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81-452: The Zip drive is a removable floppy disk storage system that was announced by Iomega in 1994 and began shipping in March 1995. Considered medium-to-high-capacity at the time of its release, Zip disks were originally launched with capacities of 100  MB , then 250 MB, and finally 750 MB. The format became the most popular of the superfloppy products which filled a niche in

162-684: A spindle that holds flat circular disks, called platters , which hold the recorded data. The platters are made from a non-magnetic material, usually aluminum alloy , glass , or ceramic . They are coated with a shallow layer of magnetic material typically 10–20 nm in depth, with an outer layer of carbon for protection. For reference, a standard piece of copy paper is 0.07–0.18 mm (70,000–180,000 nm) thick. The platters in contemporary HDDs are spun at speeds varying from 4200  rpm in energy-efficient portable devices, to 15,000 rpm for high-performance servers. The first HDDs spun at 1,200 rpm and, for many years, 3,600 rpm

243-408: A hard disk drive . A linear actuator uses the voice coil actuation technology related to modern hard disk drives. The original Zip drive has a maximum data transfer rate of about 1.4 MB/s (comparable to 8× CD-R; although some connection methods are slower, down to approximately 50 kB/s for maximum-compatibility parallel "nibble" mode) and a seek time of 28 ms on average, compared to

324-522: A stepper motor . Early hard disk drives wrote data at some constant bits per second, resulting in all tracks having the same amount of data per track, but modern drives (since the 1990s) use zone bit recording , increasing the write speed from inner to outer zone and thereby storing more data per track in the outer zones. In modern drives, the small size of the magnetic regions creates the danger that their magnetic state might be lost because of thermal effects ⁠ ⁠— thermally induced magnetic instability which

405-416: A "stopgap" technology between PMR and Seagate's intended successor heat-assisted magnetic recording (HAMR). SMR utilises overlapping tracks for increased data density, at the cost of design complexity and lower data access speeds (particularly write speeds and random access 4k speeds). By contrast, HGST (now part of Western Digital ) focused on developing ways to seal helium -filled drives instead of

486-582: A Field Generation Layer (FGL) and a Spin Injection Layer (SIL), and the FGL produces a magnetic field using spin-polarised electrons originating in the SIL, which is a form of spin torque energy. A typical HDD has two electric motors: a spindle motor that spins the disks and an actuator (motor) that positions the read/write head assembly across the spinning disks. The disk motor has an external rotor attached to

567-418: A bit cell comprising about 18 magnetic grains (11 by 1.6 grains). Since the mid-2000s, areal density progress has been challenged by a superparamagnetic trilemma involving grain size, grain magnetic strength and ability of the head to write. In order to maintain acceptable signal-to-noise, smaller grains are required; smaller grains may self-reverse ( electrothermal instability ) unless their magnetic strength

648-489: A breather port, unlike their air-filled counterparts. Other recording technologies are either under research or have been commercially implemented to increase areal density, including Seagate's heat-assisted magnetic recording (HAMR). HAMR requires a different architecture with redesigned media and read/write heads, new lasers, and new near-field optical transducers. HAMR is expected to ship commercially in late 2024, after technical issues delayed its introduction by more than

729-491: A capacity of 500 MB and cost around US$ 200 , and so backing up with Zip disks was very economical for home users—some computer suppliers such as Dell , Gateway and Apple Inc. included internal Zip drives in their machines. Zip drives also made significant inroads in the graphic arts market, as a cheaper alternative to the Syquest cartridge hard disk system. The price of additional cartridges swiftly dropped further over

810-449: A component of the IBM 305 RAMAC system. It was approximately the size of two large refrigerators and stored five million six-bit characters (3.75 megabytes ) on a stack of 52 disks (100 surfaces used). The 350 had a single arm with two read/write heads, one facing up and the other down, that moved both horizontally between a pair of adjacent platters and vertically from one pair of platters to

