System Agent
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System Agent
"Uncore" is a term used by Intel to describe the functions of a microprocessor that are not in the core, but which must be closely connected to the core to achieve high performance. It has been called "system agent" since the release of the Sandy Bridge microarchitecture. Details Typical processor cores contains the components of the processor involved in executing instructions, including the ALU, FPU, L1 and L2 cache. In contrast, Uncore functions include QPI controllers, L3 cache, snoop agent pipeline, on-die memory controller, on-die PCI Express Root Complex, and Thunderbolt controller. Other bus controllers such as SPI and LPC are part of the chipset. The Intel uncore design stems from its origin as the northbridge. The design of the Intel uncore reorganizes the functions critical to the core, making them physically closer to the core on-die, thereby reducing their access latency. Specifically, the microarchitecture of the Intel uncore is broken down into a number ...
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Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer components such as central processing units (CPUs) and related products for business and consumer markets. It is one of the world's List of largest semiconductor chip manufacturers, largest semiconductor chip manufacturers by revenue, and ranked in the Fortune 500, ''Fortune'' 500 list of the List of largest companies in the United States by revenue, largest United States corporations by revenue for nearly a decade, from 2007 to 2016 Fiscal year, fiscal years, until it was removed from the ranking in 2018. In 2020, it was reinstated and ranked 45th, being the List of Fortune 500 computer software and information companies, 7th-largest technology company in the ranking. It was one of the first companies listed on Nasdaq. Intel supplies List of I ...
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Memory Coherence
Memory coherence is an issue that affects the design of computer systems in which two or more Central processing unit, processors or Multi core, cores share a common area of memory (computers), memory. In a uniprocessor system (where there exists only one core), there is only one processing element doing all the work and therefore only one processing element that can read or write from/to a given memory location. As a result, when a value is changed, all subsequent read operations of the corresponding memory location will see the updated value, even if it is cache (computing), cached. Conversely, in multiprocessor (or Multi core, multicore) systems, there are two or more processing elements working at the same time, and so it is possible that they simultaneously access the same memory location. Provided none of them changes the data in this location, they can share it indefinitely and cache it as they please. But as soon as one updates the location, the others might work on an out-o ...
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Last Level 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 (computer science), 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 #MULTILEVEL, 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 ...
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Northbridge (computing)
In computing, a northbridge (also host bridge, or memory controller hub) is a microchip that comprises the core logic chipset architecture on motherboards to handle high-performance tasks, especially for older personal computers. It is connected directly to a CPU via the front-side bus (FSB), and is usually used in conjunction with a slower southbridge to manage communication between the CPU and other parts of the motherboard. Historically, separation of functions between CPU, northbridge, and southbridge chips was necessary due to the difficulty of integrating all components onto a single chip die. However, as CPU speeds increased over time, a bottleneck emerged due to limitations caused by data transmission between the CPU and its support chipset. The trend for integrated northbridges began near the end of the 2000s for example, the Nvidia GeForce 320M GPU in the 2010 MacBook Air was a northbridge/southbridge/GPU combo chip. On older Intel based PCs, the northbridge was ...
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Chipset
In a computer system, a chipset is a set of electronic components on one or more integrated circuits that manages the data flow between the processor, memory and peripherals. The chipset is usually found on the motherboard of computers. Chipsets are usually designed to work with a specific family of microprocessors. Because it controls communications between the processor and external devices, the chipset plays a crucial role in determining system performance. Sometimes the term "chipset" is used to describe a system on chip (SoC) used in a mobile phone. Computers In computing, the term ''chipset'' commonly refers to a set of specialized chips on a computer's motherboard or an expansion card. In personal computers, the first chipset for the IBM PC AT of 1984 was the NEAT chipset developed by Chips and Technologies for the Intel 80286 CPU. In home computers, game consoles, and arcade hardware of the 1980s and 1990s, the term ''chipset'' was used for the custom audio ...
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Low Pin Count
The Low Pin Count (LPC) bus is a computer bus used on IBM-compatible personal computers to connect low-bandwidth devices to the CPU, such as the BIOS ROM (BIOS ROM was moved to the Serial Peripheral Interface (SPI) bus in 2006), "legacy" I/O devices (integrated into Super I/O, Embedded Controller, CPLD, and/or IPMI chip), and Trusted Platform Module (TPM). "Legacy" I/O devices usually include serial and parallel ports, PS/2 keyboard, PS/2 mouse, and floppy disk controller. Most PC motherboards with an LPC bus have either a Platform Controller Hub (PCH) or a southbridge chip, which acts as the host and controls the LPC bus. All other devices connected to the physical wires of the LPC bus are peripherals. Overview The LPC bus was introduced by Intel in 1998 as a software-compatible substitute for the Industry Standard Architecture (ISA) bus. It resembles ISA to software, although physically it is quite different. The ISA bus has a 16-bit data bus and a 24-bit add ...
