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IBM 3390

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

IBM was engaged in the production of magnetic disk storage devices from 1956 until 2003, at which point it divested its hard disk drive division to Hitachi. IBM pioneered both the hard disk drive (HDD) and floppy disk drive (FDD) technologies, with numerous breakthroughs in these fields attributed to its workforce. The core mechanical architecture of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and performance benchmarks have adhered to consistent criteria dating back to the 1950s. Over time, the sector has experienced substantial decreases in cost and physical dimensions, accompanied by notable enhancements in storage capacity and operational efficiency.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not establish a significant presence in producing smaller 5.25- or 3.5-inch models. While IBM marketed its magnetic disk drives commercially, it only began offering original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM had discontinued manufacturing hard disk drives tailored exclusively for its own systems, instead providing all HDD units as OEM products.

IBM employed several designations for its magnetic disk drives, including direct-access storage device (DASD), disk file, and diskette file; however, this article adopts the widely recognized industry terms hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit holds the distinction of being IBM’s inaugural disk drive, unveiled as part of the IBM 305 RAMAC computer system on September 14, 1956. A related model, the IBM 355, was announced concurrently for the IBM 650 RAMAC system. The acronym RAMAC stood for "Random Access Method of Accounting and Control." The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, with full production units dispatched beginning November 1957 to clients such as United Airlines.

Engineered to satisfy real-time business accounting requirements, the IBM 350 offered storage for five million 6-bit characters (equivalent to 3.75 MB). It comprised fifty-two disks each measuring 24 inches in diameter, utilizing one hundred recording surfaces spinning at a speed of 1200 rpm. Data transfer rates reached up to 8,800 characters per second. The access mechanism operated by moving read/write heads both vertically and radially to select specific disk surfaces and tracks. Several enhanced versions were introduced during the late 1950s. The RAMAC 305 system with the IBM 350 was leased at a rate of $3,200 monthly. Production ceased in 1969.

The patent emerging from the RAMAC initiative is recognized as foundational for disk drive technology. Although initially rejected by IBM's Board over concerns regarding its potential impact on punch card sales, development persisted under IBM’s San Jose laboratory until receiving approval from company leadership.

The IBM 350’s enclosure measured roughly 60 inches in length, stood 68 inches tall, and was about 29 inches wide. Weighing close to one ton, it necessitated forklift equipment for relocation and was transported using large cargo aircraft. Currie Munce, then Vice President of Research at Hitachi Global Storage Technologies (which acquired IBM’s storage division), noted that while capacity could have been increased beyond five million characters, marketing hesitated to promote larger sizes at that time. Nevertheless, double-capacity models were announced in January 1959 and delivered later that year.

In recognition of its historical importance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. A restoration effort led by Al Hoagland commenced in 2002 at Santa Clara University, aiming to refurbish an IBM 350 RAMAC unit. This initiative transitioned in 2005 to the Computer History Museum, where the restored device is publicly showcased within the Revolution exhibition.

IBM 353

The IBM 353, utilized in the IBM 7030, bore resemblance to the IBM 1301 but offered a higher data transfer speed. It provided a storage capacity of 2,097,152 (221) 64-bit words, equivalent to 134,217,728 bits, and could move data at a rate of 125,000 words per second. The prototype delivered in late 1960 was the first disk drive to incorporate one read/write head per surface, flying on compressed air—a concept similar to the IBM 350's design. Production versions employed self-levitating heads comparable to those used in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an expansion for the popular IBM 650 system. It utilized the IBM 350 mechanism but featured up to three access arms instead of just one, as found in the IBM 350. Its storage capability included 6 million decimal digits plus an additional 600,000 sign indicators. Data transfer involved moving entire tracks between the magnetic core memory of the 653—an optional unit for the IBM 650 containing sixty signed 10-digit words—sufficient to accommodate a single disk track or tape record.

IBM 1405

The IBM 1405 Disk Storage Unit, launched in 1961 for the IBM 1400 series business computers, came in two variants: Model 1 offered storage for 10 million alphanumeric characters (60 million bits) across 25 disks, while Model 2 doubled that capacity with 20 million characters (120 million bits) on 50 disks. The disks were vertically stacked and rotated at a speed of 1200 rpm.

