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Magnetoresistive Random-access Memory
Magnetoresistive random-access memory (MRAM) is a type of non-volatile random-access memory which stores data in magnetic domains. Developed in the mid-1980s, proponents have argued that magnetoresistive RAM will eventually surpass competing technologies to become a dominant or even universal memory. Currently, memory technologies in use such as flash RAM and DRAM have practical advantages that have so far kept MRAM in a niche role in the market. Description Unlike conventional RAM chip technologies, data in MRAM is not stored as electric charge or current flows, but by magnetic storage elements. The elements are formed from two ferromagnetic plates, each of which can hold a magnetization, separated by a thin insulating layer. One of the two plates is a permanent magnet set to a particular polarity; the other plate's magnetization can be changed to match that of an external field to store memory. This configuration is known as a magnetic tunnel junction and is the simplest st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-volatile Random-access Memory
Non-volatile random-access memory (NVRAM) is random-access memory that retains data without applied power. This is in contrast to dynamic random-access memory (DRAM) and static random-access memory (SRAM), which both maintain data only for as long as power is applied, or forms of sequential-access memory such as magnetic tape, which cannot be randomly accessed but which retains data indefinitely without electric power. Read-only memory devices can be used to store system firmware in embedded systems such as an automotive ignition system control or home appliance. They are also used to hold the initial processor instructions required to bootstrap a computer system. Read-write memory can be used to store calibration constants, passwords, or setup information, and may be integrated into a microcontroller. If the main memory of a computer system were non-volatile, it would greatly reduce the time required to start a system after a power interruption. Current existing types of semi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Magnetoresistance
Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance effect observed in multilayers composed of alternating ferromagnetic and non-magnetic conductive layers. The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter Grünberg for the discovery of GMR. The effect is observed as a significant change in the electrical resistance depending on whether the magnetization of adjacent ferromagnetic layers are in a parallel or an antiparallel alignment. The overall resistance is relatively low for parallel alignment and relatively high for antiparallel alignment. The magnetization direction can be controlled, for example, by applying an external magnetic field. The effect is based on the dependence of electron scattering on spin orientation. The main application of GMR is in magnetic field sensors, which are used to read data in hard disk drives, biosensors, microelectromechanical systems (MEMS) and other devices. GMR multilayer structures are also used in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SONOS
SONOS, short for "silicon–oxide–nitride–oxide–silicon", more precisely, " polycrystalline silicon"—"silicon dioxide"—"silicon nitride"—"silicon dioxide"—"silicon", is a cross sectional structure of MOSFET (metal-oxide-semiconductor field-effect transistor), realized by P.C.Y. Chen of Fairchild Camera and Instrument in 1977. This structure is often used for non-volatile memories, such as EEPROM and flash memories. It is sometimes used for TFT LCD displays. It is one of CTF (charge trap flash) variants. It is distinguished from traditional non-volatile memory structures by the use of silicon nitride (Si3N4 or Si9N10) instead of "polysilicon-based FG (floating-gate)" for the charge storage material. A further variant is "SHINOS" ("silicon"—" hi-k"—"nitride"—"oxide"—"silicon"), which is substituted top oxide layer with high-κ material. Another advanced variant is "MONOS" ("metal–oxide–nitride–oxide–silicon"). Companies offering SONOS-based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroelectric RAM
Ferroelectric RAM (FeRAM, F-RAM or FRAM) is a random-access memory similar in construction to DRAM but using a ferroelectric layer instead of a dielectric layer to achieve non-volatility. FeRAM is one of a growing number of alternative non-volatile random-access memory technologies that offer the same functionality as flash memory. An FeRAM chip contains a thin film of ferroelectric material, often lead zirconate titanate, commonly referred to as PZT. The atoms in the PZT layer change polarity in an electric field, thereby producing a power-efficient binary switch. However, the most important aspect of the PZT is that it is not affected by power disruption or magnetic interference, making FeRAM a reliable nonvolatile memory. FeRAM's advantages over Flash include: lower power usage, faster write performance and a much greater maximum read/write endurance (about 1010 to 1015 cycles). FeRAMs have data retention times of more than 10 years at +85 °C (up to many decades at lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Processing Unit
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions in the program. This contrasts with external components such as main memory and I/O circuitry, and specialized processors such as graphics processing units (GPUs). The form, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the fetching (from memory), decoding and execution (of instructions) by directing the coordinated operations of the ALU, registers and other co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CPU Cache
