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IBM 1311

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

IBM was a pioneer in producing magnetic disk storage devices from 1956 until 2003, when it divested its hard disk drive division to Hitachi. The company is credited with inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), with numerous technological advancements driven by IBM’s engineering teams. The core mechanical framework of hard disk drives has remained largely unchanged since the introduction of the IBM 1301, and many performance benchmarks established in the 1950s continue to be relevant. Throughout the years, these storage solutions have experienced substantial reductions in cost and physical dimensions, coupled with notable enhancements in capacity and efficiency.

From 1969 until the mid-1980s, IBM manufactured 8-inch floppy disk drives, yet it did not become a leading producer of the smaller 5.25- or 3.5-inch variants. While IBM sold its magnetic disk drives commercially, it only started offering them under original equipment manufacturer (OEM) agreements in 1981. By 1996, IBM had discontinued producing hard disk drives solely for its own hardware, making all HDDs available as OEM products.

IBM referred to its magnetic disk storage devices by several names, including direct-access storage device (DASD), disk file, and diskette file. This article adopts the industry-standard terminology: 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, introduced on September 14, 1956, as a component of the IBM 305 RAMAC system. A related model, the IBM 355, was announced for use with the IBM 650 RAMAC system. The prototype was delivered to Zellerbach Paper Company in June 1956, with production units—including one sent to United Airlines—beginning shipment in November 1957.

Engineered to facilitate real-time business accounting applications, the IBM 350 offered a storage capacity of five million 6-bit characters (equivalent to 3.75 MB). It comprised fifty-two disks measuring 24 inches in diameter, providing one hundred recording surfaces and tracks rotating at a speed of 1200 rpm. The data transfer rate reached up to 8,800 characters per second. An access mechanism allowed read/write heads to move across selected disk pairs and tracks. Several enhanced versions were introduced during the late 1950s. The IBM RAMAC 305 system with the IBM 350 was leased at $3,200 per month and remained in service until its retirement in 1969.

A key patent from this era, US3,503,060 related to the RAMAC program, is regarded as foundational for modern disk drives. Although initially canceled due to concerns about conflicting with IBM’s punch card business, development resumed following approval from IBM’s president.

The physical dimensions of the IBM 350 cabinet were roughly 60 inches long, 68 inches tall, and 29 inches deep. Weighing approximately one ton, it required forklifts for relocation and large cargo aircraft for transportation. According to Currie Munce of Hitachi Global Storage Technologies—successor to IBM’s storage division—early marketing teams hesitated to promote higher-capacity models because they were uncertain about customer demand; nevertheless, double-capacity versions were announced in January 1959 and began shipping later that year.

In recognition of its engineering significance, the RAMAC 350 Disk File was named an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, a restoration effort led by Al Hoagland partnered with Santa Clara University to refurbish an IBM 350 RAMAC unit. In 2005, this project transitioned to the Computer History Museum located in Mountain View, California, where the restored machine is now on public display.

IBM 353

The IBM 353, implemented in the IBM 7030, bore resemblance to the IBM 1301 but featured an enhanced data transfer speed. It offered a storage capacity of 2,097,152 (221) 64-bit words, equivalent to 134,217,728 bits, and achieved a transfer rate of 125,000 words per second. A prototype delivered in late 1960 marked the first disk drive to utilize a dedicated read/write head per surface, each gliding on a cushion of compressed air—an evolution from the IBM 350 disk storage (RAMAC) design. Production versions incorporated self-levitating heads akin to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as a companion to the widely used IBM 650. It employed the IBM 350 mechanism but enhanced it by incorporating up to three access arms, compared to the single arm in the IBM 350. The device stored six million decimal digits along with 600,000 sign characters. Data transfer involved moving entire tracks between the magnetic core memory of the 653—an optional storage unit for the IBM 650 containing sixty signed 10-digit words sufficient for one disk track or tape record—and the disk unit.