Each disk surface contained 200 tracks segmented into five sectors; sectors numbered 0 through 4 were on the top side and sectors 5 through 9 on the bottom. Each sector could hold either 178 or 200 characters. Access was provided by one to three forked arms, each equipped with two read/write heads serving both surfaces of a disk. These arms moved vertically to select among disks (0–49) and horizontally across tracks (0–199). Reading or writing a sector typically required approximately 10 milliseconds.

Access times varied from a minimum of about 100 milliseconds up to a maximum of roughly 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 featured a total of 100,000 sectors that stored either 200 characters in move mode or 178 characters in load mode, which included an additional word mark bit per character; Model 1 contained half as many sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was created specifically for use with the IBM 7070 system; a second model was announced in 1959. Nonetheless, with the introduction of the IBM 1301 on June 5, 1961, many customers of the IBM 7070 and its successor, the IBM 7074, found the newer device more appealing. The technology within the IBM 7300 shared similarities with that found in earlier units such as the IBM 350, IBM 355, and IBM 1405.

IBM 1301

Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was designed for use with mainframe computers in the 7000 series as well as the IBM 1410. Each module held up to 28 million characters (168 million bits), or alternatively, when paired with the IBM 1410, stored up to approximately 25 million characters. Modules consisted of twenty-five large disks offering forty user-accessible recording surfaces and featuring two hundred fifty tracks per surface. The Model 1 configuration included one such module; Model 2 stacked two modules vertically. Disks rotated at a velocity of eighteen hundred revolutions per minute and supported data transfer rates reaching ninety thousand characters per second.

A significant advancement was its employment of an individual arm and read/write head for every recording surface; these moved collectively like a comb. This architecture minimized seek times by removing the need for repositioning heads between disks and improved maximum access time to about one hundred eighty milliseconds. The IBM 1301 also pioneered aerodynamically shaped heads that floated on a thin cushion of air above disk surfaces, thereby enhancing operational performance.

Connectivity was provided via the IBM 7631 File Control unit, which permitted integration with either an IBM 1410 or a system from the IBM 7000 series—or allowed sharing between two computers.

Leasing fees were $2,100 per month for Model 1 and $3,500 per month for Model 2; purchase prices stood at $115,500 and $185,000 respectively. The IBM 7631 controller leased at $1,185 monthly or could be bought for $56,000. All models had been retired from service by around 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit offered a fourfold increase in capacity compared to the IBM 1301, accommodating 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and achieved a data transfer speed of 180,000 characters per second, which was over 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 variant enhanced capacity further by stacking two modules together. Leasing rates were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, with purchase prices at $252,000 and $355,500 respectively. The IBM 7631 controller could be added for an additional $1,185 monthly or a $56,000 purchase fee. 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-scale business and scientific computers. Roughly comparable in size to a top-loading washing machine, it stored up to two million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven distinct models were released before being discontinued by the early 1970s.

Each IBM 1316 disk pack measures four inches in height, weighs approximately ten pounds, and contains six disks each measuring fourteen inches in diameter with ten usable recording surfaces. The disks rotate at 1500 revolutions per minute; each surface holds one hundred tracks composed of twenty sectors that store one hundred characters apiece. Read/write heads are hydraulically actuated and mechanically positioned to align with individual tracks. The disk packs are encased within a transparent plastic shell featuring a locking handle to facilitate insertion and removal.

The seven IBM 1311 models consist of master drives—housing controllers—and slave drives managed by these masters:

  1. Master drive compatible with IBM 1440, 1460, or 1240 systems; capable of controlling up to four Model 2 drives; introduced October 1962; retired February 1971.
  2. Slave drive designed to operate under master control; introduced October 1962; withdrawn January 1975.
  3. Master drive for IBM 1620 or 1710 systems; controls up to three Model 2 drives without additional features; introduced October 1962; phased out May 1971.
  4. Master drive intended for IBM 1401 systems; supports up to four Model 2 drives; introduced October 1962; discontinued February 1971.
  5. Master drive compatible with IBM 1410, 7010, or 7740 systems; manages up to four Model 2 drives; includes standard Direct Seek functionality; introduced January 1963; withdrawn May 1971.
  6. & #7 Models with limited documentation; presumed master and slave units respectively; introduced March 1968; retired February 1971.

