Architecture of a Computer System
The fundamental parts of a computer are a Central Processing Unit CPU), Input and Output Devices and Mass Storage Devices.
Let us explain the need and functions of each of the components.
CPU is the heart of the computer. It consists of three major units Arithmetic Logic Unit (ALU), control unit and primary memory or main memory. ALU performs all arithmetic and logical operations on data in accordance with the instructions. The function of control unit is like the nervous system of human body. It supervises all operations in CPU. It takes up each instruction from the programme and interprets it. It moves appropriate data from the memory to ALU and gets the required operation done on the data. It then transfers results back to the memory. It also communicates with input, output and other peripheral devices. When a job is being executed on the computer, the data as well as instruction are kept in the primary storage. This storage is a high speed memory called Random Access Memory
(RAM). Secondary storage devices are used to store large amounts of data and programs. They are generally the magnetic media called floppy disks, hard disks and tapes.
We need input and output devices to communicate with the CPU. Data as well as instructions are fed through output devices. Once the data is processed by the CPU, the results are passed on to the user through an output device.
A computer is designed to perform variety of tasks. However, it is supposed to be doing what it is generally desired to do by users. Hence, arises a problem of communication between the user and the computer. A description of the task to be performed by the computer is fed or given as input to it through an input device. A computer could have one or more input devices. However, the description of a task may be fed through only one device at a time.
If somebody were to tell us how to solve a quadratic equation, he would give a description of the method of solution. This description is fed to us through our ears which act as input device. Where does this description go after fed through our ears? We know it resides in the storage cells of our brain. Analogously, the description (information) fed to the computer through an input device, is stored in the memory of the computer.
After the task description is fed and stored in the memory of the computer, it is the central Processing Unit (CPU) that interprets this and the operation needed to perform the task as per description are executed by the CPU. These operations include arithmetic operations like addition, subtraction, multiplication and division. It can also perform variety of other operations like logical operations, controlling flow of data/ information, coordinating operations by all the devices connected to CPU etc.
Now that the specified task is performed by the computer, it must let us know what are the answers to the problem we gave it for solution. This is accomplished through an output device. The results can be displayed, printed or stored in some other form. The results obtained after solving the problem are generally known as output form the computer.
The description of the task to be performed, data to be operated up on, the output results can all be stored in Mass Storage Devices for further use, whenever needed.
These summaries the functions of all the essential component in a computer system.