GLOCK

They come in olive drab, tan, and black. Fibre channel (FC) interfaces are left to discussions of server drives. GLOCK also manufactures their own line of knives: By all regards they are of good quality and are popular due to the fact that they are easily affordable and made by GLOCK. However, as of 2005, performance of SATA and PATA disks is comparable. However, the GLOCK 25 and 28 pistols are relatively popular in nations where handguns in "military" calibers (.45 ACP, 9mm Parabellum) may not be purchased by the general public. In order for EIDE's performance to increase (while keeping the cost of the associated electronics low), it was realized that the only way to do this was to move from "parallel" interfaces to "serial" interfaces, the result of which is the SATA interface. This failure is not due to any inherent defect in the model, but due to the fact that a small pistol chambered for the .380 ACP cartridge does not meet the "sporting purposes" criteria by which imported pistols are judged. The increase in SCSI performance came at a price — its interfaces were more expensive.

GLOCK 25 or 28 pistols are not available to the general public in the United States, as they do not meet the standards required for the importation of pistols under the Gun Control Act of 1968. While EIDE was introduced, though, SCSI manufacturers continued to improve SCSI's performance. GLOCK 18/18C pistols are select fire automatic/semi-auto machine pistols and not available to the general public in most countries. These drives were known as EIDE. Rather, it is a slang term some people use to refer to GLOCKs chambered in .40 S&W. IDE manufacturers attempted to close this speed gap by introducing Logical Block Addressing (LBA). However, no such variant of the GLOCK exists at this time. IDE drives were slower because they did not have as big a cache as the SCSI drives, and they could not write directly to RAM.

Note: One can come across references to a "GLOCK 40" from time to time. Eventually, IDE manufacturers wanted the speed of IDE to approach the speed of SCSI drives. To disassemble a GLOCK handgun, follow these steps:. This advance was known as "Integrated Drive Electronics" or IDE. GLOCK guns feature tool-less disassembly to facilitate easy field maintenance. When the price of electronics dropped (and because of a demand by consumers) the electronics that had been stored on the controller card was moved to the disk drive itself. Most handguns can be disassembled for proper maintenance and cleaning. SCSI (originally named SASI for Shugart (sic) Associates) or Small Computer System Interface was an early competitor with ESDI.

The GLOCK name has been misused as a generic slang term for any expensive black handgun. It allowed for faster communication between the PC and the disk. GLOCK also claims that its "Safe Action" safety system (see above) results in smoother trigger pull. ESDI was an interface developed by Maxtor. GLOCK pistols have gained popularity due to the fact that the lower height of the barrel compared to the grip results in less torque when shooting and lower perceived recoil, which many owners feel makes the gun more comfortable to fire. Most RLL drives also needed to be "compatible" with the controllers that communicated with them. GLOCK pistols have a significantly lesser weight than a typical all-steel, or aluminum frame handgun, which has been a point of popularity for officers and private citizens that carry a concealed handgun. RLL (Run Length Limited) was a way of encoding bits onto the platters that allowed for better density.

GLOCK pistols have a great deal of popularity among police, Govt., and private citizens specifically due to the greatly reduced number of parts which comprise the gun (nearly half as many as the typical handgun), the low cost of replacement parts, and the ability to entirely disassemble the gun with a simple pin, or thin rod of any make, to fully break down the gun without the requirement of any specialized tools or time, even in the field. MFM drives required that the electronics on the "controller" be compatible with the electronics on the drive — disks and controllers had to be compatible. They contain a relatively small number of components, making in-the-field maintenance and repair simpler. As far as PC history is concerned, the major drive families have been MFM, RLL, ESDI, SCSI, IDE and EIDE, and now SATA. They are able to function under extreme conditions and to fire a wide range of ammunition types due to their rugged construction and simplicity of design. As of early 2005, the "smallest" desktop hard disk in production has a capacity of 40 gigabytes, while the largest-capacity internal drives are a half terabyte (500 gigabytes), with external drives at or exceeding one terabyte. GLOCK pistols are renowned for their reliability. In the latter half of the 1990s, hard drives with capacities of 1 gigabyte and greater became available.

