Home » Central Processing Unit

Central Processing Unit (CPU)

A Central Processing Unit is also called a processor, central processor, or microprocessor. It carries out all the important functions of a computer. It receives instructions from both the hardware and active software and produces output accordingly. It stores all important programs like operating systems and application software. CPU also helps Input and output devices to communicate with each other. Owing to these features of CPU, it is often referred to as the brain of the computer.

CPU is installed or inserted into a CPU socket located on the motherboard. Furthermore, it is provided with a heat sink to absorb and dissipate heat to keep the CPU cool and functioning smoothly.

Generally, a CPU has three components:

  • ALU (Arithmetic Logic Unit)
  • Control Unit
  • Memory or Storage Unit


Control Unit: It is the circuitry in the control unit, which makes use of electrical signals to instruct the computer system for executing already stored instructions. It takes instructions from memory and then decodes and executes these instructions. So, it controls and coordinates the functioning of all parts of the computer. The Control Unit’s main task is to maintain and regulate the flow of information across the processor. It does not take part in processing and storing data.

ALU: It is the arithmetic logic unit, which performs arithmetic and logical functions. Arithmetic functions include addition, subtraction, multiplication division, and comparisons. Logical functions mainly include selecting, comparing, and merging the data. A CPU may contain more than one ALU. Furthermore, ALUs can be used for maintaining timers that help run the computer.

Memory or Storage Unit/ Registers: It is called Random access memory (RAM). It temporarily stores data, programs, and intermediate and final results of processing. So, it acts as a temporary storage area that holds the data temporarily, which is used to run the computer.

What is CPU Clock Speed?

The clock speed of a CPU or a processor refers to the number of instructions it can process in a second. It is measured in gigahertz. For example, a CPU with a clock speed of 4.0 GHz means it can process 4 billion instructions in a second.

Types of CPU:

CPUs are mostly manufactured by Intel and AMD, each of which manufactures its own types of CPUs. In modern times, there are lots of CPU types in the market. Some of the basic types of CPUs are described below:

Single Core CPU: Single Core is the oldest type of computer CPU, which was used in the 1970s. It has only one core to process different operations. It can start only one operation at a time; the CPU switches back and forth between different sets of data streams when more than one program runs. So, it is not suitable for multitasking as the performance will be reduced if more than one application runs. The performance of these CPUs is mainly dependent on the clock speed. It is still used in various devices, such as smartphones.

Dual Core CPU: As the name suggests, Dual Core CPU contains two cores in a single Integrated Circuit (IC). Although each core has its own controller and cache, they are linked together to work as a single unit and thus can perform faster than the single-core processors and can handle multitasking more efficiently than Single Core processors.

Quad Core CPU: This type of CPU comes with two dual-core processors in one integrated circuit (IC) or chip. So, a quad-core processor is a chip that contains four independent units called cores. These cores read and execute instructions of CPU. The cores can run multiple instructions simultaneously, thereby increases the overall speed for programs that are compatible with parallel processing.

Quad Core CPU uses a technology that allows four independent processing units (cores) to run in parallel on a single chip. Thus by integrating multiple cores in a single CPU, higher performance can be generated without boosting the clock speed. However, the performance increases only when the computer’s software supports multiprocessing. The software which supports multiprocessing divides the processing load between multiple processors instead of using one processor at a time.

History of CPU:

Some of the important events in the development of CPU since its invention till date are as follows:

  • In 1823, Baron Jons Jackob Berzelius discovered silicon that is the main component of CPU till date.
  • In 1903, Nikola Tesla got gates or switches patented, which are electrical logic circuits.
  • In December 1947, John Bardeen, William Shockley, and Walter Brattain invented the first transistor at the Bell Laboratories and got it patented in 1948.
  • In 1958, the first working integrated circuit was developed by Robert Noyce and Jack Kilby.
  • In 1960, IBM established the first mass-production facility for transistors in New York.
  • In 1968, Robert Noyce and Gordon Moore founded Intel Corporation.
  • AMD (Advanced Micro Devices) was founded in May 1969.
  • In 1971, Intel introduced the first microprocessor, the Intel 4004, with the help of Ted Hoff.
  • In 1972, Intel introduced the 8008 processor; in 1976, Intel 8086 was introduced, and in June 1979, Intel 8088 was released.
  • In 1979, a 16/32-bit processor, the Motorola 68000, was released. Later, it was used as a processor for the Apple Macintosh and Amiga computers.
  • In 1987, Sun introduced the SPARC processor.
  • In March 1991, AMD introduced the AM386 microprocessor family.
  • In March 1993, Intel released the Pentium processor. In 1995, Cyrix introduced the Cx5x86 processor to give competition to Intel Pentium processors.
  • In January 1999, Intel introduced the Celeron 366 MHz and 400 MHz processors.
  • In April 2005, AMD introduced its first dual-core processor.
  • In 2006, Intel introduced the Core 2 Duo processor.
  • In 2007, Intel introduced different types of Core 2 Quad processors.
  • In April 2008, Intel introduced the first series of Intel Atom processors, the Z5xx series. They were single-core processors with a 200 MHz GPU.
  • In September 2009, Intel released the first Core i5 desktop processor with four cores.
  • In January 2010, Intel released many processors such as Core 2 Quad processor Q9500, first Core i3 and i5 mobile processors, first Core i3 and i5 desktop processors. In the same year in July, it released the first Core i7 desktop processor with six cores.
  • In June 2017, Intel introduced the first Core i9 desktop processor.
  • In April 2018, Intel released the first Core i9 mobile processor.

Next TopicHardware

You may also like