IBM 1405

The IBM 1405 Disk Storage Unit was announced in 1961 as part of the IBM 1400 series business computers. It was available in two configurations: Model 1 held 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 rotated vertically at a speed of 1200 rpm.

Each side of a disk contained 200 tracks segmented into five sectors; sectors numbered 0 through 4 were located on top surfaces and sectors 5 through 9 on bottom surfaces. Each sector accommodated between 178 and 200 characters. One to three forked access arms—each equipped with two read/write heads for top and bottom surfaces—moved both vertically and horizontally under electronic control to reach specific disks and tracks. The time required to read or write a sector was approximately 10 milliseconds.

Access times varied from as low as 100 milliseconds up to a maximum of about 700 milliseconds for Model 1 and up to 800 milliseconds for Model 2. Model 2 contained around 100,000 sectors capable of holding either 200 characters in move mode or reduced to 178 characters in load mode, which added a word mark bit per character; Model 1 had half this number of sectors.

IBM 7300

The IBM 7300 Disk Storage Unit was engineered specifically for use with the IBM 7070. Although IBM announced a second model in 1959, when the IBM 1301 was introduced on June 5, 1961, it became a more appealing choice for customers using the IBM 7070 and IBM 7074 systems. The technology within the IBM 7300 drew upon developments from earlier models 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 the IBM mainframe computers in the IBM 7000 series as well as for the IBM 1410. Each module stored approximately twenty-eight million characters (168 million bits)—with twenty-five million reserved for the IBM 1410—using twenty-five large disks that provided forty user-accessible recording surfaces, each containing two hundred fifty tracks. The Model 1 configuration included one module, whereas Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred revolutions per minute and supported data transfer rates of ninety thousand characters per second.

A significant advancement was the implementation of individual arms and read-write heads dedicated to each recording surface; these moved together in unison like a comb structure. This approach eliminated delays caused by repositioning a single head across multiple disks and reduced maximum access time to approximately one hundred eighty milliseconds. Additionally, the IBM 1301 pioneered aerodynamically shaped heads that floated on a thin air cushion above disk surfaces, enabling closer head-to-disk spacing and improved performance.

Connection was established through the IBM 7631 File Control unit, which facilitated compatibility with either IBM 1410 or IBM 7000 series computers or allowed sharing between two systems.

Leasing costs for Model 1 were $2,100 monthly or $115,500 for purchase; Model 2 leased at $3,500 per month or $185,000 to acquire. The IBM 7631 controller incurred an additional $1,185 monthly lease fee 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 offered a fourfold increase in capacity compared to the 1301, reaching 117 million 6-bit characters per module. It delivered an average access time of 165 milliseconds and data transfer speeds 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. The Model 2 configuration combined two modules to double overall storage capacity. Leasing rates were set at $5,600 per month for Model 1 and $7,900 per month for Model 2, with purchase prices of $252,000 and $355,500 respectively; the IBM 7631 controller incurred an additional $1,185 monthly lease or a $56,000 purchase cost. Production of the 1302 ceased in February 1965.

IBM 1311

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

The IBM 1316 disk pack measures about four inches in height, weighs around ten pounds, and comprises six fourteen-inch disks offering ten usable recording surfaces. These disks rotate at 1500 revolutions per minute and employ read/write heads mounted on hydraulic actuators. Each recording surface contains one hundred tracks subdivided into twenty sectors per track; each sector holds one hundred characters. The removable nature of the disk pack influenced many subsequent storage designs.

The seven IBM 1311 models included:

  1. Master drive supporting IBM 1440/1460/1240 systems; capable of controlling up to four Model 2 slave drives (1962–1971)
  2. Slave drive compatible with master drive features (1962–1975)
  3. Master drive for IBM 1620/1710 systems; manages up to three Model 2 drives without special features (1962–1971)
  4. Master drive tailored for IBM 1401 systems; controls up to four Model 2 drives (1962–1971)
  5. Master drive supporting IBM 1410/7010/7740 systems; controls up to four Model 2 drives and includes standard Direct Seek functionality (1963–1971)
  6. Presumed master drive introduced in 1968 and withdrawn in 1971
  7. Presumed slave drive companion to Model 6 introduced in 1968 and withdrawn in 1971