The gun is also used in all police services in Australia except Victoria. With early personal computers, a drive with a 20 megabyte capacity was considered large. GLOCK's website states their pistols are "in use in 65% of law enforcement agencies." The US FBI issues all agents graduating from the FBI Academy a GLOCK 22 or GLOCK 23 at the agent's preference. The capacity of hard drives has grown exponentially over time. GLOCK sidearms are very common handguns among law enforcement agencies in the United States; many estimates place GLOCK's market share among USA Police departments at over 60% (based on total number of guns sold, not percentage of departments). The appearance in the late 1990s of high-speed external interfaces such as USB and FireWire has made external disk systems popular among regular users once again, especially for users who move large amounts of data between two or more locations, and most hard disk makers now make their disks available in external cases. GLOCK claims sales of over 2.5 million handguns in over 100 countries. External SCSI drives were also popular with older microcomputers such as the Apple II series and the Commodore 64, and were also used extensively in servers, a usage which is still popular today.

Despite the controversy, GLOCK pistols still continue to be the favorite of military and law enforcement agencies worldwide. Every Mac made between 1986 and 1998 has a SCSI port on the back, making external expansion easy; also, "toaster" Macs did not have easily accessible hard drive bays (or, in the case of the Mac Plus, any hard drive bay at all), so on those models, external SCSI disks were the only reasonable option. It has been purported that because of the the specific design of the polygonal rifling in the GLOCK, owners should not shoot non-jacketed lead ammunition in a GLOCK, since lead residue can quickly build up and cause a decreased bore diameter and therefore a dangerous over pressurization in the barrel and potentially create a structural failure or warping in the chamber of the barrel. While internal drives became the system of choice on PCs, external hard drives remained popular for much longer on the Apple Macintosh and other platforms. However, there continues to be controversy over the presence of an unsupported chamber, critics arguing that it is not necessary and is a liability for the company. Hard disk makers started marketing to end users as well as OEMs, and by the mid-1990s, hard disks had become available on retail store shelves. Supporters also point out that kB!s occur in other firearms as well, particularly M1911 frame pistols. The IBM PC/XT had an internal hard disk, however, and this started a trend toward buying "bare" drives (often by mail order) and installing them directly into a system.

GLOCK, in its own defense, says that in every manual that comes with their pistols there are instructions informing the shooter of the dangers of using non-factory rated ammunition, and that if the shooter uses factory loaded, jacketed ammuntion and makes sure to properly clean and care for their firearm, the firearm will function safely. Most microcomputer hard disk drives in the early 1980s were not sold under their manufacturer's names, but by OEMs as part of larger peripherals (such as the Corvus Disk System and the Apple ProFile). The subsequent rapid expansion of gas into the chamber caused the pistols to fail, usually damaging the polymer frame and/or magazine. In fact, in its factory configuration the original IBM PC (IBM 5150) was not equipped with a hard drive. The lack of support in the chamber, usually combined with lead bullets, reloaded, or +P (over-loaded) ammunition, would cause the casing to fail. Because of this, hard disks were not commonly used with microcomputers until after 1980, when Seagate Technology introduced the ST-506, the first 5.25-inch hard drive, with a capacity of 5 megabytes. The chamber lacks full support in the rear by the feed ramp in order to facilitate feed reliability. Before the early 1980s, most hard disks had 8-inch (20 cm) or 14-inch (35 cm) platters, required an equipment rack or a large amount of floor space (especially the large removable-media drives, which were often referred to as "washing machines"), and in many cases needed high-amperage or even three-phase power hookups due to the large motors they used.

