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IBM 3370

From Alfawiki
IBM Magnetic Disk Storage Division
Company typeDivision
IndustryComputer storage
Founded1956
Defunct2003
FateSold to Hitachi
Key people
IBM workforce (inventors of HDD and FDD)
ProductsHard disk drives, floppy disk drives
ParentIBM

IBM was a pioneer in producing magnetic disk storage units from 1956 until the sale of its hard disk drive division to Hitachi in 2003. IBM's workforce was instrumental in inventing both the hard disk drive (HDD) and the floppy disk drive (FDD), contributing significantly to advancements within these fields. Since the introduction of the IBM 1301, the core mechanical structure of hard disk drives has remained largely unchanged, and performance benchmarks have adhered to consistent criteria established in the 1950s. Throughout the years, these devices have experienced dramatic reductions in price and physical dimensions, coupled with substantial improvements in storage capacity and operational speed.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not enter the market for smaller 5.25- or 3.5-inch formats on a significant scale. Although IBM continuously marketed its magnetic disk drives, it only started offering them under original equipment manufacturer (OEM) arrangements beginning in 1981. By 1996, IBM discontinued producing hard drives exclusively for its proprietary systems and transitioned to supplying all HDDs as OEM products.

IBM has referred to its magnetic disk drives using various labels, such as direct-access storage device (DASD), disk file, and diskette file. For clarity, this article employs the widely accepted industry terminology: hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage device marked the debut of the first disk drive and was introduced by IBM on September 14, 1956, as part of the IBM 305 RAMAC system. A comparable model, the IBM 355, was announced for use with the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, while production units began shipping to United Airlines in Denver by November 1957.

Engineered to facilitate real-time business accounting tasks, the IBM 350 had a capacity of five million 6-bit characters (equivalent to 3.75 MB). Its design included fifty-two disks measuring in diameter, providing one hundred recording surfaces spinning at a speed of 1200 revolutions per minute. The data transfer rate reached 8,800 characters per second. An access mechanism allowed read/write heads to move across disk pairs and tracks for data retrieval. Several enhanced variants were released throughout the late 1950s. The IBM RAMAC 305 system paired with the 350 was leased at a rate of $3,200 monthly. The unit was retired from production in 1969.

The patent emerging from the RAMAC development is regarded as foundational for disk drive technology. Initially halted by IBM's Board over concerns that it might cannibalize punch card sales, development persisted at IBM’s San Jose facility until receiving approval from IBM’s president.

The cabinet housing the device measured long, high, and wide, weighed approximately one ton, and required forklifts or large cargo aircraft for transportation. Currie Munce of Hitachi Global Storage Technologies noted that marketing initially hesitated to promote higher-capacity versions due to uncertain demand; nonetheless, double-capacity models were announced in January 1959 and shipped later that year.

In recognition of its significance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. Beginning in 2002, a restoration initiative led by Al Hoagland collaborated with Santa Clara University, culminating in its relocation in 2005 to the Computer History Museum, where it remains on public display as part of the Revolution exhibition.

IBM 353

The IBM 353, implemented on the IBM 7030, bore similarities to the IBM 1301 but offered enhanced transfer speeds. It provided a storage capacity of 2,097,152 (221) 64-bit words, equivalent to 134,217,728 bits, and achieved data transfer rates of 125,000 words per second. A prototype delivered in late 1960 was notable for being the first disk drive to employ a dedicated head per surface that floated on a cushion of compressed air, reminiscent of the IBM 350 disk storage (RAMAC). Production versions featured self-levitating heads similar to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an enhancement for the widely used IBM 650. Utilizing the IBM 350 mechanism, it incorporated up to three access arms—compared to a single arm on the IBM 350—allowing storage of six million decimal digits along with 600,000 sign indicators. This unit transferred entire tracks to and from the magnetic core memory of the 653, an optional IBM 650 component holding sixty signed 10-digit words—sufficient for one disk track or tape record—and included two additional features.

IBM 1405

Announced in 1961 for the IBM 1400 series business computers, the IBM 1405 Disk Storage Unit was offered in two variants: Model 1 provided storage for ten million alphanumeric characters (60 million bits) 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 rpm.

