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IBM 3310

From Alfawiki
IBM
IndustryComputer hardware, data storage
FoundedJune 16, 1911; 115 years ago (1911-06-16)
Headquarters
Armonk, New York
,
United States
ProductsHard disk drives, floppy disk drives, computer hardware
Websitewww.ibm.com

IBM was a pioneer in manufacturing magnetic disk storage devices from 1956 until 2003, at which point 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 its engineers. 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 similar criteria since the 1950s. Over time, the industry has witnessed dramatic decreases in both cost and physical dimensions, alongside substantial improvements in capacity and speed.

Between 1969 and the mid-1980s, IBM manufactured 8-inch floppy disk drives but did not emerge as a leading producer of the smaller 5.25- or 3.5-inch variants. While IBM sold its magnetic disk drives directly, it only began offering them under original equipment manufacturer (OEM) agreements starting in 1981. By 1996, IBM discontinued producing hard disk drives solely for its proprietary systems, instead marketing all HDDs through OEM channels.

IBM has used multiple designations for its magnetic disk products, including direct-access storage device (DASD), disk file, and diskette file. For clarity, this article adopts the widely accepted industry terms hard disk drive (HDD) and floppy disk drive (FDD).

IBM 350

The IBM 350 disk storage unit marked the advent of the first commercial disk drive and was unveiled on September 14, 1956, as part of the IBM 305 RAMAC computer system. A related model, the IBM 355, was introduced for use with the IBM 650 RAMAC system. The initial engineering prototype was delivered to Zellerbach Paper Company in June 1956, with production units shipped beginning November 1957 to clients such as United Airlines.

Engineered to support real-time business accounting applications, the IBM 350 offered a storage capacity of five million 6-bit characters (equivalent to 3.75 MB). It incorporated fifty-two disks measuring 24 inches in diameter, utilizing one hundred recording surfaces spinning at a speed of 1200 rpm. The data transfer rate reached 8,800 characters per second. Its access mechanism allowed vertical and horizontal movement of read/write heads to select specific disks and tracks. Several enhanced versions were released throughout the late 1950s. The IBM RAMAC 305 system bundled with the IBM 350 was leased at $3,200 per month. Production of the IBM 350 ceased in 1969.

The patent US3503060 originating from the RAMAC project is recognized as foundational to disk drive technology. Despite initial cancellation by IBM’s Board over fears it would undermine their punch card business, development persisted following approval from IBM’s president.

The cabinet housing the IBM 350 measured approximately 60 inches in length, stood 68 inches tall, and was 29 inches deep. Weighing close to one ton, transportation required forklifts and large cargo aircraft. According to Currie Munce of Hitachi Global Storage Technologies—which acquired IBM’s storage division—the capacity could have been expanded beyond five million characters; however, IBM’s marketing team was reluctant to promote higher-capacity units. Nevertheless, models with double that capacity were announced in January 1959 and shipped later that year.

In recognition of its engineering significance, the RAMAC 350 Disk File was declared an International Historic Landmark by The American Society of Mechanical Engineers in 1984. In 2002, a restoration initiative led by Al Hoagland commenced work on an IBM 350 RAMAC unit in collaboration with Santa Clara University. This restoration effort transitioned to the Computer History Museum in 2005, where the device is currently exhibited publicly within the Revolution gallery.

IBM 353

The IBM 353, deployed with the IBM 7030, resembled the IBM 1301 but offered a higher data transfer speed. It provided storage for 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 was notable as the first disk drive employing one head per surface that floated on compressed air, similar to the IBM 350 disk storage (RAMAC). Production versions utilized self-levitating heads comparable to those found in the IBM 1301.

IBM 355

Introduced on September 14, 1956, the IBM 355 served as an expansion for the widely used IBM 650. It incorporated the IBM 350 mechanism but featured up to three access arms instead of a single one and stored six million decimal digits plus an additional 600,000 sign characters. This device transferred entire tracks between its magnetic storage and the core memory of the 653—an optional unit for the IBM 650 that held sixty signed 10-digit words, enough to contain a single disk track or tape record.

