBM 3340 A model acting as string head.

IBM 3340

The IBM 3340 Direct Access Storage Facility, known internally as Winchester, was launched in March 1973 for use with IBM System/370. The initial release included three variants: the 3340-A2, which combined two drives with a controller, and the B2 (two drives) and B1 (single drive) models. Up to eight B-units could be connected to a single A2 controller.

This system utilized removable data modules that housed both the head and arm assembly; the access door of the module opened automatically during mechanical load and unload operations, removing the need to detach covers as required by earlier disk pack designs. It delivered an average access time of 25 milliseconds and supported data transfer rates reaching 885 kilobytes per second. The IBM 3348 Data Module was offered in three configurations: one with a 35 MB capacity and two with 70 MB, one of which incorporated 500 KB accessible through fixed heads to accelerate access times. Featuring built-in error correction, the IBM 3340 remained in production until its discontinuation in 1984.

Developed under Ken Haughton's leadership in San Jose, the original concept centered on two removable 30 MB modules—hence the codename Winchester, inspired by the Winchester .30-30 rifle. Although storage capacities grew over time, this nickname endured.

A significant breakthrough was its economical head design that eliminated the need for unloading from media. This "Winchester technology" enabled heads to land on and lift off from spinning disks, greatly simplifying the head/arm mechanism and reducing costs. This approach subsequently became an industry benchmark.

Up until the early 1990s, the terms "Winchester" or "Winnie" were commonly used to describe hard disk drives generally but have since become largely obsolete worldwide.

IBM 3344

The IBM 3344 shares similarities with the 3340 but differs by employing fixed media rather than removable IBM 3348 data modules. Each spindle accommodates four logical drives equivalent in capacity to a single 3348–70 module, and it was only available in dual-drive configurations without an A (head-of-string) variant. The 3344-B2F model is distinguished from the 3344-B2 by having fixed heads covering certain cylinders on both drives. Both models require a 3340-A2 or 3340-A2F as the head-of-string controller. Internally, the IBM 3344 matches the IBM 3350 hardware, differing solely in control unit microcode.

IBM 3350

Introduced in 1975 for IBM System/370 systems, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. It featured sealed head-disk assemblies (HDAs) that integrated both head and arm assemblies into a non-removable unit. Its disk layout consisted of 555 cylinders, 30 heads per cylinder, and approximately 19,069 bytes per track, providing around 317 MB of storage per HDA. The adoption of sealed HDAs set a precedent for future IBM DASD products.

Available models included A2, A2F, B2, B2F, C2, and C2F, each containing two HDAs. The A2 and A2F units incorporated an extra electronic board enabling connection to control units—often referred to as controllers or head-of-string units—and could form strings with up to three B2 units or combinations incorporating C2 units. Typically, the A2 model featured a string switch allowing simultaneous connections to two storage control units, facilitating concurrent input/output operations across different HDAs. Compatible controllers encompassed the 3830 Model 2, Integrated Storage Control (ISC) embedded within IBM CPUs like the 3148, and later backward-compatible models such as the 3880.

The C2 model also included a controller that provided an alternate path to itself and other units within the string; however, it mainly served as a backup should the A unit’s controller fail. Valid IBM 3350 string configurations comprised -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC- arrangements.

Models designated with "x2F" (for example, A2F) featured fixed-head regions spanning the first five cylinders on both HDAs. This design effectively eliminated seek time for those cylinders by providing immediate access and was aimed at frequently accessed data areas such as HASP or JES2 checkpoint files to minimize head movement on spool devices. Moreover, these fixed-head zones supported TSO swap data along with system swap areas utilized by OS/360 successors (MVT and SVS) as well as MVS systems—enhancing context switch performance between TSO users or batch jobs.

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

IBM 3370

Debuting in January 1979, the IBM 3370 Direct Access Storage Device was designed to support IBM 4331, 4341, and System/38 midrange systems. It contained seven fixed 14-inch platters, delivering a storage capacity of 571 MB per unit. This model was pioneering as the first hard disk drive to incorporate thin-film head technology, developed at IBM's Thomas J. Watson Research Center. The 3370 utilized a fixed-block architecture and was compatible with DOS/VSE and VM operating systems.

IBM 3375

The IBM 3375 served as a counterpart to the 3370, employing count key data architecture necessary for OS/360 and its subsequent operating systems.

