AQA A-LEVEL COMPUTER SCIENCE EXAM | QUESTIONS AND
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS (100%
CORRECT) | LATEST EXAM UPDATE
Arithmetic Logic Unit (ALU) - CORRECT ANSWER - The part of the central
processing unit that performs arithmetic computations and logical operations
Control Unit - CORRECT ANSWER - Coordinates activities in the CPU,
memory and peripherals
Clock - CORRECT ANSWER - A continuous sequence of clock pulses to step
the control unit through its operations
Registers - CORRECT ANSWER - Very fast memory stored on or near the
processor
Program Counter (PC) - CORRECT ANSWER - Holds the address of the next
instruction to be executed
Current Instruction Register (CIR) - CORRECT ANSWER - Stores the current
instruction (in binary)
Memory Address Register (MAR) - CORRECT ANSWER - Holds the address
of a memory location from which data will be read or data will be written to
Memory Buffer Register (MBR) - CORRECT ANSWER - Temporarily stores
the data read from or written to memory
Status Register (SR) - CORRECT ANSWER - Contains many bits that are set
(1) or cleared (0) depending on the result of an instruction
,Clock Speed - CORRECT ANSWER - The frequency at which the system
clock ticks
Bus Width - CORRECT ANSWER - The number of parallel signal lines or
wires allocated to a bus
Word Length - CORRECT ANSWER - The number of digits in a binary word
Cache Memory - CORRECT ANSWER - A small amount of very fast memory
Increasing Clock Speed - CORRECT ANSWER - Reduces the time taken to
execute instructions
Increasing Word Length - CORRECT ANSWER - Registers can store more
bits and the processor can process more bits in one go
Increasing Data Bus Width - CORRECT ANSWER - Enables more bits to be
transferred between main memory and the processor at one time
Increasing Address Bus Width - CORRECT ANSWER - Enables the processor
to access a larger number of main memory locations meaning it will not need to
make as much use of secondary storage
Increase Amount Of Cache Memory - CORRECT ANSWER - Increases speed
and response time as more can be stored in cache memory and main memory
needs to be accessed less often
Multicore Processors - CORRECT ANSWER - Increases throughput but
greatly increases complexity and heat production
,Increase The Number Of General Purpose Registers - CORRECT ANSWER -
More intermediate results/variables can be kept in processor registers instead of
main memory
Radio Frequency Identification (RFID) - CORRECT ANSWER - A form of
contactless identification which uses radio waves to transmit and receive data
Digital Camera - CORRECT ANSWER - A type of camera that is able to save
images and videos digitally, normally to an SD card or other form of EMMC
storage
Barcode Reader - CORRECT ANSWER - A device used to read a small
pattern of black and white parallel lines and numbers, also known as a barcode
Laser Printer - CORRECT ANSWER - A type of printer that uses electrical
charges to create an image on paper
Hard Drives - CORRECT ANSWER - A non-volatile, magnetic form of
internal or external storage, that permanently stores and retrieves data on a
computer
Solid State Drive (SSD) - CORRECT ANSWER - A non-volatile type of mass
storage similar to a hard drive that supports reading and writing data, and stores
data even without power
Optical Disk - CORRECT ANSWER - A form of secondary storage that uses
light emitted by a laser to read and write onto a disk.