Available optional enhancements comprised:

  • Direct Seek: removes the need to return to track zero before seeking a new track.
  • Scan Disk: performs rapid automatic searches for specific identifiers or conditions.
  • Seek Overlap: allows simultaneous seeking operations while reading or writing on multiple drives.
  • Track Record: boosts capacity by recording a single large record per track instead of multiple sectors—raising total capacity to roughly 18.7 million bits.

Master drives (Models 1, 3, 4, and 5) include additional power supplies and control circuitry and are approximately one foot wider than Model 2 slave drives.

IBM 2302

The IBM 2302 represents the System/360 adaptation of the 1302, modified for S/360 DASD architecture. It utilizes a fixed module containing twenty-five platters with forty-six recording surfaces in total. The Model 3 configuration includes one such module, while the Model 4 incorporates two modules. Each module is equipped with two independent access mechanisms covering the innermost and outermost sets of two hundred fifty cylinders—referred to as access groups—each featuring one read/write head per track. The average rotational latency is seventeen milliseconds, with maximum seek times reaching up to one hundred eighty milliseconds per access group. Each track holds approximately 4,985 bytes of data, resulting in an overall module capacity near one hundred twelve megabytes. Connection to IBM mainframes is established via the IBM 2841 Storage Control Unit.

IBM 2305

The IBM 2305 fixed-head storage device was launched in 1970 alongside the IBM 2835 Storage Control. Initially, it connected to System/360 models 360/85 and 360/195 through the IBM 2880 Block Multiplexor Channel. With the advent of System/370's Virtual Storage, demand for the 2305 increased, as it commonly functioned as a paging device on systems such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter utilizing specialized microcode). It was particularly well-suited for workloads involving frequently accessed small data sets like catalogs and job queues.

The smaller 2305-1 variant provides a capacity of 5.4 MB with a data transfer rate of 3.0 MB/s and an average access latency of 2.5 milliseconds. In contrast, the larger 2305-2 offers 11.2 MB at a slower rate of 1.5 MB/s and an average access time of 5 milliseconds. This blend of storage size and rapid data throughput made the device ideal for system-resident tasks, working files, indexing, and datasets requiring frequent access. Its swift response was particularly advantageous for paging operations on heavily utilized systems processing more than 1.5 transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive debuted in 1964 together with the 2841 Control Unit, supporting IBM System/360, IBM 1130, and IBM 1800 platforms. It also connected directly to the IBM System/360 Model 20 and Model 25 systems. All units employed the IBM 1316 Disk Pack, originally introduced with the IBM 1311.

Most IBM mainframes interfaced with the Model 1 version of the 2311 via the 2841 Control Unit, whereas the System/360 Model 25 utilized a Disk Attachment Control that offered comparable functionality. The disk packs used IBM's count key data variable-length record format.

Models 11 and 12, designed for use with the integrated control of the System/360 Model 20, formatted disk packs using fixed sectors; these packs were incompatible with those used by Model 1 drives.

Although mechanically akin to the IBM 1311, the 2311 featured enhanced recording technology to achieve greater data density. It stored up to 7.25 megabytes on a removable six-platter IBM 1316 disk pack. The drive employed ten read/write heads mounted on a hydraulically actuated arm with mechanical detents for precise track positioning. Each surface contained 200 tracks plus three optional spares to manage defects. The average seek time was approximately 85 milliseconds, with a data transfer speed of around 156 kilobytes per second.

Electrical interfaces were standardized across System/360 models, enabling third-party manufacturers to produce plug-compatible disk drives and fostering a competitive market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, roughly one year after System/360's introduction, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 families. Its Two Channel Switch feature permitted simultaneous connection to two channels. Mechanically similar to the IBM 2311, it incorporated recording improvements that increased data density.

The device stored about 29 million characters on a removable IBM 2316 disk pack consisting of eleven platters measuring fourteen inches in diameter, providing twenty recording surfaces. Twenty individual read/write heads were hydraulically actuated with mechanical detents for track alignment. Initial access times were comparable to those of the IBM 2311 but improved over time due to actuator enhancements. The data transfer rate was doubled to approximately 310 kilobytes per second.

