OCR computing exam questions &
answers
(2013) Explain what is meant by an interrupt - ANSWERSInterrupt sent to the processor
Request for processing time
Allows important tasks to be processed
(2013) State two types of interrupts - ANSWERSPower failure
Software interrupt
Clock interrupt
(2013) Explain the need for interrupts to have priorities - ANSWERSTo decide between
interrupts and current task
To choose which interrupt if 2 occur
To ensure most urgent task is performed first.
To ensure most efficient use of processor
(2013) Describe segmentation - ANSWERSA way of partitioning memory segments that are not
fixed size
Segments are logical divisions which complete sections the program.
(2013) State the purpose of virtual memory - ANSWERSTo allow programs to run when there is
insufficient memory available
(2013) Describe how virtual memory is used - ANSWERSUse of backing store as if it were main
memory
,Uses pages
Pages are moved from memory to backing store to make space for pages needed
(2013) Explain one problem that may occur while using virtual memory - ANSWERSDisk
threshing
More time spent transferring pages than processing
(2013) Describe the code generation phase of translation. Your answer should include reference
to optimisation - ANSWERSCode generation occurs after syntax analysis.
Produces a machine code program which is equivalent to the source program
Variables are given addresses
Relative addresses are calculated
Code optimisation makes code as efficient as possible
Increase processing speed
Number of instructions is reduced
(2013) Describe how the contents of the memory address register and the memory data
register change during the fetch-execute cycle - ANSWERSMemory address register
receives address of instruction
Holds address of data
Receives operand part of instruction from the current instruction register
Memory data register
Receives an instruction from memory location from memory address register
Receives data from memory location in address part of instruction
, (2013) Compare co-processor and parallel processor systems - ANSWERSCommon features
More than one processor working together to perform a single job
Job is split into tasks
Processors are controlled by a single operating system
Job is completed more quickly
Differences
Parallel processors can use any processor for task
Co-processors performs specific types of task only
Parallel processors need a more complex operating system
Parallel processors are synchronised
(2013) Explain the term class - ANSWERSA template for a set of objects that have state and
behaviour
They have methods and attributes represented by the rectangle on the diagram
(2013) Explain plain the term inheritance - ANSWERSA derived class inherits all the attributes
and operations from its superclass shown by the arrow on the diagram
(2013) Explain the term capsulation - ANSWERSData hiding
Data can only be accessed using operations defined for the class
Maintains data integrity
(2013) Explain the need for registers - ANSWERSFast access to data for specific purposes when
frequent access is needed
Registers are used as a temporary storage
answers
(2013) Explain what is meant by an interrupt - ANSWERSInterrupt sent to the processor
Request for processing time
Allows important tasks to be processed
(2013) State two types of interrupts - ANSWERSPower failure
Software interrupt
Clock interrupt
(2013) Explain the need for interrupts to have priorities - ANSWERSTo decide between
interrupts and current task
To choose which interrupt if 2 occur
To ensure most urgent task is performed first.
To ensure most efficient use of processor
(2013) Describe segmentation - ANSWERSA way of partitioning memory segments that are not
fixed size
Segments are logical divisions which complete sections the program.
(2013) State the purpose of virtual memory - ANSWERSTo allow programs to run when there is
insufficient memory available
(2013) Describe how virtual memory is used - ANSWERSUse of backing store as if it were main
memory
,Uses pages
Pages are moved from memory to backing store to make space for pages needed
(2013) Explain one problem that may occur while using virtual memory - ANSWERSDisk
threshing
More time spent transferring pages than processing
(2013) Describe the code generation phase of translation. Your answer should include reference
to optimisation - ANSWERSCode generation occurs after syntax analysis.
Produces a machine code program which is equivalent to the source program
Variables are given addresses
Relative addresses are calculated
Code optimisation makes code as efficient as possible
Increase processing speed
Number of instructions is reduced
(2013) Describe how the contents of the memory address register and the memory data
register change during the fetch-execute cycle - ANSWERSMemory address register
receives address of instruction
Holds address of data
Receives operand part of instruction from the current instruction register
Memory data register
Receives an instruction from memory location from memory address register
Receives data from memory location in address part of instruction
, (2013) Compare co-processor and parallel processor systems - ANSWERSCommon features
More than one processor working together to perform a single job
Job is split into tasks
Processors are controlled by a single operating system
Job is completed more quickly
Differences
Parallel processors can use any processor for task
Co-processors performs specific types of task only
Parallel processors need a more complex operating system
Parallel processors are synchronised
(2013) Explain the term class - ANSWERSA template for a set of objects that have state and
behaviour
They have methods and attributes represented by the rectangle on the diagram
(2013) Explain plain the term inheritance - ANSWERSA derived class inherits all the attributes
and operations from its superclass shown by the arrow on the diagram
(2013) Explain the term capsulation - ANSWERSData hiding
Data can only be accessed using operations defined for the class
Maintains data integrity
(2013) Explain the need for registers - ANSWERSFast access to data for specific purposes when
frequent access is needed
Registers are used as a temporary storage
