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Sudden Motion Sensor
The Sudden Motion Sensor (SMS) is Apple's motion-based data protection system used in their notebook computer systems. Apple introduced the system January 1, 2005 in its refreshed PowerBook line, and included it in the iBook line July 26, 2005. Since that time, Apple has included the system in all of their non-SSD portable systems (since October 2006), now the MacBook Pro and MacBook Air. With a triaxial accelerometer, the shock detector detects sudden acceleration, such as when the computer is dropped, and prepares the relatively fragile hard disk drive mechanism for impact. The system disengages the disk drive heads from the hard disk platters, preventing data loss and drive damage from a disk head crash. When the computer is stable, the drive operates normally again. A clicking noise can be heard when the sudden motion sensor activates. Broadly speaking, there have been two types of Sudden Motion Sensor. The sensor used in the G4-based laptops resolved shifts of 1/52 g ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Apple Inc
Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company by market capitalization, the fourth-largest personal computer vendor by unit sales and second-largest mobile phone manufacturer. It is one of the Big Five American information technology companies, alongside Alphabet, Amazon, Meta, and Microsoft. Apple was founded as Apple Computer Company on April 1, 1976, by Steve Wozniak, Steve Jobs and Ronald Wayne to develop and sell Wozniak's Apple I personal computer. It was incorporated by Jobs and Wozniak as Apple Computer, Inc. in 1977 and the company's next computer, the Apple II, became a best seller and one of the first mass-produced microcomputers. Apple went public in 1980 to instant financial success. The company developed computers featuring innovative graphical user interface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hard Disk Drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk 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 a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box. Introduced by IBM in 1956, HDDs 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 cell phones and tablets, rely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Active Hard-drive Protection
In computer hardware, active hard-drive protection refers to technology that attempts to avoid or reduce mechanical damage to hard disk drives by preparing the disk prior to impact. This approach is mainly used in laptop computers that are frequently carried around and more prone to impacts than desktop computers. Implementation Usually the system consists of accelerometers that alert the system when excess acceleration or vibration is detected. The software then tells the hard disk to unload its heads to prevent them from coming in contact with the platter, thus potentially preventing head crash. Many laptop vendors have implemented this technology under different names. Some hard-disk drives also include this technology, needing no cooperation from the system. See also * Hard disk drive failure * Head crash A head crash is a hard-disk failure that occurs when a read–write head of a hard disk drive makes contact with its rotating platter, slashing its surface and per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Western Digital
Western Digital Corporation (WDC, commonly known as Western Digital or WD) is an American computer drive manufacturer and data storage company, headquartered in San Jose, California. It designs, manufactures and sells data technology products, including data storage devices, data center systems and cloud storage services. Western Digital has a long history in the electronics industry as an integrated circuit maker and a storage products company. It is one of the largest computer hard disk drive manufacturers, along with producing solid state drives and flash memory devices. Its competitors include the data management and storage companies Seagate Technology and Micron Technology. History 1970s Western Digital was founded on April 23, 1970, by Alvin B. Phillips, a Motorola employee, as General Digital Corporation, initially a manufacturer of MOS test equipment. It was originally based in Newport Beach, California, shortly thereafter moving to Santa Ana, California, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Kernel Panic
A kernel panic (sometimes abbreviated as KP) is a safety measure taken by an operating system's kernel upon detecting an internal fatal error in which either it is unable to safely recover or continuing to run the system would have a higher risk of major data loss. The term is largely specific to Unix and Unix-like systems. The equivalent on Microsoft Windows operating systems is a stop error, often called a "blue screen of death". The kernel routines that handle panics, known as panic() in AT&T-derived and BSD Unix source code, are generally designed to output an error message to the console, dump an image of kernel memory to disk for post-mortem debugging, and then either wait for the system to be manually rebooted, or initiate an automatic reboot. The information provided is of a highly technical nature and aims to assist a system administrator or software developer in diagnosing the problem. Kernel panics can also be caused by errors originating outside kernel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gravitational Acceleration