The original Model 1 was offered as a package including nine drives sold at a single price point along with a storage control unit, one single-drive module, and two four-drive modules. Drives were installed in drawer-like assemblies allowing easy disk pack handling; this design earned them the nickname "Pizza Ovens." Only eight drives could operate simultaneously; the ninth served as an offline spare for maintenance or replacement purposes. Each drive’s system address was configured through user-swappable plugs, enabling reassignment by changing these plugs.

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

Subsequent models expanded upon these foundational capabilities:

IBM 2314 Direct Access Storage System - Variants

In 1969, IBM segmented the original facility into distinct models, each accommodating up to nine drives (with eight accessible online) connected to a 2314 Storage Control unit:

  • 2312 Disk Storage, featuring a single-drive configuration.
  • 2313 Disk Storage, equipped with four drives.
  • 2318 Disk Storage, consisting of two drives.

IBM 2319

To address the challenge posed by plug compatible vendors offering storage comparable to the 2314, IBM launched in 1970 the more affordable three-drive 2319 series. This model was developed by removing one drive from the four-drive 2313, rebranding it as the 2319 A1, and pricing it significantly lower in rental fees. This approach reduced expenses for new clients while retaining higher charges for existing customers. The 2319-A1 connects to integrated controllers designed for System/370 Models 135 and 145. Traditional 2314 DASD units such as the 2312 or 2318 are compatible with the 2319-A1. The 2319 B series supports configurations of three, six, or nine drives linked to a new 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 storage capacity of 64.5 MB. Utilizing a fixed-block architecture, the 3310 operated under DOS/VSE and VM, the only S/370 operating systems compatible with FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, was introduced in June 1970 for IBM System/370 and System/360/195 platforms. The initial offerings included the two-drive Model 1 and the single-drive Model 2. It featured removable disk packs with a capacity of 100 MB (404×19×13,030 bytes), a seek time of approximately 30 ms, and a data transfer speed of 806 kB/s. A significant advancement was its integrated error correction capability, which enhanced dependability and lowered costs by allowing for disk surface flaws to be corrected using fire codes capable of handling error bursts up to 11 bits.

Early setups paired one storage control unit (3830 Model 1) with a single 3330 drive, with options to attach up to three additional drives, forming an eight-drive configuration.

In August 1972, IBM unveiled the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control functions from storage drives. The 3830 evolved into a director-style controller overseeing multiple strings; each string began with a 3333 unit containing both controller and two drives, capable of managing up to three attached 3330 drives for a total of eight per string. The upgraded 3830 Model 2 could connect two such 3333 units, supporting up to sixteen drives under one controller, with optional string switches enabling connections to two controllers simultaneously.

By 1973, IBM announced double-density (-11) variants: the models named 3333–11 and 3330-11, along with larger-capacity (200 MB) disk packs designated as 3336–11 (808×19×13,030 bytes). Mixing single- and double-density drives within one string was not supported. Upgrading from standard models to Model-11 versions required drive modifications and complete data transfer.

The IBM 3330 line was discontinued in 1983.

IBM 3340 and 3344

The IBM 3340 and 3344 models share many characteristics; however, only the 3340 functions as the head of string. The 3344 must be connected to a 3340 A model, which acts as the head of string, since there are no A model versions of the 3344.

IBM 3340

Introduced in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility, also known as Winchester, debuted with three variants: the 3340-A2 featuring two drives and a controller, and the B2 (two drives) and B1 (one drive) models. Up to eight B-units could be linked to an A2 unit.

This system utilized removable data modules that housed both the head and arm assemblies. A mechanical load/unload mechanism opened or closed an access door to attach the module to the drive, avoiding the need to remove covers during insertion. It provided a 25-millisecond access time alongside data transfer speeds of 885 kB/s. Three versions of IBM’s 3348 Data Modules were available with capacities of 35 MB, 70 MB, and a specialized 70 MB variant featuring a 500 KB fixed-head section for accelerated access. The 3340 included error correction capabilities and was discontinued in 1984.