The cause of this malfunction was traced to issues with a purposely oversized (loose), and partially unsupported chamber in GLOCK's pistols chambered in .40 S&W, .45 ACP, .357 SIG, and 10mm. For many years, hard disks were large, cumbersome devices, more suited to use in the protected environment of a data center or large office than in a harsh industrial environment (due to their delicacy), or small office or home (due to their size and power consumption). Upon pulling the trigger, the cartridge case would rupture and cause an explosion that would tear apart the gun and often send shrapnel into the shooter's face. Project head designer/lead designer Kenneth Haughton named it after the Winchester 30-30 rifle after the developers called it the "30-30" because of its two 30 MB spindles. Controversy arose over GLOCK's safety standards when multiple cases of explosive malfunction occurred in GLOCK pistols sold to police departments in the United States. Almost all modern disk drives now use this technology, and the term "Winchester" became a common description for all hard disks, though generally falling out of use during the 1990s. GLOCK pistol kB's usually damage the firearm, with minor injury to the shooter. In 1973, IBM introduced the 3340 "Winchester" disk system the first to use a sealed head/disk assembly (HDA).

Coined by firearms reporter Dean Speir, a kB! (or kaBoom!) is the term used to describe the explosive malfunction of a firearm, with usually very costly, if not deadly, results. The first disk drive to use removable media was the IBM 1311 drive, which used the IBM 1316 disk pack to store two million characters. The GLOCK pistol does not have a external hammer and thus cannot be "cocked" or "uncocked" in the conventional manner and does not make the sort of sounds that are commonly heard in TV and movies. The IBM 1301 Disk Storage Unit, announced in 1961, introduced the usage of a separate head for each data surface. One common aspect of popular media portrayals of the GLOCK pistol is when someone pulls out or points a GLOCK pistol and the foley artists insert the sound effect of the GLOCK being "cocked" like a revolver. A single head was used for access to all the platters, making the average access time very slow. GLOCK handguns have seen much fictional exposure in action movies and TV shows that often continue to spread misconceptions about the GLOCK pistol. This drive had fifty 24 inch platters, with a total capacity of five million characters.

The most commonly available GLOCK pistols with the ILS are the G17, G19, G22, G23, G26, and the G27. The first hard disk drive was the IBM 350 Disk File, invented by Reynold Johnson and introduced in 1955 with the IBM 305 computer. The ILS is available as an option on all GLOCK pistols except for the G36, however not all ILS equipped GLOCK pistols are carried by distributors nor imported with the option. In 2005 the first cellular telephones to include hard disk drives were introduced by Samsung and Nokia. When disengaged, the ILS adds no further safety mechanisms to the GLOCK pistol. Applications for hard disk drives expanded to include personal video recorders, digital audio players, digital organizers and digital cameras. When activated, the ILS renders the GLOCK unfireable as well as making it impossible to disassemble. Hard disks are also found in network attached storage (NAS) devices, but for large volumes of data are most efficiently used in a storage area network (SAN).

This is done to give both a visual and tactile indication as to wether the lock is engaged or not. From the original use of a hard drive in a single computer, techniques for guarding against hard disk failure were developed such as the redundant array of independent disks (RAID). When activated, the lock causes a tab to protrude from the rear of the grip. However, for large (several GiB) filesystems, this data rarely occupies more than several MiB, and therefore cannot possibly account for the apparent "loss" of tens of GBs. Group key hierarchic solutions are available for law enforcement agencies. Another side point is that many people mistakenly attribute the discrepancy in reported and advertised capacities to reserved space used for file system and partition accounting information. It is cylindrical in design and, according to GLOCK, each key is absolutely unique. KiB, MiB, GiB) since their definitions are unambiguous.

The ILS is a manually activated lock that is located in the back of the pistol's grip. For this very reason, many utilities that report capacity have begun to use the aforementioned IEC standard binary prefixes (e.g. In 2003, GLOCK announced the Internal Locking System (ILS). Since utilities provided by the operating system probably define a gigabyte as 2³⁰, or 1073741824, bytes, the reported capacity of the drive will be closer to 186.26 GB (actually, GiB), a difference of well over 7 percent. In the event of failure, the weapon should be immediately taken out of service until repaired by a qualified GLOCK armorer. This uses the proper SI definition of "giga," 10⁹ and can be considered as an approximation of a gibibyte. As a part of regular field stripping and cleaning, the striker safety can and should be "function checked" to ensure that it is operational. For example, a drive advertised as 200 GB can be expected to store close to 200 x 10⁹, or 200 billion, bytes.

