IGCSEComputer ScienceCambridge (CIE)Flashcards10. Boolean LogicBoolean Logic

Boolean Logic (Cambridge (CIE) IGCSE Computer Science)

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    What is Boolean logic?

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  • What is Boolean logic?

    Boolean logic is a system used in computer science and electronics to make logical decisions, where operators are either TRUE or FALSE (often represented as 1 or 0).

  • Define the term logic gate.

    A logic gate is a visual way of representing a Boolean expression.

  • True or False?

    AND gates return TRUE only if both inputs are TRUE.

    True.

    AND gates return TRUE only if both inputs are TRUE.

  • Describe the OR gate in Boolean logic?

    OR returns TRUE if either input is TRUE.

    A logic gate diagram showing a two-input OR gate with two lines entering on the left and one line exiting on the right.

  • State the meaning of NOT in Boolean logic.

    NOT reverses the input value.

    Schematic symbol of a NOT gate with an input line on the left and an output line on the right, showing an inverted triangle with a circle at the tip.

  • What is the function of XOR in Boolean logic?

    XOR (exclusive OR) returns TRUE if either input is TRUE but NOT both.

    Diagram of a logic gate with three input lines on the left and one output line on the right, representing an AND gate.

  • What gate is this?

    Diagram of a NAND logic gate with two input lines on the left and one output line on the right, featuring a small circle representing negation on the output.

    NAND

    returns TRUE if both inputs are NOT true.

  • What gate is this?

    Illustration of a NAND gate, a basic digital logic gate with two inputs on the left and one output on the right, marked by a small circle at the output.

    NOR

    returns TRUE if both inputs are FALSE.

  • True or False?

    OR gates return TRUE if both inputs are FALSE.

    False.

    OR gates return FALSE if both inputs are FALSE.

  • What is the symbol used for AND gates?

    A basic AND gate circuit symbol with two input lines on the left converging into a curved shape and one output line extending to the right.

  • What is a logic circuit?

    A logic circuit performs logical operations on binary information.

  • True or False?

    In the exam, logic circuits can have unlimited inputs and outputs.

    False.

    In the exam, logic circuits are limited to a maximum of three inputs and one output.

  • Define Boolean expression.

    A statement that can be evaluated to either true or false.

  • What are brackets used for in Boolean expressions?

    Brackets are used to clarify the order of operations in Boolean expressions.

  • True or False?

    In a logic diagram, inputs are typically represented by letters.

    True.

    In a logic diagram, inputs are typically represented by letters.

  • Define logic diagram.

    A logic diagram is a visual representation of combinations of Boolean operators within a logic circuit.

  • Draw the logic diagram for the Boolean expression P = (A AND B) OR C

    Diagram of a logic circuit with inputs A and B connected to an AND gate, and input C connected to an OR gate, with the AND gate output also connected to the OR gate.

  • Draw the logic diagram for the Boolean expression P = (A XOR B) AND (NOT C)

    Logic circuit diagram showing an OR gate with inputs A and B, connected to an AND gate. Input C is inverted before reaching the AND gate. Output is labeled P.

  • Draw the logic diagram for the Boolean expression P = NOT(C AND (A OR B))

    Diagram of a logic circuit with inputs A and B entering an OR gate, the result and input C entering an AND gate, which leads to a NOT gate producing output P.

  • Draw the logic diagram for the Boolean expression P = (A AND B) OR (NOT C)

    Logic circuit diagram with inputs A and B going into an AND gate, input C into a NOT gate, outputs of AND and NOT gates into an OR gate, producing output P.

  • What is a truth table?

    A truth table is a tool used in logic and computer science to visualise the results of Boolean expressions.

  • True or False?

    Truth tables show only the inputs of a Boolean expression.

    False.

    Truth tables represent all possible inputs and the associated outputs for a given Boolean expression.

  • How many rows are needed in a truth table with 3 inputs?

    A truth table with 3 inputs needs 8 rows (2^3).

  • What is the output of an AND gate when both inputs are 1?

    The output of an AND gate when both inputs are 1 is 1.

  • True or False?

    In a NOR gate, the output is 1 when both inputs are 0.

    True.

    In a NOR gate, the output is 1 when both inputs are 0.

  • What is the output of an XOR gate when both inputs are 1?

    The output of an XOR gate when both inputs are 1 is 0.

  • How do you determine the number of rows in a truth table?

    The number of rows in a truth table is determined by 2^(number of inputs).

  • What are the missing inputs in the truth table?

    A

    B

    C

    0

    0

    0

    0

    0

    0

    1

    1

    0

    1

    0

    1

    0

    0

    0

    0

    1

    1

    1

    1

    0

    0

    1

    1

    0

    0

    1

    1

    0

    1

    0

    1

    0

    1

    0

    1

  • What is the output of a NOT gate when the input is 0?

    The output of a NOT gate when the input is 0 is 1.

  • Draw a truth table for the Boolean expression P = (A AND B) AND NOT C

    A

    B

    C

    P

    0

    0

    0

    0

    0

    0

    1

    0

    0

    1

    0

    0

    0

    1

    1

    0

    1

    0

    0

    0

    1

    0

    1

    0

    1

    1

    0

    1

    1

    1

    1

    0

  • What is a logic expression?

    A logic expression is a way of expressing a logic gate or logic circuit as an equation.

  • True or False?

    In a logic expression, the output appears on the right of the equals sign.

    False.

    In a logic expression, the output appears on the left of the equals sign.

  • State the logic expression for a NOT gate where A is the input and Z is the output.

    Z = NOT A.

  • True or False.

    ((NOT A) OR B) NAND C = P is a valid logic expression.

    False.

    The correct logic expression is P = ((NOT A) OR B) NAND C

  • True or False?

    The logic expression for an OR gate is Z = A NOR B.

    False.

    The logic expression for an OR gate is Z = A OR B.

  • State the logic expression for this logic diagram.

    Logic diagram showing inputs A and B going to an OR gate, and input C going to a NOT gate. Outputs of both gates then go to an AND gate, producing output P.

    P = (A XOR B) AND (NOT C)

  • State the logic expression for this logic diagram.

    Logic circuit with an OR gate taking inputs A and B, an AND gate, and a NOT gate producing output P. The AND gate also takes input C.

    P = NOT((A OR B) AND C)

    OR

    P = NOT(C AND (A OR B))

  • True or False?

    Logic expressions can represent circuits with multiple gates.

    True.

    Logic expressions can represent circuits with multiple gates.

  • State the logic expression for this logic diagram.

    A logic circuit diagram with inputs A, B connected to an AND gate, input C connected to a NOT gate. Outputs of both gates connected to an OR gate producing output P.

    P = (A AND B) OR (NOT C)

  • How are complex logic circuits expressed as logic expressions?

    Complex logic circuits are expressed as logic expressions by combining multiple operations using brackets to show the order of operations.

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