Computer logic and gates
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The document provides an overview of computer logic and gates, detailing how data is represented in binary form (1s and 0s) using electronic switches. It explains the concept of digital logic, the significance of logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR), and includes truth tables to illustrate their functions. Additionally, it covers the creation of NAND and NOR gates using basic gates and the operations performed by exclusive gates.
Computer logic and gates
- 2. COMPUTER LOGIC AND GATES Presenter: SAMINA KHAN Fazaia Degree College Risalpur
- 3. DATA REPRESENTATION IN COMPUTER • Computer is an electronic machine • It consists of millions of electronic switches . • If electronic switch is closed electricity flows • If electronic switch is open electricity does not flows
- 4. DATA REPRESENTATION IN COMPUTER • Switch has two states. • when electronic switch is closed electricity flows it is called 1 . • when electronic switch is open electricity does not flows it is called 0 . • Therefore 0 and 1 are used in computer to represent the two states of switch
- 6. How do computer represent data? • Look at your keyboard • It has many keys such as alphabet keys, number keys and special keys. • Whenever we type something using these keys, computer represent that data in 1s and 0s pattern.
- 8. How do computer represent data? • These 1s and 0s are called bits. • Bit is the abbreviation of binary digit. • Humans understand words and pictures, computer understand the binary pattern.
- 9. How the computer understand the pattern of 1s and 0s?
- 10. • Computer detects the flow of current. • 1 represents that the current flow in circuit • 0 represent that the current is not flowing.
- 12. DIGITAL LOGIC & LOGIC GATES
- 13. DIGITAL LOGIC • It is fundamental in creating electronic devices such as calculator, computer, digital watches etc • DIGITAL logic is used to create digital circuits which consists of large number of logic gates
- 14. LOGIC GATES • Logic gates are building blocks of digital circuits used in computer and many other devices . • They have two or more inputs (high or low) and produce a single output (high or low).
- 15. TRUTH TABLE • The truth table represents a digital logic circuit in table form. • It shows how a logic circuit’s output responds to all the possible combinations of the inputs using logic “1” for True and logic “0” for False.
- 16. BASIC LOGIC GATES • There are three basic logic gates: • AND GATE • OR GATE • NOT GATE
- 17. AND GATE • The AND gate has two or more inputs that can be low (0) or high (1). • The output is high when all the inputs are high. • It produces low output only when at least one of the inputs are low .
- 18. TRUTH TABLE FOR AND GATE • The truth table for AND gate for two variables.
- 20. OR GATE • An OR gate is a logic gate that performs logical OR operation. • A logical OR operation has a high output (1) if one or both the inputs to the gate are high (1). • If neither input is high, a low output (0) results.
- 21. TRUTH TABLE FOR OR GATE • The truth table of a 2 input OR gate can be represented as:
- 23. NOT GATE • Logic NOT gates provide the complement of their input signal. • When their input signal is “HIGH” their output state will NOT be “HIGH”. • When their input signal is “LOW” their output state will NOT be “LOW”.
- 24. TRUTH TABLE FOR NOT GATE • The truth table for NOT gate . • The “bubble” (o) present at the end of the NOT gate symbol above denotes a signal inversion (complementation) of the output signal. 1 0 0 1
- 26. NAND GATE • The NAND gate is a combination of an AND gate and NOT gate. • It produces low output only when all inputs are high .
- 27. TRUTH TABLE FOR NAND GATE • The truth table for NAND gate for two variables. X Y AND (A.B) NAND (A.B) 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0
- 29. NOR GATE • The NOR gate combines the OR gate and NOT gate. • It is the result of the negation of the OR operator. • It produces low output only when any input is high . • A HIGH output (1) results if both the inputs to the gate are LOW (0).
- 30. TRUTH TABLE FOR NOR GATE • The truth table for NOR gate for two variables. • The bubble indicates that the function of the or gate has been inverted.
- 33. CREATING NAND AND NOR GATE USING BASIC GATES
- 34. Creating NAND gate using AND and NOT gates • The NAND gate can be easily created by using an AND gate and NOT gate. • It is also called Negated And gate.
- 35. Creating NOR gate using OR and NOT gates • The NOR gate can be created by using OR and NOT gate.
- 36. Exclusive OR GATE(XOR gate) • An XOR gate implements an exclusive or; that is, a true output results if one, and only one, of the inputs to the gate is true. If both inputs are false or both are true, a false output results.
- 37. Exclusive OR GATE(XOR gate) • It is a type of logic gate use to perform a Boolean expression: F= X.Y+X.Y • To perform this Boolean function we need three different logic gates. oNOT gate (to find NOT of X & Y) oAND gate (to find X.Y & X.Y) oOR gate ( to perform addition operation X.Y+X.Y
- 38. TRUTH TABLE FOR Exclusive OR GATE(XOR gate) X Y 0 0 0 1 1 0 1 1 X Y 1 1 1 0 0 1 0 0 XY 0 1 0 0 XY 0 0 1 0 F= X.Y+X.Y F 0 1 1 0
- 39. SYMBOL FOR Exclusive OR GATE(XOR gate)
- 40. HOW Exclusive OR GATE WORK?
- 41. Exclusive NOR GATE(XNOR gate) • The XNOR gate is the complement of the XOR gate
- 42. TRUTH TABLE FOR Exclusive NOR GATE(XNOR gate) X Y 0 0 0 1 1 0 1 1 F= X.Y+X.Y XNOR 1 0 0 1 XOR 0 1 1 0
- 43. SYMBOL FOR Exclusive NOR GATE(XNOR gate)
- 44. References • https://www.electronics-tutorials.ws/logic/logic_4.html • https://www.vivaxsolutions.com/physics/allogicgates.aspx • https://www.tutorialspoint.com/computer_logical_organization/logic_gates.htm • https://techterms.com/definition/logicgate • https://whatis.techtarget.com/definition/logic-gate-AND-OR-XOR-NOT-NAND-NOR-and- XNOR