What is a CPU?

CPU Stands for Central Processing Unit. It is the brain of computer system. CPU basically consists of ALU ( Arithmetic Logic Unit) and CU (Control Unit). CPU is also called the microprocessor of the computer system.

The control unit must communicate with both the arithmetic/logic unit and memory.

The first microprocessor was the Intel 4004, introduced in 1971.

Click here for list of Intel Microprocessors

Microprocessor Examples

16 bits – the 8086, 8088 and 80286
The first PC’s were 16-bit machines. This meant that they could basically only work with text. They were tied to DOS, and could normally only manage one program at a time.
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A dual-core processor has two cores (e.g. AMD Phenom II X2, Intel Core Duo), a quad-core processor contains four cores (e.g. AMD Phenom II X4, the Intel 2010 core line that includes three levels of quad-core processors, see i3, i5, and i7 at Intel Core), and a hexa-core processor contains six cores (e.g. AMD Phenom II X6, Intel Core i7 Extreme Edition 980X).

Other Useful Link:

Advanced Micro Devices

How CPU Works, Working of Central Processing Unit (CPU) - ABC of Electronics