When combined with other major component failures, such as a broken slide rail, GLOCK pistols may fire unexpectedly. This trend became habit and continued to be applied to the prefixes "mega," "giga," and even "tera." Obviously the discrepancy becomes much more noticeable in reported capacities in the multiple gigabyte range, and users will often notice that the volume capacity reported by their OS is significantly less than that advertised by the hard drive manufacturer. Normal wear to the striker safety may cause the striker safety to fail if the safety is excessively worn. The IEC only standardized binary prefixes in 1999, so 2¹⁰ (1024) bytes was called a kilobyte because 1024 is "close enough" to the metric prefix kilo, which is defined as 10³ or 1000. With GLOCK pistols, like any firearm, accidental injury can still be caused by manipulating the trigger when it is not your intention to shoot. This is largely for historical reasons, since when storage capacities started to exceed thousands of bytes, there were no standard binary prefixes. Similar systems for internal safeties have since become standard for many major brand makers of semi-automatic pistols. Hard drive manufacturers often use the metric definition of the prefixes "giga" and "mega", whilst nearly all operating system utilities report capacities using binary definitions for the prefixes.

They are:. In the United Kingdom, Cumana, a manufacturer of disk drives for Acorn computers, ceased manufacturing drives in 1995. All 3 safeties are disabled one after the other when the trigger is depressed. There have also been a number of notable mergers in the hard disk industry:. GLOCK calls this the "Safe Action" system. Rodime was also an important manufacturer during the 1980s, but stopped making drives in the early 1990s amid the shakeout and now concentrates on technology licensing; they hold a number of patents related to 3.5-inch form factor hard drives. GLOCK pistols use an internal safety mechanism with three components with no external thumb activated safety switch. Many other smaller companies (like Kalok, Microscience, LaPine, Areal, Priam and PrairieTek) also did not survive the shakeout, and had disappeared by 1993; Micropolis was able to hold on until 1997, and JTS, a relative latecomer to the scene, lasted only a few years and was gone by 1999.

In fact, GLOCK pistols are made of polymer and steel, are made in Austria, are visible to X-ray equipment, and are not significantly more expensive than comparable firearms. Another notable failure was MiniScribe, who went bankrupt in 1990 after it was found that they had "cooked the books" and inflated sales numbers for several years. It doesn't show up on your airport X-ray machines, and it cost more than you make here in a month!. The first notable casualty of the business in the PC era was Computer Memories International or CMI; after the 1985 incident with the faulty 20MB AT drives, CMI's reputation never recovered, and they exited the hard drive business in 1987. That punk pulled a GLOCK 7 on me! You know what that is? It's a porcelain gun made in Germany. Dozens of former hard drive manufacturers have gone out of business, merged, or closed their hard drive divisions; as capacities and demand for products increased, profits became hard to find, and there were shakeouts in the late 1980s and late 1990s. In Die Hard 2, the character John McClane portrayed by Bruce Willis specifically refers to a non-existent GLOCK 7 with many fictitious characteristics:. Toshiba is a major manufacturer of 2.5-inch and 1.8-inch notebook drives.

Contrary to popular movies like Die Hard 2: Die Harder and In the Line of Fire, neither GLOCK nor any other gun maker has ever produced a "ceramic" or "plastic" firearm which is undetectable by ordinary security screening devices. Fujitsu continues to make specialist notebook and SCSI drives but exited the mass market in 2001. In addition, virtually all of these "plastic" parts contain embedded steel to make them functional, not to make them "detectable". Most of the world's hard disks are now manufactured by just a handful of large firms: Seagate, Maxtor (now owned by Seagate), Western Digital, Samsung, and Hitachi, the former drive manufacturing division of IBM. In fact, 83% (by weight) of the GLOCK pistol is ordinary gun steel and the "plastic" parts are in fact a dense polymer known as 'Polymer 2' which is radio-opaque and thus also shows up under X-ray security equipment. See also: hard disk drive partitioning, master boot record, file system, drive letter assignment, boot sector. It has since become an urban legend that to this day continues to appear in news reports and movies, and has even been a topic of debate in the United States Congress. ATA drives larger than 8 GiB are always accessed by LBA, due to the 8 GiB limit described above.

