Central Processing Unit (CPU) consists of the following features −

• CPU is considered as the brain of the computer.
• CPU performs all types of data processing operations.
• It stores data, intermediate results, and instructions (program).
• It controls the operation of all parts of the computer.

CPU itself has following three components.

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

Memory or Storage Unit

This unit can store instructions, data, and intermediate results. This unit supplies information to other units of the computer when needed. It is also known as internal storage unit or the main memory or the primary storage or Random Access Memory (RAM).

Its size affects speed, power, and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of the memory unit are −

• It stores all the data and the instructions required for processing.
• It stores intermediate results of processing.
• It stores the final results of processing before these results are released to an output device.
• All inputs and outputs are transmitted through the main memory.

Control Unit

This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations.

Functions of this unit are −

• It is responsible for controlling the transfer of data and instructions among other units of a computer.
• It manages and coordinates all the units of the computer.
• It obtains the instructions from the memory, interprets them, and directs the operation of the computer.
• It communicates with Input/Output devices for transfer of data or results from storage.
• It does not process or store data.

ALU (Arithmetic Logic Unit)

This unit consists of two subsections namely,

• Arithmetic Section
• Logic Section

Arithmetic Section

Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations.

Logic Section

Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data.

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.