Encapsulation - CORRECT ANSWER - Combining properties and methods
together into an object
, Normalisation - CORRECT ANSWER - The process of decomposing a flat-
file into the best possible design for a relational database
Encryption - CORRECT ANSWER - Using an algorithm to change data so
that it can only be read by the intended recipient
Cipher - CORRECT ANSWER - The algorithm which is used to encrypt or
decrypt
Plaintext - CORRECT ANSWER - The unencrypted message
Ciphertext - CORRECT ANSWER - The encrypted message
Symmetric Encryption - CORRECT ANSWER - The same key is used for
both the encryption and decryption algorithm, and for the whole message
Asymmetric Encryption - CORRECT ANSWER - Different keys are used to
encrypt and decrypt
Machine Code - CORRECT ANSWER - Code written in binary which can be
read by the computer
Instruction Set - CORRECT ANSWER - All of the different possible
instructions the computer can carry out
Operation Code - CORRECT ANSWER - Part of the binary code which tells
us what operation is being carried out
Operand - CORRECT ANSWER - Part of the binary code which tells us what
to carry out the instruction on
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS (100%
CORRECT) | LATEST EXAM UPDATE
Arithmetic Logic Unit (ALU) - CORRECT ANSWER - The part of the central
processing unit that performs arithmetic computations and logical operations
Control Unit - CORRECT ANSWER - Coordinates activities in the CPU,
memory and peripherals
Clock - CORRECT ANSWER - A continuous sequence of clock pulses to step
the control unit through its operations
Registers - CORRECT ANSWER - Very fast memory stored on or near the
processor
Program Counter (PC) - CORRECT ANSWER - Holds the address of the next
instruction to be executed
Current Instruction Register (CIR) - CORRECT ANSWER - Stores the current
instruction (in binary)
Memory Address Register (MAR) - CORRECT ANSWER - Holds the address
of a memory location from which data will be read or data will be written to
Memory Buffer Register (MBR) - CORRECT ANSWER - Temporarily stores
the data read from or written to memory
Status Register (SR) - CORRECT ANSWER - Contains many bits that are set
(1) or cleared (0) depending on the result of an instruction
,Clock Speed - CORRECT ANSWER - The frequency at which the system
clock ticks
Bus Width - CORRECT ANSWER - The number of parallel signal lines or
wires allocated to a bus
Word Length - CORRECT ANSWER - The number of digits in a binary word
Cache Memory - CORRECT ANSWER - A small amount of very fast memory
Increasing Clock Speed - CORRECT ANSWER - Reduces the time taken to
execute instructions
Increasing Word Length - CORRECT ANSWER - Registers can store more
bits and the processor can process more bits in one go
Increasing Data Bus Width - CORRECT ANSWER - Enables more bits to be
transferred between main memory and the processor at one time
Increasing Address Bus Width - CORRECT ANSWER - Enables the processor
to access a larger number of main memory locations meaning it will not need to
make as much use of secondary storage
Increase Amount Of Cache Memory - CORRECT ANSWER - Increases speed
and response time as more can be stored in cache memory and main memory
needs to be accessed less often
Multicore Processors - CORRECT ANSWER - Increases throughput but
greatly increases complexity and heat production
,Increase The Number Of General Purpose Registers - CORRECT ANSWER -
More intermediate results/variables can be kept in processor registers instead of
main memory
Radio Frequency Identification (RFID) - CORRECT ANSWER - A form of
contactless identification which uses radio waves to transmit and receive data
Digital Camera - CORRECT ANSWER - A type of camera that is able to save
images and videos digitally, normally to an SD card or other form of EMMC
storage
Barcode Reader - CORRECT ANSWER - A device used to read a small
pattern of black and white parallel lines and numbers, also known as a barcode
Laser Printer - CORRECT ANSWER - A type of printer that uses electrical
charges to create an image on paper
Hard Drives - CORRECT ANSWER - A non-volatile, magnetic form of
internal or external storage, that permanently stores and retrieves data on a
computer
Solid State Drive (SSD) - CORRECT ANSWER - A non-volatile type of mass
storage similar to a hard drive that supports reading and writing data, and stores
data even without power
Optical Disk - CORRECT ANSWER - A form of secondary storage that uses
light emitted by a laser to read and write onto a disk.
Encapsulation - CORRECT ANSWER - Combining properties and methods
together into an object
, Normalisation - CORRECT ANSWER - The process of decomposing a flat-
file into the best possible design for a relational database
Encryption - CORRECT ANSWER - Using an algorithm to change data so
that it can only be read by the intended recipient
Cipher - CORRECT ANSWER - The algorithm which is used to encrypt or
decrypt
Plaintext - CORRECT ANSWER - The unencrypted message
Ciphertext - CORRECT ANSWER - The encrypted message
Symmetric Encryption - CORRECT ANSWER - The same key is used for
both the encryption and decryption algorithm, and for the whole message
Asymmetric Encryption - CORRECT ANSWER - Different keys are used to
encrypt and decrypt
Machine Code - CORRECT ANSWER - Code written in binary which can be
read by the computer
Instruction Set - CORRECT ANSWER - All of the different possible
instructions the computer can carry out
Operation Code - CORRECT ANSWER - Part of the binary code which tells
us what operation is being carried out
Operand - CORRECT ANSWER - Part of the binary code which tells us what
to carry out the instruction on