Available optional features comprised:

  • Direct Seek: Removes the need to return to track zero before seeking a new track
  • Scan Disk: Enables automated rapid searching for specific identifiers or conditions
  • Seek Overlap: Permits overlapping seek operations with reading or writing across multiple drives
  • Track Record: Enhances capacity by recording a single large record per track instead of multiple sectors—allowing up to approximately 18.7 million bits total

Master drives (Models 1,3,4,5) incorporate additional power supplies and control circuitry, resulting in a width roughly one foot greater than that of the Model 2 slave drives.

IBM 2302

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

This model employs a fixed module containing twenty-five platters, providing forty-six surfaces for data storage. The Model 3 configuration includes one such module, while Model 4 consists of two modules. Each module is equipped with two independent access mechanisms—one dedicated to the innermost 250 cylinders and another handling the outermost 250 cylinders—referred to as access groups. Each mechanism features one read/write head per track. Rotational latency averages seventeen milliseconds with a maximum delay of thirty-four milliseconds; maximum seek time within each access group is up to one hundred eighty milliseconds. Tracks hold approximately four thousand nine hundred eighty-five bytes; factoring in formatting and alternate tracks, each module offers a total capacity of around one hundred twelve megabytes. The IBM 2302 interfaces with mainframe systems through the IBM 2841 Storage Control Unit.

IBM 2305

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

The demand for the 2305 surged following the System/370 introduction of Virtual Storage, where it frequently served as a paging device across various models such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter requiring specialized microcode). It was also well-suited for managing high-transaction small data sets like catalogs and job queues.

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

Engineered for rapid and continuous retrieval of small volumes of data, the 2305's combination of capacity and speed made it ideal for system-resident functions such as work files, job queues, indices, and frequently accessed datasets. Its swift response times rendered it especially effective in environments demanding over 1.5 paging transactions per second under heavy system load.

IBM 2311

Introduced in 1964 alongside the 2841 Control Unit, the IBM 2311 Disk Storage Drive was developed for use with the IBM System/360 family and also found application in the IBM 1130 and IBM 1800 systems. It connects directly to System/360 Models 20 and 25. All units utilize removable IBM 1316 Disk Packs, originally introduced with the IBM 1311.

While the Model 1 connects through the 2841 Control Unit, the System/360 Model 25 employs a Disk Attachment Control providing comparable functionality. Disk packs employ IBM's count key data variable record length format. Models 11 or 12, designed for use with the Model 20's integrated control unit, write disk packs using a fixed sector format; these packs are incompatible with those used by Model 1 drives.

Mechanically akin to the IBM 1311 but featuring enhanced recording technology to achieve greater data density, the IBM 2311 stores up to 7.25 megabytes on a six-platter removable disk pack. It includes ten read/write heads mounted on a hydraulically actuated arm, each platter surface containing 200 tracks plus three reserved tracks. The average seek time is approximately 85 milliseconds, while data transfer rates reach up to 156 kB/s.

Uniform electrical interfaces across System/360 models facilitated third-party manufacturers in producing plug compatible disk drives, thereby encouraging a competitive market for IBM-compatible storage hardware.

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 series systems. Featuring a Two Channel Switch, it allowed simultaneous connection to two system channels. Building upon the foundation laid by the IBM 2311, it offered increased data density and expanded storage capacity.

This drive utilized an elevated IBM 2316 disk pack containing eleven platters (amounting to twenty recording surfaces), capable of storing roughly twenty-nine million characters. Equipped with twenty read/write heads mounted on a hydraulically actuated arm, each surface contained approximately two hundred tracks. Subsequent versions improved upon the original average access time of about eighty-five milliseconds and doubled data transfer rates to approximately 310 kB/s.