IBM 3380

Introduced on June 11, 1980, the IBM 3380 Direct Access Storage Device used thin-film head technology and offered a storage capacity of 2.52 GB per unit. Each unit consisted of two hard disk assemblies, each equipped with two actuators accessing 630 MB. It achieved a data transfer rate of 3 MB/s and an average seek time of 16 milliseconds. Initial pricing ranged from $81,000 to $142,200. However, shipments were postponed until October 1981 due to tribological challenges between the read/write heads and disk media.

The standard setup included one A unit paired with up to three B units; since each device contained four drives, configurations could extend to strings of up to 16 devices. These units were commonly connected to IBM 3880 storage controllers featuring dual-path connections that allowed simultaneous I/O operations targeting separate HDAs.

In February 1985, IBM released the Extended Capability Models (3380 E), doubling density to provide 5.04 GB per unit with two actuators of 1.26 GB each on two disk assemblies.

A higher-capacity variant, the 3380 K model, was announced in August 1987 offering 7.562 GB per unit through two actuators holding 1.89 GB each. Models J and K introduced an optional four-path mode enabling up to 32 devices per string and four concurrent I/O operations when connected via an IBM 3990 storage control unit.

The IBM 3380 series comprised twelve models: six A-units (which included controller logic and acted as string heads for IBM storage controllers), five B-units (designed to connect with A- or C-units), and one C-unit (which provided direct channel attachment).

Production ceased in May 1996 after an impressive fifteen-year lifespan, surpassing typical expectations for disk drive durability.

IBM 3390

The IBM 3390 Direct Access Storage Device family was launched in November 1989, offering capacities up to 22 gigabytes distributed across multiple drives. Pricing varied between $90,000 and $795,000 depending on configuration and size.

A typical 3390 string featured a central A unit containing four or eight devices, optionally accompanied by one or two B units supporting up to twelve devices each. Operating in four-path mode when connected to an IBM 3990 storage controller, the system could manage a second string simultaneously—allowing up to sixty-four devices within the subsystem.

Each Hard Disk Assembly (HDA) housed two actuator-head units along with platters; Model 1 provided an unformatted capacity of 1.89 GB per HDA, Model 2 doubled this to 3.78 GB per HDA. The Model 3 upgrade released in 1991 increased capacity further to 5.67 GB per HDA, while the Model 9 from 1993 expanded it again to reach 11.3 GB per HDA.

Differing from previous DASD models that utilized large AC motors with belt drives, the IBM 3390 HDAs incorporated direct-drive DC motors enclosed within the assembly.

The release of the Model 9 marked IBM's final offering in its line of Single Large Expensive Disk (SLED) drives.

IBM 9345

Launched 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 was a full-height 5¼-inch drive accommodating up to eight 130 mm platters, offering a maximum storage capacity of 1.5 GB. Notably, it was the first HDD to utilize magnetoresistive (MR) heads, which significantly improved both performance and reliability.

IBM 9340

In October 1991, IBM released the 9345 DASD within the 9340 family—a channel-attached count key data (CKD) direct access storage subsystem designed for IBM mainframes such as the ES/9000 series. The 9345 Model 1 contained two HDDs each with 1.0 GB capacity, whereas Model 2 featured two HDDs of 1.5 GB each.

From a functional perspective, the 9340/9345 closely resembled the IBM 3990/3390 models but differed by lacking a non-volatile RAM cache found in the 3990 and having a shorter maximum block length compared to the 3390. The operating system’s Input/Output Supervisor (IOS) detected these devices through the IECCINIT initializer, which recognized their absence of non-volatile cache and adjusted device type designations accordingly.

9330 family of disk drives

1. The 9331 Diskette Unit models 1 and 11 included a single 8-inch floppy disk drive; models 2 and 12 featured 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 employed the "Kestrel" HDD, engineered at IBM Hursley in the UK—an 850 MB device with three 14-inch platters and dual rotary actuators accessing six surfaces. This rack-mounted unit was introduced in October 1986 alongside the IBM 9370 Information System. No original equipment manufacturer (OEM) variants of this HDD have been documented.
6. The 9336 Disk Unit made use of the IBM 0681 HDD, also known as Redwing.
7. The 9337 Disk Array Subsystem incorporated either IBM’s 0662 (Spitfire) or 0663 (Corsair) hard disk drives.

