A computer is an electronic device which is capable of receiving the inputs (data from the user), storing it for a desired period of time, manipulating it according to the set of instructions (called program) and producing the output to the user in desired form. It performs a variety of operations in accordance to the set of instructions.
Basic architecture of a computer system consists of:
Input Unit – responsible to give data to a computer. E.g. Keyboard, Mouse etc…
CPU (Central Processing Unit) – consists of three components:
Memory Unit (MU): Three types of Memory devices are there: Internal Memory/Main Memory: It is a semi-conductor memory used for storing programs as well as data using programs execution. It is directly accessible to the CPU. It is further divided into: RAM (Random Access Memory) ROM (Read Only Memory)
External Memory: can be attached to the computer and used as a storage medium. E.g. USB Flash Drives, external hard drives. Cache Memory: It is a high speed buffer between the CPU and the Main Memory. The CPU consults the Cache and when it cannot find the instructions, it looks into Main Memory.
Control Unit (CU): Control Unit is also called the Central Nervous System of the computer and the CPU itself is called the brain or heart of the computer. Control Unit manages the flow of control.
Arithmetic and Logical Unit (ALU): It is fundamental Building block of the CPU. Any Arithmetic or Logical operation to be performed is performed by the ALU. Even the basic Microprocessors also contain the ALU. ALU can also be designed to calculate any operations.
Output Unit – responsible for providing information to the user. E.g. Printer, Monitor etc…
The working of computer system is as follows:
To perform any task on the computer, the user provides input to the computer with the help of input devices and then the input devices forwards the request of the user to the CPU which then processes data using its three main components i.e. the Memory Unit, Control Unit and Arithmetic and Logical Unit and then after processing the data, the Control Unit (which controls all other devices) forwards the processed data i.e. the information to the output devices and is displayed to the user.