Developed in San Jose under Ken Haughton’s leadership, its original design centered on two removable modules each holding 30 MB—hence the "Winchester" nickname inspired by the .30-30 rifle. Even after capacity expansions, this codename remained.

A significant breakthrough was its cost-effective head design that eliminated the need for unloading heads from the media. This "Winchester technology" enabled heads to land on and lift off from spinning disks, drastically simplifying head and arm mechanics while cutting costs. This approach rapidly became an industry standard in disk drive manufacturing.

The term Winchester or Winnie was widely used to describe hard drives into the early 1990s but has since largely disappeared from common usage worldwide.

IBM 3344

The IBM 3344 closely resembles the 3340 but differs by employing fixed media rather than removable 3348 data modules. Each spindle accommodates four logical drives with storage capacity equivalent to a single 70 MB 3348 module. This model is offered exclusively in dual-drive configurations and lacks an A (head of string) variant. The 3344-B2F differs from the standard 3344-B2 by having fixed heads over certain cylinders on both drives. Both versions require a 3340-A2 or 3340-A2F unit to serve as head of string. Internally, the IBM 3344 shares architecture with the IBM 3350; distinctions exist only in control unit microcode.

IBM 3350

The IBM 3350 Direct Access Storage Facility, codenamed Madrid, was introduced in 1975 for use with IBM System/370 systems. It featured sealed head-disk assemblies (HDAs) that integrated heads and arms into a single unit without removable components. The disk geometry consisted of 555 cylinders, each with 30 heads and tracks containing 19,069 bytes, resulting in roughly 317 MB capacity per HDA. This sealed design became standard for IBM DASD devices moving forward.

Models designated A2, A2F, B2, B2F, C2, and C2F each contained two HDAs. The A2 and A2F models included an extra electronic board enabling connection to the control unit; these units functioned as controllers or heads of string. Storage units were arranged in strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. The A2 model commonly incorporated a string switch allowing simultaneous connections to two storage control units for parallel I/O operations across different HDAs.

Compatible storage control units encompassed IBM’s 3830 Model 2 and Integrated Storage Control (ISC) embedded within CPUs such as the 3148, 3158, or 3168; subsequent models like the IBM 3880 maintained backward compatibility. The C2 unit also contained a controller that acted as a secondary path for itself and other units but operated only when the primary controller in an A unit was powered down.

Permissible IBM 3350 string configurations included -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC- arrangements.

"x2F" variants (for example, A2F) incorporated fixed-head areas covering the first five cylinders on both HDAs, eliminating seek time within this region. This feature optimized access for frequently used data such as HASP or JES checkpoint information by minimizing head movement on spool devices. It also supported TSO swap data alongside system swap data utilized by OS/360 successors (MVT, SVS) and MVS systems, enhancing efficiency during context switches between TSO users or batch jobs.

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

IBM 3370

Debuting in January 1979 for IBM's 4331, 4341, and System/38 midrange systems, the IBM 3370 Direct Access Storage Device comprised seven fixed 14-inch platters, delivering a storage capacity of 571 MB per unit. It 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 on S/370 platforms.

IBM 3375

The IBM 3375 served as a counterpart featuring count key data architecture, designed to work with OS/360 and its subsequent operating systems.

IBM 3380

Released on June 11, 1980, the IBM 3380 employed film head technology and offered a total capacity of 2.52 GB per unit. Each unit consisted of two hard disk assemblies equipped with independent actuators, each accessing 630 MB. It supported a data transfer speed of 3 MB/s and an average access time of 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges involving the interaction of heads and media, shipments commenced in October 1981.

The typical setup included one A unit accompanied by up to three B units; each 3380 housed four devices. These could be connected in strings reaching up to sixteen devices, commonly interfaced with a 3880 storage control unit that enabled two concurrent I/O processes on separate HDAs.

In February 1985, IBM unveiled the double-density Extended Capability Models (3380 E), doubling capacity to 5.04 GB per unit—featuring two actuators managing 1.26 GB each across two disk assemblies.

A triple capacity variant, the 3380 K model, was launched in August 1987 with a capacity of 7.562 GB per unit—two actuators controlling 1.89 GB each—and offered an optional four-path mode permitting up to thirty-two devices per string through a 3990 storage control unit that supported four simultaneous I/O operations.

