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A system on a chip or system on chip (SoC or SOC) is an integrated circuit (IC) that integrates all components of a computer or other electronic system into a single chip. It may contain digital, analog, mixed-signal, and often radio-frequency functions—all on a single chip substrate. SoCs are very common in the mobile electronics market because of their low power consumption.〔Pete Bennett, EE Times. "(The why, where and what of low-power SoC design )." December 2, 2004. Retrieved July 28, 2015.〕 A typical application is in the area of embedded systems. The contrast with a microcontroller is one of degree. Microcontrollers typically have under 100 KB of RAM (often just a few kilobytes) and often really ''are'' single-chip-systems, whereas the term SoC is typically used for more powerful processors, capable of running software such as the desktop versions of Windows and Linux, which need external memory chips (flash, RAM) to be useful, and which are used with various external peripherals. In short, for larger systems, the term ''system on a chip'' is hyperbole, indicating technical direction more than reality: a high degree of chip integration, leading toward reduced manufacturing costs, and the production of smaller systems. Many systems are too complex to fit on just one chip built with a processor optimized for just one of the system's tasks. When it is not feasible to construct a SoC for a particular application, an alternative is a system in package (SiP) comprising a number of chips in a single package. In large volumes, SoC is believed to be more cost-effective than SiP since it increases the yield of the fabrication and because its packaging is simpler.〔EE Times. "(The Great Debate: SOC vs. SIP )." March 21, 2005. Retrieved July 28, 2015.〕 Another option, as seen for example in higher end cell phones is package on package stacking during board assembly. The SoC chip includes processors and numerous digital peripherals, and comes in a ball grid package with lower and upper connections. The lower balls connect to the board and various peripherals, with the upper balls in a ring holding the memory buses used to access NAND flash and DDR2 RAM. Memory packages could come from multiple vendors. == Structure == A typical SoC consists of: * a microcontroller, microprocessor or digital signal processor (DSP) core – multiprocessor SoCs (MPSoC) having more than one processor core * memory blocks including a selection of ROM, RAM, EEPROM and flash memory * timing sources including oscillators and phase-locked loops * peripherals including counter-timers, real-time timers and power-on reset generators * external interfaces, including industry standards such as USB, FireWire, Ethernet, USART, SPI * analog interfaces including ADCs and DACs * voltage regulators and power management circuits A bus – either proprietary or industry-standard such as the AMBA bus from ARM Holdings – connects these blocks. DMA controllers route data directly between external interfaces and memory, bypassing the processor core and thereby increasing the data throughput of the SoC. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「System on a chip」の詳細全文を読む スポンサード リンク
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