Each disk surface contained 200 tracks segmented into five sectors; sectors numbered 0 through 4 were located on upper surfaces, while sectors 5 through 9 were on lower surfaces. Each sector accommodated either 178 or 200 characters. Between one and three forked access arms, each equipped with two read/write heads (one on top and one on bottom), moved vertically to select among disks (0–49) and horizontally to choose tracks (0–199). Each track comprised ten sectors. Reading or writing a sector required approximately 10 milliseconds.

Access times ranged from around 100 milliseconds up to a maximum of 800 milliseconds for Model 2 and up to 700 milliseconds for Model 1. Model 2 contained one hundred thousand sectors capable of holding either two hundred characters in move mode or one hundred seventy-eight characters plus a word mark bit in load mode. Model 1 had fifty thousand sectors.

IBM 7300

Designed for compatibility with the IBM 7070, the IBM 7300 Disk Storage Unit was announced with a model two variant in 1959. However, the launch of the IBM 1301 on June 5, 1961, offered a more compelling option for users of both the IBM 7070 and IBM 7074. The technology utilized in the IBM 7300 shared similarities with that found in the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

The IBM 1301 Disk Storage Unit was unveiled on June 2, 1961, targeting the 7000 series mainframe computers as well as the IBM 1410. It provided storage capacity of twenty-eight million characters (168 million bits) per module—reduced to twenty-five million characters when configured with the IBM 1410. Each module incorporated twenty-five large disks featuring forty user-accessible recording surfaces and two hundred fifty tracks per surface. The Model 1 consisted of a single module; Model 2 stacked two modules vertically. Disks rotated at a speed of eighteen hundred rpm and achieved data transfer rates of ninety thousand characters per second.

A significant advancement was the implementation of an individual arm and read/write head for every recording surface, all moving simultaneously like a comb. This architecture minimized seek times by removing the need to reposition arms between disks and enhanced access speeds, reducing maximum access time to as low as one hundred eighty milliseconds.

The IBM 1301 was also pioneering in its use of aerodynamically shaped heads that hovered on a thin cushion of air above disk surfaces, enabling closer spacing and improved performance.

Connection to host systems was facilitated by the IBM 7631 File Control unit, which supported integration with either IBM 1410 or IBM 7000 series machines or allowed sharing between two computers.

Pricing details indicated that leasing the IBM 1301 Model 1 cost $2,100 monthly or $115,500 for purchase; Model 2 was priced at $3,500 per month or $185,000 outright. The IBM 7631 controller added $1,185 monthly lease or $56,000 purchase price. All models were retired from service by around 1970.

IBM 1302

Launched in September 1963, the IBM 1302 Disk Storage Unit expanded the storage capacity of its predecessor, the 1301, by four times, reaching 117 million 6-bit characters per module. It offered an average access latency of 165 milliseconds and supported data transfer speeds of 180,000 characters per second—over double the throughput of the 1301. Each storage module was equipped with two separate access mechanisms dedicated to the inner and outer cylinders. The Model 2 variant increased total capacity by incorporating two stacked modules. Leasing fees were set at $5,600 per month for Model 1 and $7,900 per month for Model 2; purchase costs amounted to $252,000 and $355,500 respectively. Additionally, the IBM 7631 controller was available for lease at $1,185 monthly or for purchase at $56,000. Production of the 1302 ceased in February 1965.

IBM 1311

Introduced on October 11, 1962, the IBM 1311 Disk Storage Drive was designed for mid-range business and scientific computing applications. Comparable in size to a top-loading washing machine, it accommodated 2 million characters on a removable IBM 1316 disk pack. Throughout the 1960s, seven different models were released before being phased out in the early 1970s.

Each IBM 1316 disk pack measures roughly 4 inches in height and weighs about 10 pounds. It comprises six disks measuring 14 inches each, providing ten usable recording surfaces. The disks rotate at a speed of 1500 revolutions per minute and employ ten read/write heads mounted on a hydraulically controlled arm. Every surface contains 100 tracks with 20 sectors each; every sector holds 100 characters. To safeguard against damage during handling, the disk packs are encased in a transparent plastic shell.

