AQA A-LEVEL COMPUTER SCIENCE PAPER
2 ACTUAL EXAM PAPER 2026 QUESTIONS
WITH SOLUTIONS GRADED A+
◉Control bus. Answer: Bi-directional. The purpose is to transmit
command, timing and specific status information between system
components.
◉Control lines (3). Answer: Control lines include:
- Clock (synchronise operations)
- Reset (Initialises all components)
- Interrupt request (a device is requesting access to the CPU)
◉Data bus. Answer: Bi-directional, consisting of 2^3/4...8 separate
lines for a path to move data/instructions between system
components.
◉Address bus. Answer: Holds the address in RAM that the processor
is accessing. It is uni-directional. The address is only transmitted in
one direction - from the processor to main memory (RAM).
,◉I/O controllers. Answer: A device which interfaces between an I/O
device and processor.
◉How do I/O controllers work?. Answer: Every device has a
different controller connecting to the control bus. I/O controllers
receive I/O requests from the processor, and send control signals to
the device. Manage flow of data to/from the device.
◉What does the controller consist of?. Answer: - Interface to allow
connection of controller to system/IO bus
- A set of data/command/status registers
- Interface enabling connection of controller to cable connecting
device to the computer
◉The stored program concept?. Answer: Machine code instructions
are fetched and executed serially by a processor that performs
arithmetic and logical operations.
- Must be resident in main memory to be executed
- Machine code instructions are fetched from memory one at a time,
decoded and executed in the processor.
◉Harvard architecture?. Answer: Instructions and data stored in
separate memory units, each with its own bus. Two different
memories can have different characteristics. (Embedded systems)
, ◉Advantage of Harvard architecture?. Answer: Can be faster than
Von Neumann as data/instructions can be fetched in parallel instead
of competing for the same bus.
◉Each relation holds. Answer: Data about a single entity
◉Entity. Answer: A category of interest about data that needs to be
recorded
◉Attribute. Answer: Used to represent a characteristic that
describes an entity
◉Primary Key. Answer: A field in a database that acts as a unique
identifier for each record
◉Foreign Key. Answer: An attribute that creates a link between
tables
◉Composite Primary Key. Answer: Two or more fields used as
unique identifiers for the same record
◉Flat File. Answer: A table that holds all data
2 ACTUAL EXAM PAPER 2026 QUESTIONS
WITH SOLUTIONS GRADED A+
◉Control bus. Answer: Bi-directional. The purpose is to transmit
command, timing and specific status information between system
components.
◉Control lines (3). Answer: Control lines include:
- Clock (synchronise operations)
- Reset (Initialises all components)
- Interrupt request (a device is requesting access to the CPU)
◉Data bus. Answer: Bi-directional, consisting of 2^3/4...8 separate
lines for a path to move data/instructions between system
components.
◉Address bus. Answer: Holds the address in RAM that the processor
is accessing. It is uni-directional. The address is only transmitted in
one direction - from the processor to main memory (RAM).
,◉I/O controllers. Answer: A device which interfaces between an I/O
device and processor.
◉How do I/O controllers work?. Answer: Every device has a
different controller connecting to the control bus. I/O controllers
receive I/O requests from the processor, and send control signals to
the device. Manage flow of data to/from the device.
◉What does the controller consist of?. Answer: - Interface to allow
connection of controller to system/IO bus
- A set of data/command/status registers
- Interface enabling connection of controller to cable connecting
device to the computer
◉The stored program concept?. Answer: Machine code instructions
are fetched and executed serially by a processor that performs
arithmetic and logical operations.
- Must be resident in main memory to be executed
- Machine code instructions are fetched from memory one at a time,
decoded and executed in the processor.
◉Harvard architecture?. Answer: Instructions and data stored in
separate memory units, each with its own bus. Two different
memories can have different characteristics. (Embedded systems)
, ◉Advantage of Harvard architecture?. Answer: Can be faster than
Von Neumann as data/instructions can be fetched in parallel instead
of competing for the same bus.
◉Each relation holds. Answer: Data about a single entity
◉Entity. Answer: A category of interest about data that needs to be
recorded
◉Attribute. Answer: Used to represent a characteristic that
describes an entity
◉Primary Key. Answer: A field in a database that acts as a unique
identifier for each record
◉Foreign Key. Answer: An attribute that creates a link between
tables
◉Composite Primary Key. Answer: Two or more fields used as
unique identifiers for the same record
◉Flat File. Answer: A table that holds all data
