OCR A LEVEL COMPUTER SCIENCE EXAM | QUESTIONS AND
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS (100%
CORRECT) | LATEST EXAM UPDATE
ALU, - CORRECT ANSWER - Arithmetic Logic Unit: "The part of the CPU
where data is processed and manipulated. This processing and manipulation
normally consists of arithmetic operations or logical comparisons allowing a
program to make decisions."
Control Unit, - CORRECT ANSWER - "The part of the CPU that manages the
execution of instructions. The control unit fetches each instruction in sequence,
and decodes and synchronises it before executing it by sending control signals
to other parts of the computer."
Register, - CORRECT ANSWER - "Tiny areas of extremely fast memory
located in the CPU normally designed for a specific purpose, where data or
control information is stored temporarily."
PC, - CORRECT ANSWER - Program Counter: "A register in the control unit
which holds the address of the next instruction to be executed."
ACC, - CORRECT ANSWER - Accumulator: "A special register within the
ALU. It is used to hold the data currently being processed by the central
processor. Any data to be processed is stored temporarily in the accumulator, the
results ending up back in the accumulator being stored in the memory unit."
MAR, - CORRECT ANSWER - Memory Address Register: "A register in the
CPU that stores the address of the memory location currently in use. In the fetch
phase, this would be the address of the instruction being loaded; in the execute
phase, it would be the address of the data being used."
,MDR, - CORRECT ANSWER - Memory Data Register: "A register in the
CPU that stores data being transferred to and from the immediate-access store.
It acts as a buffer, allowing the central processor and memory unit to act
independently without being affected by minor differences in operation. A data
item will be copied to the MDR ready for use at the next clock pulse, when it
can either be used by the central processor or be stored in main memory."
CIR, - CORRECT ANSWER - Current Instruction Register: "A register in the
control unit that stores the address of the next instruction currently being
executed and decoded."
Busses, - CORRECT ANSWER - "A common physical pathway shared by
signals to and from several components of a computer."
Data Bus, - CORRECT ANSWER - "The part of the bus which carries the
actual information."
Address Bus, - CORRECT ANSWER - "The part of the bus which carries
identification about where the data is being sent."
Control Bus, - CORRECT ANSWER - "This bus carries command and control
signals to and from every other component of a computer."
Fetch-Decode-Execute, - CORRECT ANSWER - "The complete process of
retrieving an instruction from store, decoding it and carrying it out. Also known
as the instruction cycle."
CPU, - CORRECT ANSWER - Central Processing Unit: "The main part of the
computer, consisting of the registers, ALU and control unit."
Clock Speed, - CORRECT ANSWER - "Measured in Hertz, the clock speed is
the frequency at which the internal clock generates pulses. The higher the clock
,rate, the faster the computer may work. The "clock" is the electronic unit that
synchronises related components by generating pulses at a constant rate."
Cores, - CORRECT ANSWER - "A part of a multi-core processor. A multi-
core processor is a single component with two or more independent actual
CPUs, which are the units responsibly for the fetch-decode-execute cycle."
Cache, - CORRECT ANSWER - "A part of the main store between the central
processor and the rest of the memory. It has extremely fast access, so sections of
a program and its associated data are copied there to take advantage of its short
fetch cycle."
Pipelining, - CORRECT ANSWER - "Successive steps of an instruction
sequence are executed in turn by a sequence of cores able to operate
concurrently, so that another instruction can be begun before the previous one is
finished."
Von Neumann Architecture, - CORRECT ANSWER - "Traditional computer
architecture that forms the basis of most digital computer systems. A single
control unit manages program control flow following a linear sequence of
"fetch-decode-execute""
Harvard Architecture, - CORRECT ANSWER - "A computer architecture with
physically separate storage and signal pathways for instructions and data. These
early machines had data storage entirely contained within the central processing
unit, and provided no access to the instruction storage as data."
Contemporary Architecture, - CORRECT ANSWER - "Any modern set of
disciplines that describes the functionality, the organisation and the
implementation of computer systems."
CISC, - CORRECT ANSWER - Complex Instruction Set Computer: "A design
that produces a complicated and expensive integrated circuit capable of
, performing a large variety of complex instructions. Complex instructions can be
executed with few machine cycles."
RISC, - CORRECT ANSWER - Reduced Instruction Set Computer: "A design
that produces a simple, cheap integrated circuit with a basic range of machine
instructions. Relies on speed as complex instructions take many machine
cycles."
GPU, - CORRECT ANSWER - Graphical Processing Unit: "A specialised
electronic circuit designed to rapidly manipulate and alter memory to accelerate
the creation of images in a frame buffer intended for output to a display. Modern
GPUs highly parallel structure makes them more effective than general-purpose
CPUs for algorithms where processing of large blocks of data is done in
parallel."
Multicore System, - CORRECT ANSWER - "Development of CISC
architecture with several sets of CPU components in one microprocessor."
Parallel Processor System, - CORRECT ANSWER - "The simultaneous use of
several processors to perform a single job. A job may be split into a number of
tasks each of which may be processed by any available processor."
Input Device, - CORRECT ANSWER - "Any peripheral device that can accept
data, presented in the appropriate machine-readable form, decode it and transmit
it as electrical pulses to the CPU"
Output Device, - CORRECT ANSWER - "Any peripheral device that
translates signals from the computer into a human-readable form or into a form
suitable for reprocessing by the computer at a later stage."