891-1087: A decade, from earlier projections as early as 2009. HAMR's planned successor, bit-patterned recording (BPR), has been removed from the roadmaps of Western Digital and Seagate. Western Digital's microwave-assisted magnetic recording (MAMR), also referred to as energy-assisted magnetic recording (EAMR), was sampled in 2020, with the first EAMR drive, the Ultrastar HC550, shipping in late 2020. Two-dimensional magnetic recording (TDMR) and "current perpendicular to plane" giant magnetoresistance (CPP/GMR) heads have appeared in research papers. Some drives have adopted dual independent actuator arms to increase read/write speeds and compete with SSDs. A 3D-actuated vacuum drive (3DHD) concept and 3D magnetic recording have been proposed. Depending upon assumptions on feasibility and timing of these technologies, Seagate forecasts that areal density will grow 20% per year during 2020–2034. The highest-capacity HDDs shipping commercially in 2024 are 32 TB. The capacity of

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972-641: A line of internal and external recordable CD drives under the Zip brand in the late 1990s, called the ZipCD 650. It used regular CD-R media and had no format relation to the magnetic Zip drive. The external models were installed in a Zip-drive-style case, and used standard USB 1.1 connections. Iomega used the DirectCD software from Adaptec to allow UDF drive-letter access to CD-R or CD-RW media. The company released an open standard CD-R drive and CD-RW media under

1053-485: A lower data-transfer rate due to lower rotational speed. The Zip drive was Iomega's third generation of products, different from Iomega's earlier Bernoulli Boxes in many ways, including the absence of the Bernoulli plate of the earlier products. Zip drives were produced in multiple interfaces including: Parallel port external Zip drives are actually SCSI drives with an integrated Parallel-to-SCSI controller, meaning

1134-475: A removable disk module, which included both the disk pack and the head assembly, leaving the actuator motor in the drive upon removal. Later "Winchester" drives abandoned the removable media concept and returned to non-removable platters. In 1974, IBM introduced the swinging arm actuator, made feasible because the Winchester recording heads function well when skewed to the recorded tracks. The simple design of

1215-538: A second set. Variants of the IBM 350 were the IBM 355 , IBM 7300 and IBM 1405 . In 1961, IBM announced, and in 1962 shipped, the IBM ;1301 disk storage unit, which superseded the IBM 350 and similar drives. The 1301 consisted of one (for Model 1) or two (for model 2) modules, each containing 25 platters, each platter about 1 ⁄ 8 -inch (3.2 mm) thick and 24 inches (610 mm) in diameter. While

1296-423: A sequential read or write operation, after the drive accesses all the sectors in a track, it repositions the head(s) to the next track. This will cause a momentary delay in the flow of data between the device and the computer. In contrast, optical audio and video discs use a single spiral track that starts at the innermost point on the disc and flows continuously to the outer edge. When reading or writing data, there

1377-570: A standard 1.44 MB floppy's effective ≈16 kB/s and ≈200 ms average seek time. Typical desktop hard disk drives from mid-to-late 1990s revolve at 5,400 rpm and have transfer rates from 3 MB/s to 10 MB/s or more, and average seek times from 20 ms to 14 ms or less. Early-generation Zip drives were in direct competition with the SuperDisk (LS-120) drives, which hold 20% more data and can also read standard 3 + 1 ⁄ 2 -inch 1.44 MB diskettes, but they have

1458-616: A swing arm drive, the IBM 0680 (Piccolo), with eight inch platters, exploring the possibility that smaller platters might offer advantages. Other eight inch drives followed, then 5 + 1 ⁄ 4  in (130 mm) drives, sized to replace the contemporary floppy disk drives . The latter were primarily intended for the then fledgling personal computer (PC) market. Over time, as recording densities were greatly increased, further reductions in disk diameter to 3.5" and 2.5" were found to be optimum. Powerful rare earth magnet materials became affordable during this period, and were complementary to

1539-423: A thin film of ferromagnetic material on both sides of a disk. Sequential changes in the direction of magnetization represent binary data bits . The data is read from the disk by detecting the transitions in magnetization. User data is encoded using an encoding scheme, such as run-length limited encoding, which determines how the data is represented by the magnetic transitions. A typical HDD design consists of