In physics, gravitational acceleration is the acceleration of an object in free fall within a vacuum (and thus without experiencing drag (physics), drag). This is the steady gain in speed caused exclusively by the force of gravitational attraction. All bodies accelerate in vacuum at the same rate, regardless of the masses or compositions of the bodies; the measurement and analysis of these rates is known as gravimetry. At a fixed point on the surface, the magnitude of gravity of Earth, Earth's gravity results from combined effect of gravitation and the centrifugal force from Earth's rotation. At different points on Earth's surface, the free fall acceleration ranges from , depending on altitude, latitude, and longitude. A conventional standard gravity, standard value is defined exactly as . Locations of significant variation from this value are known as gravity anomaly, gravity anomalies. This does not take into account other effects, such as buoyancy or drag. Relation to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Head Crash
A head crash is a hard-disk failure that occurs when a read–write head of a hard disk drive makes contact with its rotating platter, slashing its surface and permanently damaging its magnetic media. It is most often caused by a sudden severe motion of the disk, for example the jolt caused by dropping a laptop to the ground while it is operating or physically shocking a computer. Head details A head normally rides on a thin film of moving air entrapped at the surface of its platter (some drives manufactured by Conner Peripherals in the mid-1990s used a thin liquid layer instead). The distance between the head and platter is called the flying height. The topmost layer of the platter is made of a Teflon-like material that acts like a lubricant. Underneath is a layer of sputtered carbon. These two layers protect the magnetic layer (data storage area) from most accidental touches of the read-write head. The disk read-and-write head is made using thin film techniques that i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hard Disk Platters
A hard disk drive platter (or disk) is the circular disk on which magnetic data is stored in a hard disk drive. The rigid nature of the platters in a hard drive 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, requiring two heads per platter. 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 material of the main ''magnetic medium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Disk Read-and-write Head
A disk read-and-write head is the small part of a disk drive which moves above the disk platter and transforms the platter's magnetic field into electrical current (reads the disk) or, vice versa, transforms electrical current into magnetic field (writes the disk). The heads have gone through a number of changes over the years. In a hard drive, the heads ''fly'' above the disk surface with clearance of as little as 3 nanometres. The flying height has been decreasing with each new generation of technology to enable higher areal density. The flying height of the head is controlled by the design of an air bearing etched onto the disk-facing surface of the ''slider''. The role of the air bearing is to maintain the flying height constant as the head moves over the surface of the disk. The air bearings are carefully designed to maintain the same height across the entire platter, despite differing speeds depending on the head distance from the center of the platter. If the head hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass. The SI unit for acceleration is metre per second squared (, \mathrm). For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Data Protection
Information privacy is the relationship between the collection and dissemination of data, technology, the public expectation of privacy, contextual information norms, and the legal and political issues surrounding them. It is also known as data privacy or data protection. Data privacy is challenging since attempts to use data while protecting an individual's privacy preferences and personally identifiable information. The fields of computer security, data security, and information security all design and use software, hardware, and human resources to address this issue. Authorities Laws Authorities by country Information types Various types of personal information often come under privacy concerns. Cable television This describes the ability to control what information one reveals about oneself over cable television, and who can access that information. For example, third parties can track IP TV programs someone has watched at any given time. "The addition of any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Shock Detector
A shock detector, shock indicator, or impact monitor is a device which indicates whether a physical shock or impact has occurred. These usually have a binary output ( go/no-go) and are sometimes called ''shock overload devices''. Shock detectors can be used on shipments of fragile valuable items to indicate whether a potentially damaging drop or impact may have occurred. They are also used in sports helmets to help estimate if a dangerous impact may have occurred.Harris, C. M., and Peirsol, A. G. "Shock and Vibration Handbook", 2001, McGraw Hill, ISBN 0-07-137081-1 By contrast, a shock data logger is a data acquisition system for analysis and recording of shock pulses. Overview Shocks and impacts are often specified by the peak acceleration expressed in g-s (sometimes called g-forces). The form of the shock pulse and particularly the duration are equally important. For example, a short 1 ms 300 g shock has little damage potential and is not usually of interest but a 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |