Computer systems consist of three components as shown in below image: Central Processing Unit, Input devices and Output devices. Input devices provide data input to processor, which processes data and generates useful information that’s displayed to the user through output devices. This is stored in computer’s memory.
Central Processing Unit
The Central Processing Unit (CPU) is called "the brain of computer" as it controls operation of all parts of computer. It consists of two components: Arithmetic Logic Unit (ALU), and Control Unit.
Arithmetic Logic Unit (ALU):
Data entered into computer is sent to RAM, from where it is then sent to ALU, where rest of data processing takes place. All types of processing, such as comparisons, decision-making and processing of non-numeric information takes place here and once again data is moved to RAM.
Control Unit:
As name indicates, this part of CPU extracts instructions, performs execution, maintains and directs operations of entire system.
Functions of Control Unit:
Control unit performs following functions −
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It controls all activities of computer
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Supervises flow of data within CPU
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Directs flow of data within CPU
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Transfers data to Arithmetic and Logic Unit
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Transfers results to memory
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Fetches results from memory to output devices
Memory Unit:
This is unit in which data and instructions given to computer as well as results given by computer are stored. Unit of memory is "Byte".