1620-499: A tiny fraction of the detected errors end up as not correctable. Examples of specified uncorrected bit read error rates include: Within a given manufacturers model the uncorrected bit error rate is typically the same regardless of capacity of the drive. The worst type of errors are silent data corruptions which are errors undetected by the disk firmware or the host operating system; some of these errors may be caused by hard disk drive malfunctions while others originate elsewhere in

1701-475: A true SCSI bus implementation but without the electrical buffering circuits necessary for connecting other external devices. Early Zip 100 drives use an AIC 7110 SCSI controller and later parallel drives (Zip Plus and Zip 250) used what was known as Iomega MatchMaker. The drives are identified by the operating system as "IMG VP0" and "IMG VP1" respectively. Early external SCSI-based Zip drives were packaged with an included SCSI adapter known as Zip Zoom. The Zip Zoom

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1782-730: A type of non-volatile storage , retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box . Hard disk drives were introduced by IBM in 1956, and were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers , though personal computing devices produced in large volume, like mobile phones and tablets , rely on flash memory storage devices. More than 224 companies have produced HDDs historically , though after extensive industry consolidation, most units are manufactured by Seagate , Toshiba , and Western Digital . HDDs dominate

1863-408: Is a "superfloppy" disk drive that has all of the standard 3 + 1 ⁄ 2 -inch floppy drive's convenience, but with much greater capacity options and with performance that is much improved over a standard floppy drive. However, Zip disk housings are similar to but slightly larger than those of standard 3 + 1 ⁄ 2 -inch floppy disks. In the Zip drive, the heads fly in a manner similar to

1944-429: Is a relabeled ISA Adaptec SCSI host controller. Also, originally sold separately was a PCMCIA-to-SCSI adapter for laptop compatibility, also a relabeled Adaptec. Driver support: NB 3: Requires a driver older than 5.x. Zip disks must be used in a drive with an equal or greater storage capacity. Higher-capacity drives can read lower-capacity media. The 250 MB drive writes much more slowly to 100 MB disks than

2025-476: Is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads , usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are

2106-446: Is capable of scheduling reads and writes efficiently on the platter surfaces and remapping sectors of the media that have failed. Modern drives make extensive use of error correction codes (ECCs), particularly Reed–Solomon error correction . These techniques store extra bits, determined by mathematical formulas, for each block of data; the extra bits allow many errors to be corrected invisibly. The extra bits themselves take up space on

2187-590: Is commonly known as the " superparamagnetic limit ". To counter this, the platters are coated with two parallel magnetic layers, separated by a three-atom layer of the non-magnetic element ruthenium , and the two layers are magnetized in opposite orientation, thus reinforcing each other. Another technology used to overcome thermal effects to allow greater recording densities is perpendicular recording (PMR), first shipped in 2005, and as of 2007 , used in certain HDDs. Perpendicular recording may be accompanied by changes in

2268-421: Is divided into logical blocks (collection of sectors). Blocks are addressed using their logical block addresses (LBA). Read from or write to disk happens at the granularity of blocks. Originally the disk capacity was quite low and has been improved in one of several ways. Improvements in mechanical design and manufacture allowed smaller and more precise heads, meaning that more tracks could be stored on each of

2349-669: Is improving faster than HDDs. NAND has a higher price elasticity of demand than HDDs, and this drives market growth. During the late 2000s and 2010s, the product life cycle of HDDs entered a mature phase, and slowing sales may indicate the onset of the declining phase. The 2011 Thailand floods damaged the manufacturing plants and impacted hard disk drive cost adversely between 2011 and 2013. In 2019, Western Digital closed its last Malaysian HDD factory due to decreasing demand, to focus on SSD production. All three remaining HDD manufacturers have had decreasing demand for their HDDs since 2014. A modern HDD records data by magnetizing