The Model 1 configuration comprised nine drives sold as an integrated unit alongside a storage control unit and drive modules. The drives were installed in drawer-like assemblies enabling easy disk pack access; this design earned them the nickname "Pizza Ovens." Although only eight drives were accessible simultaneously, a ninth drive functioned as an offline spare to facilitate maintenance without interrupting operation. Drive addresses could be customized by swapping plugs to designate active or spare units.

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

Subsequent models expanded upon this architectural design:

IBM 2314 Direct Access Storage Series

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

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

IBM 2319

To respond to competition from plug compatible manufacturers producing subsystems equivalent to the 2314, IBM launched the cost-effective three-drive 2319 module in 1970. This model was developed by removing one drive from the four-drive 2313 and renaming it as the 2319 A1, which was then offered at a significantly lower rental price. This approach reduced costs for new customers while preserving higher charges for existing clients. The 2319-A1 interfaces with integrated controllers designed for System/370 Models 135 and 145. Additionally, traditional 2314 DASD units such as the 2312 or 2318 can connect to the 2319-A1. The 2319 B series supports configurations of three, six, or nine drives linked to the updated 2314 Model B Storage Control Unit.

IBM 3310

Released 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), compatible with DOS/VSE and VM operating systems—the only S/370 operating systems that supported FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, debuted in June 1970 targeting IBM System/370 and System/360/195 platforms. Initially available as Model 1 with two drives and Model 2 with a single drive, it employed removable disk packs holding approximately 100 MB (404×19×13,030 bytes). The device delivered an access time of 30 ms and data transfer speeds reaching 806 kB/s. A key advancement was the inclusion of integrated error correction via fire codes, which improved reliability and lowered costs by tolerating imperfections on disk surfaces.

The standard setup comprised one storage control unit (3830 Model 1) connected to either one or up to four physically linked 3330 drives, allowing strings of up to eight drives in total.

In August 1972, IBM introduced the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated the control unit from the drive strings. The enhanced 3830 functioned as a director-style controller capable of managing multiple drive strings simultaneously. The initial unit in each string, known as the 3333, combined a controller with two drives and could oversee up to three additional attached 3330 drives for a maximum of eight drives per string. The upgraded 3830 Model 2 supported two such strings per controller (up to sixteen drives), with optional string switches enabling dual-controller connectivity.

In 1973, IBM released double-density (-11) variants including the models: 3333–11, 3330-11, and the higher-capacity 3336–11 Disk Packs offering up to 200 MB (808×19×13,030 bytes). Mixing single-density and double-density drives within a single string was not permitted. Although field upgrades from original models to Model-11 versions were possible, they were complex processes requiring drive conversion plus complete data migration.

The IBM 3330 product line was discontinued in 1983.

IBM 3340 and 3344

Although the IBM 3340 and 3344 share many characteristics, only the 3340 can function as the head of string; the 3344 must be connected to a 3340 A model serving in that role.

IBM 3340

Introduced in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility, known by its codename Winchester, came in three variants: the 3340-A2 (which included two drives and a controller), the B2 (two drives), and the B1 (one drive). Up to eight B-units could be linked to a single A2 controller.

This system utilized removable data modules that housed both the head and arm assemblies; a mechanical load/unload mechanism allowed an access door to open or close, enabling module attachment without needing to remove covers during insertion. The drive offered a 25-millisecond access time and a data transfer speed of 885 kB/s. Three types of IBM 3348 Data Modules were available: one with a 35 MB capacity and two with 70 MB, one of which included a fixed-head area of 500 KB for quicker access. The 3340 also incorporated error correction features and remained in production until its withdrawal in 1984.

Developed under Ken Haughton in San Jose, the original design aimed for two removable modules of approximately 30 MB each—hence the Winchester nickname, inspired by the Winchester .30-30 rifle. Although storage capacities increased over time, the codename persisted.

A significant breakthrough was its economical head design that did not necessitate unloading from the disk surface. This "Winchester technology" allowed heads to land on and lift off from spinning disks, simplifying and reducing costs of the actuator mechanism. This approach became widely adopted across the industry.