The claim that they could not was first made in an article published in the Washington Post on January 13, 1985, entitled, "Quaddafi Buying Austrian Plastic Pistol." In this article, vocal gun control advocate Jack Anderson made the allegations, which were then reported without fact-checking by the Associated Press and further reported by many United States television news stations and newspapers. To maintain some degree of compatibility with older computers, LBA mode generally has to be requested explicitly by the host computer. Contrary to early reports, GLOCK pistols do set off metal detectors and can indeed be detected by X-ray machines, due to their metal barrels and slides. ATA drives can either use their native CHS parameters (only on very early drives; hard drives made since the early 1990s use zone bit recording, and thus don't have a set number of sectors per track), use a "translated" CHS profile (similar to what SCSI host adapters provide), or run in ATA LBA mode, as specified by ATA-2. GLOCK also offers pistols chambered in .357 SIG, .380 ACP, 10 mm Auto, .45 ACP, and the new .45 GAP (GLOCK Automatic Pistol). Because PCs use CHS addressing internally, the BIOS code on PC SCSI host adapters does CHS-to-LBA translation, and provides a set of CHS drive parameters that tries to match the total number of LBA blocks as closely as possible. The GLOCK 22 is currently (as of mid-2005) the single most popular police sidearm in use in the United States; because of their ease of use, reliability, and low price, GLOCK pistols in general are in use by over 60% of the police officers in the US. SCSI mode page commands can be used to get the physical specifications of the disk, but this is not used to read or write data; this is an artifact of the early days of SCSI, circa 1986, when a disk attached to a SCSI bus could just as well be an ST-506 or ESDI drive attached through a bridge (and therefore having a CHS configuration that was subject to change) as it could be a native SCSI device.

GLOCK was the first manufacturer to offer models chambered in the cartridge (GLOCK 22 & GLOCK 23 - 1990), beating Smith & Wesson to the marketplace with their own cartridge. SCSI drives, however, have always used LBA addressing, which describes the disk as a linear, sequentially-numbered set of blocks. GLOCK pistols are popular with law enforcement agencies and defense-minded private citizens, especially when chambered for modern, powerful cartridges such as the .40 S&W. The 8.4 and 128 GiB limits are soft limits: the PC simply ignores the extra capacity and reports a drive of the maximum size it is able to communicate with. Its first pistol model was the GLOCK 17 (so named because it was the 17th patent of the company), a 9 mm Luger Parabellum handgun with a 17 round capacity (unusually large at the time), introduced in the early 1980s as a response to the Austrian army asking for a new sidearm. The 2.1, 4.2 and 32 GiB limits are hard limits: fitting a drive larger than the limit results in a PC that refuses to boot, unless the drive includes special jumpers to make it appear as a smaller capacity. According to GLOCK, this is technically incorrect. Even after the introduction of LBA, similar limitations reappeared several times over the following years: at 2.1, 4.2, 8.4, 32, and 128 GiB.

The names of the company and its products are often referred to as "Glock" and not as "GLOCK". When drives larger than 504 MiB began to appear in the mid-1990s, many system BIOSes had problems communicating with them, requiring LBA BIOS upgrades or special driver software to work correctly. The GLOCK corporate name and the pistol model designations are spelled with all uppercase letters. The origin of the CHS limit lies in a combination of the limitations of IBM's BIOS interface (which allowed 1024 cylinders, 256 heads and 64 sectors; sectors were counted from 1, reducing that number to 63, giving an addressing limit of 8064 MiB or 7.8 GiB), and a hardware limitation of the AT's hard disk controller (which allowed up to 65536 cylinders and 256 sectors, but only 16 heads, putting its addressing limit at 2^28 bits or 128 GiB). They later supplied the Austrian Army with machine gun belts, practice hand grenades, plastic clips, field knives and entrenching tools. The traditional CHS limit was 1024 cylinders, 16 heads and 63 sectors; on a drive with 512-byte sectors, this comes to 504 MiB (528 megabytes). The company started life manufacturing curtain rods. CHS describes the disk space in terms of its physical dimensions, data-wise; this is the traditional way of accessing a disk on IBM PC compatible hardware, and while it works well for floppies (for which it was originally designed) and small hard disks, it caused problems when disks started to exceed the design limits of the PC's CHS implementation.