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Serial Peripheral Interface Bus
Serial Peripheral Interface (SPI) is a de facto standard (with many #Variations, variants) for Comparison of synchronous and asynchronous signalling, synchronous serial communication, used primarily in embedded systems for short-distance wired communication between integrated circuits. SPI follows a master–slave (technology), master–slave architecture, where a master device Signaling (telecommunications), orchestrates communication with one or more slave devices by driving the clock signal, clock and chip select signals. Some devices support changing master and slave roles on the fly. Motorola's original specification (from the early 1980s) uses four logic signals, aka lines or wires, to support full duplex communication. It is sometimes called a ''four-wire'' serial bus to contrast with Serial Peripheral Interface#Three-wire, three-wire variants which are half duplex, and with the ''two-wire'' I²C and 1-Wire serial buses. Typical #Applications, applications include interf ...
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Thunderbolt (interface)
Thunderbolt is the brand name of a Interface (computing)#Hardware interfaces, hardware interface for the connection of external peripherals to a computer. It was developed by Intel in collaboration with Apple Inc., Apple. It was initially marketed under the name Light Peak, and first sold as part of an end-user product on 24 February 2011. Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into two Serial communication, serial signals and provides Direct current, DC power via a single cable. Up to six peripherals may be supported by one connector through various Network topology, topologies. Thunderbolt 1 and 2 use the same electrical connector, connector as Mini DisplayPort (MDP), whereas Thunderbolt 3, 4, and 5 use the USB-C connector, and support USB devices. Description Thunderbolt controllers multiplexing, multiplex one or more individual data lanes from connected PCIe and DisplayPort devices for transmission via two duplex Thunderbolt lanes, then de-multip ...
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PCI Express Root Complex
In a PCI Express (PCIe) system, a root complex device connects the CPU and memory subsystem to the PCI Express switch fabric composed of one or more PCIe or PCI devices. A root complex is sometimes referred to PCI root bridge. The root complex generates transaction requests on behalf of the CPU A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ..., which is interconnected through a local bus. Root complex functionality may be integrated in the chipset and/or the CPU. A root complex may contain more than one PCI Express port and multiple switch devices can be connected to ports on the root complex or cascaded. Device Memory Map The PCIe Root Complex holds a master copy of a 'Type 1 Configuration Table' that defines the host memory space that is accessible from each Endpoint device ...
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Memory Controller
A memory controller, also known as memory chip controller (MCC) or a memory controller unit (MCU), is a digital circuit that manages the flow of data going to and from a computer's main memory. When a memory controller is integrated into another chip, such as an integral part of a microprocessor, it is usually called an integrated memory controller (IMC). Memory controllers contain the logic necessary to read and write to dynamic random-access memory (DRAM), and to provide the critical memory refresh and other functions. Reading and writing to DRAM is performed by selecting the row and column data addresses of the DRAM as the inputs to the multiplexer circuit, where the demultiplexer on the DRAM uses the converted inputs to select the correct memory location and return the data, which is then passed back through a multiplexer to consolidate the data in order to reduce the required bus width for the operation. Memory controllers' bus widths range from 8-bit in earlier systems ...
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Instruction Pipeline
In computer engineering, instruction pipelining is a technique for implementing instruction-level parallelism within a single processor. Pipelining attempts to keep every part of the processor busy with some instruction by dividing incoming Machine code, instructions into a series of sequential steps (the eponymous "Pipeline (computing), pipeline") performed by different Central processing unit#Structure and implementation, processor units with different parts of instructions processed in parallel. Concept and motivation In a pipelined computer, instructions flow through the central processing unit (CPU) in stages. For example, it might have one stage for each step of the von Neumann architecture, von Neumann cycle: Fetch the instruction, fetch the operands, do the instruction, write the results. A pipelined computer usually has "pipeline registers" after each stage. These store information from the instruction and calculations so that the logic gates of the next stage can do th ...
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L3 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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