Throughout the early 1990s, "Winchester" or "Winnie" was commonly used as a general term for hard disk drives but has since largely disappeared from global usage.

IBM 3344

The IBM 3344 shares many similarities with the 3340 but differs by employing fixed media rather than removable IBM 3348 data modules. Each spindle contains four logical drives, each equating to the capacity of a single 70 MB IBM 3348 module. Available only in dual-drive configurations, it does not include an A model capable of serving as head of string. The 3344-B2F variant is distinguished from the 3344-B2 by having fixed heads over certain cylinders on both drives. Both models require connection to a 3340-A2 or 3340-A2F unit functioning as head of string. Internally, the IBM 3344 shares its architecture with the IBM 3350; distinctions are confined to differences in control unit microcode.

IBM 3350

Released in 1975 for IBM System/370, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. It introduced sealed, non-removable head-disk assemblies (HDAs) that integrated both head and arm components, establishing a design benchmark for subsequent IBM DASD products. Its disk geometry consisted of 555 cylinders, 30 heads, and tracks containing 19,069 bytes each, resulting in approximately 317 MB capacity per HDA.

Available models included A2, A2F, B2, B2F, C2, and C2F—all featuring two HDAs per unit. The A2 and A2F models contained an additional electronic board facilitating connection to control units—often referred to as controllers or head-of-string units. These units were arranged into strings beginning with an A2 or A2F unit followed by up to three B2 units or combinations including C2 units. Typically, the A2 featured a string switch enabling simultaneous I/O operations through connections to two storage control units. Compatible controllers encompassed devices such as the 3830 Model 2, Integrated Storage Control (ISC) within CPUs like the IBM 3148, and later models including the IBM 3880.

The C2 model also included a controller acting as a secondary path providing redundancy if the A unit's controller failed; however, it supported fewer connections than the A unit. Accepted string configurations comprised -A, -AB, -ABB, -ABBB, -AC-, -ABC-, and -ABBC-.

Models with "x2F" suffixes (for example, A2F) featured fixed-head zones spanning the first five cylinders on both HDAs to reduce seek times within this region to zero. This area was generally reserved for frequently accessed checkpoint data used by HASP or JES2 spooling systems—significantly decreasing head movement on spool devices. Additionally, it accommodated TSO swap data and system swap data within MVT, SVS, and MVS environments, thereby enhancing context-switching efficiency between TSO sessions or batch jobs.

The IBM 3350 series was discontinued in September 1994.

IBM 3370

Debuting in January 1979 for IBM 4331, 4341, and System/38 midrange systems, the IBM 3370 was equipped with seven fixed 14-inch platters, delivering a total storage capacity of 571 MB per unit. It was pioneering as the first hard disk drive to incorporate thin-film head technology, developed at the 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 complement to the 3370 by implementing count key data architecture, which was essential for OS/360 and its subsequent operating systems.

IBM 3380

Introduced on June 11, 1980, the IBM 3380 employed thin-film head technology and offered a capacity of 2.52 GB per unit, composed of two hard disk assemblies each containing two actuators accessing 630 MB. It achieved a data transfer speed of 3 MB/s and an average seek time of 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges between the heads and media surfaces, deliveries commenced in October 1981.

A typical configuration consisted of one A unit with up to three B units; each 3380 housed four devices, enabling up to sixteen devices per string. These units were generally connected to a 3880 storage control unit featuring dual paths, permitting two concurrent I/O operations directed at separate HDAs.

In February 1985, IBM launched the Extended Capability Model (3380 E) with double density, doubling capacity to 5.04 GB per unit through two actuators of 1.26 GB each across two assemblies.

The Model K followed in August 1987, tripling capacity to 7.562 GB per unit by employing two actuators of 1.89 GB each. Both Models J and K supported four-path mode connectivity, which doubled the number of devices to a maximum of thirty-two per string when attached to a 3990 storage control unit, enabling four simultaneous I/O processes.