The IBM 3380 series encompassed twelve models: six A-units (which serve as string leaders with controller logic connecting to IBM storage control units), five B-units (which connect to A- or C-units), and one C-unit (designed for direct connection to IBM channels).

Production ceased in May 1996 after an impressive fifteen-year lifespan, significantly exceeding the usual service duration for disk drives.

IBM 3390

Introduced in November 1989, the IBM 3390 Direct Access Storage Device family provided capacities up to 22 gigabytes distributed over multiple drives. System pricing varied from $90,000 up to $795,000 depending on configuration and storage size.

A typical 3390 configuration consists of a central A unit containing four or eight devices, optionally flanked by one or two B units each housing up to twelve devices. Operating in four-path mode, it connects to a 3990 storage control unit capable of supporting an additional 3390 string, allowing as many as sixty-four devices within the subsystem.

Hard Disk Assemblies (HDAs) feature two actuator-head units along with platters; Model 1 offers a pre-format capacity of 1.89 GB per HDA while Model 2 provides 3.78 GB. The Model 3 upgrade introduced in 1991 increased capacity to 5.67 GB per HDA, followed by the Model 9 in 1993 which further expanded it to 11.3 GB per HDA.

Unlike prior DASD designs that utilized large AC motors with belts for rotation, the HDAs in the 3390 series are powered by enclosed DC motors directly driving the platters. The Model 9 represented IBM’s final announcement of a Single Large Expensive Disk (SLED) drive.

IBM 9345

Released in November 1990, the IBM 9345 hard disk drive was introduced as a Request Price Quotation (RPQ) specifically for IBM’s SuperComputing Systems Extensions (SCSE). Engineered at IBM’s San Jose facility under the project name Sawmill, this drive offered capacities up to 1.5 GB within a full-height 5¼-inch enclosure, utilizing eight 130 mm platters. It was distinguished as the first HDD to incorporate Magneto-Resistive (MR) head technology.

IBM 9340

In October 1991, IBM launched the 9345 DASD as part of the 9340 family—a channel-attached count key data (CKD) DASD subsystem designed for IBM mainframes, including the ES/9000 series. The 9345 Model 1 housed two 1.0 GB drives, whereas Model 2 contained two 1.5 GB drives.

From an operational standpoint, the 9340/9345 paralleled the 3990/3390 series but did not feature the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length compared to the 3390.

IBM’s OS Input/Output Supervisor (IOS) identified this hardware through a specialized initializer called IECCINIT, which recognized that the 9340 lacked non-volatile cache and that the 9345 had diminished track capacity. Consequently, it was assigned a unique device type distinct from the 3990/3390 series.

9330 family of disk drives

  1. The 9331 Diskette Unit models 1 and 11 incorporated one 8-inch floppy disk drive; models 2 and 12 included one 5-inch floppy disk drive.
  2. The IBM 0667 HDD powered the 9332 Direct Access Storage Device.
  3. The high-performance IBM 9333 Disk Drive Subsystem utilized either IBM 0664 or IBM 0681 hard drives depending on configuration.
  4. The IBM 9334 Disk Expansion Unit allowed connection of one to four SCSI hard disks to RS/6000 systems.
  5. The IBM-developed "Kestrel" HDD, an 850 MB hard disk with three 14-inch platters and dual rotary actuators accessing multiple surfaces, was featured in the IBM 9335 Direct Access Storage Subsystem. Announced alongside the IBM 9370 Information System in October 1986, it was designed for rack mounting and had no known OEM equivalents.
  6. The IBM 9336 Disk Unit employed the IBM 0681 hard disk drive (Redwing).
  7. The IBM 9337 Disk Array Subsystem used either IBM’s 0662 (Spitfire) or 0663 (Corsair) hard drives.

IBM 2310

Introduced in 1964 with the IBM 1800 and subsequently in 1965 with the IBM 1130, the IBM 2310 Removable Cartridge Drive most likely first shipped with the latter system. It stored up to 512,000 sixteen-bit words (equivalent to 1,024,000 bytes) on an IBM 2315 cartridge, which contained a single oxide-coated aluminum platter encased within a plastic shell and accessed by two read/write heads.

