OR versus XOR: the row where both inputs are 1
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A = 1 and B = 1. What does an OR gate output?
2. A = 1 and B = 1. What does an XOR gate output?
3. Which gate gives a different output from OR only in the row where A = 1 and B = 1?
4. Which statement describes XOR correctly?
5. A shop sign says 'You may have a free drink or a free snack, but not both.' Which gate matches this wording?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1A = 1, B = 1, A OR B | AOR is shown outputting 0 when both inputs are 1. OR is inclusive, so it must output 1 whenever at least one input is 1, including both. | |
| 2A = 1, B = 1, A XOR B | BXOR is shown outputting 1 when both inputs are 1. XOR must output 0 in this row because it needs exactly one input to be 1. | |
| 3The only row where the OR and XOR output columns differ is the row where both inputs are 1 | CA B | OR XOR 1 1 | 1 0 | |
| 4Everyday 'either...or but not both' wording describes XOR, for example you can have tea or coffee but not both | DOutputs 1, because OR is inclusive and accepts one input or both inputs being 1 | |
| 5A B | XOR 1 1 | 1 | EX = A XOR B | |
| 6A B | OR 1 1 | 0 | FOutputs 0, because XOR is exclusive and needs exactly one input to be 1 |
C
Definitions
XOR
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
X = A ___ B
2.
X = A OR B
A = 1, B = 1
X = _
3.
A = 1, B = 1
X = A XOR B
X = _
4.
A B OR XOR
1 1 _ 0
5.
Tea or coffee, or both: X = A __ B
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
X = A OR B
B
A=1, B=1 -> X=0
C
A=1, B=0 -> X=1
D
A=0, B=0 -> X=0
Question 2
A
A B | OR | XOR
B
0 0 | 0 | 0
C
1 1 | 1 | 1
D
1 0 | 1 | 1
Question 3
A
A <- 1
B
B <- 1
C
X <- A OR B
D
OUTPUT X // prints 0
Question 4
A
Either tea or coffee, not both
B
Gate needed: XOR
C
Tea and coffee both 1: X = 1
D
Only tea is 1: X = 1
Question 5
A
OR gate, inputs A and B
B
A=1, B=1 gives X=0
C
A=1, B=0 gives X=1
D
A=0, B=0 gives X=0
Answer Key
OR versus XOR: the row where both inputs are 1
Section A: Quick Questions
Q1
A — 1
Q2
B — 0
Q3
A — XOR
Q4
A — Outputs 1 when exactly one input is 1
Q5
B — XOR
Section B: Match the Pairs
Q1
A = 1, B = 1, A OR B → Outputs 1, because OR is inclusive and accepts one input or both inputs being 1
Q2
A = 1, B = 1, A XOR B → Outputs 0, because XOR is exclusive and needs exactly one input to be 1
Q3
The only row where the OR and XOR output columns differ is the row where both inputs are 1 → A B | OR XOR
1 1 | 1 0
Q4
Everyday 'either...or but not both' wording describes XOR, for example you can have tea or coffee but not both → X = A XOR B
Q5
A B | XOR
1 1 | 1 → XOR is shown outputting 1 when both inputs are 1. XOR must output 0 in this row because it needs exactly one input to be 1.
Q6
A B | OR
1 1 | 0 → OR is shown outputting 0 when both inputs are 1. OR is inclusive, so it must output 1 whenever at least one input is 1, including both.
Section C: Definitions
Q1
XOR — Exclusive OR: outputs 1 when exactly one input is 1. When A and B are both 1 it outputs 0, but OR outputs 1 in that row. XOR means one or the other, but not both.Section D: Fill in the Blanks
Q1
X = A XOR BQ2
X = A OR B
A = 1, B = 1
X = 1Q3
A = 1, B = 1
X = A XOR B
X = 0Q4
A B OR XOR
1 1 1 0Q5
Tea or coffee, or both: X = A OR BSection E: Spot the Error
Q1
A — The results show X=0 when both inputs are 1, which is XOR behaviour. OR would output 1 in that row. The line should be X = A XOR B.
Q2
C — When A and B are both 1, OR outputs 1 but XOR outputs 0, because XOR means one or the other but not both. The row should be 1 1 | 1 | 0.
Q3
C — With A and B both 1, OR would give 1, but the program expects 0. It should use XOR: X <- A XOR B.
Q4
C — 'Either...or, not both' describes XOR. When both inputs are 1, XOR outputs 0, so the line should say X = 0.
Q5
B — OR is inclusive, so it outputs 1 when both inputs are 1. The line should be A=1, B=1 gives X=1.