L 2 basic computer organization
- 1. BASIC COMPUTER ORGANIZATION Avishek Bose Lecturer, Daffodil International University
- 2. Learning Objectives • In this lecture you will learn about: Basic operations performed by all types of computer systems Basic organization of a computer system Input unit and its functions Output unit and its functions Storage unit and its functions Types of storage used in a computer system Arithmetic Logic Unit (ALU) Control Unit (CU) Central Processing Unit (CPU) Computer as a system
- 3. The Five Basic Operations of a Computer System • Inputting. The process of entering data and instructions into the computer system • Storing. Saving data and instructions to make them readily available for initial or additional processing whenever required • Processing. Performing arithmetic operations (add, subtract, multiply, divide, etc.) or logical operations (comparisons like equal to, less than, greater than, etc.) on data to convert them into useful information • Outputting. The process of producing useful information or results for the user such as a printed report or visual display • Controlling. Directing the manner and sequence in which all of the above operations are performed
- 4. Basic Organization of a Computer System
- 5. Input Unit An input unit of a computer system performs the following functions: ① It accepts (or reads) instructions and data from outside world ② It converts these instructions and data in computer acceptable form ③ It supplies the converted instructions and data to the computer system for further processing
- 6. Output Unit An output unit of a computer system performs the following functions: ① It accepts the results produced by the computer, which are in coded form and hence, cannot be easily understood by us ② It converts these coded results to human acceptable (readable) form ③ It supplies the converted results to outside world
- 7. Storage Unit • The storage unit of a computer system holds (or stores) the following : ① Data and instructions required for processing (received from input devices) ② Intermediate results of processing ③ Final results of processing, before they are released to an output device
- 8. Two Types of Storage ① Primary storage • Used to hold running program instructions • Used to hold data, intermediate results, and results of ongoing processing of job(s) • Fast in operation • Small Capacity • Expensive • Volatile (looses data on power dissipation)
- 9. Two Types of Storage ② Secondary storage • Used to hold stored program instructions • Used to hold data and information of stored jobs • Slower than primary storage • Large Capacity • Lot cheaper than primary storage • Retains data even without power
- 10. Arithmetic Logic Unit (ALU) • Arithmetic Logic Unit of a computer system is the place where the actual executions of instructions takes place during processing operation
- 11. Control Unit (CU) • Control Unit of a computer system manages and coordinates the operations of all other components of the computer system • The control unit is a component of a computer's central processing unit (CPU) that directs operation of the processor. It controls communication and co-ordination between input/output devices. It reads and interprets instructions and determines the sequence for processing the data. • It directs the operation of the other units by providing timing and control signals. • All computer resources are managed by the CU (Control Unit). • It directs the flow of data between the Central Processing Unit (CPU) and the other devices.
- 12. Central Processing Unit (CPU) • It is the brain of a computer system • It is responsible for controlling the operations of all other units of a computer system
- 13. The System Concept • A system has following three characteristics: ① A system has more than one element ② All elements of a system are logically related ③ All elements of a system are controlled in a manner to achieve the system goal • A computer is a system as it comprises of integrated components (input unit, output unit, storage unit, and CPU) that work together to perform the steps called for in the executing program
- 14. Key Words/Phrases • Arithmetic Logic Unit (ALU) • Output interface • Auxiliary storage • Output unit • Central Processing Unit (CPU) • Outputting • Computer system • Primate storage • Control Unit (CU) • Processing • Controlling • Secondary storage • Input interface • Storage unit • Input unit • Storing • Inputting • System • Main memory