What a logic gate is

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What a logic gate is

Name:
Date:
Class:
A

Quick Questions

Shade in the A or B circle for each question.

1. A logic gate takes binary inputs and gives how many outputs?
A Two outputs
B One output
2. Which values can the input or output of a logic gate have?
A Only 0 or 1
B Any number from 0 to 9
3. Which statement describes a logic gate?
A A program that changes its rule each time it runs
B An electronic component that follows a fixed rule
4. The same inputs are given to a gate twice. What happens to the output?
A It is the same both times
B It may be different each time
5. How many inputs can a gate in the IGCSE 0478 course have?
A One or two
B Always exactly four
B

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left columnRight column
1X = NOT A AA gate gives a single output, not two. It also takes only one or two inputs, not three.
2X = A AND B BGate inputs and outputs can only be binary values 0 or 1, so 2 and 3 are not valid.
3A logic gate takes binary inputs, which can only be 0 or 1, and gives one output that is also 0 or 1. C1 OR 0 = 1
4A gate follows a fixed rule, so the same inputs always give the same output. DA gate with two inputs A and B and one output X. The output is 1 only when both inputs are 1.
5A = 2, B = 1, X = 3 EA = 1, B = 0, X = 1
6A, B, C -> gate -> X, Y FA gate with one input A and one output X. The output is always the opposite binary value of the input.
C

Definitions

logic gate
D

Fill in the Blanks

Complete each line of code by filling in the missing parts.

1.
X = A ___ B
2.
X = ___ A
3.
Inputs: A = 1, B = 0 Gate: AND Output: X = _
4.
A gate input can only be 0 or _
5.
Inputs: A and B Output: _ X = A OR B
E

Spot the Error

Shade in the letter of the line that contains an error.

Question 1
A GATE AND
B INPUT A = 1
C INPUT B = 0
D OUTPUT X = 2
Question 2
A GATE NOT
B INPUT A = 7
C OUTPUT X = 0
Question 3
A GATE OR
B INPUT A = 0
C INPUT B = yes
D OUTPUT X = 1
Question 4
A GATE NOT
B INPUT A = 0
C OUTPUT X = 1, Y = 0
Question 5
A PROCESSOR HAS ONE GATE
B EACH GATE: 1 OR 2 INPUTS
C EACH GATE: 1 OUTPUT

Answer Key

What a logic gate is
Section A: Quick Questions
Q1
B — One output
Q2
A — Only 0 or 1
Q3
B — An electronic component that follows a fixed rule
Q4
A — It is the same both times
Q5
A — One or two
Section B: Match the Pairs
Q1
X = NOT A → A gate with one input A and one output X. The output is always the opposite binary value of the input.
Q2
X = A AND B → A gate with two inputs A and B and one output X. The output is 1 only when both inputs are 1.
Q3
A logic gate takes binary inputs, which can only be 0 or 1, and gives one output that is also 0 or 1. → A = 1, B = 0, X = 1
Q4
A gate follows a fixed rule, so the same inputs always give the same output. → 1 OR 0 = 1
Q5
A = 2, B = 1, X = 3 → Gate inputs and outputs can only be binary values 0 or 1, so 2 and 3 are not valid.
Q6
A, B, C -> gate -> X, Y → A gate gives a single output, not two. It also takes only one or two inputs, not three.
Section C: Definitions
Q1
logic gate — An electronic component that takes one or two binary inputs (0 or 1) and gives one binary output (0 or 1) by a fixed rule. Processors are built from many gates.
Section D: Fill in the Blanks
Q1
X = A AND B
Q2
X = NOT A
Q3
Inputs: A = 1, B = 0 Gate: AND Output: X = 0
Q4
A gate input can only be 0 or 1
Q5
Inputs: A and B Output: X X = A OR B
Section E: Spot the Error
Q1
D — A logic gate's output can only be binary, 0 or 1. The value 2 is not allowed, so the line should be OUTPUT X = 0.
Q2
B — Gate inputs are binary, so they can only be 0 or 1. The line should be INPUT A = 1.
Q3
C — A gate input must be the binary digit 0 or 1, not a word. The line should be INPUT B = 1.
Q4
C — A logic gate produces a single output. It cannot give two outputs, so the line should be OUTPUT X = 1.
Q5
A — A processor is built from many logic gates working together, not just one. The line should say PROCESSOR HAS MANY GATES.