IBM 1405

Launched in 1961 for the IBM 1400 family of mid-range business computers, the IBM 1405 Disk Storage Unit was available in two variants. Model 1 had a capacity of ten million alphanumeric characters (60 million bits) distributed across 25 disks; Model 2 doubled this capacity to twenty million characters (120 million bits) using fifty disks. The disks were arranged vertically and rotated at a speed of 1200 rpm.

Each disk surface contained 200 tracks segmented into five sectors. Sectors numbered from 0 to 4 were located on the top sides, while numbers 5 to 9 appeared on the bottom sides. Sector capacity ranged between 178 and 200 characters. Between one and three fork-shaped 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). Reading or writing a sector took approximately ten milliseconds.

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

IBM 7300

The IBM 7300 Disk Storage Unit was engineered for use with the IBM 7070, with a second model announced in 1959. Nevertheless, after IBM released the 1301 on June 5, 1961, it became a more appealing choice for customers using the IBM 7070 and IBM 7074 systems. The technology behind the IBM 7300 shared similarities with that of the IBM 350, IBM 355, and IBM 1405 units.

IBM 1301

Unveiled on June 2, 1961, the IBM 1301 Disk Storage Unit was designed to support the 7000 series mainframe computers as well as the IBM 1410. Each module stored twenty-eight million characters (168 million bits), with a slightly lower capacity of twenty-five million characters for the IBM 1410. Every module contained twenty-five large disks featuring forty user-accessible recording surfaces and two hundred fifty tracks per surface. The Model 1 consisted of one module; Model 2 stacked two modules vertically. Disks revolved at a speed of eighteen hundred rpm, enabling data transfer rates up to ninety thousand characters per second.

A significant advancement was the implementation of an independent arm and read-write head assembly for each recording surface, moving simultaneously like a comb. This design minimized seek time by removing delays caused by repositioning heads and enhanced access speeds, reducing maximum access time to one hundred eighty milliseconds.

The IBM 1301 was also pioneering in its use of aerodynamically shaped heads that floated on a thin air cushion above disk surfaces, improving performance substantially.

Connection was facilitated through the IBM 7631 File Control unit, which allowed integration with either an IBM 1410 or a system from the IBM 7000 series or enabled sharing between two computers.

Leasing charges for Model 1 were $2,100 monthly or $115,500 for outright purchase; Model 2 leased at $3,500 per month or could be bought for $185,000. The IBM 7631 controller added $1,185 monthly lease fees or a $56,000 purchase price. All models were discontinued by the year 1970.

IBM 1302

Introduced 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 was equipped with two separate access mechanisms dedicated to the inner and outer cylinders. A Model 2 variant expanded capacity by stacking two such modules. Leasing fees 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 incurred additional costs of $1,185 monthly or a purchase price of $56,000. The IBM 1302 was discontinued in February 1965.

IBM 1311

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

Each IBM 1316 disk pack measures approximately four inches in height and weighs around ten pounds. It contains six disks measuring fourteen inches in diameter, providing ten recording surfaces—excluding the unused outer surfaces. A hydraulic actuator moves ten read/write heads simultaneously across the tracks while the disks rotate at 1,500 revolutions per minute. Each surface includes one hundred tracks with twenty sectors per track; each sector holds one hundred characters. The disk pack is enclosed within a transparent plastic casing featuring a locking handle to ensure secure installation and removal.

The seven IBM 1311 models are as follows:

  1. Master drive designed for IBM 1440, 1460, or 1240 systems; capable of controlling up to four Model 2 drives (1962–1971).
  2. Slave drive compatible with master drive features (1962–1975).
  3. Master drive for IBM 1620 or 1710 systems managing up to three Model 2 drives (1962–1971).
  4. Master drive intended for IBM 1401 systems controlling up to four Model 2 drives (1962–1971).
  5. Master drive compatible with IBM 1410, 7010, or 7740 systems controlling four Model 2 drives; equipped with standard Direct Seek capability (1963–1971).
  6. and #7 Presumed master and slave drives introduced in March 1968 and retired by February 1971.

