Basic Organization of Computer and Block Level Description of the Functional Units 

Computer

A computer can be defined as a fast electronic calculating machine that accepts the (data) digitized input information process it as per the list of internally stored instructions and produces the resulting information. List of instructions are called programs & internal storage is called computer memory.

 The different types of computers are

 1. Personal computers: - This is the most common type found in homes, schools, Business offices etc., It is the most common type of desk top computers with processing and storage units along with various input and output devices.

 2. Note book computers: - These are compact and portable versions of PC.

 3. Work stations: - These have high resolution input/output (I/O) graphics capability, but with same dimensions as that of desktop computer. These are used in engineering applications of interactive design work. 

4. Enterprise systems: - These are used for business data processing in medium to large corporations that require much more computing power and storage capacity than work stations. Internet associated with servers have become a dominant worldwide source of all types of information.

 5. Super computers: - These are used for large scale numerical calculations required in the applications like weather forecasting etc.

Basic Organization of a Computer System

Any computer can perform the four basic operations of Input, Processing, Output, and Storage (IPOS). These operations constitute the IPOS cycle. The internal design or structure of a computer may differ from one system to another though the basic operations remain the same. Figure 1.1 provides a block diagram of a computer. The figure displays all the functional units of a computer which carry out the basic computer operations. The lines in the figure indicate the flow of instructions and data, while the Control Unit and the Arithmetic/Logical Unit together direct the flow of control in the central processing unit

Figure 1.1 Basic Organization of a Computer System

A computer can process data, pictures, sound and graphics. They can solve highly complicated problems quickly and accurately. A computer as shown in Fig1.1 performs basically five major computer operations or functions irrespective of their size and make. These are

1) It accepts data or instruction by way of input.

2) It stores data.

3) It can process data as required by the user.

4) It gives results in the form of output.

5) And controls all the operation inside the computer

We discuss below each of these Computer operation

1. Input: This is the process of entering data and programs in to the computer system. You should know that computer is an electronic machine like any other machine which takes as inputs raw data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing

2. Storage: The process of saving data and instructions permanently is known as storage. Data has to be fed into the system before the actual processing starts. It is because the processing speed of Central Processing Unit (CPU) is so fast that the data has to be provided to CPU with the same speed. Therefore the data is first stored in the storage unit for faster access and processing. This storage unit or the primary storage of the computer system is designed to do the above functionality. It provide space for storing data and instructions.

The storage unit performs the following major functions:

• All data and instructions are stored here before and after processing.

• Intermediate results of processing are also stored here.

3. Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit. 

4. Output: This is the process of producing results from the data for getting useful information. Similarly the output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. Again the output is also stored inside the computer for further processing.

5. Control: The manner how instructions are executed and the above operations are performed. Controlling of all operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations inside the computer.

6. Memory unit: Memory unit is an essential components of a digital computer .It is where all data intermediate and final results are stored. The data read from the main storage or an input unit are transferred to the computer memory where they are available for processing. This memory unit is used to hold the instruction to be executed and data to processed.

Functional Units

Central Processing Unit (CPU)

The ALU and the CU of a computer system are jointly known as the central processing unit. You may call CPU as the brain of any computer system. It is just like brain that takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.

Arithmetic Logic Unit (ALU)

Logical Unit After you enter data through the input device it is stored in the primary storage unit. The actual processing of the data and instruction are performed by Arithmetic Logical Unit. The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. Data is transferred to ALU from storage unit when required. After processing the output is returned back to storage unit for further processing or getting stored.

Control Unit (CU) 

The next component of computer is the Control Unit, which acts like the supervisor seeing that things are done in proper fashion. Control Unit is responsible  for  coordinating various operations using time signal. The control unit determines the sequence in which computer programs and instructions are executed. Things like processing of programs stored in the main memory, interpretation of the instructions and issuing of signals for other units of the computer to execute them. It also acts as a switch board operator when several users access the computer simultaneously. Thereby it coordinates the activities of computer’s peripheral equipment as they perform the input and output.

References :-

1) Basic Organization of Computer - http://www.expertsmind.com/learning/basic-organization-of-a-computer-system-assignment-help-7342872543.aspx [ Accessed on 10-2-2020 ]

2) Functional Unit of computer - shttps://www.edudose.com/computer/functional-units-of-a-computer/ [ Accessed on 10-2-2020 ]