IBM 5444

The IBM 5444, released in September of 1969 as part of System/3 development at IBM’s Hursley laboratory in England under the codename Dolphin, utilized a single-disk cartridge known as the IBM 5440 containing one fourteen-inch platter. It was offered in three variants:

  • Model 1: included one fixed disk and one removable disk, each providing one hundred tracks per surface; cartridge capacity stood at approximately 1.23 MB
  • Model 2: featured one fixed plus one removable disk, each with two hundred tracks per surface; cartridge capacity doubled to roughly 2.46 MB
  • Model 3: consisted solely of a removable disk with two hundred tracks per surface; cartridge capacity also measured about 2.46 MB

IBM 62GV

The IBM 62GV, introduced in May of 1974 from IBM’s Hursley facility under the project name Gulliver, initially offered a storage capacity of five megabytes. Subsequent iterations (62TM models) expanded capacity first to ten megabytes and then to fourteen megabytes. This model incorporated a Swinging Arm actuator mechanism coupled with a single fourteen-inch platter—a design that became one of IBM’s most widely licensed electromechanical innovations and was extensively adopted across numerous hard drives over several decades. Approximately 177,000 units of the IBM 62GV were shipped, making it the first hard disk drive model to surpass sales of one hundred thousand units.

OEM and Small Systems Hard Drives

This segment details HDDs manufactured by IBM that were marketed as OEM products and utilized in IBM small systems, including the System/3, System/32, /34, /36, and AS/400 series. Drives are identified by their OEM model numbers and organized according to the date of their initial customer delivery.

IBM 0680

The 0680 model began shipping in 1979, primarily deployed across IBM small systems and entry-level System/370 machines as the 3310 direct access storage device. The OEM variant, designated as 0680, was introduced in September 1981. Created at IBM's Hursley laboratory in the United Kingdom under the codename Piccolo, it initially provided a maximum capacity of 65MB through six 8-inch (210 mm) platters featuring an enhanced rotary actuator.

A higher-capacity iteration known as the 62SW was released in June 1984; however, it experienced limited market uptake due to pricing similar to that of the 62GV.

IBM 0676

The 0676 model was first delivered in November 1982 as part of the 5247 Disk Storage Unit for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota, under the internal designation 21ED, this 8-inch HDD offered initial storage options of either 15 or 30 MB via two or four 210 mm platters. In 1983, it was incorporated into the S/36's 5360 System Unit. By 1984, its capacity doubled through increased tracks per surface and was subsequently included in the System/36's 5362 System Unit.

IBM 0665

Introduced in October 1985 within the PC AT (5170) chassis, the 0665 was developed at IBM Rochester under the codename "Pixie." This 5-inch hard drive came with storage capacities of 20, 30, and 44 MB.

IBM 0667

The 0667 debuted in August 1986. Also developed at IBM Rochester with the codename "Grant," this full-height ESDI hard drive measured 5 inches and supported up to four 130 mm platters with a capacity of 70 MB. It was available as an option on select PC RT models (6150, 6151, 6152) and within System/36 Model System Units (5363, 5364).

IBM 0669

Released in 1987 and developed at IBM Rochester under the codename "Grant-Prime," the 0669 was a full-height, 5-inch HDD capable of storing up to 115 MB across four 130 mm platters. It served as the internal storage device for both the System/36 5363 and Series 1 4956 System Units.

IBM 0671

Also launched in 1987, the 0671—known internally as "Lee"—was an ESDI full-height, five-inch hard drive supporting up to eight 130 mm platters for a maximum capacity of approximately 316 MB. This model represented IBM’s inaugural use of thin metal film recording surfaces. By 1988, it was incorporated into the IBM AS/400 9404 System Unit configuration, accommodating two or three drives.

IBM 0661

The 0661 appeared in 1989 as model number 371. Developed under the codename "Lightning" at IBM Rochester and Hursley labs, it was a SCSI hard drive featuring up to eight 95 mm platters (14 heads) with a capacity of around 320 MB. A subsequent "Turbo" version offering up to 400 MB was launched in 1990. This drive became standard equipment on various IBM systems including certain AS/400 System Unit Model CXX configurations.