Mainly known for being the manufacturer of polymer-framed pistols, GLOCK also produces equipment such as field knives and entrenching tools (shovels). The more recent mode is the LBA (Logical Block Addressing), used by SCSI drives and newer ATA drives (ATA drives power up in CHS mode for historical reasons). . The older mode is CHS addressing (Cylinder-Head-Sector), used on old ST-506 and ATA drives and internally by the PC BIOS. GLOCK is an Austrian defense contractor (named after the founder Gaston Glock) founded in 1963 in Deutsch-Wagram, near Vienna, Austria. Addressing modes There are two modes of addressing the data blocks on more recent hard disks. Reassembly takes place in the reverse order. Most FireWire/IEEE 1394 models are able to daisy-chain in order to continue adding peripherals without requiring additional ports on the computer itself.

Slide the barrel forward and remove the barrel. FireWire/IEEE 1394 and USB(1.0/2.0) hard disks are external units containing generally ATA or SCSI drives with ports on the back allowing very simple and effective expansion and mobility. Depress the recoil spring on the slide and remove the recoil assembly. Serial ATA does away with master/slave setups entirely, placing each drive on its own channel (with its own set of I/O ports) instead. With the catch fully lowered push the slide forward and completely off. This was mostly remedied by the mid-1990s, when ATA's specfication was standardised and the details began to be cleaned up, but still causes problems occasionally (especially with CD-ROM and DVD-ROM drives, and when mixing Ultra DMA and non-UDMA devices). With the slide in this position, lower the catch located on either side of the pistol between the slide and the trigger. ATA drives have typically had no problems with interleave or data rate, due to their controller design, but many early models were incompatible with each other and couldn't run in a master/slave setup (two drives on the same cable).

(Cocking the gun will inhibit disassembly.). The SCSI bus speed had no bearing on the drive's internal speed because of buffering between the SCSI bus and the drive's internal data bus; however, many early drives had very small buffers, and thus had to be reformatted to a different interleave (just like ST-506 drives) when used on slow computers, such as early IBM PC compatibles and Apple Macintoshes. Pull the slide back approximately 3mm, making sure the gun does not cock. SCSI originally had just one speed, 5 MHz (for a maximum data rate of 5 megabytes per second), but later this was increased dramatically. Pull the trigger and confirm no round was fired. ESDI drives typically also had jumpers to set the number of sectors per track and (in some cases) sector size. Aim the barrel in a safe direction, away from any persons, animals, or objects. a 15 or 20 megabit drive wouldn't run on a 10 megabit controller).

Let the slide return. ESDI also supported multiple data rates (ESDI drives always used 2,7 RLL, but at 10, 15 or 20 megabits per second), but this was usually negotiated automatically by the drive and controller; most of the time, however, 15 or 20 megabit ESDI drives weren't downward compatible (i.e. Remove any cartridge or brass in the chamber. (An RLL-certified drive could run on a MFM controller, but with 1/3 less data capacity and speed.). Pull the slide back and engage the slide lock. In some cases, the drive was overengineered just enough to allow the MFM-certified model to run at the faster data rate; however, this was often unreliable and was not recommended. Remove the magazine. Many ST-506 interface drives were only certified by the manufacturer to run at the lower MFM data rate, while other models (usually more expensive versions of the same basic drive) were certified to run at the higher RLL data rate.

Drop Safety: the far end of the same extension bar locks the striker into place from the rear until the trigger is pulled. Later on, controllers using 2,7 RLL (or just "RLL") encoding increased this by half, to 7.5 megabits per second; it also increased drive capacity by half. Striker Safety: a spring-loaded pin attached by an extension bar to the trigger assembly blocks the striker from striking the primer (Percussion cap) of the cartridge until the trigger is pulled. The first ST-506 disks used Modified Frequency Modulation (MFM) encoding (which is still used on the common "1.44 MB" (1.4 MiB) 3.5-inch floppy), and ran at a data rate of 5 megabits per second. Trigger Safety: a lever mechanism contained within the trigger that prevents the trigger from moving unless the lever is depressed. Back in the days of the ST-506 interface, the data encoding scheme was also important. A hard disk is generally accessed over one of a number of bus types, including ATA (IDE, EIDE), Serial ATA, SCSI, SAS, FireWire (aka IEEE 1394), USB, and Fibre Channel.