Storage Device, - CORRECT ANSWER - "Any medium (optical, magnetic,
solid state and even paper which holds data or programs"
ANSWERS | VERIFIED AND WELL DETAILED ANSWERS (100%
CORRECT) | LATEST EXAM UPDATE
ALU, - CORRECT ANSWER - Arithmetic Logic Unit: "The part of the CPU
where data is processed and manipulated. This processing and manipulation
normally consists of arithmetic operations or logical comparisons allowing a
program to make decisions."
Control Unit, - CORRECT ANSWER - "The part of the CPU that manages the
execution of instructions. The control unit fetches each instruction in sequence,
and decodes and synchronises it before executing it by sending control signals
to other parts of the computer."
Register, - CORRECT ANSWER - "Tiny areas of extremely fast memory
located in the CPU normally designed for a specific purpose, where data or
control information is stored temporarily."
PC, - CORRECT ANSWER - Program Counter: "A register in the control unit
which holds the address of the next instruction to be executed."
ACC, - CORRECT ANSWER - Accumulator: "A special register within the
ALU. It is used to hold the data currently being processed by the central
processor. Any data to be processed is stored temporarily in the accumulator, the
results ending up back in the accumulator being stored in the memory unit."
MAR, - CORRECT ANSWER - Memory Address Register: "A register in the
CPU that stores the address of the memory location currently in use. In the fetch
phase, this would be the address of the instruction being loaded; in the execute
phase, it would be the address of the data being used."
,MDR, - CORRECT ANSWER - Memory Data Register: "A register in the
CPU that stores data being transferred to and from the immediate-access store.
It acts as a buffer, allowing the central processor and memory unit to act
independently without being affected by minor differences in operation. A data
item will be copied to the MDR ready for use at the next clock pulse, when it
can either be used by the central processor or be stored in main memory."
CIR, - CORRECT ANSWER - Current Instruction Register: "A register in the
control unit that stores the address of the next instruction currently being
executed and decoded."
Busses, - CORRECT ANSWER - "A common physical pathway shared by
signals to and from several components of a computer."
Data Bus, - CORRECT ANSWER - "The part of the bus which carries the
actual information."
Address Bus, - CORRECT ANSWER - "The part of the bus which carries
identification about where the data is being sent."
Control Bus, - CORRECT ANSWER - "This bus carries command and control
signals to and from every other component of a computer."
Fetch-Decode-Execute, - CORRECT ANSWER - "The complete process of
retrieving an instruction from store, decoding it and carrying it out. Also known
as the instruction cycle."
CPU, - CORRECT ANSWER - Central Processing Unit: "The main part of the
computer, consisting of the registers, ALU and control unit."
Clock Speed, - CORRECT ANSWER - "Measured in Hertz, the clock speed is
the frequency at which the internal clock generates pulses. The higher the clock
,rate, the faster the computer may work. The "clock" is the electronic unit that
synchronises related components by generating pulses at a constant rate."
Cores, - CORRECT ANSWER - "A part of a multi-core processor. A multi-
core processor is a single component with two or more independent actual
CPUs, which are the units responsibly for the fetch-decode-execute cycle."
Cache, - CORRECT ANSWER - "A part of the main store between the central
processor and the rest of the memory. It has extremely fast access, so sections of
a program and its associated data are copied there to take advantage of its short
fetch cycle."
Pipelining, - CORRECT ANSWER - "Successive steps of an instruction
sequence are executed in turn by a sequence of cores able to operate
concurrently, so that another instruction can be begun before the previous one is
finished."
Von Neumann Architecture, - CORRECT ANSWER - "Traditional computer
architecture that forms the basis of most digital computer systems. A single
control unit manages program control flow following a linear sequence of
"fetch-decode-execute""
Harvard Architecture, - CORRECT ANSWER - "A computer architecture with
physically separate storage and signal pathways for instructions and data. These
early machines had data storage entirely contained within the central processing
unit, and provided no access to the instruction storage as data."
Contemporary Architecture, - CORRECT ANSWER - "Any modern set of
disciplines that describes the functionality, the organisation and the
implementation of computer systems."
CISC, - CORRECT ANSWER - Complex Instruction Set Computer: "A design
that produces a complicated and expensive integrated circuit capable of
, performing a large variety of complex instructions. Complex instructions can be
executed with few machine cycles."
RISC, - CORRECT ANSWER - Reduced Instruction Set Computer: "A design
that produces a simple, cheap integrated circuit with a basic range of machine
instructions. Relies on speed as complex instructions take many machine
cycles."
GPU, - CORRECT ANSWER - Graphical Processing Unit: "A specialised
electronic circuit designed to rapidly manipulate and alter memory to accelerate
the creation of images in a frame buffer intended for output to a display. Modern
GPUs highly parallel structure makes them more effective than general-purpose
CPUs for algorithms where processing of large blocks of data is done in
parallel."
Multicore System, - CORRECT ANSWER - "Development of CISC
architecture with several sets of CPU components in one microprocessor."
Parallel Processor System, - CORRECT ANSWER - "The simultaneous use of
several processors to perform a single job. A job may be split into a number of
tasks each of which may be processed by any available processor."
Input Device, - CORRECT ANSWER - "Any peripheral device that can accept
data, presented in the appropriate machine-readable form, decode it and transmit
it as electrical pulses to the CPU"
Output Device, - CORRECT ANSWER - "Any peripheral device that
translates signals from the computer into a human-readable form or into a form
suitable for reprocessing by the computer at a later stage."
Storage Device, - CORRECT ANSWER - "Any medium (optical, magnetic,
solid state and even paper which holds data or programs"