Available optional enhancements included:

  • Direct Seek: Removes the need to return to zero before initiating a seek operation.
  • Scan Disk: Enables automated rapid searches based on identifiers or specific conditions.
  • Seek Overlap: Permits simultaneous seeks and read/write operations across multiple drives.
  • Track Record: Increases storage capacity by writing a single large record per track instead of multiple sectors; this raises total storage to roughly 17.9 million bits in Move Mode and nearly 18.8 million bits in Load Mode.

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

IBM 2302

The IBM 2302 represents the System/360 adaptation of the 1302, formatted specifically for S/360 DASD architecture. It employs a fixed module composed of twenty-five platters providing forty-six recording surfaces. The Model 3 configuration includes one such module; the Model 4 houses two modules. Each module features two independent access mechanisms—designated access groups—serving the innermost and outermost sets of 250 cylinders respectively. Each mechanism supports one read/write head per track. Rotational latency averages seventeen milliseconds with a maximum of thirty-four milliseconds; maximum seek time per access group is capped at one hundred eighty milliseconds. Tracks hold up to 4,985 bytes each, resulting in a total module capacity of approximately 112 megabytes. Connection to IBM mainframes is facilitated through the IBM 2841 Storage Control Unit.

IBM 2305

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

With the advent of Virtual Storage on System/370, the 2305 became highly sought after, frequently utilized as a paging storage unit on platforms such as the 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (the latter employing specialized microcode). Additionally, it served efficiently for high-transaction small data sets including catalogs and job queues.

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

Engineered for rapid and continuous access to modest-sized data volumes, the 2305's combination of capacity and speed made it well-suited for system-resident files, work files, job queues, indices, and frequently accessed datasets. Its swift response times rendered it particularly effective as a paging device in systems experiencing transaction rates exceeding 1.5 per second.

IBM 2311

The IBM 2311 Disk Storage Drive was introduced in 1964 alongside the 2841 Control Unit, designed for deployment across the IBM System/360 family and compatible with the IBM 1130 and IBM 1800 systems. It connects directly to the IBM System/360 Model 20 and Model 25. All units utilize removable IBM 1316 Disk Packs, which were initially launched with the IBM 1311.

The Model 1 version of the 2311 connects to most IBM mainframes through the 2841 Control Unit, while on the System/360 Model 25 it interfaces via a Disk Attachment Control offering comparable capabilities. The disk packs employ IBM's count key data variable-length record format.

Models 11 and 12, integrated with System/360 Model 20’s control unit, utilize a fixed sector formatting scheme. Due to these format differences, disk packs are not interchangeable between Model 1 drives and Models 11 or 12.

Although mechanically akin to the IBM 1311, the IBM 2311 features enhanced recording technology that supports higher data density. Each removable IBM 1316 disk pack holds up to 7.25 megabytes across six platters spinning as a single assembly. The drive contains ten read/write heads mounted on a hydraulically actuated arm that locks onto tracks prior to operation. Each platter surface accommodates up to 200 tracks plus three spare tracks reserved for defects. The average seek time is approximately 85 milliseconds with a data transfer rate of around 156 kB/s.

Its standardized electrical interfaces ensured compatibility across multiple IBM platforms and encouraged third-party manufacturers to develop plug-compatible disk drives, fostering a competitive market for IBM-compatible storage devices.

IBM 2314 Disk Access Storage Facility Model 1

Released in April 1965, the IBM 2314 Disk Access Storage Facility Model 1 was designed for use with both System/360 and System/370 systems. Featuring a Two Channel Switch capability, it allowed simultaneous connections to two system channels. While its disk mechanism resembled that of the IBM 2311, it offered increased data density and faster transfer speeds.

This drive stored roughly twenty-nine million characters on a removable IBM 2316 disk pack that expanded from six to eleven platters compared to its predecessor. The eleven disks measured in diameter and provided twenty recording surfaces accessed by twenty individual read/write heads mounted on a hydraulically actuated arm; each surface contained up to two hundred tracks. Initial access times matched those of the IBM 2311 but were improved in later iterations through actuator enhancements. Data transfer rates doubled to approximately 310 kB/s.