2430-418: Is increased, but known write head materials are unable to generate a strong enough magnetic field sufficient to write the medium in the increasingly smaller space taken by grains. Magnetic storage technologies are being developed to address this trilemma, and compete with flash memory –based solid-state drives (SSDs). In 2013, Seagate introduced shingled magnetic recording (SMR), intended as something of

2511-637: Is no need to stop the flow of data to switch tracks. This is similar to vinyl records, except vinyl records started at the outer edge and spiraled in toward the center. The disk drive interface is the mechanism/protocol of communication between the rest of the system and the disk drive itself. Storage devices intended for desktop and mobile computers typically use ATA ( PATA ) and SATA interfaces. Enterprise systems and high-end storage devices will typically use SCSI , SAS , and FC interfaces in addition to some use of SATA. Hard disk A hard disk drive ( HDD ), hard disk , hard drive , or fixed disk

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2592-455: Is sent from the computer processor to the BIOS into a chip controlling the data transfer. This is then sent out to the hard drive via a multi-wire connector. Once the data is received onto the circuit board of the drive, they are translated and compressed into a format that the individual drive can use to store onto the disk itself. The data is then passed to a chip on the circuit board that controls

2673-460: Is shaped rather like an arrowhead and is made of doubly coated copper magnet wire . The inner layer is insulation, and the outer is thermoplastic, which bonds the coil together after it is wound on a form, making it self-supporting. The portions of the coil along the two sides of the arrowhead (which point to the center of the actuator bearing) then interact with the magnetic field of the fixed magnet. Current flowing radially outward along one side of

2754-421: Is simply the number of disk surfaces times the number of blocks/surface times the number of bytes/block. In certain legacy IBM CKD drives the data was stored on magnetic disks with variable length blocks, called records; record length could vary on and between disks. Capacity decreased as record length decreased due to the necessary gaps between blocks. Digital disk drives are block storage devices . Each disk

2835-588: Is specified in unit prefixes corresponding to powers of 1000: a 1- terabyte (TB) drive has a capacity of 1,000 gigabytes , where 1 gigabyte = 1 000 megabytes = 1 000 000 kilobytes (1 million) = 1 000 000 000 bytes (1 billion). Typically, some of an HDD's capacity is unavailable to the user because it is used by the file system and the computer operating system , and possibly inbuilt redundancy for error correction and recovery. There can be confusion regarding storage capacity, since capacities are stated in decimal gigabytes (powers of 1000) by HDD manufacturers, whereas

2916-645: The Apple Macintosh . Many Macintosh computers made between 1986 and 1998 featured a SCSI port on the back, making external expansion simple. Older compact Macintosh computers did not have user-accessible hard drive bays (indeed, the Macintosh 128K , Macintosh 512K , and Macintosh Plus did not feature a hard drive bay at all), so on those models, external SCSI disks were the only reasonable option for expanding upon any internal storage. HDD improvements have been driven by increasing areal density , listed in

2997-572: The Shannon limit and thus provide the highest storage density available. Typical hard disk drives attempt to "remap" the data in a physical sector that is failing to a spare physical sector provided by the drive's "spare sector pool" (also called "reserve pool"), while relying on the ECC to recover stored data while the number of errors in a bad sector is still low enough. The S.M.A.R.T ( Self-Monitoring, Analysis and Reporting Technology ) feature counts

3078-467: The disk form beginning in 1956 with the " IBM 350 disk storage unit ".) Audio information was originally recorded by analog methods (see Sound recording and reproduction ). Similarly the first video disc used an analog recording method. In the music industry, analog recording has been mostly replaced by digital optical technology where the data is recorded in a digital format with optical information. The first commercial digital disk storage device

3159-536: The 100 MB disk and the 250 MB such that if the larger disk is inserted in a smaller-capacity drive, the disk is immediately ejected again without any attempt being made to access it. The 750 MB disk has no reflective spot. Zip drives initially sold well after their shipments began in 1995, owing to their low price and high (for the time) capacity. The drive was initially sold for just under US$ 200 with one cartridge included, and additional 100 MB cartridges for US$ 20. At this time hard disks typically had

