Basic Digital Techniques.
Basic Digital Techniques.
What is a NAND gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is an OR gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is a NOR gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is a NOT gate (also known as an INVERTER)?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is an EXCLUSIVE OR gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is an EXCLUSIVE NOR gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is an AND gate?
Logic circuitry uses three main operations: "AND", "OR" and "NOT". The "NOT" is also called negation, complement or inversion. AND: true if both inputs are true. NAND: AND followed by a NOT, false when both inputs are true (AND, NAND: all inputs have a desired state). OR: true if either input is true. NOR: OR followed by a NOT, false if either input is true (OR,NOR: at least one input has desired state). XOR: true if both inputs are complementary. XNOR: XOR followed by a NOT, false if both inputs are complementary (XOR,XNOR: only one input has a desired state).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What is a flip-flop circuit?
The "flip-flop" is a bistable multivibrator. The adjective "bistable" alludes to two possible stable states, set or reset. The circuit remains in one of the two states until a change is triggered. The terms "flip-flop" and "latch" are sometimes used interchangeably. Simple logic gates implement Combinational Logic: the output is determined only by the current inputs. In Sequential Logic, the output depends on current inputs and the exact sequence of prior events. [ Nowadays, purists will tell you that a latch follows the input levels (transparency) before a final value is locked-in; a flip-flop captures data strictly on a clock transition (edge-triggered). ]
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The "flip-flop" is a bistable multivibrator. The adjective "bistable" alludes to two possible stable states, set or reset. The circuit remains in one of the two states until a change is triggered. The terms "flip-flop" and "latch" are sometimes used interchangeably. Simple logic gates implement Combinational Logic: the output is determined only by the current inputs. In Sequential Logic, the output depends on current inputs and the exact sequence of prior events. [ Nowadays, purists will tell you that a latch follows the input levels (transparency) before a final value is locked-in; a flip-flop captures data strictly on a clock transition (edge-triggered). ]
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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What type of digital logic is also known as a latch?
The "flip-flop" is a bistable multivibrator. The adjective "bistable" alludes to two possible stable states, set or reset. The circuit remains in one of the two states until a change is triggered. The terms "flip-flop" and "latch" are sometimes used interchangeably. Simple logic gates implement Combinational Logic: the output is determined only by the current inputs. In Sequential Logic, the output depends on current inputs and the exact sequence of prior events. [ Nowadays, purists will tell you that a latch follows the input levels (transparency) before a final value is locked-in; a flip-flop captures data strictly on a clock transition (edge-triggered). ]
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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In a multivibrator circuit, when one transistor conducts, the other is:
The transistors in a multivibrator circuit alternate between two states: conduction and cut-off. The Astable multivibrator can be used as a square-wave generator. The Monostable multivibrator assumes the alternate state for a given period when triggered. The Bistable multivibrator is used in latch and flip-flop circuits.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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