2. Functional Components of Computing System.pptx

Functional Components of Computing System.pptx

1. ECE 3004 – Computer Organization and Architecture

2. Module 1: Introduction to Computing Systems Dr. J. Florence Gnana Poovathy Assistant Professor (SG – 1) SENSE, VIT

3. Functional Components of a Computing System Three units of a computer Input unit – takes input from the user CPU – processes that input Memory unit – stores data and instructions while processing Digital computer – a programmable machine that reads the binary data , processes that data and communicates the binary data as output

4. Functional Components of a Digital Computer Input Output ALU CU MU CPU

5. Input Unit Consists of input devices attached to the computer Takes input, converts to binary form that the computer understands Ex???

6. Central Processing Unit (CPU) Processes the received input Called the brain of the computer because it is the control center of the computer Fetches instructions from memory Uses these instructions to perform the jobs given by the user Data is fetched either from input device or from memory Three main components Arithmetic and logic unit (ALU) Control Unit (CU) Memory unit (MU)

7. Arithmetic and Logic Unit (ALU) Perform mathematical calculations Takes logical decisions Arithmetic operations Addition Subtraction Multiplication Division Logical operations Comparisons AND, OR etc.

8. How ALU works? Information is processed in terms of binary digits Transistor switches are used since there are only two possibilities – open or close

9. Continued… Open transistor – no current flow – 0 Closed transistor – current flow present – 1 Operations can be done by connecting multiple transistors One transistor can be programmed to control another Ex. Turn the first transistor ON or OFF according to the state of the second transistor This arrangement is called gate

10. A simple gate – NOT gate Uses only a single transistor Other gates – OR, AND, XOR etc.

11. Control Unit Controls the data flow in and out of the processor It also controls the operations of the ALU, memory and I/O devices It carries out the i nstructions stored in the memory It decodes those instructions, interprets it and sends control signals to the I/O devices

12. Memory registers Temporary unit of storage in CPU Data stored here are directly used by the processor Different sizes – 16, 32,64 Functions of register Storing data Storing address Instruction locations User registers can be used to store data and address by the user Accumulator is the main register – it always has an operand that would be used by the ALU

13. Memory Used for storage of data and instructions Internal memory is divided into many locations each of which has a dedicated address So entire memory need not be searched When program is executed, the data is copied in the internal memory and is stored there till the execution is over. This is called RAM SRAM – Static RAM – has circuits that retain the data as long as the power is ON – made up of flip-flops DRAM – Dynamic RAM – stores binary data in the form of electrical charges using capacitors – data is lost after a period of time and hence capacitors must be charged periodically

14. Output unit Consists of output devices attached to the computer Converts binary data from CPU to human-understandable form Ex???