The original Model 1 configuration included nine disk drives sold as one package; components shipped separately included a storage control unit, one single-drive module, and two four-drive modules totaling nine drives altogether. Drives were installed in drawers facilitating easy disk pack replacement and earned the nickname "Pizza Ovens." Only eight drives operated concurrently while the ninth remained offline as a spare to enable maintenance without interrupting operations. Drive system addresses were configurable via user-swappable plugs allowing flexible assignment including designation of spares.

By adding a 2844 Control Unit, two System/360 channels could simultaneously access different drives within this facility.

Subsequent versions of the IBM 2314 built upon this initial design:

IBM 2314 Direct Access Storage System - Model Variants

In 1969, IBM segmented the storage system into distinct models, permitting up to nine drives (with eight accessible online) to be connected to a 2314 Storage Control. These included:

  • 2312 Disk Storage, featuring a single-drive unit.
  • 2313 Disk Storage, comprising four drives in one module.
  • 2318 Disk Storage, containing two drives per module.

IBM 2319

To challenge competitors offering plug-compatible alternatives to the 2314 series, IBM launched the cost-effective three-drive 2319 module in 1970. This was essentially a 2313 with one drive removed, rebranded as the 2319 A1 and provided at significantly lower leasing costs. This approach reduced expenses for new clients while preserving premium rental fees for existing users. The 2319-A1 interfaces exclusively with integrated controllers on System/370 Models 135 and 145; it is also compatible with traditional 2314 DASD devices like the 2312 and 2318. The 2319 B series expanded options by supporting configurations of three, six, or nine drives connected to a newly introduced 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. It supported DOS/VSE and VM operating systems—the only S/370 OS variants compatible with FBA devices.

IBM 3330

The IBM 3330 Direct Access Storage Facility, also known by its codename Merlin, debuted in June 1970 targeting IBM System/370 and System/360/195 platforms. The initial offerings were the two-drive Model 1 and the single-drive Model 2. Each removable disk pack stored 100 MB, with an access latency of approximately 30 milliseconds and a data transfer speed of 806 kB/s. A significant innovation was built-in error correction employing fire codes, which improved reliability and reduced costs by allowing tolerance for imperfections on disk surfaces.

Originally, one storage control unit (3830 Model 1) managed up to four drives in a chain (maximum eight drives per chain). In August 1972, IBM introduced the 3830 Model 2 Storage Control alongside the 3333 Disk Storage and Control, which separated control functions from the drives themselves. The 3830 Model 2 functioned as a director-style controller overseeing multiple chains; at the head of each chain was the 3333 unit combining a controller with two drives and capable of managing up to three attached IBM 3330 units (totaling eight drives). Two such 3333 units could be linked to a single controller for a maximum of sixteen drives, with optional string switches allowing connections to dual controllers.

In 1973, IBM rolled out double-density (-11) variants—3333–11, 3330-11, and 3336–11—that doubled disk pack capacity to 200 MB. Mixing standard and double-density drives within the same chain was unsupported. Upgrading from original models to Model-11 versions was feasible in the field but involved substantial drive modifications and data transfers.

The IBM 3330 series was discontinued in 1983.

IBM 3340 and IBM 3344

While sharing many characteristics, the IBM 3340 and IBM 3344 differ in that only the 3340 can serve as the head of string; no A model exists for the IBM 3344, which must connect to a head-of-string IBM 3340 A model unit.

IBM 3340

Introduced in March 1973 for the IBM System/370, the IBM 3340 Direct Access Storage Facility was internally known as Winchester. The product lineup included three variants: the 3340-A2 featuring two drives and a controller, along with the B2 (two drives) and B1 (single drive) models. The B-series units could be connected to an A2 controller, supporting up to eight drives in total.

This system utilized removable data modules that incorporated both the head and arm assembly; during mechanical load and unload operations, the module’s access door opened to engage with the drive, eliminating the need to remove protective covers as was necessary with previous disk pack designs. It delivered an average access time of 25 milliseconds and a data transfer rate of 885 kB/s. The IBM 3348 Data Modules came in three versions: one with a 35 MB capacity and two with 70 MB, one of which included a 500 KB segment accessible through fixed heads for quicker data retrieval. The 3340 featured built-in error correction capabilities and remained in production until its withdrawal in 1984.