The IBM 1311 lineup included seven models: master drives (Models 1, 3, 4, and 5), which incorporated controllers, and slave drives (Model 2) that were managed by master units. Depending on system compatibility—such as with IBM 1440 or IBM 1401 systems—master drives could control multiple slave drives. Key withdrawal dates for these models spanned from early 1971 to early 1975.

Available optional features comprised:

  • Direct Seek: Removes the need to return to track zero before initiating a seek operation.
  • Scan Disk: Facilitates rapid automated searching.
  • Seek Overlap: Permits simultaneous overlapping of seek operations and read/write processes across multiple drives.
  • Track Record: Enhances capacity by recording one large record per track instead of multiple sectors, increasing total storage to approximately 18 million bits under various modes.

Master drives were approximately one foot wider than slave drives due to additional power supply units and control circuitry.

IBM 2302

The IBM 2302 represents the System/360 evolution of the 1302, redesigned to fit within the S/360 direct access storage device (DASD) framework. Each non-removable module consists of 25 platters with recording surfaces on 46 sides. Model 3 includes a single module while Model 4 contains two modules. Every module is equipped with two independent access mechanisms—referred to as access groups—each responsible for either the innermost or outermost set of 250 cylinders. Each access group possesses one read/write head per track. Average rotational latency is approximately 17 milliseconds, with a maximum delay up to 34 ms; maximum seek time within an access group is around 180 ms. Each track holds about 4,985 bytes; total formatted capacity per module is near 112 megabytes including space reserved for alternate tracks. The IBM 2302 interfaces with IBM mainframes through the IBM 2841 Storage Control Unit.

IBM 2305

Released in 1970, the IBM 2305 fixed-head storage unit was designed to operate with the IBM 2835 Storage Control and connected to System/360 models 85 and 195 through the IBM 2880 Block Multiplexor Channel.

The introduction of Virtual Storage on System/370 significantly boosted the 2305’s popularity, where it frequently 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 also well-suited for handling small, high-transaction data sets including catalogs and job queues.

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

Engineered for rapid, continuous access to limited data volumes, the 2305’s combination of speed and capacity made it ideal for system-resident tasks such as work files, job queues, indices, and frequently accessed datasets. Its swift response times were particularly advantageous when deployed as a paging device in systems managing transaction rates exceeding 1.5 per second.

IBM 2311

The IBM 2311 Disk Storage Drive debuted in 1964 alongside the 2841 Control Unit, supporting the entire IBM System/360 range as well as compatibility with the IBM 1130 and IBM 1800. It could also connect directly to System/360 Model 20 and Model 25 machines. All units utilized the IBM 1316 Disk Pack, which was initially introduced with the IBM 1311.

The Model 1 version of the 2311 connects to most IBM mainframes through the 2841 Control Unit; however, on the System/360 Model 25 it interfaces via a Disk Attachment Control unit that serves as its controller. The disk packs employ IBM's count key data format allowing variable record lengths.

Models 11 and 12—designed for use with the integrated control of System/360 Model 20—write disk packs using a fixed sector format, rendering them incompatible with Model 1 disk packs.

While mechanically resembling the IBM 1311, the 2311 improved recording technology to achieve higher data density. It stores up to 7.25 megabytes on a removable six-platter IBM 1316 disk pack. The drive features ten read/write heads mounted on a hydraulically actuated arm with mechanical detents for precise track alignment. Each platter surface contains 200 tracks plus three optional spares. Its average seek time is approximately 85 milliseconds, with data transfer rates reaching up to 156 kB/s.

The electrical interface standardization across System/360 models allowed third-party vendors to manufacture plug-compatible disk drives, which contributed to the emergence of an independent market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Launched in April of 1965, the IBM 2314 Disk Access Storage Facility Model 1 supported both System/360 and System/370 platforms. Featuring a Two Channel Switch capability, it could connect simultaneously to two system channels. The mechanical design resembled that of the IBM 2311 but offered increased data density.

