Basic Components of a Computer System

A computer can be viewed as a system, which consists of a number of interrelated components that work together with the aim of converting data into information. In a computer system, processing is carried out electronically, usually with little or no intervention from the user.To attain information, data is entered through input unit, processed by central processing unit (CPU), and displayed through output unit. In addition, computers require memory to process data and store output. All these parts (the central processing unit, input, output, and memory unit) are referred to as hardware of the computer.

There are several computer systems in the market with a wide variety of makes, models, and peripherals.In general, a computer system comprises the following components:

• Input Unit: This unit accepts instructions and data.
• Central Processing Unit (CPU): This unit performs processing of instructions and data inside the computer.
• Output Unit: This unit communicates the results to the user.
• Memory/Storage Unit: This unit stores temporary and final results.

• The input unit is formed by attaching various input devices such as keyboard, mouse, light pen, and so on to a computer. An input device is an electromechanical device that accepts instructions and data from the user. Since the data and instructions entered through different input devices will be in different form,the input unit converts them into the form that the computer can understand. After this, the input unit supplies the converted instructions and data to the CPU for further processing.

Central Processing Unit

The arithmetic/logic unit (ALU) contains the electronic circuitry that executes all arithmetic and logical operations on the data made available to it. The data required to perform the arithmetic and logical functions are inputs from the designated registers. ALU comprises the following two units:

• Arithmetic unit:The arithmetic unit contains the circuitry that is responsible for performing the actual computing and carrying out the arithmetic calculations, such as addition, subtraction, multiplication, and division. It can perform these operations at a very high speed.

• The control unit of the CPU contains circuitry that uses electrical signals to direct the entire computer system to carry out, or execute, stored program instructions. This unit checks the correctness of sequence of operations. It fetches program instructions from the primary storage unit, interprets them, and ensures correct execution of the program. It also controls the input/output devices and directs the overall functioning of the other units of the computer.

Registers

• Registers are special-purpose, high-speed temporary memory units that hold various types of information such as data, instructions, addresses, and the intermediate results of calculations. Essentially, they hold the information that the CPU is currently working on. Registers can be thought of as CPU’s working memory, a special additional storage location that offers the advantage of speed. They work under the direction of the control unit to accept, hold, and transfer instructions or data and perform arithmetic or logical comparisons at high speed.

Output Unit

• The output unit is formed by attaching output devices such as printer, monitor, and plotter to the computer. An output device is used to present the processed data (results) to the user. The basic task of output unit is just opposite to that of input unit. It takes the outputs (which are in machine-coded form) from the CPU, converts them into the user understandable form such as characters, graphical, or audio visual,and supplies the converted results to the user with the help of output devices.

• A computer system incorporates storage unit to store the input entered through input unit before processing starts and to store the results produced by the computer before supplying them to the output unit.The storage unit of a computer comprises two types of memory/storage: primary and secondary. The primary memory holds the instructions and data currently being processed by the CPU, the intermediate results produced during the course of calculations, and the recently processed data.
• While the instructions and data remain in primary memory, the CPU can access them directly and quickly. Due to the limited size of primary memory, a computer employs secondary memory, which is extensively used for storing data and instructions. It supplies the stored information to other units of the computer as and when required.

Conclusion