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core, which stores copies of the data from frequently used main memory locations. Most CPUs have a hierarchy of multiple cache levels (L1, L2, often L3, and rarely even L4), with different instruction-specific and data-specific caches at level 1. The cache memory is typically implemented with static random-access memory (SRAM), in modern CPUs by far the largest part of them by chip area, but SRAM is not always used for all levels (of I- or D-cache), or even any level, sometimes some latter or all levels are implemented with eDRAM. Other types of caches exist (that are not counted towards the "cache size" of the most important caches mentioned above), such as the translation lookaside buffer (TLB) which is part of the memory management unit (MMU) w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information – a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems. Flip-flops and latches are used as data storage elements. A flip-flop is a device which stores a single ''bit'' (binary digit) of data; one of its two states represents a "one" and the other represents a "zero". Such data storage can be used for storage of ''state'', and such a circuit is described as sequential logic in electronics. When used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state (and hence, previous inputs). It can also b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Random-access Memory
Static random-access memory (static RAM or SRAM) is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed. The term ''static'' differentiates SRAM from DRAM (''dynamic'' random-access memory) — SRAM will hold its data permanently in the presence of power, while data in DRAM decays in seconds and thus must be periodically refreshed. SRAM is faster than DRAM but it is more expensive in terms of silicon area and cost; it is typically used for the cache and internal registers of a CPU while DRAM is used for a computer's main memory. History Semiconductor bipolar SRAM was invented in 1963 by Robert Norman at Fairchild Semiconductor. MOS SRAM was invented in 1964 by John Schmidt at Fairchild Semiconductor. It was a 64-bit MOS p-channel SRAM. The SRAM was the main driver behind any new CMOS-based technology fabrication process since 1959 when CMOS was invented. In 1965 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physikalisch-Technische Bundesanstalt
The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute of the Federal Republic of Germany, with scientific and technical service tasks. It is a higher federal authority and a public-law institution directly under federal government control, without legal capacity, under the auspices of the Federal Ministry for Economic Affairs and Energy. Tasks Together with NIST in the USA and the NPL in Great Britain, PTB ranks among the leading metrology institutes in the world. As the National Metrology Institute of Germany, PTB is Germany's highest and only authority in terms of correct and reliable measurements. The Units and Time Act Bundesgesetzblatt (Federal Law Gazette), volume 2008, part I, No. 28, p. 1185 ff., 11 July 2008] assigns all tasks which are related with the realization and dissemination of the units to PTB. All legally relevant aspects regarding the units as well as PTB’s responsibilities have been combined in this Act. Previously, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charge Pump
A charge pump is a kind of DC-to-DC converter that uses capacitors for energetic charge storage to raise or lower voltage. Charge-pump circuits are capable of high efficiencies, sometimes as high as 90–95%, while being electrically simple circuits. Description Charge pumps use some form of switching device to control the connection of a supply voltage across a load through a capacitor. In a two stage cycle, in the first stage a capacitor is connected across the supply, charging it to that same voltage. In the second stage the circuit is reconfigured so that the capacitor is in series with the supply and the load. This doubles the voltage across the load - the sum of the original supply and the capacitor voltages. The pulsing nature of the higher voltage switched output is often smoothed by the use of an output capacitor. An external or secondary circuit drives the switching, typically at tens of kilohertz up to several megahertz. The high frequency minimizes the amount of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-power Electronics
Low-power electronics are electronics, such as notebook processors, that have been designed to use less electric power than usual, often at some expense. In the case of notebook processors, this expense is processing power; notebook processors usually consume less power than their desktop counterparts, at the expense of lower processing power. History Watches The earliest attempts to reduce the amount of power required by an electronic device were related to the development of the wristwatch. Electronic watches require electricity as a power source, and some mechanical movements and hybrid electromechanical movements also require electricity. Usually, the electricity is provided by a replaceable battery. The first use of electrical power in watches was as a substitute for the mainspring, to remove the need for winding. The first electrically powered watch, the Hamilton Electric 500, was released in 1957 by the Hamilton Watch Company of Lancaster, Pennsylvania. The first quartz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Refresh
Memory refresh is the process of periodically reading information from an area of computer memory and immediately rewriting the read information to the same area without modification, for the purpose of preserving the information."refresh cycle" in Memory refresh is a background maintenance process required during the operation of semiconductor dynamic random-access memory (DRAM), the most widely used type of computer memory, and in fact is the defining characteristic of this class of memory. In a DRAM chip, each bit of memory data is stored as the presence or absence of an electric charge on a small capacitor on the chip. As time passes, the charges in the memory cells leak away, so without being refreshed the stored data would eventually be lost. To prevent this, external circuitry periodically reads each cell and rewrites it, restoring the charge on the capacitor to its original level. Each memory refresh cycle refreshes a succeeding area of memory cells, thus repeatedly re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