3240-516: The 100 MB drive, and the Iomega software is unable to perform a "long" (thorough) format on a 100 MB disk (They can be formatted in any version of Windows as normal; the advantage of the Iomega software is that the long format can format the 100 MB disks with a slightly higher capacity. 250 MB disks format to the same size either way). The 750 MB drive has read-only support for 100 MB disks. The retroreflective spot differs between

3321-526: The HDD, but allow higher recording densities to be employed without causing uncorrectable errors, resulting in much larger storage capacity. For example, a typical 1  TB hard disk with 512-byte sectors provides additional capacity of about 93  GB for the ECC data. In the newest drives, as of 2009 , low-density parity-check codes (LDPC) were supplanting Reed–Solomon; LDPC codes enable performance close to

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3402-481: The IBM GV (Gulliver) drive, invented at IBM's UK Hursley Labs, became IBM's most licensed electro-mechanical invention of all time, the actuator and filtration system being adopted in the 1980s eventually for all HDDs, and still universal nearly 40 years and 10 billion arms later. Like the first removable pack drive, the first "Winchester" drives used platters 14 inches (360 mm) in diameter. In 1978, IBM introduced

3483-555: The SCSI interface prevalent on those platforms. They have also found a small niche in the music production community, as SCSI-compatible Zip drives can be used with vintage samplers and keyboards of the 1990s. Zip disks were still in use in aviation until at least 2014. Jeppesen distributed navigation database updates, and Universal Avionics supplies TAWS , UniLink and Performance databases for upload into flight management systems via 100 and 250 MB Zip disks. Iomega also produced

3564-491: The Zip drive as the 15th worst technology product of all time. Nonetheless, in 2007, PC World rated the Zip drive as the 23rd best technology product of all time despite its known problems. Zip drives are still used today by retro-computing enthusiasts as a means to transfer large amounts (compared to the retro hardware) of data between modern and older computer systems. The Commodore-Amiga , Atari ST , Apple II , and "old world" Macintosh communities often use drives with

3645-456: The access to the drive. The drive is divided into sectors of data stored onto one of the sides of one of the internal disks. An HDD with two disks internally will typically store data on all four surfaces. The hardware on the drive tells the actuator arm where it is to go for the relevant track, and the compressed information is then sent down to the head, which changes the physical properties, optically or magnetically, for example, of each byte on

3726-507: The advantages of magnetic media over optical media and flash memory, in terms of long-term file storage stability and high erase/rewrite cycles, still affords them a niche in the data-storage arena. In September 1998, a class action suit was filed against Iomega over a type of Zip drive failure dubbed the " Click of Death ", accusing Iomega of violation of the Delaware Consumer Fraud Act. In 2006, PC World rated

3807-416: The advent of inexpensive recordable CD and DVD drives for computers, followed by USB flash drives, pushed the Zip drive out of the mainstream market. Nevertheless, during their prime, Zip disks greatly eased the exchange of files that were too big to fit into a standard 3 + 1 ⁄ 2 -inch floppy or an email attachment, and there was no high-speed connection to transfer the file to the recipient. However,

3888-443: The arrowhead and radially inward on the other produces the tangential force . If the magnetic field were uniform, each side would generate opposing forces that would cancel each other out. Therefore, the surface of the magnet is half north pole and half south pole, with the radial dividing line in the middle, causing the two sides of the coil to see opposite magnetic fields and produce forces that add instead of canceling. Currents along

3969-450: The case of embedded servo, otherwise known as sector servo technology). The servo feedback optimizes the signal-to-noise ratio of the GMR sensors by adjusting the voice coil motor to rotate the arm. A more modern servo system also employs milli and/or micro actuators to more accurately position the read/write heads. The spinning of the disks uses fluid-bearing spindle motors. Modern disk firmware

4050-441: The connection between the drive and the host. The rate of areal density advancement was similar to Moore's law (doubling every two years) through 2010: 60% per year during 1988–1996, 100% during 1996–2003 and 30% during 2003–2010. Speaking in 1997, Gordon Moore called the increase "flabbergasting", while observing later that growth cannot continue forever. Price improvement decelerated to −12% per year during 2010–2017, as

