Note on Components of Computer System: Input, output, Processor and Storage

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COMPONENTS OF COMPUTERSYSTEM

The computer is a device that operated upon information or data. It is an electronic device which accepts inputs data, stores the data, does arithmetic and logic operations and provides the outputs in the desired format. The computer receives data, process it, produces output and stores it for further references. So, a computer should have at least four major components to perform these tasks. A block diagram of the basic computer organization has the following functional units..

Fig: Block diagram of computer architecture

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Input Unit

The input unit is formed by the input devices attached to the computer. Input devices are used to interact with a computer system or used enter data and instructions to the computer. These devices convert input data and instructions into a suitable binary form such as ASCII, which can be acceptable by the computer. In brief, an input unit performs the following function:

  • It accepts data and instruction from the outside worlds.
  • It converts these data and instruction into computer understandable from a binary form.
  • It supplied the converted data and instruction to the computer system for further processing.

E.g of input devices are keyboard, mouse, scanner etc.

Memory Unit

This unit is also called storage unit. The data and instructions, which are entered through an input unit must be stored on the computer before the actual processing starts. The result produces by the computer after processing is also kept somewhere before passed to the output units. If intermediate results are produced during processing, it should be stored in somewhere in memory. The storage unit of a computer performs all these needs. In brief, the specific functions performed by the storage unit are as follow:

  • It stored data and instructions, which are entered through input devices.
  • It stores an intermediate result of processing.
  • It stores the final result of processing before these results are passed to an output device.

The storage unit of computers consists of two types of memory or storage: primary and secondary storage:

i. Primary Storage

Memory storage that communicates directly with CPU is called main memory. It enables the computer to store, at least temporarily data and instruction. It is mainly used to hold data and instructions and as well as the intermediate result of processing which the computer system is currently working on. Primary memory is volatile, that is, it lose its content when power supply is off. The Random access memory (RAM) is an example of a primary to main memory.

ii. Secondary Storage

Auxiliary storage is also known as secondary storage. It is the memory that supplements the main memory. These are a non-volatile memory. It is mainly used to transfer data to program from one computer to another computer. There is high capacity storage devices used to store data and program permanently. These are also used as backup devices which allows to store the valuable information as backup on which you are working on. The examples of secondary memory are Magnetic Disk, Optical disk, etc.

Central Processing Unit (CPU)

CPU is the component that actually responsible for interpreting and executing most of the commands from the computer hardware and software and also controls the operation of all other components such as memory unit, input and output devices. It simply accepts binary data as input and processes data according to those instructions and provides the result as output. It is the logic machine. So, its main function is run the program by fetching instructions from the RAM, evaluating and executing them in sequence. In summary, the function of CPU are as follow:

  • Read instruction from memory
  • Communicate with all peripherals using the system bus.
  • It controls the sequence of instructions.
  • It controls the flow of data from one component to another component.
  • Performs the computing task specified in the program.

The CPU has three components responsible for different function, these components are Control units, arithmetic-logical unit (ALU) and Register.

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Fig: Components of CPU

Control Unit

The control unit provides the necessary timing and control signals to all the operations on the computer. It controls the flow of data between the CPU, memory and peripherals. It also controls the entire operation of a computer. It obtains the instructions from the program stored in the main memory, interprets the instructions and issues the signals, which cause the other units of the system to execute them. So, it is considered as a central nervous system of a computer that provides status, control and timing signals necessary for the operation of other parts of CPU, memory and I/O devices. The main functions of control units are given below:

  • It performs the data processing operations with the aid of program prepared by the user and send control signals to various parts of the computer system.
  • It gives commands to transfer data from the input devices to the memory to an arithmetic logic unit.
  • It also transfers the results from ALU to the memory and then to the output devices.
  • It stores a program in the memory.
  • It fetches the required instruction from the main storage and decode each instruction and hence execute them in sequence.

Arithmetic Logic Unit

This is the area of CPU where various computing functions are performed on data. The ALU performs arithmetic operations such as addition, subtraction, multiplication and division and logical operation such as comparison AND, OR and Exclusive OR. The result of an operation is stored in Accumulator or in some register. The main functions of ALU are as follow:

  • It accepts operands from registers.
  • It performs arithmetic and logic operations.
  • It returns a result to register or a memory.

