You may have heard different answers to this question. One of the most common is that in which they associate the CPU name with the set of pieces that make the computer work, that “box” where one has the hard disk, motherboard and so on. Well, this “crate” is not the CPU but the computer case. But some people insist on using this erroneous nomenclature.
The CPU – Central Processing Unitor Central Processing Unit (CPU) in Portuguese – is an integrated circuit that controls all the operations and the functioning of the computer, responsible for the execution of calculations, logical decisions, and instructions that result in all the tasks that a computer can do. It acts by interpreting and executing the instructions provided by software – programs, games, etc. – and returning results. To do a mathematical calculation, for example, we humans use the brain. Already the computer uses the CPU. Hence comes the term “computer brain”. Some people may be wondering – But the “computer brain” is not the processor?
CPU, processor or microprocessor?
Currently, all components that make up the CPU are integrated into a single chip called a microprocessor. This is used on current computers, such as the one you are using right now. Intel and AMD are microprocessor developers. A processor, in turn, already a somewhat more abstract denomination. Every microprocessor is a processor, but not every processor is a microprocessor. A microcontroller, for example, is also a processor.
Despite this difference, in practice the three names can be used to refer to the same element – unless you work or research on computer architecture, digital circuits, and so on.
Among other factors, what determines the “speed” of a CPU is the number of instructions it is able to execute per second. At this “speed” the clock name is given and the Hertz measure (Hz) is used to calculate it, being 1Hz equivalent to 1 instruction per second. A CPU clocked at 500 Mhz, for example, is capable of running 500 million instructions per second. Already a more current one, with 2.4 GHz, is able to realize 2 billion and 400 million instructions per second. But where do the symbols MHz and GHz come from? See the table below.
But the clock is not everything on a CPU. Its performance also depends on the instruction set capable of processing, amount of cache memory, among others. But that is already a subject for an upcoming article!