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Western Digital Raptor
The Western Digital Raptor (often marketed as WD Raptor, 2.5" models known as VelociRaptor) is a discontinued series of high performance hard disk drives produced by Western Digital first marketed in 2003. The drive occupied a niche in the enthusiast, workstation and small-server market. Traditionally, the majority of servers used hard drives featuring a SCSI interface because of their advantages in both performance and reliability over consumer-level ATA drives. Although pitched as an “enterprise-class drive”, it won favor with the PC gaming and enthusiast community because the drive was capable of speeds usually found only on more expensive SCSI drives. Adopting the SATA interface meant that it could be used easily on all modern motherboards with no separate host adapter card. Also, integration was made easier still by the inclusion of a standard 4-pin Molex power connector in addition to the standard SATA power port. This, however, was available only in 3.5" models. De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Drive Platter
A hard disk drive platter or hard disk is the circular magnetic disk on which digital data is stored in a hard disk drive. The rigid nature of the platters is what gives them their name (as opposed to the flexible materials which are used to make floppy disks). Hard drives typically have several platters which are mounted on the same spindle. A platter can store information on both sides, typically requiring two recording heads per platter, one per surface. Design The magnetic surface of each platter is divided into small sub-micrometer-sized magnetic regions, each of which is used to represent a single binary unit of information. A typical magnetic region on a hard-disk platter (as of 2006) is about 200–250 nanometers wide (in the radial direction of the platter) and extends about 25–30 nanometers in the down-track direction (the circumferential direction on the platter), corresponding to about 100 billion bits per square inch of disk area (15.5 Gbit/cm2). The ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycarbonate
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transparent. They are easily worked, injection molding, molded, and thermoforming, thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique resin identification code, resin identification code (RIC) and are identified as "Other", 7 on the RIC list. Products made from polycarbonate can contain the precursor monomer bisphenol A (BPA). Structure Carbonate esters have planar OC(OC)2 cores, which confer rigidity. The unique O=C bond is short (1.173 Å in the depicted example), while the C-O bonds are more ether-like (the bond distances of 1.326 Å for the example depicted). Polycarbonates received their name because they are polymers containing carbonate ester, carbonate groups (−O−( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Native Command Queuing
In computing, Native Command Queuing (NCQ) is an extension of the Serial ATA protocol allowing hard disk drives to internally optimize the order in which received read and write commands are executed. This can reduce the amount of unnecessary drive head movement, resulting in increased performance (and slightly decreased wear of the drive) for workloads where multiple simultaneous read/write requests are outstanding, most often occurring in Server (computing), server-type applications. History Native Command Queuing was preceded by Parallel ATA's version of Tagged Command Queuing (TCQ). ATA's attempt at integrating TCQ was constrained by the requirement that ATA host bus adapters use Industry Standard Architecture, ISA bus device protocols to interact with the operating system. The resulting high CPU overhead and negligible performance gain contributed to a lack of market acceptance for ATA TCQ. NCQ differs from TCQ in that, with NCQ, each command is of equal importance, but NCQ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BIOS
In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the booting process (power-on startup). The firmware comes pre-installed on the computer's motherboard. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS firmware was originally proprietary to the IBM PC; it was reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. The interface of that original system serves as a ''de facto'' standard. The BIOS in older PCs initializes and tests the system hardware components ( power-on self-test or POST for short), and loads a boot loader from a mass storage device which then initializes a kernel. In the era of DOS, the BIOS provided BIOS interrupt calls for the keyboard, display, st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megabyte
The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities. In the computer and information technology fields, other definitions have been used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as (220 B), a quantity that conveniently expresses the binary architecture of digital computer memory. Standards bodies have deprecated this binary usage of the mega- prefix in favor of a new set of binary prefixes, by means of which the quantity 220 B is named mebibyte (symbol MiB). Definitions The unit megabyte is commonly used for 10002 (one million) bytes or 10242 bytes. The interpretation of using base 1024 originated as technical jargon for the byte m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Bearing
Fluid bearings are bearing (mechanical), bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly. They can be broadly classified into two types: fluid dynamic bearings (also known as hydrodynamic bearings) and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and is pressurized by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces. Fluid bearings are frequently used in high load, high speed or high precision applications where ordinary ball bea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Western Digital WD740 1 (dark1)
Hard means something that is difficult to do. It may also refer to: * Hardness, resistance of physical materials to deformation or fracture * Hard water, water with high mineral content Arts and entertainment * ''Hard'' (TV series), a French TV series * Hard (band), a Hungarian hard rock supergroup * Hard (music festival), in the U.S. Albums * ''Hard'' (EP), Goodbye Mr Mackenzie, 1993 * ''Hard'' (Brainpower album), 2008 * ''Hard'' (Gang of Four album), 1983 * ''Hard'' (Jagged Edge album), 2003 * ''Hard'' (Shinee album), 2023, and its title track * ''Hard'', a 2017 EP from the band The Neighbourhood Songs * "Hard" (Rihanna song), 2009 * "Hard" (Sophie song), 2014 * "Hard", a song by Royce da 5'9" from the 2016 album ''Layers'' * "Hard", a song by Why Don't We from the 2018 album ''8 Letters'' * "Hard", a song by Poppy from the 2023 album ''Zig'' Places * Hard, Austria * Hard (Zürich), Switzerland Other uses * Hard (surname) * Hard architecture, impersonal windowless b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megabyte
The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities. In the computer and information technology fields, other definitions have been used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as (220 B), a quantity that conveniently expresses the binary architecture of digital computer memory. Standards bodies have deprecated this binary usage of the mega- prefix in favor of a new set of binary prefixes, by means of which the quantity 220 B is named mebibyte (symbol MiB). Definitions The unit megabyte is commonly used for 10002 (one million) bytes or 10242 bytes. The interpretation of using base 1024 originated as technical jargon for the byte m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revolutions Per Minute
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 defines a physical quantity called ''rotation'' (or ''number of revolutions''), dimensionless, whose instantaneous rate of change is called ''rotational frequency'' (or ''rate of rotation''), with units of reciprocal seconds (s−1). A related but distinct quantity for describing rotation is ''angular frequency'' (or ''angular speed'', the magnitude of angular velocity), for which the SI unit is the radian per second (rad/s). Although they have the same dimensions (reciprocal time) and base unit (s−1), the hertz (Hz) and radians per second (rad/s) are special names used to express two different but proportional ISQ quantities: frequency and angular frequency, respectively. The conversions between a frequency and an angular frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