Most spin at only 4,200 rpm or 5,400 rpm, though the newest top models spin at 7,200 rpm. Notebook hard drives, which are physically smaller than their desktop counterparts, tend to be slower and have less capacity. The fastest workstation and server hard drives spin at 15,000 rpm, and can achieve sequential media transfer speeds of up to 100 MB/s. In 2005, a typical workstation hard disk might store between 80 GB and 500 GB of data, rotate at 7,200 to 10,000 rpm, and have a sequential media transfer rate of over 50 MB/s.

Consequently, hard disks can store much more data than floppy disk, and access and transmit it faster. Using rigid platters and sealing the unit allows much tighter tolerances than in a floppy disk. This means that no failures attributed to the head-disk interface were seen before at least 50,000 start-stop cycles during testing. For example, the Maxtor DiamondMax series of desktop hard drives are rated to 50,000 start-stop cycles.

However, the decay rate is not linear — when a drive is younger and has fewer start/stop cycles, it has a better chance of surviving the next startup than an older, higher-mileage drive (as the head literally drags along the drive's surface until the air bearing is established). Most manufacturers design the sliders to survive 50,000 contact cycles before the chance of damage on startup rises above 50%. The sliders (the part of the heads that are closest to the disk and contain the pickup coil itself) are designed to reliably survive a number of landings and takeoffs from the disk surface, though wear and tear on these microscopic components eventually takes its toll. While the disk is spinning, the heads are supported by an air bearing and experience no physical contact wear.

Spring tension from the head mounting constantly pushes the heads towards the disk. When a sudden, sharp movement is detected by the built-in motion sensor in the PowerBook, internal hard disk heads automatically unload themselves into the parking zone to reduce the risk of any potential data loss or scratches made. Apple Computer has created a technology for their new PowerBook line of laptop computers called Sudden Motion Sensor, or SMS. Other manufacturers also use this technology.

IBM pioneered drives with "head unloading" technology that lifts the heads off the platters onto "ramps" instead of having them rest on the platters, reducing the risk of stiction. Newer drives are designed such that the rotational inertia in the platters is used to safely park the heads in the case of unexpected power loss. However, especially in old models, sudden power interruptions or a power supply failure can result in the drive shutting down with the heads in the data zone, which increases the risk of data loss. Normally, when powering down, a hard disk moves its heads to a safe area of the disk, where no data is ever kept (the landing zone).

Head crashes can be caused by electronic failure, a sudden power failure, physical shock, wear and tear, or poorly manufactured disks. For Giant Magnetoresistive (GMR) heads in particular, a minor head crash from contamination (that does not remove the magnetic surface of the disk) will still result in the head temporarily overheating, due to friction with the disk surface, and renders the disk unreadable until the head temperature stabilizes. Due to the extremely close spacing of the heads and disk surface, any contamination of the read-write heads or disk platters can lead to a head crash — a failure of the disk in which the head scrapes across the platter surface, often grinding away the thin magnetic film. This air passes through an internal filter to remove any leftover contaminants from manufacture, any particles that may have somehow entered the drive, and any particles generated by head crash.

The air inside the operating drive is constantly moving too, being swept in motion by friction with the spinning disk platters. You can see these breather holes on all drives -- they usually have a warning sticker next to them, informing the user not to cover the holes. Very high humidity year-round will cause accelerated wear of the drive's heads (by increasing stiction, or the tendency for the heads to stick to the disk surface, which causes physical damage to the disk and spindle motor). The filter also allows moisture in the air to enter the drive.