IBM 0681

Shipping commenced in April 1990 for the 0681, developed at IBM Hursley under the codename "Redwing." This marked the final HDD produced by that facility. The drive was a full-height five-inch unit delivering up to approximately 857 MB via twelve 130 mm platters and introduced PRML data decoding technology. It powered the early-1992-launched 9333 Disk Drive Subsystem, which later featured an enhanced-density variant capable of storing up to about 1.07 GB.

IBM 0663

Introduced in late 1991 under the codename "Corsair," the 0663 was a compact 3-inch hard disk drive featuring a half-height (1.6-inch) form factor. It offered up to 1 GB storage capacity across eight 95 mm platters. This model, utilized in select PS/2 and RS/6000 systems, marked IBM's first OEM HDD equipped with Magnetoresistive (MR) heads.

IBM 0664

Released in November 1992, the 0664—developed at IBM Rochester, Minnesota, under the name "Allicat"—was a full-height 5-inch hard drive with a height of 3.25 inches. It essentially combined two 3-inch drives, providing up to 2.013 GB capacity distributed over eight 95 mm disks.

IBM 0662

The 0662 debuted in June 1993 at IBM Rochester under the designation "Spitfire." This full-height (1 inch) 3-inch HDD delivered 1.05 GB of storage using three disks or five recording surfaces. It served as the internal storage solution for IBM’s 9336 Disk Unit and 9337 Disk Array.

Floppy disk drive

IBM pioneered the development of the floppy disk drive starting with the 8-inch FDD in 1971, initially as a read-only program loader. In 1973, IBM introduced its first read/write floppy drive as part of the 3740 Data Entry System. Although IBM established foundational standards for 8-inch floppy drives, it did not market these drives independently, allowing the broader industry to advance on its own.

At one time, IBM was the leading OEM buyer of 5-inch floppy disk drives, opting for double-sided models with a track density of 48 tracks per inch—specifications that became industry benchmarks. Despite intentions to produce these and smaller formats internally, IBM ceased such manufacturing plans by 1985. An earlier initiative in 1983 to OEM the smaller 4-inch DemiDiskette did not succeed.

"Star" series of HDDs

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

IBM's first HDD compared to its final models

The table below contrasts IBM's inaugural HDD—the RAMAC 350—with its last-generation "Star" series drives. It illustrates substantial reductions in physical size and cost alongside remarkable improvements in storage capacity and operational efficiency over a span of nearly five decades.

Parameter (units) RAMAC 350 Ultrastar 146Z10 Deskstar 180GXP Travelstar 80GN Improvement over 46 years (maximum)
Announcement date Sep 1956 Jul 2002 Oct 2002 Nov 2002
Storage capacity (GB) 0.004 146 180 80 ×48,000
Physical dimensions (inches) 60×68×29 4×1×5.75 4×1×5.75 2.75×0.38×3.95
Physical dimensions (mm) 1500×1700×700 102×25×146 102×25×146 70×9.5×100
Volume (in³) 118,320 23 23 4 ×29,161
Volume (liters) 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$) \$34,500 (\$234,000 adjusted to 2002 dollars) \$1,200 \$360 \$420
Cost per megabyte (Template:US$) \$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
Areal density (kilobits/mm²) 0.003 40,708 71,765 108,500
Volumetric density (GB/in³) 0.00000003 6 8 20
Volumetric density (MB/cm³) 0.000002 388 478 1,203
Average 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

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

IBM 7320 Drum

Introduced in 1962, the IBM 7320 is a storage unit based on magnetic drum technology.

IBM 2301 Drum

The IBM 2301, a magnetic drum storage device, was released in the late 1960s.

IBM 2303 Drum

Debuting in 1964, the IBM 2303 is another magnetic drum storage apparatus.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell utilizes short strips of magnetic tape for data retention. It accommodates ten detachable cells, each with a capacity of 40 MB, resulting in an aggregate storage of 400 MB.

IBM 3850 Mass Storage System

Launched in 1974, the IBM 3850 Mass Storage System operates as a tape cartridge library. It stages data onto IBM 3330 or 3350 disk drives, which are then presented as virtualized 3330 drives.

See also

External links

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