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A processor in a computing device is the brain of the machine where all the calculations take place. Also known as the Central Processing Unit (CPU), it processes instructions and manipulates data after fetching them from the personal computer’s Random Access Memory (RAM).

Today processors are more compact and are designed for multitasking, unlike earlier models, which were bulky and designed for specific tasks only. This has led to the popularisation of the Integrated Circuit (IC) design, which allows a large number of transistors to be assembled on a single semiconductor-based die, or “chip”. Because of the IC, increasingly complex CPUs can be made more compact, which has in turn allowed them to be used in smaller and various digital devices far beyond the limited application of dedicated computing machines.

Speed has been another beneficial factor of the microprocessor design. Synchronous microprocessors have clock rates ranging from tens of megahertz to several gigahertz. Moreover, the ability to construct exceedingly small transistors on an IC has been directly proportional to the complexity and number of transistors in a single CPU. This is described by Moore’s law, which predicted that the number of transistors on an integrated circuit would increase exponentially, doubling approximately every two years.

The processor usually tends to get measured by “clock speed”. There is an internal clock and external clock speed. The internal clock speed is a measure of how many times the processor “thinks” per second, denoted by hertz. If the processor has an internal clock speed of 2000 megahertz (2.0Ghz), it means that the processor operates at 2 billion cycles per second. Logically faster processors should offer greater performance, but there are other factors like the processor’s internal design and the applications being run on the system, which also affect performance.

The processor’s internal clock speed is calculated by multiplying many times the speed of the system clock. The processor has to communicate with other components in the computer. This usually happens at lower speeds, derived from the system clock. The speed of the system clock itself is a measure of the speed of the “front side bus” – the path that data travels on between the processor and memory. Therefore increasing the speed of the system clock instead of increasing the processor’s internal speed can often mean better performance.

As designers try to pack more punch into a processor, they have to deal with speed, performance, heat dissipation and size issues. With the advent of microprocessors, today processors appear in everything from automobiles to mobile phones and children’s toys.