IBM 2310

The IBM 2310 Removable Cartridge Drive debuted in 1964 with the IBM 1800 system and appeared in the IBM 1130 in 1965, most likely shipping first with the latter in late that year. It stored a total of 512,000 sixteen-bit words (equivalent to 1,024,000 bytes) on an IBM 2315 cartridge. This cartridge housed a single oxide-coated aluminum platter enclosed within a plastic casing featuring openings for both read/write heads and their actuator arm.

IBM 5444

Introduced in September 1969 as part of System/3, the IBM 5444 was developed at IBM’s Hursley laboratory in England under the codename Dolphin. It operated using a disk cartridge called the 5440, which contained one fourteen-inch platter. Three distinct models were available:

• Model 1: included one fixed and one removable disk, each with a track density of 100 tracks per surface, providing a cartridge capacity of approximately 1.23 MB
• Model 2: featured one fixed and one removable disk with increased track density of 200 tracks per surface, doubling cartridge capacity to about 2.46 MB
• Model 3: comprised a single removable disk with the same track density as Model 2, offering a cartridge capacity of roughly 2.46 MB

IBM 62GV

The IBM 62GV, released starting May 1974, was developed at IBM’s Hursley facility under the project name Gulliver. Its initial storage capacity was set at five megabytes, with subsequent versions such as the 62TM model expanding capacity to ten megabytes and others reaching up to fourteen megabytes. It employed a Swinging Arm actuator mechanism paired with one fourteen-inch platter. This actuator design became IBM’s most extensively licensed electro-mechanical innovation, widely adopted across HDDs throughout the following decades into the late twentieth century. Approximately 177,000 units of the IBM 62GV were sold, marking it as the first hard drive to surpass sales of one hundred thousand units.

OEM and Small Systems Hard Drives

This section details IBM-produced hard disk drives supplied as OEM components and for IBM’s smaller platforms such as the System/3, System/32, /34, /36, and AS/400. Drives are referenced by their OEM model designations and arranged by their initial shipment dates.

IBM 0680

Initially released in 1979, the 0680 was utilized across numerous IBM small systems and entry-level System/370 models as the 3310 direct access storage device. Officially introduced as the 0680 OEM variant in September 1981, it was engineered at IBM’s Hursley laboratory in the United Kingdom under the codename Piccolo. This model comprised six 8-inch (210 mm) platters equipped with an enhanced rotary actuator, delivering a starting capacity of up to 65MB.

A higher-capacity iteration known as the 62SW was launched in June 1984; however, its market penetration was limited due to pricing that closely matched the 62GV model.

IBM 0676

The 0676 debuted in November 1982 as part of the 5247 Disk Storage Unit for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota under the designation 21ED, this 8-inch HDD initially offered capacities of either 15 or 30 MB distributed over two or four platters. In 1983, it was integrated into the S/36’s 5360 System Unit. By 1984, its capacity doubled through increased track density per surface and was subsequently employed in the System/36’s 5362 System Unit.

IBM 0665

Introduced in October 1985 within 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 became available in August 1986. Created at IBM Rochester with the codename "Grant," it was a full-height ESDI hard drive sized at 5¼ inches. This model supported up to four 130 mm platters and provided a maximum capacity of 70 MB. It was offered as an optional component for select PC RT models (6150, 6151, 6152) and System/36 Model Units (5363, 5364).

IBM 0669

Released in 1987, the 0669 was developed at IBM Rochester under the codename "Grant-Prime." It was a full-height hard drive with a size of five inches, comprising up to four 130 mm platters and reaching capacities as high as 115 MB. This drive served as the internal storage solution for both the System/36 5363 and Series 1 4956 System Units.

IBM 0671

Also introduced in 1987, the 0671—coded "Lee" during development at IBM Rochester—was a full-height ESDI drive measuring five inches. It supported up to eight platters of 130 mm each for a maximum capacity of approximately 316 MB. Notably, it represented IBM’s initial application of thin metal film recording surfaces. By 1988, this model was incorporated into the AS/400’s 9404 System Unit configurations, accommodating two or three drives.

IBM 0661

The 0661, known as model 371, launched in 1989. Originally developed under the name "Lightning" at IBM facilities in Rochester and Hursley, UK, it was a SCSI hard drive featuring up to eight platters measuring 95 mm with fourteen read/write heads. A subsequent "Turbo" version offering up to 400 MB appeared in 1990. This drive became standard equipment on prominent IBM systems such as the AS/400 System Unit Model CXX.