This drive accommodated roughly 29 million characters on a removable IBM 2316 disk pack composed of eleven disks—significantly expanding capacity compared to the six-disk IBM 1316 pack. The eleven disks measured in diameter and provided twenty recording surfaces, each containing around 200 tracks. Twenty read/write heads were hydraulically positioned with mechanical detents ensuring precise alignment. Although initial access times matched those of the IBM 2311, subsequent enhancements reduced latency further. Data transfer speeds doubled to approximately 310 kB/s.

The original Model 1 configuration bundled nine drives together under one price category; individual components shipped separately included a storage control unit, one single-drive module, and two four-drive modules totaling nine drives in all. Drives were installed within drawers that allowed straightforward disk pack access and gained the nickname "Pizza Ovens" due to their distinctive appearance. While only eight drives could be accessed concurrently, the ninth served as an offline spare enabling maintenance without interrupting operations. Drive addresses were assigned using user-swappable plugs permitting physical reassignment of addresses and designation of spare drives.

An optional 2844 Control Unit could be added to allow two System/360 channels concurrent access to different drives within this facility.

Later versions of the IBM 2314 expanded upon these foundational features:

IBM 2314 direct access storage series

In 1969, IBM separated the facility into distinct models, permitting up to nine drives (with eight active simultaneously) connected to a 2314 Storage Control. These included:

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

IBM 2319

To rival plug-compatible manufacturers producing storage subsystems comparable to the 2314, IBM launched in 1970 the cost-effective three-drive module known as the 2319 series. This was developed by removing one drive from the four-drive 2313 configuration and reintroducing it as the 2319 A1 model, offered at a notably reduced leasing rate. This approach lowered expenses for new clients while preserving 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 can interface with the 2319-A1. The 2319 B series supports configurations of three, six, or nine drives connected to a new 2314 Model B Storage Control Unit.

IBM 3310

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

IBM 3330

The IBM 3330 Direct Access Storage Facility, codenamed Merlin, debuted in June 1970 for use with IBM System/370 and System/360/195 mainframes. Initial offerings included the two-drive Model 1 and the single-drive Model 2. Removable disk packs stored 100 MB each (404×19×13,030 bytes), featuring access times of approximately 30 ms and data transfer speeds of 806 kB/s. A notable advancement was built-in error correction using fire codes, which improved dependability and lowered costs by accommodating disk surface flaws.

The standard setup involved one storage control unit (3830 Model 1) connected to a single 3330 drive, with up to three additional drives mechanically linked in a chain—allowing a maximum of eight drives per chain.

In August 1972, IBM introduced the 3830 Model 2 Storage Control along with the 3333 Disk Storage and Control, which separated control functions from the drive chain. The 3830 evolved into a director-style controller managing multiple chains. The leading unit in each chain, the 3333, combined a controller with two drives and could oversee up to three attached 3330 drives, totaling eight drives per chain. The 3830 Model 2 supported connection of two such units for up to sixteen drives per controller; optional string switches permitted linking two controllers.

In 1973, IBM rolled out double-density (-11) variants: the models 3333–11, 3330-11, and larger-capacity 3336–11 Disk Packs capable of storing up to 200 MB (808×19×13,030 bytes). Mixing single- and double-density drives within one chain was not allowed. Upgrades from original models to Model-11 versions were feasible in the field but required converting drives and complete data migration.

The IBM 3330 was discontinued in 1983.

IBM 3340 and 3344

While the IBM 3340 and 3344 share many characteristics, only the 3340 model can function as the head of a string. The 3344 lacks an A model variant; therefore, it must connect to a 3340 A model to serve as the head of string.

IBM 3340

The IBM 3340 Direct Access Storage Facility, nicknamed Winchester, was introduced in March 1973 for the IBM System/370 platform. It came in three variants: the 3340-A2 featuring two drives and a controller, and the B2 (two drives) and B1 (single 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. The access door on these modules opened and closed mechanically during loading and unloading without requiring removal of a cover. It delivered an access time of 25 milliseconds and supported data transfer rates of 885 kB/s. The IBM 3348 Data Modules were available in three capacities: 35 MB, 70 MB, and a special 70 MB version with a fixed-head segment of 500 KB for accelerated access. The 3340 incorporated error correction features and remained in production until its withdrawal in 1984.