Developed under Ken Haughton at IBM’s San Jose facility, the design initially targeted two removable modules each holding 30 MB—hence the nickname Winchester, inspired by the Winchester .30-30 rifle. Although storage capacities increased over time, the codename endured.

A major breakthrough was its cost-effective head design that allowed heads to remain on the media without unloading. This "Winchester technology" enabled heads to land on and lift off from spinning disks, dramatically simplifying head and arm mechanisms while reducing manufacturing expenses. This approach set a precedent widely adopted across disk drive production.

The term Winchester or Winnie remained popular as a descriptor for hard disk drives into the early 1990s but has since become less common.

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 accommodates four logical drives, each offering capacity equivalent to that of a 3348–70 module. The system is available exclusively as dual-drive models, without an A-series (head-of-string) variant. The 3344-B2F version includes fixed heads covering certain cylinders on both drives. Both the 3344-B2 and 3344-B2F require connection to a 3340-A2 or 3340-A2F as head of string. Internally, the IBM 3344 shares its architecture with the IBM 3350; distinctions arise solely from differences in control unit microcode.

IBM 3350

Released in 1975 for IBM System/370 platforms, the IBM 3350 Direct Access Storage Facility bore the codename Madrid. It introduced sealed, non-removable head-disk assemblies (HDAs) that combined the head and arm assembly into a single unit—an approach that became standard for IBM DASD products thereafter. Each HDA contained 555 cylinders with 30 heads per cylinder and stored approximately 19,069 bytes per track, resulting in roughly 317 MB of total storage capacity.

Available models included A2, A2F, B2, B2F, C2, and C2F; each configuration housed two HDAs. The A2 and A2F versions incorporated an additional electronics board facilitating connection to control units—commonly referred to as controllers or head-of-string units—which could be arranged in various string configurations such as -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC-. Typically, A2 models featured a string switch enabling dual attachment to storage control units like the IBM 3830 Model 2 or integrated storage controllers within CPUs such as the IBM 3148. Subsequent controllers (e.g., model 3880) maintained backward compatibility with these arrangements. The C2 models included secondary controllers designed to provide failover capabilities but supported limited connectivity options.

The "x2F" variants incorporated fixed head zones spanning the first five cylinders on each HDA, effectively eliminating seek time within this region. This enhancement improved performance for frequently accessed checkpoint areas used by HASP or JES2 spooling systems and optimized swap data handling in TSO and MVS environments by minimizing head movement and accelerating context switches.

Production of the IBM 3350 line ceased in September 1994.

IBM 3370

In January 1979, IBM introduced the IBM 3370 Direct Access Storage Device, designed for use with IBM 4331, 4341, and System/38 midrange systems. This unit contained seven fixed 14-inch platters, delivering a storage capacity of 571 MB per device. It was notable for being 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 environments.

IBM 3375

The IBM 3375 served as a complementary model employing count key data architecture, which was necessary for operating systems such as OS/360 and its successors.

IBM 3380

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

The typical setup included one A unit paired with up to three B units; every IBM 3380 contained four devices, allowing a maximum of sixteen devices on a single string. These were generally connected to a 3880 storage control unit via dual paths, enabling two simultaneous I/O operations directed at separate hard disk assemblies.

In February 1985, IBM introduced the Extended Capability Model (3380 E) featuring double density and doubling capacity to 5.04 GB per unit—comprised of two actuators with 1.26 GB each on two assemblies.

By August 1987, the triple-capacity variant named the 3380 K was launched, offering 7.562 GB per unit with two actuators of 1.89 GB each. Models K and J provided an optional four-path mode that supported up to thirty-two devices per string when linked to a 3990 storage control unit, allowing four concurrent I/O processes.

The IBM 3380 series consisted of twelve models: six A-units (which acted as string heads with additional logic for connection to storage control units), five B-units (which attached to A- or C-units), and one C-unit (which connected directly to an IBM channel).

Manufacturing continued until May 1996, giving the IBM 3380 an unusually long market tenure spanning fifteen years—well beyond typical disk drive lifespans.

IBM 3390

Launched in November 1989, the IBM 3390 Direct Access Storage Device family offered capacities up to twenty-two gigabytes across multiple drives. Pricing for complete systems varied from $90,000 to $795,000 depending on configuration and storage size.