IBM 0681

Emerging in April 1990 from IBM Hursley’s lab under the codename Redwing—the final HDD developed there—the 0681 provided up to an impressive 857 MB capacity within a full-height five-inch form factor using twelve platters sized at 130 mm. It introduced PRML (Partial Response Maximum Likelihood) data decoding technology. This drive powered the launch of the 9333 Disk Drive Subsystem in early 1992, with a higher-density variant offering up to approximately 1.07 GB becoming available by May that year.

IBM 0663

Released in late 1991 under the codename "Corsair," the 0663 was a compact 3-inch hard disk drive with a height equivalent to a half-height 5-inch drive (1.6 inches). It provided up to 1 GB of storage across eight 95 mm platters. This model appeared in select PS/2 and RS/6000 systems and marked IBM's first use of Magnetoresistance (MR) Heads in an OEM disk drive.

IBM 0664

Debuting in November 1992 and developed at IBM Rochester, Minnesota, under the codename "Allicat," the 0664 was a full-height 5-inch hard drive (3.25 inches tall). It combined two 3-inch drives to deliver a maximum capacity of 2.013 GB using eight 95 mm disks.

IBM 0662

Introduced in June 1993 with the codename "Spitfire" at IBM Rochester, the 0662 was a full-height 3-inch hard disk drive (1 inch high) offering 1.05 GB of storage distributed across three platters or five surfaces. It was primarily utilized internally within the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered the floppy disk drive technology by launching the original 8-inch FDD in 1971, initially as a read-only program loading device. The company released its first read/write version in 1973 with the introduction of the 3740 Data Entry System. Although IBM established early standards for 8-inch floppy drives, it did not market these drives independently, allowing the broader industry to develop without direct IBM influence.

At one stage, IBM was the largest consumer of OEM 5-inch floppy drives, backing the two-sided model featuring 48 tracks per inch, which eventually became the industry norm. Despite plans to manufacture these and smaller formats, IBM ceased all such production efforts by 1985. Its attempt in 1983 to OEM a 4-inch DemiDiskette failed to gain traction.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division introduced three distinct hard drive lines: the Travelstar series of 2-inch drives designed for notebook computers; the Deskstar series of 3-inch drives targeted at desktop PCs; and the Ultrastar series of high-performance 3-inch drives aimed at advanced computing systems.

Comparison between IBM's first and latest HDDs

The table below contrasts IBM's pioneering RAMAC 350 hard disk with its final three "Star" series OEM HDD models, illustrating remarkable advancements in storage capacity and performance alongside drastic reductions in size and cost over a span of nearly five decades.

Parameter (units)	RAMAC 350	Ultrastar 146Z10	Deskstar 180GXP	Travelstar 80GN	Improvement over 46 years (maximum)
Announcement date	Sep 1956	Jul 2002	Oct 2002	Nov 2002
Storage capacity (GB)	0.004	146	180	80	×48,000
Physical dimensions (inches)	60×68×29	4×1×5.75	4×1×5.75	2.75×0.38×3.95
Physical dimensions (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)	Approx. 2374 watts (8100 BTUs/hour), up to 5500 VA depending on model	16	10.3	1.85	×1,283
Power efficiency (MB/watt)	0.0016	9,125	17,476	43,243	×27,375,856
Retail price (Template:US$)	\$34,500 (\$234,000 adjusted to 2002 dollars)	\$1,200	\$360	\$420
Cost per MB (Template:US$)	\$9,200 (\$68,000 adjusted to 2002 dollars)	\$0.0082	\$0.0020	\$0.0053
Data density (megabits/in²)	0.002	26,263	46,300	70,000
Data density (kilobits/mm²)	0.003	40,708	71,765	108,500
Volume density (GB/in³)	0.00000003	6	8	20
Volume density (MB/cm³)	0.000002	388	478	1,203
Average rotational latency (ms)	25	3	4	7
Average seek time (ms)	600	5.9	10.2	12
Data transfer rate (MB/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 DASD technologies encompass the following:

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 a magnetic drum-based storage device.

IBM 2303 Drum

The IBM 2303 magnetic drum storage device made its debut in 1964.

IBM 2321 Data Cell

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

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System is a tape cartridge library that staged data onto IBM 3330 or 3350 disk drives, effectively simulating virtual disk drives for the host 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: Collection of Disk Drive Articles
• Magnetic Disk Heritage Center
• A Quarter Century of Disk File Innovation, IBM Journal of Research and Development, 1981
• EE Times: The Eventful Evolution of Disk Drives
• IBM 1311 Disk Storage Drive
• IBM 2314 Direct Access Storage