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

Manufacture continued until May 1996, marking a significant production span of fifteen years for this IBM disk drive lineup.

IBM 3390

The IBM 3390 Direct Access Storage Device family was introduced in November 1989, providing storage capacities up to twenty-two gigabytes distributed over multiple drives. Pricing for systems varied from $90,000 to $795,000 based on configuration and capacity.

A typical 3390 string included a central A unit containing four or eight devices along with up to two B units, each holding as many as twelve devices. Operating in four-path mode and connected to a 3990 storage control unit, it could support an additional string for a total maximum of sixty-four devices within one subsystem.

Each Hard Disk Assembly (HDA) consisted of two actuator-head pairs and platters. Model 1 offered a capacity of 1.89 GB per HDA; Model 2 doubled this to 3.78 GB per HDA. Announced in September 1991, Model 3 increased capacity further to 5.67 GB per HDA, while Model 9 introduced in May 1993 expanded it again to 11.3 GB per HDA.

Unlike earlier DASD designs that used large AC motors with belt drives, the HDAs in the 3390 series incorporated directly driven DC motors housed within the enclosure. The Model 9 represented IBM's final iteration of Single Large Expensive Disk (SLED) technology.

IBM 9345

Released 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’s San Jose facility under the project name Sawmill. This full-height 5¼-inch HDD supported up to eight 130 mm platters, delivering a maximum storage capacity of 1.5 GB. It was distinguished as the first HDD to incorporate magnetoresistive (MR) head technology.

IBM 9340

In October 1991, IBM launched the 9345 DASD within the 9340 family—a channel-attached count key data (CKD) DASD subsystem designed for IBM mainframes, including those in the ES/9000 series. The 9345 Model 1 comprised two drives each with 1.0 GB capacity, while Model 2 doubled that with two drives of 1.5 GB each.

While functionally similar to the 3990 and 3390 models, the 9340/9345 lacked the non-volatile RAM cache found on the 3990 and featured a reduced maximum block length compared to the 3390.

The OS Input/Output Supervisor (IOS) identified device specifics through a specialized initializer called IECCINIT, which also handled other DASD types. During initialization, the OS detected the absence of non-volatile cache in the 9340 and recognized the diminished track capacity on the 9345, resulting in these devices being assigned distinct device types separate from those of the 3990/3390.

9330 family of disk drives

  1. Models 1 and 11 of the 9331 Diskette Unit contained a single 8-inch floppy disk drive; models 2 and 12 included one 5-inch floppy disk drive.
  2. The 9332 Direct Access Storage Device utilized the IBM 0667 hard disk drive.
  3. The High Performance Disk Drive Subsystem, designated as model 9333, employed either IBM 0664 or IBM 0681 HDDs depending on configuration.
  4. The 9334 Disk Expansion Unit provided connectivity for one to four SCSI hard drives to RS/6000 systems.
  5. The Direct Access Storage Subsystem model 9335 incorporated the "Kestrel" HDD, engineered at IBM Hursley in the UK—an 850 MB unit featuring three 14-inch platters and dual rotary actuators enabling access to multiple surfaces. This rack-mountable system was unveiled in October 1986 alongside the IBM 9370 Information System. No known OEM variants exist.
  6. The IBM 0681 HDD (Redwing) powered the model 9336 Disk Unit.
  7. The Disk Array Subsystem model 9337 operated using IBM's IBM 0662 (Spitfire) or IBM 0663 (Corsair) hard drives.

IBM 2310

Introduced initially in 1964 with the IBM 1800 and later appearing with the IBM 1130 in late 1965, the IBM 2310 Removable Cartridge Drive stored data on an IBM 2315 cartridge. This cartridge comprised a single oxide-coated aluminum disk measuring fourteen inches, encased in plastic with openings for read/write heads and arm access. It held a total of 512,000 words of sixteen bits each (equivalent to approximately one million bytes).