A typical IBM 3390 string includes a central A unit housing four or eight devices, optionally accompanied by one or two B units containing as many as twelve devices each. Operating in four-path mode and connected to a 3990 storage control unit, this arrangement could be expanded by adding a second string for a total of sixty-four devices per subsystem.

The Hard Disk Assemblies (HDAs) feature dual actuator-head mechanisms along with platters: Model 1 provided an unformatted capacity of 1.89 GB per HDA; Model 2 doubled this to 3.78 GB per HDA. The Model 3 upgrade released in 1991 increased capacity further to 5.67 GB per HDA, while the Model 9 introduced in 1993 tripled it again to reach 11.3 GB per HDA.

Unlike previous DASD designs that employed belt-driven AC motors, the IBM 3390 HDAs utilized directly driven DC motors enclosed within the device casing. The Model 9 marked IBM's final single large expensive disk (SLED) drive offering.

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 drive accommodated up to eight 130 mm platters, delivering a maximum storage capacity of 1.5 GB. It was distinguished as the first HDD to utilize Magnetoresistive (MR) read/write heads.

IBM 9340

In October 1991, IBM launched the 9345 DASD within the 9340 family—a channel-attached count key data (CKD) DASD subsystem compatible with IBM mainframe systems such as the ES/9000 series. The 9345 Model 1 contained two HDDs each with 1.0 GB capacity, whereas Model 2 comprised two drives each offering 1.5 GB.

From a functional standpoint, the 9340/9345 subsystems paralleled the performance of IBM’s 3990/3390 series but did not include the non-volatile RAM cache found in the 3990, and offered a shorter maximum block length compared to the 3390.

The Input/Output Supervisor (IOS) in the operating system identified these devices using a specialized initializer named IECCINIT, which also handled other DASD types. During initialization, IOS detected that the 9340 lacked non-volatile caching and that the 9345 had reduced track capacity, assigning device types distinct from those of the 3990 and 3390 accordingly.

9330 family of disk drives

  1. Models 1 and 11 of the 9331 Diskette Unit incorporated a single 8-inch floppy disk drive (FDD), while models 2 and 12 featured one 5¼-inch FDD.
  2. The IBM 0667 HDD powered the 9332 Direct Access Storage Device.
  3. The high-performance subsystem, modelled as the 9333, utilized either IBM 0664 or IBM 0681 hard drives depending on configuration.
  4. The 9334 Disk Expansion Unit provided connectivity for one to four SCSI hard disks to RS/6000 systems.
  5. The IBM-developed "Kestrel" HDD—an innovative unit with three large (14-inch) platters and dual rotary actuators enabling access to multiple surfaces—was employed in the rack-mountable 9335 Direct Access Storage Subsystem. Announced in October 1986 alongside the IBM 9370 Information System, this drive offered an 850 MB capacity and had no known OEM counterparts.
  6. The IBM 0681 HDD (Redwing) was used in the 9336 Disk Unit.
  7. The disk array subsystem, modelled as the 9337, incorporated either IBM’s 0662 (Spitfire) or 0663 (Corsair) hard drives.

IBM 2310

Introduced in conjunction with the IBM 1800 in 1964 and later with the IBM 1130 in 1965—most likely first shipping with the latter in late ’65—the IBM 2310 Removable Cartridge Drive stored data on an IBM 2315 cartridge. This cartridge contained a single oxide-coated aluminum platter encased within a plastic shell and was accessible by two read/write heads. Its storage capacity was approximately 512,000 words of sixteen bits each (equivalent to about one megabyte).

