Basic Logic gates
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Logic gates are the basic building blocks of digital circuits and perform logical operations. The main logic gates are AND, OR, and NOT. An AND gate outputs 1 only if all its inputs are 1. An OR gate outputs 1 if any of its inputs are 1. A NOT gate inverts its single input. Logic gates are constructed from diodes, transistors, and resistors on a silicon chip and their inputs and outputs represent either 1 or 0, true or false. Combination gates like NAND and NOR are derived from basic logic gates and their truth tables define the output for all possible input combinations.
Basic Logic gates
- 1. LOGIC GATES
- 2. WHAT ARE LOGIC GATES? The Logic Gate is the simplest integrated circuit (IC). They are called logic gates because the circuits act like gates in a fence. The gate is either open or closed depending on the conditions set.
- 3. THE BASIC LOGIC GATES AND : acts in the same way as two switches are placed in series. X equals A and B X= A.B OR: operates like a circuit with two switches placed in parallel. X equals A or B X= A+B NOT: acts in the same way as a transistor. It is an INVERTER. A with a bar is read as Not A
- 4. LOGIC GATES consist of diodes, transistors and resistors assembled in a silicon chip.
- 5. LOGIC GATES SYMBOL AND TRUTH TABLES At any given time, every terminal may have an input or output of 1(high) or 0 (low). In most logic gates, the low state is approx. 0 volt, while the high state is 5 volts or 6 volts in some.
- 6. Take Note: The inputs and outputs of logic gates are either 1 or 0 which stands for Yes or No; True or False; or high or low voltages respectively.
- 7. OTHER TYPES OF LOGIC GATES These are the simplest combination gates derived from the basic logic gates. NAND gate is a combination of AND and NOT gate. NOR gate is an OR and NOT gate combination.
- 8. OTHER TYPES OF LOGIC GATES TRUTH TABLES
- 9. TRY THIS! A system of AND gates with 5 inputs A B C D E What is the final output in X if A = 1 and B = 0, C = 0, D = 1 and E = 1 ? X
- 10. TRY THIS! A = 1 and B = 0, What is the final output at X? X
- 11. A system of combination of gates. A B C D Determine the output in X if A and B are both 1 and C and D are both 0? X
- 12. TRY THIS!
- 13. TRY THIS!