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Memory Controller
The memory controller is a digital circuit that manages the flow of data going to and from the computer's main memory. A memory controller can be a separate chip or integrated into another chip, such as being placed on the same die or as an integral part of a microprocessor; in the latter case, it is usually called an integrated memory controller (IMC). A memory controller is sometimes also called a memory chip controller (MCC) or a memory controller unit (MCU). A common form of memory controller is the memory management unit (MMU) which in many operating systems implements virtual addressing. History Most modern desktop or workstation microprocessors use an ''integrated memory controller'' (IMC), including microprocessors from Intel, AMD, and those built around the ARM architecture. Prior to K8 (circa 2003), AMD microprocessors had a memory controller implemented on their motherboard's northbridge. In K8 and later, AMD employed an integrated memory controller. Likewis ...
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Main Memory
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann arch ...
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UltraSPARC T1
Sun Microsystems' UltraSPARC T1 microprocessor, known until its 14 November 2005 announcement by its development codename "Niagara", is a multithreading, multicore CPU. Designed to lower the energy consumption of server computers, the CPU typically uses 72 W of power at 1.4 GHz. Afara Websystems pioneered a radical thread-heavy SPARC design. The company was purchased by Sun, and the intellectual property became the foundation of the CoolThreads line of processors, starting with the T1. The T1 is a new-from-the-ground-up SPARC microprocessor implementation that conforms to thUltraSPARC Architecture 2005 specificationand executes the full SPARC V9 instruction set. Sun has produced two previous multicore processors (UltraSPARC IV and IV+), but UltraSPARC T1 was its first microprocessor that is both multicore ''and'' multithreaded. Security was built-in from the very first release on silicon, with hardware cryptographic units in the T1, unlike general purpose processor from ...
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Capacitors
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of a capacitor is known as capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit. The capacitor was originally known as the condenser, a term still encountered in a few compound names, such as the ''condenser microphone''. The physical form and construction of practical capacitors vary widely and many types of capacitor are in common use. Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, or an electrolyte. The nonconducting dielectric acts to increase the capacitor's char ...
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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 ...
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Dynamic Random Access Memory
Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxide-semiconductor (MOS) technology. While most DRAM memory cell designs use a capacitor and transistor, some only use two transistors. In the designs where a capacitor is used, the capacitor can either be charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. The electric charge on the capacitors gradually leaks away; without intervention the data on the capacitor would soon be lost. To prevent this, DRAM requires an external ''memory refresh'' circuit which periodically rewrites the data in the capacitors, restoring them to their original charge. This refresh process is the defining characteristic of dynamic random-access memory, in contrast to static random-access memory (SRA ...
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L4 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) whic ...
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DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal computers, workstations, printers, and servers. They are the predominant method for adding memory into a computer system. The vast majority of DIMMs are standardized through JEDEC standards, although there are proprietary DIMMs. DIMMs come in a variety of speeds and sizes, but generally are one of two lengths - PC which are and laptop (SO-DIMM) which are about half the size at . History DIMMs (Dual In-line Memory Module) were a 1990s upgrade for SIMMs (Single In-line Memory Modules) as Intel P5-based Pentium processors began to gain market share. The Pentium had a 64-bit bus width, which would require SIMMs installed in matched pairs in order to populate the data bus. The processor would then access the two SIMMs in parallel. DIMMs were i ...
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Centaur (computing)
POWER8 is a family of superscalar multi-core microprocessors based on the Power ISA, announced in August 2013 at the Hot Chips conference. The designs are available for licensing under the OpenPOWER Foundation, which is the first time for such availability of IBM's highest-end processors. Systems based on POWER8 became available from IBM in June 2014. Systems and POWER8 processor designs made by other OpenPOWER members were available in early 2015. Design POWER8 is designed to be a massively multithreaded chip, with each of its cores capable of handling eight hardware threads simultaneously, for a total of 96 threads executed simultaneously on a 12-core chip. The processor makes use of very large amounts of on- and off-chip eDRAM caches, and on-chip memory controllers enable very high bandwidth to memory and system I/O. For most workloads, the chip is said to perform two to three times as fast as its predecessor, the POWER7. POWER8 chips comes in 6- or 12-core variants; ea ...
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POWER8
POWER8 is a family of superscalar multi-core microprocessors based on the Power ISA, announced in August 2013 at the Hot Chips conference. The designs are available for licensing under the OpenPOWER Foundation, which is the first time for such availability of IBM's highest-end processors. Systems based on POWER8 became available from IBM in June 2014. Systems and POWER8 processor designs made by other OpenPOWER members were available in early 2015. Design POWER8 is designed to be a massively multithreaded chip, with each of its cores capable of handling eight hardware threads simultaneously, for a total of 96 threads executed simultaneously on a 12-core chip. The processor makes use of very large amounts of on- and off-chip eDRAM caches, and on-chip memory controllers enable very high bandwidth to memory and system I/O. For most workloads, the chip is said to perform two to three times as fast as its predecessor, the POWER7. POWER8 chips comes in 6- or 12-core variants; e ...
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PA-7300LC
The PA-7100LC is a microprocessor that implements the PA-RISC 1.1 instruction set architecture (ISA) developed by Hewlett-Packard (HP). It is also known as the ''PCX-L'', and by its code-name, ''Hummingbird''. It was designed as a low-cost microprocessor for low-end systems. The first systems to feature the PA-7100LC were introduced in January 1994. These systems used 60 and 80 MHz parts. A 100 MHz part debuted in June 1994. The PA-7100LC was the first PA-RISC microprocessor to implement the MAX-1 multimedia instructions, an early single instruction, multiple data (SIMD) multimedia instruction set extension that provided instructions for improving the performance of MPEG video decoding. The PA-7100LC was based on the PA-7100. Major improvements were improved superscalar execution and an extra integer unit. The PA-7100LC also implemented architectural improvements including the MAX-1 multimedia instructions, uncacheable memory pages, and bi-endian support. Superscalar e ...
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Alpha 21066
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which is the West Semitic word for " ox". Letters that arose from alpha include the Latin letter A and the Cyrillic letter А. Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ( ː or short ( . Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ. * ὥρα = ὥρᾱ ''hōrā'' "a time" * γλῶσσα = γλῶσσᾰ ''glôssa'' "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent the open front unrounded vowel . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks ...
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Northbridge (computing)
In computing, a northbridge (also host bridge, or memory controller hub) is one of two chips comprising the core logic chipset architecture on a PC motherboard. A northbridge is connected directly to a CPU via the front-side bus (FSB) to handle high-performance tasks, and is usually used in conjunction with a slower southbridge to manage communication between the CPU and other parts of the motherboard. Since the 2010s, die shrink and improved transistor density have allowed for increasing chipset integration, and the functions performed by northbridges are now often incorporated into other components (like southbridges or CPUs themselves). As of 2019, Intel and AMD had both released chipsets in which all northbridge functions had been integrated into the CPU. Modern Intel Core processors have the northbridge integrated on the CPU die, where it is known as the uncore or system agent. On older Intel based PCs, the northbridge was also named external memory controller hub ('' ...
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