: The central part of the computer is the CPU . The CPU, of course, refers to the central part of the computer that was used the day before. Now CPU is just a microprocessor. The Central Processing Unit or CPU is the most important part of a computer. The CPU is called the brain of the computer. In many cases it is simply called a processor. It is the job of the CPU to interpret the instructions of a program and to process the data. CPUs are made up of many integrated circuits. The Central Processing Unit (CPU) is a combination of multiple chips and a combination of multiple cards used to process data in second generation and third generation mainframes , miniframes and supercomputers. After the invention of the single chip microprocessor in 1960, microprocessors replaced other CPUs. The computer's input , output , memory and other circuits are controlled by the CPU.