IBM 5444

Announced in September of 1969 as part of System/3 and developed at IBM’s Hursley laboratory in England under the project name Dolphin, the IBM 5444 utilized a single-disk cartridge known as the IBM 5440 containing one fourteen-inch platter. It was available in three configurations:

  • Model 1: featured one fixed disk plus one removable disk, each offering one hundred tracks per surface; cartridge capacity was approximately 1.23 MB
  • Model 2: included one fixed disk and one removable disk with two hundred tracks per surface; cartridge capacity reached about 2.46 MB
  • Model 3: contained only one removable disk with two hundred tracks per surface; cartridge capacity also approximately 2.46 MB

IBM 62GV

The IBM 62GV, first shipped in May of 1974 and developed at IBM’s Hursley facility under code name Gulliver, initially provided five megabytes of storage capacity. Subsequent versions designated as '62TM' increased this capacity to ten and then fourteen megabytes. It employed a Swinging Arm actuator design paired with a single fourteen-inch platter—a mechanism invented at Hursley that became IBM’s most widely licensed electro-mechanical innovation. This actuator design along with its filtration system gained widespread adoption across hard drives throughout the following decade and remains an industry standard nearly four decades later, with over ten billion units produced globally. Approximately one hundred seventy-seven thousand units of the IBM 62GV were shipped, 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 hard disk drives marketed as OEM units and designed for IBM small systems such as the System/3, System/32, /34, /36, and AS/400. The drives are identified by their OEM model numbers and arranged according to their initial shipment dates.

IBM 0680

The 0680 model was initially shipped in 1979, primarily supporting IBM small systems and entry-level System/370 machines as the 3310 direct access storage device. Officially announced as the 0680 OEM product in September 1981, it was engineered at IBM’s Hursley laboratory in the UK under the project name Piccolo. This drive incorporated six 8-inch (210 mm) platters, delivering a starting storage capacity of up to 65MB alongside an enhanced rotary actuator design.

A double-capacity variant known as the 62SW became available in June 1984; however, its market penetration was limited because its cost per megabyte was comparable to the more premium 62GV model.

IBM 0676

Released in November 1982, the 0676 served as a 5247 Disk Storage Unit for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota with the internal designation 21ED, this hard drive featured 8-inch platters and offered storage options of either 15 or 30 MB by utilizing two or four 210 mm disks. In 1983, it was integrated into the System/36’s 5360 System Unit. Its capacity was doubled in 1984 through an increase in tracks per surface and later incorporated into the System/36’s upgraded 5362 Unit.

IBM 0665

The 0665 made its debut in October 1985 within the PC AT (5170) chassis. Created under the codename "Pixie" at IBM Rochester, this was a 5¼-inch hard disk drive available with capacities of 20, 30, and 44 MB.

IBM 0667

The 0667 was introduced in August 1986. Designed at IBM Rochester under the project name "Grant," it was a full-height ESDI hard disk drive measuring 5¼ inches and capable of housing up to four 130 mm platters with a maximum capacity of 70 MB. This model was offered as an optional storage device on select PC RT models (6150, 6151, 6152) as well as on System/36 Model System Units (5363, 5364).

IBM 0669

Launched in 1987 and developed at IBM Rochester under the codename "Grant-Prime," the 0669 was a full-height hard disk drive measuring five inches. It supported up to four 130 mm disks with a total capacity reaching as high as 115 MB. This drive functioned as the internal storage for both the System/36’s 5363 and Series 1’s 4956 System Units.

IBM 0671

Also introduced in 1987, the 0671 was developed at IBM Rochester under the codename "Lee." It featured an ESDI full-height five-inch form factor accommodating up to eight 130 mm platters for a maximum capacity of approximately 316 MB. This model represented IBM’s initial implementation of thin metal film recording surfaces. By 1988, it had been incorporated into the AS/400’s 9404 System Unit configurations supporting two or three drives.

IBM 0661

The 0661, released in 1989 as model number 371, was developed jointly at IBM Rochester and Hursley under the codename "Lightning." It was a SCSI hard disk drive with up to eight disks measuring 95 mm each (14 heads), providing a capacity of around 320 MB. A subsequent "Turbo" variant offering increased capacity of approximately 400 MB became available in 1990. This drive became standard equipment on prominent IBM platforms including the AS/400 System Unit Model CXX.