IBM 5444

The IBM 5444, launched in September of 1969 alongside System/3, was engineered at IBM’s Hursley laboratory in England under the codename Dolphin. It utilized a single-disk cartridge—the IBM 5440—which housed a fourteen-inch platter. Three variants were available:

  • Model 1: featured one fixed and one removable disk, each having one hundred tracks per surface; cartridge capacity reached approximately 1.23 MB
  • Model 2: included one fixed and one removable disk with two hundred tracks per surface; cartridge capacity was about 2.46 MB
  • Model 3: consisted solely of one removable disk offering two hundred tracks per surface; cartridge capacity also measured around 2.46 MB

IBM 62GV

The IBM 62GV, introduced in May 1974 from IBM's Hursley facility (internally named Gulliver), initially provided a storage capacity of 5 MB. Subsequent variants, including the 62TM, expanded storage up to 10 MB and 14 MB. It incorporated a Swinging Arm actuator paired with a single 14-inch platter. This actuator mechanism, engineered at Hursley, became IBM's most widely licensed electro-mechanical innovation and established a global benchmark for hard disk drives. Throughout its manufacturing run, roughly 177,000 units of the IBM 62GV were delivered, making it the first HDD model to surpass 100,000 units sold.

OEM and Small Systems HDDs

This segment covers IBM-produced hard drives marketed as OEM offerings and for IBM’s smaller system lines such as System/3, System/32, /34, /36, and AS/400. Drives are referenced by their OEM model designations and organized by their initial shipment dates to customers.

IBM 0680

Introduced in 1979 across many IBM small systems and entry-level System/370 configurations as the 3310 direct access storage device, the 0680 was formally announced as an OEM model in September 1981. Developed at IBM’s Hursley lab in the UK under the codename Piccolo, it initially supported capacities up to 65 MB through six 8-inch (210 mm) platters utilizing an enhanced rotary actuator.

A higher-capacity iteration, the 62SW, was released in June 1984 but experienced limited market adoption due to pricing competition with the 62GV.

IBM 0676

The 0676 made its debut in November 1982 as part of the IBM System/23 Datamaster’s 5247 Disk Storage Unit. Created at IBM Rochester, Minnesota under the internal name 21ED, this 8-inch HDD offered starting capacities of either 15 or 30 MB via two or four 210 mm platters. By 1983, it was incorporated into the System/36’s 5360 System Unit. Its capacity was doubled in 1984 by increasing tracks per surface and later utilized in the System/36’s 5362 System Unit.

IBM 0665

Released in October 1985 within the PC AT (5170) chassis, the 0665 was developed at IBM Rochester under the codename "Pixie." This drive measured 5¼ inches and was available with storage options of 20, 30, or 44 MB.

IBM 0667

The 0667 arrived on the market in August 1986. Designed at IBM Rochester and known internally as "Grant," it was a full-height ESDI hard drive sized at 5¼ inches with capacities reaching up to 70 MB across as many as four 130 mm platters. This model was offered as an optional component for select PC RT models (6150, 6151, 6152) and System/36 Model System Units (5363, 5364).

IBM 0669

Shipped in 1987, the 0669 was developed at IBM Rochester under the codename "Grant-Prime." It featured a full-height form factor with a five-inch footprint and provided storage up to 115 MB using four 130 mm platters. This HDD served internally within System/36 Model 5363 and Series 1 Model 4956 System Units.

IBM 0671

The 0671, launched in 1987 and internally called "Lee" at IBM Rochester, was a full-height ESDI drive sized at five inches offering capacities up to 316 MB through up to eight platters measuring 130 mm each. This unit represented IBM's initial deployment of thin metal film recording technology. In 1988, it was integrated into the IBM AS/400 Model 9404 System Unit, supporting configurations of two or three drives.

IBM 0661

Introduced in 1989 as model 371, the 0661 was developed collaboratively under the codename "Lightning" at both IBM Rochester and Hursley labs. It was a SCSI HDD with eight platters measuring 95 mm each (equipped with fourteen heads), initially offering a capacity of 320 MB. A "Turbo" upgrade delivering up to 400 MB followed in 1990. This drive became a standard component within prominent IBM systems such as the AS/400 System Unit Model CXX.

IBM 0681

Released in April 1990 from IBM Hursley's laboratory under the project name "Redwing," the 0681 represented the final hard disk drive developed at that site. It featured a maximum capacity of 857 MB utilizing twelve 130 mm platters within a full-height 5-inch enclosure. Notably, it was the first HDD to implement PRML (Partial Response Maximum Likelihood) data decoding technology. This model was integral to the 9333 Disk Drive Subsystem introduced in early 1992, which subsequently offered an upgraded version with 1.07 GB storage.