The logical operations of ALU give the computer the decision-making ability.

Registers

Registers are the high-speed temporary storage locations in the CPU made from electronic devices such as transistors, flip-flops, etc. So, registers can be thought as CPU’s working memory. Register are primarily used to store data temporarily during the execution of a program and are accessible to the user through instructions. These are the part of Control unit and ALU rather than of memory. Hence, their contents can be handled much faster than the contents of memory. Although the number of registers varies from computer to computer. There are some registers which are common to all computers. Five registers that are essential for instruction execution are:

  • Program Counter (PC): Contains the address of the next instruction to be fetched.
  • Instruction Register (IR): Contains the instruction most recently fetched.
  • Memory Address registers (MAR): Contain the address of a location in memory for read and write operation.
  • Memory Buffer Register (MBR): It contains the value to be stored in memory or the last value read from memory.
  • Accumulator (ACC): An accumulator is a general purpose register used for storing temporary result and result produced by the arithmetic logic unit.

Output Unit

The output unit is formed by the output devices attached to the computer. Output devices are used to present result produced by the computer to the users. The output from the computer is in the form electric signals, which is then converted into human understandable form into human readable form.

The examples of output devices are the monitor, printer and speaker.

The main functions of the output unit are as follow:

  • Accepts the result produced by the computer which is in electric binary signals.
  • It then converts the result into human readable form.
  • Finally, it supplied the converted results to the outside word.

We can also discuss some of the categories of a computer system. Some of the categories of computer system are:

  • Hardware
  • Software
  • Data or information
  • Procedure (data which the computer converts)
  • User
  • Communication

  1. Hardware

Hardware refers to the part of the computer which we can touch. It is the physical devices of the computer. It consists of interconnected electronic equipment that controls everything the computer does. It includes input devices, input devices, output devices, processing devices and storage devices. Example of hardware are keyboard, monitor, CPU, hard disk and RAM.

  1. Software

The software is the term used to describe the instruction that tells the hardware, what and how to perform a task. Without software, the hardware is useless. Examples of software are Window 7, MS office, Internet explorer, etc.

  1. Data/Information

The function of a computer system is to convert data into information. Data can be considered as the raw facts whether in a paper, electronic or the other form that is processed by the computer. In other words , data consist of the raw facts and figures that are processed to form information. Information is summarized data or manipulated or processed data.

  1. People

People constitute the most important parts of the computer system. People operate the computer hardware and create the computer software. They also follow a certain procedure when using the hardware and software.

  1. Procedure

The procedure is a description of how things are done, step for accomplishing a result. Procedure for a computer system appears in documentation manual, also known as reference manual which contains instruction, rules, and guidelines to follow when using hardware and software. When you buy a microcomputer or software package, it comes with one or more documentation manuals.

  1. Communication

When one computer system is set up to share data and information electronically with another computer system, communication becomes a system element. In other words, the manner on which the various individual system are connected by wires, cables, phone lines, microwave, Wi-Fi or satellite is an element of the total computer system.

(Dilli , 2015)

Bibliography

Dilli , S. P., Singh, k. E., Khadka , D., Bhatta, K. D., Baral, N., Saud, R. S., . Dangi, R. (2015). Fundamental of Computer Science. Kathmandu: KEC publication and Distribution.

Adhikari,Deepak et.al.,Compute Science-XI,Asia Publication Pvt.Ltd,ktm

  • The input units are formed by the input devices attached to the computer. Input devices are used to interact with a computer system or used enter data and instructions to the computer.
  • This unit is also called storage unit. 

  • Memory storage that communicates directly with CPU is called main memory.
  • Auxiliary storage is also known as secondary storage. It is the memory that supplements the main memory.
  • CPU is the component that actually responsible for interpreting and executing most of the commands from the computer hardware and software and also controls the operation of all other components such as memory and input and output devices. 
  • The CPU has three components responsible for different function, these components are Control units, arithmetic-logical unit (ALU) and Register.

  • Arithmetic Logic Unit is the area of CPU where various computing functions are performed on data.

  • Registers are the high-speed temporary storage locations in the CPU made from electronic devices such as transistors, flip-flops etc
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Manish

How does ALU processes?


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Sam

What is differentiate between RAM and ROM?


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