Processor (computing)

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Circuits of a microprocessor at 200x magnification 80486DX2 200x.png
Circuits of a microprocessor at 200x magnification

In computing, a processor or processing unit is an electronic circuit which performs operations on some external data source, usually memory or some other data stream. The term is frequently used to refer to the central processor (central processing unit) in a system, but typical computer systems (especially SoCs) combine a number of specialised "processors".

Computing Activity that uses computers

Computing is any activity that uses computers to manage, process, and communicate information. It includes development of both hardware and software. Computing is a critical, integral component of modern industrial technology. Major computing disciplines include computer engineering, software engineering, computer science, information systems, and information technology.

Electronic circuit electrical circuit with active components such as transistors, valves and integrated circuits; electrical network that contains active electronic components, generally nonlinear and require complex design and analysis tools

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. To be referred to as electronic, rather than electrical, generally at least one active component must be present. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another.

Central processing unit Central component of any computer system which executes input/output, arithmetical, and logical operations

A central processing unit (CPU), also called a central processor or main processor, is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions. The computer industry has used the term "central processing unit" at least since the early 1960s. Traditionally, the term "CPU" refers to a processor, more specifically to its processing unit and control unit (CU), distinguishing these core elements of a computer from external components such as main memory and I/O circuitry.


Von Neumann architecture computer architecture where code and data share a common bus

The von Neumann architecture—also known as the von Neumann model or Princeton architecture—is a computer architecture based on a 1945 description by the mathematician and physicist John von Neumann and others in the First Draft of a Report on the EDVAC. That document describes a design architecture for an electronic digital computer with these components:

The control unit (CU) is a component of a computer's central processing unit (CPU) that directs the operation of the processor. It tells the computer's memory, arithmetic and logic unit and input and output devices how to respond to the instructions that have been sent to the processor.

Arithmetic logic unit digital circuits

An arithmetic logic unit (ALU) is a combinational digital electronic circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on floating point numbers. An ALU is a fundamental building block of many types of computing circuits, including the central processing unit (CPU) of computers, FPUs, and graphics processing units (GPUs). A single CPU, FPU or GPU may contain multiple ALUs.

See also

Microprocessor Computer processor contained on an integrated-circuit chip

A microprocessor is a computer processor that incorporates the functions of a central processing unit on a single integrated circuit (IC), or at most a few integrated circuits. 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 as output. Microprocessors contain both combinational logic and sequential digital logic. Microprocessors operate on numbers and symbols represented in the binary number system.

Multi-core processor Microprocessor with more than one processing unit

A multi-core processor is a computer processor integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions, as if the computer had several processors. The instructions are ordinary CPU instructions but the single processor can run instructions on separate cores at the same time, increasing overall speed for programs that support multithreading or other parallel computing techniques. Manufacturers typically integrate the cores onto a single integrated circuit die or onto multiple dies in a single chip package. The microprocessors currently used in almost all personal computers are multi-core. A multi-core processor implements multiprocessing in a single physical package. Designers may couple cores in a multi-core device tightly or loosely. For example, cores may or may not share caches, and they may implement message passing or shared-memory inter-core communication methods. Common network topologies to interconnect cores include bus, ring, two-dimensional mesh, and crossbar. Homogeneous multi-core systems include only identical cores; heterogeneous multi-core systems have cores that are not identical. Just as with single-processor systems, cores in multi-core systems may implement architectures such as VLIW, superscalar, vector, or multithreading.

Related Research Articles

Intel 8088 microprocessor model

The Intel 8088 microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 had an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however. In fact, according to the Intel documentation, the 8086 and 8088 have the same execution unit (EU)—only the bus interface unit (BIU) is different. The original IBM PC was based on the 8088, as were its clones.

Microcode is a computer hardware technique that interposes a layer of organisation between the CPU hardware and the programmer-visible instruction set architecture of the computer. As such, the microcode is a layer of hardware-level instructions that implement higher-level machine code instructions or internal state machine sequencing in many digital processing elements. Microcode is used in general-purpose central processing units, although in current desktop CPUs it is only a fallback path for cases that the faster hardwired control unit cannot handle.