4131-638: The disks. Advancements in data compression methods permitted more information to be stored in each of the individual sectors. The drive stores data onto cylinders, heads, and sectors . The sector unit is the smallest size of data to be stored in a hard disk drive, and each file will have many sector units assigned to it. The smallest entity in a CD is called a frame, which consists of 33 bytes and contains six complete 16-bit stereo samples (two bytes × two channels × six samples = 24 bytes). The other nine bytes consist of eight CIRC error-correction bytes and one subcode byte used for control and display. The information

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4212-449: The disks; the stator windings are fixed in place. Opposite the actuator at the end of the head support arm is the read-write head; thin printed-circuit cables connect the read-write heads to amplifier electronics mounted at the pivot of the actuator. The head support arm is very light, but also stiff; in modern drives, acceleration at the head reaches 550 g . The actuator is a permanent magnet and moving coil motor that swings

4293-632: The drive, thus storing the information. A file is not stored in a linear manner; rather, it is held in the best way for quickest retrieval. Mechanically there are two different motions occurring inside the drive. One is the rotation of the disks inside the device. The other is the side-to-side motion of the head across the disk as it moves between tracks. There are two types of disk rotation methods: Track positioning also follows two different methods across disk storage devices. Storage devices focused on holding computer data, e.g., HDDs, FDDs, and Iomega zip drives , use concentric tracks to store data. During

4374-467: The earlier IBM disk drives used only two read/write heads per arm, the 1301 used an array of 48 heads (comb), each array moving horizontally as a single unit, one head per surface used. Cylinder-mode read/write operations were supported, and the heads flew about 250 micro-inches (about 6 μm) above the platter surface. Motion of the head array depended upon a binary adder system of hydraulic actuators which assured repeatable positioning. The 1301 cabinet

4455-443: The growth of areal density slowed. The rate of advancement for areal density slowed to 10% per year during 2010–2016, and there was difficulty in migrating from perpendicular recording to newer technologies. As bit cell size decreases, more data can be put onto a single drive platter. In 2013, a production desktop 3 TB HDD (with four platters) would have had an areal density of about 500 Gbit/in which would have amounted to

4536-416: The heads to the desired position. A metal plate supports a squat neodymium–iron–boron (NIB) high-flux magnet . Beneath this plate is the moving coil, often referred to as the voice coil by analogy to the coil in loudspeakers , which is attached to the actuator hub, and beneath that is a second NIB magnet, mounted on the bottom plate of the motor (some drives have only one magnet). The voice coil itself

4617-427: The largest hard drive had a capacity of 15 TB, while the largest capacity SSD had a capacity of 100 TB. As of 2018 , HDDs were forecast to reach 100 TB capacities around 2025, but as of 2019 , the expected pace of improvement was pared back to 50 TB by 2026. Smaller form factors, 1.8-inches and below, were discontinued around 2010. The cost of solid-state storage (NAND), represented by Moore's law ,

4698-412: The late 1990s portable storage market. However, it was never popular enough to replace the standard 3 + 1 ⁄ 2 -inch floppy disk . Zip drives fell out of favor for mass portable storage during the early 2000s as CD-RW and USB flash drives became prevalent. The Zip brand later covered internal and external CD writers known as Zip-650 or Zip-CD, despite the dissimilar technology. The Zip drive

4779-444: The magnetization of the material passing immediately under it. In modern drives, there is one head for each magnetic platter surface on the spindle, mounted on a common arm. An actuator arm (or access arm) moves the heads on an arc (roughly radially) across the platters as they spin, allowing each head to access almost the entire surface of the platter as it spins. The arm is moved using a voice coil actuator or, in some older designs,

4860-422: The manufacturing of the read/write heads to increase the strength of the magnetic field created by the heads. In 2004, a higher-density recording media was introduced, consisting of coupled soft and hard magnetic layers. So-called exchange spring media magnetic storage technology, also known as exchange coupled composite media , allows good writability due to the write-assist nature of the soft layer. However,

