AS Level Computer Science chapter 3: Hardware MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
25 exam-style questions on Hardware, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. How does EEPROM differ from EPROM?
A
EEPROM can be written only once; EPROM can be rewritten
B
EEPROM is erased electrically in place; EPROM by UV light
C
EEPROM is volatile, but EPROM keeps its data without power
D
EEPROM is erased using UV light, but EPROM electrically
Show answer
Answer: B. EPROM is erased by shining ultraviolet light through a window, usually after removing the chip. EEPROM is erased and rewritten electrically while in the circuit.
2. In the eight-row truth table for X = NOT (A OR B) AND C, how many rows have X = 1?
A
1
B
2
C
3
D
4
Show answer
Answer: A. NOT (A OR B) is 1 only when A = 0 and B = 0, and C must also be 1. Only the row A = 0, B = 0, C = 1 gives X = 1.
3. In a laser printer, what makes the toner stick to the correct parts of the drum?
A
an electrostatic pattern formed by the laser
B
heat from the fuser unit as the drum turns
C
a magnetic field produced by the print head
D
liquid ink sprayed through tiny nozzles onto it
Show answer
Answer: A. The laser changes the charge on parts of the rotating drum to form an electrostatic image, and charged toner is attracted only to those areas. The fuser later melts the toner onto the paper.
4. For which inputs does an XOR gate output 1?
A
when the two inputs are different
B
when both of the inputs are 1
C
when both of the inputs are 0
D
when at least one of the inputs is 1
Show answer
Answer: A. XOR (exclusive OR) is 1 when exactly one input is 1. 'At least one' describes OR, which also gives 1 for inputs 1, 1.
5. Which description matches a logic circuit for X = (A XOR B) AND NOT C?
A
A and B into an AND gate; its output and C into an XOR gate
B
A and B into an XOR gate; C into a NOT gate; both outputs into an AND gate
C
A into a NOT gate; its output and B into an XOR gate; that and C into an AND gate
D
A and B into an XOR gate; its output and C into a NAND gate
Show answer
Answer: B. A XOR B needs an XOR gate, NOT C a NOT gate, and the two results are joined by AND. A NAND gate would invert the whole AND, which is a different expression.
6. A and B are inputs to a NAND gate. Its output and C are inputs to an OR gate. The OR output passes through a NOT gate to give X. Which expression represents the circuit?
A
X = (A NAND B) OR NOT C
B
X = NOT (A AND B) OR C
C
X = NOT ((A NAND B) OR C)
D
X = (A AND B) OR NOT C
Show answer
Answer: C. Work from the inputs: A NAND B, then (A NAND B) OR C, then NOT of the whole OR output. The NOT applies to the OR output, not just to C.
7. For the expression X = (A AND B) OR NOT C, which input row gives X = 0?
A
A = 1, B = 1, C = 1
B
A = 0, B = 1, C = 0
C
A = 1, B = 0, C = 1
D
A = 0, B = 0, C = 0
Show answer
Answer: C. X = 0 needs A AND B = 0 and NOT C = 0 (C = 1). Row A = 1, B = 0, C = 1 gives 0 OR 0 = 0. The first row gives 1 OR 0 = 1.
8. Which is a drawback of embedded systems?
A
they use a large amount of power when running
B
they are expensive to mass produce in large numbers
C
their firmware is hard to upgrade or change
D
they need a full keyboard and monitor to operate
Show answer
Answer: C. Embedded systems are cheap, small and low-power, but their program is usually held in firmware, so updating or adding features is difficult.
9. A light L is on when exactly one of the two switches P and Q is on. Which expression describes L?
A
L = P XOR Q
B
L = P OR Q
C
L = P NAND Q
D
L = P NOR Q
Show answer
Answer: A. 'Exactly one' is the XOR function. P OR Q would also light the lamp when both switches are on, and NAND is 1 when both are off.
10. Which is the only pair of inputs that makes a NOR gate output 1?
A
A = 0, B = 0
B
A = 0, B = 1
C
A = 1, B = 0
D
A = 1, B = 1
Show answer
Answer: A. NOR is NOT OR. A OR B is 0 only when both are 0, so NOR is 1 only for that row.
25, each with the answer and a short explanation, across 2 topics: Computers and their components, Logic gates and logic circuits. Every chapter test draws ten of them, so you can take it many times.
Is the AS Level Computer Science chapter 3 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