Developed in San Jose under Ken Haughton's leadership, the original design aimed at two removable 30 MB modules—hence the codename Winchester, inspired by the Winchester .30-30 rifle. Despite increasing storage capacities over time, the name persisted.

A significant breakthrough was the cost-effective head design that allowed heads to land on and lift off from spinning disks without unloading, simplifying the head and arm mechanism while reducing expenses. This approach, known as "Winchester technology," became an industry standard for disk drives.

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

IBM 3344

The IBM 3344 is similar in design to the 3340 but employs fixed media rather than removable IBM 3348 data modules. Each spindle contains four logical drives, each matching the capacity of a single 70 MB IBM 3348 module. The device is only available as a dual-drive model and does not include an A (head of string) variant. The 3344-B2F differs by having fixed heads covering certain cylinders on both drives. Both the 3344-B2 and 3344-B2F models require connection to a 3340-A2 or 3340-A2F acting as head of string. Internally, the IBM 3344 shares its architecture with the IBM 3350; their distinction lies solely in differences within the control unit’s microcode.

IBM 3350

The IBM 3350, with the codename Madrid, was launched in 1975 for deployment with IBM System/370. It featured sealed head-disk assemblies (HDAs) that integrated both head and arm components, establishing a new standard for IBM DASD devices. The disk geometry consisted of 555 cylinders, 30 heads per cylinder, and each track containing 19,069 bytes, resulting in approximately 317 million bytes per HDA.

Models such as A2, A2F, B2, B2F, C2, and C2F included two HDAs each. The A2 and A2F variants also incorporated an additional electronics board enabling connection to a control unit; these were known as controllers or head-of-string units. Storage strings were configured starting with an A2 or A2F unit followed by up to three B2 units or combinations like two B2s plus one C2. Typically, the A2 unit contained a string switch that allowed simultaneous I/O operations by connecting to two separate storage control units. Compatible controllers included models such as the IBM 3830 Model 2, ISC integrated into CPUs like the IBM 3148/3158/3168, and later backward-compatible units including the IBM 3880. The C2 unit also housed a controller serving as a backup path but could only connect to one storage control unit; it was utilized when the primary controller on the A unit failed.

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

The "x2F" models (for example, A2F) featured fixed-head regions spanning the first five cylinders on both HDAs, effectively eliminating seek time within this area. This section was commonly reserved for frequently accessed data such as HASP or JES checkpoint files to minimize head movement on spool devices. It also supported TSO swap space and system swap areas for operating system successors to OS/360, improving context switch efficiency between users or batch jobs.

The IBM 3350 series remained in service until its retirement in September 1994.

IBM 3370

In January 1979, IBM launched the IBM 3370 Direct Access Storage Device, designed for IBM 4331, 4341, and System/38 midrange systems. This unit incorporated seven fixed 14-inch platters, delivering a total capacity of 571 MB per device. Notably, it was the pioneer in utilizing thin-film head technology, a development originating from the Thomas J. Watson Research Center. The 3370 operated with a fixed-block architecture and was compatible with DOS/VSE and VM operating systems—the only S/370 platforms supporting FBA devices.

IBM 3375

The IBM 3375 was introduced as a complementary model to the 3370, employing count key data (CKD) architecture necessary for OS/360 and its subsequent operating systems.

IBM 3380

Debuted on June 11, 1980, the IBM 3380 Direct Access Storage Device incorporated film head technology and provided a storage capacity of 2.52 GB per unit. Each unit consisted of two hard disk assemblies (HDAs), each with two independent actuators capable of accessing 630 MB. It achieved a data transfer rate of 3 MB/s with an average access time of approximately 16 milliseconds. Initial pricing ranged between $81,000 and $142,200. Due to tribological challenges involving the interaction between heads and media, shipments commenced in October 1981.

Standard setups featured one A unit combined with up to three B units; each 3380 contained four devices, enabling up to sixteen devices per string. These devices typically connected to an IBM 3880 storage control unit, which provided dual paths for simultaneous I/O operations targeting distinct HDAs.