StrongARM family of computer microprocessors

The StrongARM is a family of computer microprocessors developed by Digital Equipment Corporation and manufactured in the late 1990s which implemented the ARM v4 instruction set architecture. It was later sold to Intel in 1997, who continued to manufacture it before replacing it with the XScale in the early 2000s.

Superscalar processor CPU that implements instruction-level parallelism within a single processor

A superscalar processor is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor that can execute at most one single instruction per clock cycle, a superscalar processor can execute more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to different execution units on the processor. It therefore allows for more throughput than would otherwise be possible at a given clock rate. Each execution unit is not a separate processor, but an execution resource within a single CPU such as an arithmetic logic unit.

The Intel i860 was a RISC microprocessor design introduced by Intel in 1989. It was one of Intel's first attempts at an entirely new, high-end instruction set architecture since the failed Intel iAPX 432 from the 1980s. It was released with considerable fanfare, slightly obscuring the earlier Intel i960, which was successful in some niches of embedded systems, and which many considered to be a better design. The i860 never achieved commercial success and the project was terminated in the mid-1990s.

UltraSPARC microprocessor developed by Sun Microsystems

The UltraSPARC is a microprocessor developed by Sun Microsystems and fabricated by Texas Instruments, introduced in mid-1995. It is the first microprocessor from Sun to implement the 64-bit SPARC V9 instruction set architecture (ISA). Marc Tremblay was a co-microarchitect.


The Blackfin is a family of 16-/32-bit microprocessors developed, manufactured and marketed by Analog Devices. The processors have built-in, fixed-point digital signal processor (DSP) functionality supplied by 16-bit multiply–accumulates (MACs), accompanied on-chip by a microcontroller. It was designed for a unified low-power processor architecture that can run operating systems while simultaneously handling complex numeric tasks such as real-time H.264 video encoding.

In computer architecture, 24-bit integers, memory addresses, or other data units are those that are 24 bits wide. Also, 24-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.

In computer architecture, a transport triggered architecture (TTA) is a kind of processor design in which programs directly control the internal transport buses of a processor. Computation happens as a side effect of data transports: writing data into a triggering port of a functional unit triggers the functional unit to start a computation. This is similar to what happens in a systolic array. Due to its modular structure, TTA is an ideal processor template for application-specific instruction-set processors (ASIP) with customized datapath but without the inflexibility and design cost of fixed function hardware accelerators.

Bit slicing is a technique for constructing a processor from modules of processors of smaller bit width, for the purpose of increasing the word length; in theory to make an arbitrary n-bit CPU. Each of these component modules processes one bit field or "slice" of an operand. The grouped processing components would then have the capability to process the chosen full word-length of a particular software design.

AMD Am2900

Am2900 is a family of integrated circuits (ICs) created in 1975 by Advanced Micro Devices (AMD). They were constructed with bipolar devices, in a bit-slice topology, and were designed to be used as modular components each representing a different aspect of a computer control unit (CCU). By using the bit slicing technique, Am2900 family was able to implement a CCU with data, addresses, and instructions to be any multiple of 4 bits by multiplying the number of ICs. One major problem with this modular technique was that it required a larger number of ICs to implement what could be done on a single CPU IC. The Am2901 chip was the arithmetic-logic unit (ALU), and the "core" of the series. It could count using 4 bits and implement binary operations as well as various bit-shifting operations.

R4000 RISC microprocessor

The R4000 is a microprocessor developed by MIPS Computer Systems that implements the MIPS III instruction set architecture (ISA). Officially announced on 1 October 1991, it was one of the first 64-bit microprocessors and the first MIPS III implementation. In the early 1990s, when RISC microprocessors were expected to replace CISC microprocessors such as the Intel i486, the R4000 was selected to be the microprocessor of the Advanced Computing Environment (ACE), an industry standard that intended to define a common RISC platform. ACE ultimately failed for a number of reasons, but the R4000 found success in the workstation and server markets.

In computer architecture, 12-bit integers, memory addresses, or other data units are those that are 12 bits wide. Also, 12-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.

In computer architecture, 16-bit integers, memory addresses, or other data units are those that are 16 bits wide. Also, 16-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 16-bit microcomputers are computers in which 16-bit microprocessors were the norm.

Signetics 8X300

The 8X300 is a microprocessor produced and marketed by Signetics starting 1976 as a second source for the SMS 300 by Scientific Micro Systems, Inc.