2.3/2.4/2.5

Question 1

top down modular design

Answer 1

solving a larger problem by breaking it down into a top down modular design using stepwise refinement task is split into smaller subtasks
aim to end up with sub tasks that perform a single function or task

Question 2

advantages of top down modular design

Answer 2

makes problem easier to solve as subtasks are smaller and simpler
may be reusable
breaking it down helps see what needs to be done
more than one person can work on a task at a time

Question 3

passing parameters by value

Answer 3

value for subroutine is created as a copy for the original
once it’s passed in parameter is held in a seperate memory location and is only available to that subroutine
the copy is now a local variable of that subroutine

Question 4

passing parameters by reference
a pointer that contains the memory address of the original variable is created this means that any changes to that value from within the called subroutine will not affect the value of the original variable

Question 5

identifying sub procedures

Answer 5

sequence of steps grouped together and given its own name
order in which operations are to be performed is important
several can be executed simultaneously within a program
some require data from other subroutines

Question 6

determining logical decision

Answer 6

should be clear what sort of approach is best for achieving your solution
evaluate conditions, convenience, responsibility, importance

Question 7

parallelism

Answer 7

can support 2 or more actions executing at the same time

Question 8

benefits of parallelism

Answer 8

performance increase for graphics processing

several tasks performed simultaneously

Question 9

trade offs of parallelism

Answer 9

overhead associated with using more than one processor/core

Question 10

concurrency

Answer 10

a program is running more than one process at the same time

Question 11

benefits of concurrency

Answer 11

users can interact with applications with other tasks are running

Question 12

availability of services

Answer 12

long running task won’t delay short running ones

Question 13

controllability

Answer 13

task requiring preconditions to proceed can be suspended and resumed later

Question 14

resource consumption

Answer 14

threads can consume resources in regard to scheduling, context, context switching and synchronisation

Question 15

non determinism

Answer 15

mastering an exponential number of interleaving due to different schedules