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

The triple-capacity variant, the 3380 K model, appeared in August 1987 offering 7.562 GB per unit—comprising two actuators of 1.89 GB on two assemblies—and optionally supporting four-path connectivity through the IBM 3990 storage control unit. This allowed up to thirty-two devices per string with four concurrent I/O operations.

The IBM 3380 series comprised twelve models: six A-units acting as string leaders with controller logic interfacing with IBM storage controls; five B-units connecting to A- or C-units; and one C-unit designed for direct connection to an IBM channel.

After more than fifteen years in production—the longest lifespan among most disk drives at that time—IBM discontinued the final models in May 1996.

IBM 3390

Launched in November 1989, the IBM 3390 Direct Access Storage Device family offered capacities up to 22 GB distributed across multiple drives. System prices varied from $90,000 to $795,000 depending on configuration and size.

A typical 3390 string consists of a central A unit housing four or eight devices, optionally accompanied by one or two B units supporting up to twelve devices each. The system operates in four-path mode connected to an IBM 3990 storage control unit, which can manage an additional 3390 string—enabling up to sixty-four devices within a subsystem.

The drives are organized into Hard Disk Assemblies (HDAs): Model 1 delivers 1.89 GB per HDA; Model 2 provides double that at 3.78 GB; the Model 3 upgrade introduced in 1991 increased capacity to 5.67 GB per HDA; and the Model 9 released in 1993 expanded this further to 11.3 GB per HDA.

Distinct from prior DASD units that utilized large AC motors and belts, the IBM 3390 employed a DC motor integrated within the enclosure for direct drive operation. The Model 9 marked IBM’s final iteration of Single Large Expensive Disk (SLED) technology.

IBM 9345

Introduced in November 1990 as a Request Price Quotation (RPQ) within IBM's SuperComputing Systems Extensions (SCSE), the IBM 9345 hard disk drive was engineered at IBM’s San Jose facility under the project name Sawmill. This full-height 5¼-inch drive, utilizing eight 130 mm platters, offered storage capacities up to 1.5 GB. Notably, it was the first HDD to incorporate Magnetoresistive (MR) head technology.

IBM 9340

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

From a functional standpoint, the 9340/9345 series paralleled the capabilities of the 3990/3390 drives but did not include the non-volatile RAM cache found in the 3990 and supported a shorter maximum block length compared to the 3390.

The operating system’s Input/Output Supervisor (IOS) identified this device through a dedicated initializer named IECCINIT, which also handled other DASD models. During system initialization, it was recognized that the 9340 lacked non-volatile cache and that the 9345 had fewer tracks per surface, resulting in assignment of a device type distinct from that of the 3990/3390 series.

9330 family of disk drives

  1. The 9331 Diskette Unit came in models 1 and 11 with one 8-inch floppy disk drive, while models 2 and 12 contained one 5¼-inch floppy disk drive.
  2. The IBM 0667 hard disk was utilized by the 9332 Direct Access Storage Device.
  3. The High Performance Disk Drive Subsystem, modelled as the 9333, employed either IBM 0664 or IBM 0681 hard disks depending on configuration.
  4. The 9334 Disk Expansion Unit allowed connection of one to four SCSI hard drives to RS/6000 systems.
  5. Featuring an IBM-designed "Kestrel" hard drive with an 850 MB capacity, three large 14-inch platters, and dual rotary actuators accessing multiple surfaces, the 9335 Direct Access Storage Subsystem was announced in October 1986 alongside the IBM 9370 Information System. It was designed for rack mounting and had no known OEM adaptations.
  6. The IBM 0681 hard drive (Redwing) powered the operation of the 9336 Disk Unit.
  7. The Disk Array Subsystem designated as model 9337 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 and was introduced to the IBM 1130 line in 1965, likely shipping first with the latter towards late that year. It stored a total of 512,000 sixteen-bit words (equivalent to just over one million bytes) on an IBM 2315 cartridge—a single aluminum disk coated with oxide measuring fourteen inches housed within a plastic enclosure accessible by a read/write arm.