They have a permeable filter (a breather filter) between the top cover and inside of the drive, to allow the pressure inside and outside the drive to equalize while keeping out dust and dirt. Hard disk drives are not airtight. This does not apply to pressurized enclosures, like an airplane cabin.) Modern drives include temperature sensors and adjust their operation to the operating environment. (Specially manufactured sealed and pressurized drives are needed for reliable high-altitude operation, above about 10,000 feet.

If the air pressure is too low, the air will not exert enough force on the flying head, the head will not be at the proper height, and there is a risk of head crashes and data loss. A hard disk drive requires a certain range of air pressures in order to operate properly. Another common misconception is that a hard drive is totally sealed. Instead, the system relies on air pressure inside the drive to support the heads at their proper flying height while the disk is in motion.

Contrary to popular belief a hard disk drive does not contain a vacuum. given the submicroscopic gap between the heads and disk. The disk surface and the drive's internal environment must therefore be kept immaculately clean to prevent damage from fingerprints, hair, dust, smoke particles, etc. The hard disk's read-write heads fly on an air bearing (a cushion of air) only nanometres above the disk surface.

The (mostly) sealed enclosure protects the drive internals from dust, condensation, and other sources of contamination. technology, by which impending failures can often be predicted, allowing the user to be alerted in time to prevent data loss. Also, most major hard drive and motherboard vendors now support S.M.A.R.T. Modern drive firmware is capable of scheduling reads and writes efficiently on the disk surfaces and remapping sectors of the disk which have failed.

The associated electronics control the movement of the read-write armature and the rotation of the disk, and perform reads and writes on demand from the disk controller. The armature moves the heads radially across the platters as they spin, allowing each head access to the entirety of the platter. Moving along and between the platters on a common armature are read-write heads, with one head for each platter surface. A typical hard disk drive design consists of a central axis or spindle upon which the platters spin at a constant rotational velocity.

The information can be read by a read-write head which senses electrical change as the magnetic fields pass by in close proximity as the platter rotates. Information is written to the disk by transmitting an electromagnetic flux through an antenna or read-write head that is very close to a magnetic material, which in turn changes its polarization due to the flux. Each platter has a planar magnetic surface on which digital data may be stored. A hard disk uses rigid rotating platters (disks).

. A hard disk drive (HDD, or also hard drive) is a non-volatile data storage device that stores data on a magnetic surface layered onto hard disk platters. 2005 - Introduction of faster SAS (Serial Attached SCSI). 2005 - Serial ATA 3G standardized.

2005 - 500 GB hard drive. 2003 - Serial ATA introduced. 2002 - 137 GB addressing space barrier broken. 1998 - UltraDMA/33 and ATAPI standardized.

1997 - 10 gigabyte hard drive (CS). 1995 - 2 gigabyte hard drive (CS). 1994 - ATA-1 standardized. 1991 - 100 megabyte hard drive (CS).

1986 - Standardization of SCSI. 1980 - first 5.25-inch Winchester drive, the Shugart ST-506, 5 megabyte (CS). 1956 - first commercial hard disk, the IBM 350 RAMAC disk drive, 5 megabyte. (CS) denotes an improvement in the consumer market.

In December 2005, however, Maxtor itself was acquired by Seagate for USD1.9 billion. Quantum bought DEC's storage division in 1994, and later (2000) sold the hard disk division to Maxtor to concentrate on tape drives. In 2003, following the controversy over the mass failures of its Deskstar 75GXP range, hard disk pioneer IBM sold the majority of its disk division to Hitachi, who renamed it Hitachi Global Storage Technologies. JTS infamously merged with Atari in 1996, giving it the capital it needed to bring its drive range into production.

In 1995, Conner Peripherals announced a merger with Seagate (who had earlier bought Imprimis from CDC), which was completed in early 1996. Tandon sold its disk manufacturing division to Western Digital (which was then a controller maker and ASIC house) in 1988; by the early 1990s Western Digital disks were among the top sellers. Random access time: from 5 ms to 15 ms. Outer Zone: from 74.0 MB/sec to 111.4 MB/sec.

Inner Zone: from 44.2 MB/sec to 74.5 MB/sec. Transfer Rate