IBM 0681

Introduced in April of 1990 from IBM Hursley (code named Redwing), the 0681 represented the final HDD developed at that facility. It delivered up to an impressive capacity of 857 MB within a full-height five-inch enclosure containing twelve platters sized at 130 mm each. Notably, it was IBM’s first hard drive to utilize PRML (Partial Response Maximum Likelihood) data decoding technology. This model powered the IBM 9333 Disk Drive Subsystem launched in early 1992. An enhanced version featuring increased density with a capacity of approximately 1.07 GB followed in May of that year.

IBM 0663

Introduced in late 1991 under the project name "Corsair," the 0663 was a compact 3-inch hard disk drive with a half-height (1.6-inch) form factor. It delivered up to 1 GB of storage across eight 95 mm platters. This model appeared in specific PS/2 and RS/6000 systems and marked IBM's inaugural use of Magnetoresistance (MR) heads in an OEM disk drive.

IBM 0664

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

IBM 0662

The 0662, launched in June 1993 and created at IBM Rochester with the codename "Spitfire," was a full-height (1-inch tall) 3-inch HDD. It offered 1.05 GB of storage utilizing three platters or five disk surfaces and was deployed internally within the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology by introducing the 8-inch floppy disk drive in 1971 as a read-only device for program loading, followed by its first read/write version in 1973 with the release of the 3740 Data Entry System. Although IBM established early standards for 8-inch floppy drives, it did not market these drives independently, allowing third-party development to flourish.

At one time, IBM was the largest original equipment manufacturer (OEM) buyer of 5-inch floppy drives; its selection of two-sided drives with 48 tracks per inch helped cement this format as the industry benchmark. Despite preparations to produce these and smaller sizes internally, IBM discontinued all such initiatives by 1985. Its attempt in 1983 to OEM a smaller 4-inch DemiDiskette failed to gain traction.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three new families of hard disk drives: the Travelstar series featuring 2-inch drives for notebook computers; the Deskstar line consisting of 3-inch desktop drives; and the Ultrastar series with high-performance 3-inch drives designed for demanding applications.

IBM's first HDD versus its last HDDs

The following table contrasts IBM's initial hard disk drive, the RAMAC 350, with its final three OEM models from the "Star" series. This comparison illustrates substantial advancements in cost reduction and miniaturization alongside significant gains in storage capacity and operational efficiency.

Parameter (units) RAMAC 350 Ultrastar 146Z10 Deskstar 180GXP Travelstar 80GN Maximum improvement over 46 years
Announcement date Sep 1956 Jul 2002 Oct 2002 Nov 2002
Capacity (GB) 0.004 146 180 80 48,000
Size (inches) 60×68×29 4×1×5.75 4×1×5.75 2.75×0.38×3.95
Size (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) ~2374 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
Areal density (Mb/in²) 0.002 26,263 46,300 70,000
Areal density (Kb/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 Distinct from HDDs and FDDs

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

IBM 7320 Drum

The IBM 7320, launched in 1962, represents a magnetic drum storage apparatus.

IBM 2301 Drum

Introduced during the late 1960s, the IBM 2301 is another example of a magnetic drum storage mechanism.

IBM 2303 Drum

The IBM 2303, which debuted in 1964, also utilizes magnetic drum technology for data storage.

IBM 2321 Data Cell

Announced in 1964, the IBM 2321 Data Cell employs short strips of magnetic tape as its storage medium. It accommodates ten detachable cells, each with a capacity of 40 MB, culminating in a total storage size of 400 MB.

IBM 3850 Mass Storage System

The IBM 3850 Mass Storage System, unveiled in 1974, functions as a tape cartridge library. It stages data onto IBM 3330 or 3350 disk drives and presents these as virtual devices to the host system.

See also

External links

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