Microprocessor
A microprocessor is a computer processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's central processing unit (CPU). The IC is capable of interpreting and executing program instructions and performing arithmetic operations.[1] The microprocessor is a multipurpose, clock-driven, register-based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, and provides results (also in binary form) as output. Microprocessors contain both combinational logic and sequential digital logic, and operate on numbers and symbols represented in the binary number system.
The integration of a whole CPU onto a single or a few integrated circuits using Very-Large-Scale Integration (VLSI) greatly reduced the cost of processing power. Integrated circuit processors are produced in large numbers by highly automated metal–oxide–semiconductor (MOS) fabrication processes, resulting in a relatively low unit price. Single-chip processors increase reliability because there are fewer electrical connections that can fail. As microprocessor designs improve, the cost of manufacturing a chip (with smaller components built on a semiconductor chip the same size) generally stays the same according to Rock's law.
Before microprocessors, small computers had been built using racks of circuit boards with many medium- and small-scale integrated circuits, typically of TTL type. Microprocessors combined this into one or a few large-scale ICs. While there is disagreement over who deserves credit for the invention of the microprocessor, the first commercially available microprocessor was the Intel 4004, designed by Federico Faggin and introduced in 1971.[2]
Continued increases in microprocessor capacity have since rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.
A microprocessor is distinct from a microcontroller including a system on a chip.[3][4]A microprocessor is related but distinct from a digital signal processor.
Embedded applications[edit]
Thousands of items that were traditionally not computer-related include microprocessors. These include household appliances, vehicles (and their accessories), tools and test instruments, toys, light switches/dimmers and electrical circuit breakers, smoke alarms, battery packs, and hi-fi audio/visual components (from DVD players to phonograph turntables). Such products as cellular telephones, DVD video system and HDTV broadcast systems fundamentally require consumer devices with powerful, low-cost, microprocessors. Increasingly stringent pollution control standards effectively require automobile manufacturers to use microprocessor engine management systems to allow optimal control of emissions over the widely varying operating conditions of an automobile. Non-programmable controls would require bulky, or costly implementation to achieve the results possible with a microprocessor.
A microprocessor control program (embedded software) can be tailored to fit the needs of a product line, allowing upgrades in performance with minimal redesign of the product. Unique features can be implemented in product line's various models at negligible production cost.
Microprocessor control of a system can provide control strategies that would be impractical to implement using electromechanical controls or purpose-built electronic controls. For example, an internal combustion engine's control system can adjust ignition timing based on engine speed, load, temperature, and any observed tendency for knocking—allowing the engine to operate on a range of fuel grades.
Market statistics[edit]
In 1997, about 55% of all CPUs sold in the world were 8-bit microcontrollers, of which over 2 billion were sold.[67]
In 2002, less than 10% of all the CPUs sold in the world were 32-bit or more. Of all the 32-bit CPUs sold, about 2% are used in desktop or laptop personal computers. Most microprocessors are used in embedded control applications such as household appliances, automobiles, and computer peripherals. Taken as a whole, the average price for a microprocessor, microcontroller, or DSP is just over US$6 (equivalent to $10.16 in 2023).[68]
In 2003, about $44 billion (equivalent to about $73 billion in 2023) worth of microprocessors were manufactured and sold.[69] Although about half of that money was spent on CPUs used in desktop or laptop personal computers, those count for only about 2% of all CPUs sold.[68] The quality-adjusted price of laptop microprocessors improved −25% to −35% per year in 2004–2010, and the rate of improvement slowed to −15% to −25% per year in 2010–2013.[70]
About 10 billion CPUs were manufactured in 2008. Most new CPUs produced each year are embedded.[71]