4941-420: The most commonly used operating systems report capacities in powers of 1024, which results in a smaller number than advertised. Performance is specified as the time required to move the heads to a track or cylinder (average access time), the time it takes for the desired sector to move under the head (average latency , which is a function of the physical rotational speed in revolutions per minute ), and finally,

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5022-545: The next few years, as more companies began supplying them. Eventually, the suppliers included Fujifilm , Verbatim , Toshiba and Maxell , Epson and NEC . NEC also produced a licensed 100 MB drive model with its brand name. Sales of Zip drives and disks declined steadily from 1999 to 2003. Zip disks had a relatively high cost per megabyte compared to the falling costs of then-new CD-R and CD-RW discs. The growth of hard disk drives to multi-gigabyte capacity made backing up with Zip disks less economical. Furthermore,

5103-559: The norm in most computer installations and reached capacities of 300 megabytes by the early 1980s. Non-removable HDDs were called "fixed disk" drives. In 1963, IBM introduced the 1302, with twice the track capacity and twice as many tracks per cylinder as the 1301. The 1302 had one (for Model 1) or two (for Model 2) modules, each containing a separate comb for the first 250 tracks and the last 250 tracks. Some high-performance HDDs were manufactured with one head per track, e.g. , Burroughs B-475 in 1964, IBM 2305 in 1970, so that no time

5184-534: The platters, increasing areal density. Normally hard drive recording heads have a pole called a main pole that is used for writing to the platters, and adjacent to this pole is an air gap and a shield. The write coil of the head surrounds the pole. The STO device is placed in the air gap between the pole and the shield to increase the strength of the magnetic field created by the pole; FC-MAMR technically doesn't use microwaves, but uses technology employed in MAMR. The STO has

5265-416: The revenue of hard disk drives as of 2017 . Though SSDs have four to nine times higher cost per bit, they are replacing HDDs in applications where speed, power consumption, small size, high capacity and durability are important. As of 2019 , the cost per bit of SSDs is falling, and the price premium over HDDs has narrowed. The primary characteristics of an HDD are its capacity and performance . Capacity

5346-494: The same ZipCD name. Early models of ZipCD drives were relabeled Philips drives, which were also so unreliable that a class action lawsuit succeeded. Later models were sourced from Plextor . Disk storage (The spelling disk and disc are used interchangeably except where trademarks preclude one usage, e.g., the Compact Disc logo. The choice of a particular form is frequently historical, as in IBM's usage of

5427-427: The speed at which the data is transmitted (data rate). The two most common form factors for modern HDDs are 3.5-inch, for desktop computers, and 2.5-inch, primarily for laptops. HDDs are connected to systems by standard interface cables such as SATA (Serial ATA), USB , SAS ( Serial Attached SCSI ), or PATA (Parallel ATA) cables. The first production IBM hard disk drive, the 350 disk storage , shipped in 1957 as

5508-438: The stack of disk platters when the drive was powered down. Instead, the heads were allowed to "land" on a special area of the disk surface upon spin-down, "taking off" again when the disk was later powered on. This greatly reduced the cost of the head actuator mechanism, but precluded removing just the disks from the drive as was done with the disk packs of the day. Instead, the first models of "Winchester technology" drives featured

5589-450: The swing arm actuator design to make possible the compact form factors of modern HDDs. As the 1980s began, HDDs were a rare and very expensive additional feature in PCs, but by the late 1980s, their cost had been reduced to the point where they were standard on all but the cheapest computers. Most HDDs in the early 1980s were sold to PC end users as an external, add-on subsystem. The subsystem

5670-439: The table above. Applications expanded through the 2000s, from the mainframe computers of the late 1950s to most mass storage applications including computers and consumer applications such as storage of entertainment content. In the 2000s and 2010s, NAND began supplanting HDDs in applications requiring portability or high performance. NAND performance is improving faster than HDDs, and applications for HDDs are eroding. In 2018,

