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An application-specific integrated circuit (ASIC) , is an integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use. For example, a chip designed to run in a digital voice recorder or a high-efficiency Bitcoin miner is an ASIC. Application-specific standard products (ASSPs) are intermediate between ASICs and industry standard integrated circuits like the 7400 or the 4000 series. As feature sizes have shrunk and design tools improved over the years, the maximum complexity (and hence functionality) possible in an ASIC has grown from 5,000 gates to over 100 million. Modern ASICs often include entire microprocessors, memory blocks including ROM, RAM, EEPROM, flash memory and other large building blocks. Such an ASIC is often termed a SoC (system-on-chip). Designers of digital ASICs often use a hardware description language (HDL), such as Verilog or VHDL, to describe the functionality of ASICs. Field-programmable gate arrays (FPGA) are the modern-day technology for building a breadboard or prototype from standard parts; programmable logic blocks and programmable interconnects allow the same FPGA to be used in many different applications. For smaller designs or lower production volumes, FPGAs may be more cost effective than an ASIC design even in production. The non-recurring engineering (NRE) cost of an ASIC can run into the millions of dollars. ==History== The initial ASICs used gate array technology. Ferranti produced perhaps the first gate-array, the ULA (Uncommitted Logic Array), around 1980 . An early successful commercial application was the ULA circuitry found in the 8-bit ZX81 and ZX Spectrum low-end personal computers, introduced in 1981 and 1982. These were used by Sinclair Research (UK) essentially as a low-cost I/O solution aimed at handling the computer's graphics. Some versions of ZX81/Timex Sinclair 1000 used just four chips (ULA, 2Kx8 RAM, 8Kx8 ROM, Z80A CPU) to implement an entire mass-market personal computer with built-in BASIC interpreter. Customization occurred by varying the metal interconnect mask. ULAs had complexities of up to a few thousand gates. Later versions became more generalized, with different base dies customised by both metal and polysilicon layers. Some base dies include RAM elements. 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「Application-specific integrated circuit」の詳細全文を読む スポンサード リンク
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