IBM 0663

The 0663, known internally as "Corsair," debuted in late 1991 as a compact 3-inch hard drive standing only 1.6 inches tall (half-height). It provided up to 1 GB capacity spread over eight 95 mm platters. This drive was incorporated into select PS/2 and RS/6000 computer models and marked IBM's initial use of magnetoresistive (MR) heads in an OEM disk drive.

IBM 0664

Introduced in November 1992 and developed at IBM Rochester, Minnesota under the codename "Allicat," the 0664 was a full-height (3.25-inch tall) 5-inch hard disk drive. It combined two 3-inch drives to achieve a total capacity of up to 2.013 GB across eight 95 mm platters.

IBM 0662

The 0662, released in June 1993 and created under the name "Spitfire" at IBM Rochester, was a full-height (1 inch high) 3-inch HDD delivering 1.05 GB using three platters or five recording surfaces. It served as the internal storage solution for the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive

IBM pioneered floppy disk technology, launching the first 8-inch floppy disk drive in 1971 as a read-only program loader, followed by its initial read/write model in 1973 within the 3740 Data Entry System. Although IBM established early standards for the 8" FDD format, it never sold these drives independently, allowing industry-wide standards to evolve separately.

At one point, IBM was the largest original equipment manufacturer (OEM) buyer of 5-inch floppy drives. Its preference for two-sided drives with a density of 48 tracks per inch helped solidify this format as an industry benchmark. Despite plans to produce these and smaller form factors internally, IBM terminated all such manufacturing initiatives by 1985. Additionally, its attempt in 1983 to OEM the smaller 4-inch DemiDiskette was unsuccessful.

"Star" series of HDDs

On October 17, 1994, IBM's Storage Systems division unveiled three distinct hard drive product lines: the Travelstar series featuring compact 2-inch drives for laptops, the Deskstar line with 3-inch drives designed for desktop computers, and the Ultrastar series of high-performance 3-inch drives aimed at demanding systems.

IBM's first HDD versus its last HDDs

The following table contrasts IBM's inaugural hard disk drive, the RAMAC 350, with three final models from its "Star" series of OEM HDDs. This comparison underscores significant advancements in cost reduction and miniaturization alongside 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
Capacity (gigabytes) 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 (millimeters) 1500×1700×700 102×25×146 102×25×146 70×9.5×100
Volume (cubic inches) 118,320 23 23 4 ×29,161
Volume (liters) 1,939 0.4 0.4 0.1
Weight (pounds) 2,140 1.7 1.4 0.2 ×1,244
Weight (kilograms) 971 0.8 0.64 0.095
Power consumption (watts) Approximately 2374 watts (~8100 BTUs/hour), up to 5500 VA depending on configuration 16 10.3 1.85 ×1,283
Power efficiency (megabytes per watt) 0.0016 9,125 17,476 43,243 ×27,375,856
Price at launch (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 per square inch) 0.002 26,263 46,300 70,000 ×35,000,000
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 ×622,100,131
Volumetric density (megabytes per cubic centimeter) 0.000002 388 478 1,203
Average latency (milliseconds) 25 3 4 7 ×8
Average seek time (milliseconds) 600 5.9 10.2 12 >50× improvement
Data transfer rate (megabytes per second) 0.001 103 29.4 43.75 >11,700× increase


DASD Devices Beyond 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 technologies classified as DASDs include the following:

IBM 7320 Drum

Introduced in 1962, the IBM 7320 represents a magnetic drum storage unit developed by IBM.

IBM 2301 Drum

The IBM 2301, launched in the late 1960s, is another magnetic drum-based storage apparatus.

IBM 2303 Drum

Debuting in 1964, the IBM 2303 is a further example of IBM’s magnetic drum storage devices.

IBM 2321 Data Cell

The IBM 2321 Data Cell, revealed in 1964, employs short strips of magnetic tape for data retention. This system accommodates ten removable cells, each with a capacity of 40 MB, culminating in a total storage of 400 MB.

IBM 3850 Mass Storage System

Announced in 1974, the IBM 3850 Mass Storage System functions as a tape cartridge library. It stages data onto IBM 3330 or 3350 disk drives, which are then presented to the system as virtual disk drives.

See also

External links

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