5751-400: The thermal stability is determined only by the hardest layer and not influenced by the soft layer. Flux control MAMR (FC-MAMR) allows a hard drive to have increased recording capacity without the need for new hard disk drive platter materials. MAMR hard drives have a microwave generating spin torque generator (STO) on the read/write heads which allows physically smaller bits to be recorded to

5832-475: The top and bottom of the coil produce radial forces that do not rotate the head. The HDD's electronics controls the movement of the actuator and the rotation of the disk and transfers data to/from a disk controller . Feedback of the drive electronics is accomplished by means of special segments of the disk dedicated to servo feedback. These are either complete concentric circles (in the case of dedicated servo technology) or segments interspersed with real data (in

5913-436: The total cost of ownership of data on disk including power and management remains larger than that of tape. Disk storage is now used in both computer storage and consumer electronic storage, e.g., audio CDs and video discs ( VCD , DVD and Blu-ray ). Data on modern disks is stored in fixed length blocks, usually called sectors and varying in length from a few hundred to many thousands of bytes. Gross disk drive capacity

5994-491: The total number of errors in the entire HDD fixed by ECC (although not on all hard drives as the related S.M.A.R.T attributes "Hardware ECC Recovered" and "Soft ECC Correction" are not consistently supported), and the total number of performed sector remappings, as the occurrence of many such errors may predict an HDD failure . The "No-ID Format", developed by IBM in the mid-1990s, contains information about which sectors are bad and where remapped sectors have been located. Only

6075-433: The usual filtered air. Since turbulence and friction are reduced, higher areal densities can be achieved due to using a smaller track width, and the energy dissipated due to friction is lower as well, resulting in a lower power draw. Furthermore, more platters can be fit into the same enclosure space, although helium gas is notoriously difficult to prevent escaping. Thus, helium drives are completely sealed and do not have

6156-499: The volume of storage produced ( exabytes per year) for servers. Though production is growing slowly (by exabytes shipped ), sales revenues and unit shipments are declining, because solid-state drives (SSDs) have higher data-transfer rates, higher areal storage density, somewhat better reliability, and much lower latency and access times. The revenues for SSDs, most of which use NAND flash memory , slightly exceeded those for HDDs in 2018. Flash storage products had more than twice

6237-520: Was about the size of three large refrigerators placed side by side, storing the equivalent of about 21 million eight-bit bytes per module. Access time was about a quarter of a second. Also in 1962, IBM introduced the model 1311 disk drive, which was about the size of a washing machine and stored two million characters on a removable disk pack . Users could buy additional packs and interchange them as needed, much like reels of magnetic tape . Later models of removable pack drives, from IBM and others, became

6318-427: Was lost physically moving the heads to a track and the only latency was the time for the desired block of data to rotate into position under the head. Known as fixed-head or head-per-track disk drives, they were very expensive and are no longer in production. In 1973, IBM introduced a new type of HDD code-named " Winchester ". Its primary distinguishing feature was that the disk heads were not withdrawn completely from

6399-513: Was not sold under the drive manufacturer's name but under the subsystem manufacturer's name such as Corvus Systems and Tallgrass Technologies , or under the PC system manufacturer's name such as the Apple ProFile . The IBM PC/XT in 1983 included an internal 10 MB HDD, and soon thereafter, internal HDDs proliferated on personal computers. External HDDs remained popular for much longer on

6480-489: Was the IBM 350 which shipped in 1956 as a part of the IBM 305 RAMAC computing system. The random-access , low-density storage of disks was developed to complement the already used sequential-access , high-density storage provided by tape drives using magnetic tape . Vigorous innovation in disk storage technology, coupled with less vigorous innovation in tape storage, has reduced the difference in acquisition cost per terabyte between disk storage and tape storage; however,

6561-408: Was the norm. As of November 2019 , the platters in most consumer-grade HDDs spin at 5,400 or 7,200 rpm. Information is written to and read from a platter as it rotates past devices called read-and-write heads that are positioned to operate very close to the magnetic surface, with their flying height often in the range of tens of nanometers. The read-and-write head is used to detect and modify

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