IBM 5444

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

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

IBM 62GV

First released in May of 1974, the IBM 62GV originated from IBM’s Hursley lab under its project name Gulliver and initially provided five megabytes of storage capacity. Subsequent versions expanded this to ten megabytes (designated as model 62TM) and fourteen megabytes respectively. Its design incorporated a Swinging Arm actuator paired with a single fourteen-inch platter. This actuator mechanism—conceived at Hursley—became IBM’s most extensively licensed electromechanical innovation and saw widespread adoption throughout hard disk drives worldwide over ensuing decades. Approximately one hundred seventy-seven thousand units of the IBM 62GV were sold, marking it as the first HDD model to surpass sales of one hundred thousand units.

OEM and Small Systems Hard Drives

This segment details IBM-produced hard disk drives marketed as OEM components and for IBM’s smaller computing platforms such as the System/3, System/32, /34, /36, and AS/400 series. Drives are cataloged by their OEM model designations and organized by their initial shipment dates.

IBM 0680

Introduced in 1979, the 0680 was deployed across many IBM small systems and entry-level System/370 models as the 3310 direct access storage device. Officially announced under the 0680 designation in September 1981, it was engineered at IBM Hursley in the UK (internally called Piccolo), featuring a maximum capacity of 65MB through six 8-inch platters and an enhanced rotary actuator mechanism.

A higher-capacity variant known as the 62SW appeared in June 1984 but experienced limited sales due to its price per megabyte being comparable to the 62GV model.

IBM 0676

The 0676 emerged in November 1982 as a Disk Storage Unit 5247 for the IBM System/23 Datamaster. Developed at IBM Rochester, Minnesota (code-named 21ED), this 8-inch HDD initially offered storage options of either 15 or 30MB utilizing two or four platters. By 1983, it was incorporated into the S/36’s 5360 System Unit; its capacity was doubled in 1984 by increasing the track density per surface for the subsequent 5362 System Unit.

IBM 0665

Released in October 1985 within the PC AT (5170) chassis, the 0665 was a 5¼-inch hard disk developed at IBM Rochester (code-named "Pixie"). It provided storage choices of 20, 30, and 44MB.

IBM 0667

The 0667 became available starting August 1986. Created at IBM Rochester (code-named "Grant"), this full-height ESDI HDD measured 5¼ inches and supported up to four platters with a total capacity of 70MB. It was offered as an optional drive for specific PC RT models (6150, 6151, 6152) and System/36 Model System Units (5363, 5364).

IBM 0669

Introduced in 1987 and developed at IBM Rochester under the code name "Grant-Prime," the 0669 was a full-height hard drive with a form factor of five inches. It utilized four platters measuring 130 mm each to deliver up to 115 MB of storage. This drive served as the internal storage solution for System/36 model 5363 and Series 1 model 4956 System Units.

IBM 0671

Also launched in 1987, the 0671 was developed at IBM Rochester with the code name "Lee." This full-height five-inch ESDI HDD supported up to eight platters of 130 mm diameter, reaching capacities as high as 316 MB. Notably, it represented IBM’s initial implementation of thin metal film technology for recording surfaces. By 1988, it was integrated into the AS/400's 9404 System Unit, capable of housing two or three drives.

IBM 0661

The 0661, first shipped in 1989 as model number 371, originated from collaborative development efforts at IBM Rochester and Hursley. This SCSI HDD featured eight platters measuring 95 mm each with fourteen read/write heads and provided a capacity of approximately 320 MB. A subsequent "Turbo" version delivering up to 400 MB followed in 1990. The drive became a standard component across multiple IBM platforms including the AS/400 System Unit Model CXX.

IBM 0681

Debuting in April of 1990, the 0681 was produced at IBM Hursley under the project name Redwing—the final hard disk from that facility. It offered a full-height five-inch form factor with twelve platters sized at 130 mm each and reached capacities up to approximately 857 MB. This model introduced PRML (Partial Response Maximum Likelihood) data decoding technology. It powered the IBM 9333 Disk Drive Subsystem released in early 1992, which later saw an upgraded version boasting a higher density of around 1.07 GB added that May.

