Computer System Class - 9

This PowerPoint Presentation will help the students of Class - 9 to revise the concept that How a Computer works, What is the basic organization of a Computer and so on. It will help the students to clear their doubts and score good marks in examination

1. COMPUTER SYSTEM Subtit

2. WHAT IS A COMPUTER ? A Computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. A computer system includes the hardware, operating system and peripheral equipment. Characteristics of a computer are – Speed, Accuracy, Cost Effectiveness, Diligence, Storage Capacity, Versatility, Time Saving, Automation and Security. Limitations of a computer are – Zero I.Q., Lack in decision making power and Dependence on external { electricity } power.

3. DESIGN OF A COMPUTER SYSTEM A computer responds to a set of instructions in a well-defined manner. It executes a list of instructions called Program . HARDWARE :- The physical components of a computer system that can be felt, seen and touched are called Hardware . SOFTWARE :- It is a collection of computer programs, procedures and documentations that perform certain tasks using the hardware components.

4. IPO CYCLE The IPO Cycle is defined as a computer procedure for the processing of information. In computation, it is a critical process through which users get the desired outcome. It comprises mainly of three elements; input, process, and output.

5. OPERATIONS OF A COMPUTER Five basic operations of a computer system are: Inputting - This is the act of feeding in the data and instruction to the computer. Processing - The task of performing calculations and comparisons are known as processing. Outputting – It is the process showing out results of an operation. Storing – It is the process of storing and saving of data and instructions. Controlling – It is process of managing the order or the sequence in which the above operations will be performed.

6. INPUT UNIT It accepts (or reads) instructions and data from outside. It converts these instructions and data in computer acceptable form. It supplies the converted instructions and data to the computer system for further processing.

7. OUTPUT UNIT It accepts the results produced by the CPU. It converts these coded results to human acceptable form. It supplies the converted results to outside world.

8. STORAGE UNIT When a user enters data using input devices, the computer system stores this data in memory unit i.e. Storage Unit . The storage unit uses a set of pre-programmed instructions to further transmit this data to other parts of CPU. Storage units of all the computers are comprised of two types of memories: Primary Memory and Secondary Memory .

9. PRIMARY MEMORY Primary Memory is computer memory that a processor or computer accesses first or directly. It allows a processor to access running execution applications and services that are temporarily stored in a specific memory location. Primary memory is also known as Main Memory . It compromises of two types of memory technology, i.e. ROM ( Read Only Memory ) and RAM ( Random Access Memory ).

10. SECONDARY MEMORY Secondary Memory as it is not directly accessible through the CPU and is non-volatile. Secondary devices have a much larger storage capacity and the cost of secondary memory is less as compared to primary memory. It is also called Permanent Storage . USBs, DVDs, CDs, Blu-Ray Disc are example of Removable Storage Secondary Memory Media whereas the Hard Disk Drive and Floppy Disc are examples of Fixed Storage Secondary Memory Media .

11. CENTRAL PROCESSING UNIT ( CPU ) A Central Processing Unit ( CPU ), also called a Central Processor , is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions in the program. This contrasts with external components such as main memory and I/O circuitry. Control unit ( CU ) and Arithmatic Logic Unit ( ALU ) are the parts of CPU.

12. CONTROL UNIT ( CU ) The Control Unit acts like a traffic police. Its main function is to control and co-ordinates the flow of instructions and data between all the other parts of CPU. It is a sort of manager of all operations that takes place within the system.

13. ARITHMATIC LOGIC UNIT ( ALU ) An Arithmetic Logic Unit ( ALU ) is a digital circuit used to perform arithmetic and logic operations. It represents the fundamental building block of the central processing unit (CPU) of a computer. Modern CPUs contain very powerful and complex ALUs. In addition to ALUs, modern CPUs contain a control unit (CU).

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