IBM 0663

Launched toward the end of 1991 and internally called "Corsair," the 0663 was a compact hard disk measuring three inches with a half-height profile of approximately 1.6 inches. It could store up to one gigabyte across eight platters each measuring ninety-five millimeters. This drive appeared in select PS/2 and RS/6000 systems and represented IBM’s first OEM product employing Magnetoresistive (MR) head technology.

IBM 0664

Released in November 1992, the 0664 was developed under the codename "Allicat" at IBM's Rochester facility in Minnesota. This full-height 5-inch hard disk drive, measuring 3.25 inches in height, combined two 3-inch drives and featured a maximum capacity of 2.013 GB distributed across up to eight 95 mm platters.

IBM 0662

The 0662 became available in June 1993 and was created as "Spitfire" at IBM Rochester. It was a full-height (1-inch tall) 3-inch hard disk drive offering 1.05 GB storage on three platters or five recording surfaces. This model was utilized internally within the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM was a trailblazer in floppy disk technology, launching the 8-inch floppy disk drive in 1971 primarily as a read-only program loading device, followed by its first read/write floppy disk drive in 1973 with the introduction of the 3740 Data Entry System. Although IBM established initial standards for 8-inch floppy drives, it refrained from selling these drives separately, allowing the broader market to develop independently.

At one point, IBM was the largest original equipment manufacturer (OEM) buyer of 5-inch floppy disk drives, and its preference for two-sided drives with 48 tracks per inch helped solidify this configuration as the industry norm. Despite planning to produce smaller form factors, IBM abandoned these initiatives by 1985. Notably, its attempt in 1983 to OEM a 4-inch DemiDiskette did not succeed.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division introduced three distinct hard disk drive product lines: the Travelstar series featuring 2-inch drives for notebook computers, the Deskstar series with 3-inch drives intended for desktop systems, and the Ultrastar line of 3-inch drives designed for high-performance computing environments.

IBM's first HDD compared to its final HDD models

The table below contrasts IBM’s inaugural hard disk drive, the RAMAC 350, with the last three models from its "Star" series of OEM hard drives. It demonstrates remarkable advancements including substantial reductions in physical size and cost alongside dramatic enhancements in storage capacity and operational efficiency.

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 (gigabytes) 0.004 146 180 80 48,000-fold
Dimensions (inches) 60×68×29 4×1×5.75 4×1×5.75 2.75×0.38×3.95
Dimensions (millimeters) 1500×1700×700 102×25×146 102×25×146 70×9.5×100
Volume (cubic inches) 118,320 23 23 4 29,161-fold
Volume (liters) 1,939 0.4 0.4 0.1
Weight (pounds) 2,140 1.7 1.4 0.2 1,244-fold reduction
Weight (kilograms) 971 0.8 0.64 0.095
Power consumption (watts) 8100 BTUs/hour (2374 watts), varies up to 5500 VA depending on model 16 10.3 1.85 1,283-fold improvement
Power efficiency (megabytes per watt) 0.0016 9,125 17,476 43,243 \+27 million times
Areal density (megabits per square inch) 0.002 26,263 46,300 70,000
Areal density (kilobits per square millimeter) 0.003 40,708 71,765 108,500
Volumetric density (gigabytes per cubic inch) 0.00000003 6 8 20
Volumetric density (megabytes per cubic centimeter) 0.000002 388 478 1,203
Average rotational latency (milliseconds) 25 3 4 7
Average seek time (milliseconds) 600 5.9 10.2 12
Data transfer rate (megabytes per second) 0.001 103 29.4 43.75


DASD Devices Distinct from HDDs and FDDs

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

IBM 7320 Drum

The IBM 7320 represents a magnetic drum storage apparatus that IBM introduced in 1962.

IBM 2301 Drum

Debuting in the late 1960s, the IBM 2301 is another type of magnetic drum storage device.

IBM 2303 Drum

The IBM 2303, which became available in 1964, is also a magnetic drum-based storage unit.

IBM 2321 Data Cell

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

IBM 3850 Mass Storage System

Introduced in 1974, the IBM 3850 Mass Storage System functions as a tape cartridge library that stages data onto IBM 3330 or IBM 3350 disk drives, thereby emulating virtual disk drives for the host system.

See also

External links

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